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Chapter 3

The Geology of Middle-earth

by Sanford S. Kaplan
April 20, 2012 with updates 2022, 2024


This work is dedicated to my wife, Joanne,
who was with me through the start of my geologic career.
I will treasure always the time we spent together working
on my M.S. or PhD manuscripts, raising our children,
working on your psychology papers, and sharing our
hopes for the future. You left me too soon, my sweet wife.


This Chapter was reviewed by Richard “Dick” Ehrman, the Water Resources Coordinator for the
Lower Platte South Natural Resources District, in Lincoln, Nebraska, for geologic
accuracy and verisimilitude. A geologic review was also performed by Del Stuefer.
Many thanks to Del and Dick for their careful and thorough
Proofreading, and knowledge of all things geologic.
I. Introduction
    First Question
    Second Question
    Some Additional Comments
    Plate Tectonics and Geology
II. Geologic “Evidence” in the Lord of the Rings
    Textural References
        Tables: Geologic References Within the LotR Text
            Table: The Fellowship of the Ring
            Table: The Two Towers
            Table: The Return of the King
    Additional Geological Evidence
        Some Basic Metallurgy
        Iron Ore
        Dwarf Mining in the LoTR and The Hobbit. Includes some dwarven history.
        Summary of Dwarven Mine-works in Middle-earth
            Table: Dwarven Mining Activity in Middle-earth
        The Coal Mining Connection
        An Important Piece of the Puzzle: Gems and Jewels
        Some Igneous Petrology
        Other Geologic References in The Hobbit and the LoTR
        Some Geologic Puzzles
            The “Fence” Around Mordor
            The Geographic Extent of the Misty Mountains and the White Mountains
                Table: Misty Mountains and Modern-Day Mountain Ranges on Earth
        Additional Meteorological Evidence
III. Putting it All Together
    The European Example
    The North American Example
    Modern Plate Tectonics
        The Tectonic Framework of Middle-earth
            Table: Geologic Timeline of Orogenic Events on Middle-earth: Age Ga
            Table: Geologic Timeline of Orogenic Events on Middle-earth: Age Ma
IV. IV: Conclusion
V. Review of Extant Literature

I. Introduction

In attempting any interpretation of the geology of Middle-earth, two important issues immediately present themselves, and need to be considered before commencing a geologic analysis of the Lord of the Rings (LotR).

First Question

In a book that consistently takes pains to describe the landscape and geography of Middle-earth, why did Tolkien provide so few geologic reference points within the text that might allow a geologist to consider the geology of that landscape?

Second Question

What exactly constitutes the terroir of a geologic study of Middle-earth? In the Silmarillion, Tolkien creates a considerably larger landscape for Middle-earth that includes the huge province of Beleriand, divided into its smaller western and eastern halves, as well as the many forests of Doriath, and the regions of Nevrast, Dor-Lómin, Hithlum, Arvernien, Himlad, and the notorious Taur-nu-Fuin, to name only a few. The Silmarillion map additionally includes the sharp, jagged, volcanic peaks of Thangorodrim, about 150 miles north of Beleriand.1 This map also reveals the presence of mountain ranges, including the Ered Lómin, Ered Wethrin, the Mountains of Mithrim, and the Ered Gorgoroth surrounding the Taur-nu-Fuin in an oval of imposing mountains, steep and jagged to the west, gentling to the east. Further to the east within the world of the Silmarillion lay the mountains of the Ered Luin, and Eriador further east, before encountering the Misty Mountains still further to the east, and the White Mountains to the south. The geologic framework of this larger Middle-earth presents several large-scale geologic problems, and some of these issues are also expressed in the geography of the lands to the East, including Eriador, Rhovanian, and Gondor. Do the lands in the Silmarillion merit discussion in a study of the geology of Middle-earth?

The answers to the questions posed above may provide a basis for formulating the scope of this chapter, and justify some of the delimiting decisions that were made regarding the geology of Middle-earth.

First, J.R.R. Tolkien himself bemoaned the absence in his writings about Middle-earth of any specific geologic, linguistic, or historical background beyond what he included in his published texts. Many readers and critics refer to the entire collection of Tolkien’s writings about Middle-earth as the Tolkien Legendarium. A legendarium is simply a collection of tales or legends relating to events somewhere in the distant past. Tolkien’s Legendarium therefore includes all of the lands described in, as basic sources, the Silmarillion (1977), the Hobbit (1937), and the Lord of the Rings (1954-55). As large as these works are, Tolkien often expressed the idea that his writings did not include enough material to fully flesh out the world of Middle-earth. In the Introduction to Unfinished Tales of Númenor and Middle-earth (1992), Christopher Tolkien notes that “In a letter of the following year [1956] he [Tolkien] wrote: ‘…while many like you demand maps, others wish for geological indications rather than places; many want Elvish grammar, phonologies, and specimens; some want metrics and prosodies….’” The writing and publication history of the Lord of the Rings (LotR) is long, and full of turns and false starts. 2 The sheer size and history of Tolkien’s world, as published by Sir Stanley Unwin, possibly precluded inclusion of a lot of supplemental material that Tolkien might have liked to have seen published, resulting, perhaps, in Tolkien’s somewhat frustrated comment above. Furthermore, although no doubt receiving a well-rounded education at Oxford, focused on his interests in language and philology, Tolkien’s curriculum apparently did not include any coursework in geology.3

It is generally acknowledged that the One Ring was made of gold, as were all of the Dwarven Rings, as it is stated in the Silmarillion. When he recounted the history of the One Ring to Frodo, Gandalf stated that Sméagol strangled Déagol, “because the gold looked so bright and beautiful.” Of course, the gold in the Ring had to be enhanced by Sauron in some way such that it could withstand temperatures far higher than the normal melting point of ordinary gold, and Gandalf even says this to Frodo (FR-I-2). Gandalf points out to Frodo that the small fire in his hearth could not melt even ordinary gold, suggesting that the One Ring was made of some kind of extraordinary gold (FR-I-2). It should be noted here that Tolkien wrote that Saruman, when asked about the fate of the One Ring by the White Council, stated that “Into Anduin it fell, and long ago, I deem, it was rolled to the Sea,” as reported by Gandalf at the Council of Elrond in the Fellowship of the Ring (FR-II-2). Any student who has survived an introductory course in college geology would probably remember that gold (Au, specific gravity 19.32), a very dense metal,4 may accumulate in lag (placer) deposits in river beds simply because it is too dense to be rolled along a stream bed, as other, lighter minerals can. The mineral quartz, for example, with a specific gravity of 2.65, is readily rolled along stream beds, and accumulates at the shore line, when the flow of a stream ends as it enters the ocean. Thus, Saruman’s statement is highly suspect, geologically speaking, and perhaps reflects a lack of Tolkien’s geologic knowledge, although he certainly did realize, as noted in the Prologue to the LoTR, that “the shape of all lands has been changed.”

Given Tolkien’s love of nature and the outdoors, his delight in long walks in the countryside, there can be no doubt that Tolkien felt a close relationship with his natural environment that is reflected in his writing. Tolkien displays a good knowledge of general geographic terminology useful for an outdoorsman. Nevertheless, although appreciating nature and exulting in its bounteous beauty throughout his works, Tolkien was not in a position to provide too much geologic information as a result a lack of his personal geologic grounding, and publishing limitations, due to the high costs of publication encountered by Allen and Unwin, Ltd.

Consider, for example, Tolkien’s naming of “Rhudaur” (“trollshaws”) in the Common Speech. The maps in the LotR show the presence of the “Trollshaws” to the west of the Misty Mountains, and north of the Great East-West Road. Tolkien’s use of the word “shaw” as a geographic feature is typically British, in that a “shaw” forms a wild, non-cultivated boundary between fields, or between a field and a road. “Hedges” are well-maintained, cultivated plant rows that serve the same purpose. The word “shaw” itself is derived from the Old English sceaga, cf. Old Norse skógr, or Danish skov. By Middle-English times, the noun had transformed into a more recognizable scheawen, from which one can easily see that linguistic shortening could produce shaw. Tolkien would no doubt enjoy the use of “shaw” in his work, considering its Old English roots.

Perhaps this usage is symptomatic of Tolkien’s general knowledge of geographic terminology, gained through his exposure to and love of the natural world, but which also reflects his lack of specific geologic knowledge.

To consider the second question posed above regarding the terroir to be considered in a geologic study of Middle-earth, it is essential to look at Tolkien’s conception of the evolution of Middle-earth. According to Shippey (1982, 2005), the world mapped out and portrayed in the Silmarillion, through the First and Second Ages, was envisioned by Tolkien to exist on a flat disk. Due to the cataclysmic forces unleashed by the War of Wrath at the end of the First Age, the lands of Beleriand, including the vast mountain ranges depicted on the map provided in the Silmarillion, were sunk below sea-level and drowned. The rebellion of most of the Númenoreans, encouraged and abetted by Sauron at the end of the Second Age, resulted in the Downfall of Númenor, and the conversion of the flat disk of Middle-earth to its current round shape.

Tolkien, well-aware of the Biblical story of Noah's Flood5, that in turn may have been based on the earlier Sumerian Atrahasis Epic (17th Century BCE), and the later, better-known Epic of Gilgamesh (13th to 10th Century BCE), may have sought to use this common flood myth to link his narrative to a story deeply embedded in the human experience. All of these accounts involved world-wide flooding, with catastrophic results for all then-extant living things. Tolkien may have also been influenced by the story of the drowning of Atlantis, and possibly incorporated a similar theme into his account of the drowning of Númenor at the end of the Second Age of Middle-earth, as well as the sinking of Beleriand.

Figure 1. Inspired by Tolkien's Spherical-earth Cosmology (Shippey, 1982, 2005).

Earth model

Tolkien's earth-model for the origin of the continents and oceans, as presented in Figure 1, and to borrow a phrase from Alfred Wegener,6, is not supportable based upon contemporary geologic thought and geographic evidence, and a consideration of Tolkien’s own motivations in writing the LoTR is discussed below.

The first key point that bears on the rejection of the larger Silmarillion landscape for consideration in this paper is based upon an understanding of specific gravity, or density. Density, or how “heavy” an object feels as compared to a similar-sized object, is a function of several factors, including the atomic structure of an element, the packing of atoms within a crystal lattice, and the resultant “closeness” of different atoms in a given mineral. Specific gravity is simply a means of standardizing the density of different materials by comparing them to the specific gravity of water, a readily available material at the Earth’s surface. By converting density calculations to specific gravity, the units of density (grams per cubic centimeter) are lost, and the specific gravity of a substance is a simple number indicated how many times it is heavier (or lighter) than a similar volume of water, that is defined as having a specific gravity of one.

Geologists have sampled innumerable specimens of rocks from all over the continental areas of the Earth, and have similarly collected actual samples of ocean floor rock. Occasional specimens of ocean floor have sometimes been caught up in continental blocks, and are available for sampling. The result of this massive collection and analytical effort has been to establish that the rocks that constitute the continental crust have an average specific gravity of 2.7, while oceanic crust contains rocks that have an average specific gravity of 3.0. Both the oceanic and continental crusts lie over the solid, uppermost part of Earth’s vast mantle, that has a specific gravity of about 5.0. Simply stated, both oceanic and continental crust “float” on a denser solid Upper Mantle, and continental crust is less dense than oceanic crust. Continental crust therefore cannot sink in the manner envisioned in the Silmarillion. Thus, the drowning of huge mountain ranges under the waves is not a part of modern geologic thinking, all occurrences of localized flooding events notwithstanding. Of course there have been large-scale flooding events in Earth’s long history, but these have generally occurred in low, flat-lying areas, such as the valleys of the Tigris and Euphrates rivers in modern-day Iraq that may have given rise to the Biblical story of Noah’s Flood. There is no indication of continental-sized flooding in the extant geologic record that would support the flooding, or drowning, of large continental areas that include mountain ranges! Relatively low-lying, possibly flatter areas of continents may indeed be flooded over the course of geologic time, and later uplifted once again, but these low-lying areas did not, at the time, include any mountainous terranes.7 The kind of continental flooding that invaded the western part of the North American continent during the Cretaceous Period occurred over the course of millions-of-years, hardly an instantaneous (geologically speaking) event (see Flores and Kaplan, 1985).

The second argument against including the Silmarillion map of the First and Second Ages of Middle-earth is based upon Tolkien’s own reasons for creating the world of Middle-earth. Figure 1 depicts the disk-shaped, flat world of the Silmarillion that morphed into the round world of the Third Age. Tolkien appreciated the “national myths” of Finland, and bemoaned the fact that England lacked a similar story. One of Tolkien’s goals was, in fact, to create a “national myth” for his beloved England. Of considerable interest is his prologue to the Fellowship of the Ring, on which he writes “Those days, the Third Age of Middle-earth, are now long past, and the shape of all lands has been changed; but the regions in which hobbits then lived were doubtless the same as those in which they still linger: the North-West of the Old World, east of the Sea.” The Hobbits, whose home, The Shire, occupies the northwest of Middle-earth, may be a surrogate for the English, who similarly live in the “northwest” of the “Old World.” This corner of Middle-earth, this England for which Tolkien created his masterwork, exists on the round-world we live on today. Tolkien’s Middle-earth is different from our world, but still recognizably very much the same. Note the illustration of the Round World in the Third Age in Figure 1 above. This world geographically resembles our world of today, and “The Shire” (England) occupies the northwest corner. In Tolkien’s own mind, perhaps, the stories of the First and Second Ages were myths, and the land in which they occurred, that is to say, the land of the Silmarillion, was mythic, and not real. If Tolkien was trying to write a “national myth” for England, he at least had to base his story on a world that included the England he was writing for! The converse is also true: the geologic hypotheses and theories that characterize our world today were also operative in the Middle-earth of the LoTR…recognizably our own world at some time in the past.

The important conclusion of all this is that by the time of the action in the LoTR, at the end of the Third Age of Middle-earth, knowledge of the events in the First and Second Ages, and the world in which they occurred, was already a matter of hazy legend. On the basis of Tolkien’s inclinations in writing his saga, and the geologic impossibility of drowning huge segments of continental crust as reported in the Silmarilion, this essay will focus only on the “real world” map of Middle-earth at the end of the Third Age, as encountered in the LoTR, and presented on the maps included therein. This is the world that forms the basis for our modern, round world…and its denizens for whom Tolkien was writing.

Some Additional Comments

This chapter might be of more interest for those who have a “passing knowledge” of the principles of Geology, as provided by any introductory text to the science of Geology, written at a college-level. It is certainly NOT intended to be a professional geologic article, appearing in any one of the many geologic publications. Although some grounding in geology would enhance one’s reading of this chapter, however, the explanations herein are aimed a general audience, and it is hoped they will be understood by all. Where necessary, some geologic concepts will be introduced as required.

Many of the distance measurements in the LoTR are expressed in terms of “leagues,” a term not as common today as it was in the past. The word “league” is derived from an old Celtic measurement, and was taken up by the Romans during their stay in the British Isles. The Romans changed the name of the term to “leuga”, and at one time was a common measure of distance throughout western Europe. The approximate distance of a league is 3.5 statute miles, or roughly the amount of ground that could be covered by a walking person in an hour’s time.

One final note: geologists generally divide rocks into three broad categories: (1) igneous rocks (“born of fire”) derived from cooling liquid magma or lava, (2) sedimentary rocks formed through the deposition of sediments carried from higher areas to lower areas, where they can accumulate and become hardened into rock (lithified), and (3) metamorphic rocks, that result from the changes in pre-existing igneous, sedimentary, or even metamorphic rocks. Metamorphism most typically occurs at great depth of burial, under conditions of increasing temperature and pressure. Igneous and metamorphic rocks are often referred to as “hard rock,” while sedimentary rocks are commonly called “soft rock,” hence, hard rock geology focuses on igneous and metamorphic rocks, while soft rock geology features sedimentary rocks. Sedimentary rocks cover about 75% of the Earth’s continental surface, but the continental crust of the Earth is 75% igneous rock, about 20% metamorphic rock, and only 5% sedimentary rock. The reason for the apparent predominance of sedimentary rocks at the surface of the Earth is that they accumulate only in near-surface environments. These terms will be further developed within this chapter.

Plate Tectonics and Geology

Alfred Wegener initially proposed in 1912 that over the course of geologic time, the modern-day continents of the Earth have moved, and changed position. An important aspect of this idea is provided by the shape of South American and Africa, that, since the “discovery” of South America, has long intrigued geologists and geographers. Although not as pronounced, the shapes of North America, northwestern Africa, and Europe, on opposite sides of the present-day Atlantic Ocean, have also interested geologists and others, including Wegener. Although based on shrewd observation that provided an explanation for many disparate geologic discoveries, Wegener’s model for the origin of continents and oceans, that has often been referred to as “Continental Drift,” was not widely accepted, and was often held up to ridicule by most geologists. One of the principal objections to Wegener’s model was that he failed to account for a mechanism through which continents could “move.” Considered by most establishment geologists to be a “fatal flaw,” the entire hypothesis as proposed by Wegener, even though it provided a neat explanation for some theretofore unrelated geologic evidence, was generally rejected as a valid scientific hypothesis. A few geologists, however, maintained interest in Wegener’s ideas throughout the first half of the Twentieth Century. Arthur Holmes, author of the influential Principles of Physical Geology, included a final chapter in his book in which he suggested (1920) that convecting plumes within the Earth’s mantle provided a force that could move continents. This chapter appeared in later editions as well, and was refined in Holmes’ 1944 edition of his book. Other geologists, mainly in the Southern Hemisphere, had always been impressed by Wegener’s discussion of how moving continents could account for the widespread distribution of continental animal and plant fossils, such as those of the Permian8 coastal reptile Mesosaurus, in such widely disparate regions as South America, Antarctica, India, and Australia. Another example of a land-animal distributed in widely separated areas today would be the Triassic-aged Lystrosaurus, a plant-eating dicynodont. The seed-fern Glossopteris, a tree-like form found in the Permian, has been found on all the southern continents. It is hard to explain how freshwater and coastal animals and land-plants could somehow traverse the present-day, wide oceans separating these areas one from the other without invoking some sort of continental-scale movement. Some of the ideas offered by mainstream geologists during the early 20th Century including geologic structures such as “land bridges,” or processes like “island hopping,” whereby animals and plants could move from continent to continent. Most of these ideas today lay on what Leon Trotsky so elegantly called the “dust bin of history,” and met an inglorious end due to inanition. The voices raised in support of the continental drift hypothesis when first proposed, however, were few and far between.

As is often the case, however, wartime needs spur a burst of technological advances. Originally developed during World War I as a means to detect German submarines operating in the North Atlantic Ocean, the first devices using sound waves traveling through a liquid medium and “bouncing back” to a receiving sensor were called “ASDIC.” Robert Boyle, a Canadian physicist working for the British Board of Invention and Research during the war, developed in 1916 a technique using piezoelectric quartz crystals9 to produce sound detection equipment. With the end of World War I, the pace of technological development of ASDIC slowed, but as World War II approached, interest once again surged in the development of sound detecting technology. In September, 1940, the United Kingdom provided scientists in the U.S. with their ASDIC technology. Furthermore, American scientists had already been at work on their own form of sonar technology in the 1930s, and used the name “sonar” to demonstrate its approximation of radar imaging using far different techniques.

While serving as a Professor of Geology at Princeton University in the 1930s, where he specialized in igneous petrology10, Harry Hess went on active duty in the U.S. Navy during World War II where he eventually assumed command of the U.S.S. Cape Johnson. While at sea, Hess kept the fathometer,11 on his ship on fulltime. A fathometer uses sonar technology to record the depth to the seafloor (and to objects within the sea, such as submarines), and Hess noted a highly variable topography of the ocean floor, including flat-topped mountains and high peaks, that was inconsistent with the generally held notion that the seafloors were flat, featureless plains. Sometime later, Hess named the flat-topped mountains “guyots” in honor of the first geology professor at Princeton. Musing upon his findings during the war, Hess considered the implications of these features for the structure of the Earth’s surface. While serving as Chairman of the Princeton Geology Department, Hess hosted a meeting (26 March 1957)12 at which Bruce Heezen, a geologist at Columbia University’s Lamont-Doherty Geological Observatory, presented a paper on his finding of a rift in the Mid-Atlantic ridge. Heezen discovered this rift using the somewhat improved sonar techniques available in the 1950s. Based upon this, and his knowledge of the significance of density differences between continental crust and ocean floor, Hess proposed in 1960 (published in 1962) a daring hypothesis and framed it in terms of “an essay in geopoetry,” in an attempt to have other geologists put aside their preexisting hypotheses (or prejudices) and consider the possibility of a moving seafloor. Hess’ paper provided a theoretical framework upon with the modern Theory of Plate Tectonics could be developed. Robert S. Dietz had meanwhile (1961) proposed an idea of a “spreading seafloor.” Part of Hess’ model required that new seafloor is created by upwelling magma at mid-oceanic ridges, and then is displaced away from the ridge by the upwelling of newer, younger magma.

Simultaneously, graduate student Fred Vine was working under Drummond Matthews at the Department of Geodesy and Geophysics, University of Cambridge, and his PhD dissertation dealt with magnetism in the sea floor. Aware of Hess’ work, Vine and Matthews hypothesized that new ocean crust created by upwelling magma at the mid-oceanic ridges is moved away from the ridge, and that the cooling magma retained the magnetic signature of the time at which it was formed. Since the magnetic field of the Earth switches over time, magma that cooled through the Curie Point would retain the magnetic orientation that was impressed upon it in its liquid form. Hence, magnetic evidence from the ocean floor showed parallel bands (stripes) of cooled ocean crust that had normal or reversed magnetic inclinations, and matched each other on opposite sides of the mid-oceanic ridge. The work of Vine and Matthews was published in September, 1963. In a sorry story, but unfortunately a sometimes typical occurrence in the scientific process, the Canadian geologist Lawrence Morley had written two letters to Nature (February, 1963) and the Journal of Geophysical Research (April, 1963), that outlined the very same ideas as put forward by Vine and Matthews. Both of Morley’s letters were rejected for publication due, no doubt, to their “outlandish” ideas. To amend this wrong, the ocean-floor magnetic stripe evidence is today referred to as the Morley-Vine-Matthews hypothesis, and is a key element in the proof of the sea-floor spreading theory that underpins out modern conception of Plate Tectonics.

The last element of the theory of Plate Tectonics as it applies to the LoTR was provided by a combination of geologists, using the model of sea-floor spreading and continental movement, and applying it to explain the origin of mountains (tectonic belts) around the world and over time. In 1961, Robert S. Dietz published a paper in Nature that expanded on the concept of sea-floor spreading. Aware of Hess’ work, and having read the paper by Dietz and the published version of Hess’ “Essay in Geopoetry” published in 1962, J. Tuzo Wilson changed his personal viewpoint of fixed continental positions, and accepted the more revolutionary model of sea-floor spreading the resultant movement of continental-sized “plates.” In a series of papers that discussed Dietz’s work, and applied the new orogenic models to different areas of the world, Wilson became a staunch advocate of Plate Tectonics. Wilson’s major contribution to the Theory of Plate Tectonics involved his conception of the birth and death (the lifecycle) of an ocean basin, that has since become known as the “Wilson Cycle.” Wilson’s change of heart possibly inspired other geologists around the world to reexamine their views about continental motion, and helped generate a tidal wave of papers discussing the “New Global Tectonics.” Geologists Kevin Burke and John Dewey, working at the State University of New York in Albany, followed Wilson’s lead and began in the 1970s to publish a long series of papers that demonstrated the applicability of Plate Tectonics to different mountain ranges around the world. The bottom line is that the concept of Plate Tectonics, based upon the model of sea-floor spreading, has been elevated to the scientific rank of a “Theory,” and serves as the present-day paradigm for the formation of continents and oceans, and the features contained therein.

It is not the intent of this essay to provide an in-depth review of the history and processes of Plate Tectonics, but the essence of the idea must be presented here to provide a basis for evaluating the overall tectonics of Middle-earth as presented on the maps provided in the LoTR.

The present-day conception of the Earth’s crust suggests that the solid, outermost crust consists of two different types of crust: continental and oceanic. Both of these types of crust lie above the solid uppermost part of the Earth’s Mantle, and these combined elements form the lithosphere of the Earth, or the zone of solid rock. The lithosphere lies above the less-solid Asthenosphere, that, although solid, is somewhat plastic. Convection of heat due to radioactive decay within the Asthenosphere results in the movement of less-dense molten magma upwards towards the surface of the Earth. This magma is extruded at oceanic ridges, and as new magma is forced upwards, the cooling magma is pushed away from the mid-ocean ridge, as described above. New seafloor is created at the ridges, and the accumulated oceanic crust drifts away from the “spreading center” at the ridge. Since the Earth is spherical, and is not likely expanding, oceanic crust cannot continuously be created and spread, so at some point, oceanic crust must be subsumed back into the Earth’s Mantle. This occurs at places called subduction zones, where oceanic crust is forced downwards, and the now cool crust sinks into the Mantle. Carried along with this moving crust (lithosphere) may be segments of continental crust, that cannot be subsumed, due to its lighter specific gravity. As a result of all this, the Earth’s lithosphere is broken into a series of “plates,” some of which are quite large, and a few of which are relatively small. Large plates include the North American Plate, or the Eurasian Plate, while smaller plates include the Farallon or Nazca plates, for example. Most plates consist of some portion of both continental and oceanic crust, the Pacific Plate, however, consists only of oceanic crust. Since continental crust cannot be subsumed, if it should happen that two pieces of continental crust “collide” due to sea-floor spreading, a massive mountain range could form as the rocks between and within the colliding pieces of continental crust are squeezed, folded, and uplifted. Such, in a nutshell, is how Plate Tectonics operates. Other mountain ranges can be formed through volcanism, as a subducting ocean crust may be remelted at depth, and the subsequent magma (less dense that the surround material) will rise to the surface, and form a continental or oceanic volcanic arc. Over the course of geologic time, continental blocks have collided, been split apart, and move about quite irregularly, but the net result of a collision, on a continental scale, is a mountain range. With this in mind, one can begin to consider the overarching tectonic framework of Middle-earth.

II. Geologic “Evidence” in the Lord of the Rings

Textual References

As noted, actual geologic references in the LoTR are few and far between. The presence of a detailed map of Middle-earth in the LoTR provides, however, a basis for some large-scale geologic analysis describing the overall geologic structure of Middle-earth as presented in the LoTR. Therefore, this section will first consider the limited geologic notes found in the LoTR texts itself, and then move on to a discussion of the LoTR map and its possible geologic interpretation. The data in this section will appear in the form of a table, that provides the geologic “clue” as written in the LoTR, and where it appears referenced in the book, using the Book-Volume-Chapter format used in previous chapters of this collection.

Geologic References Within the LoTR Text

The Fellowship of the Ring (page numbers refer to the Houghton Mifflin Edition of 1994, 13th)
Geologic "Clue" Text Reference
& Page Number
Geologic Comments or Notes
Bilbo is lost in the black orc-mines in the Misty Mountains. Prologue No mention is provided as to what is being mined.
The map of The Shire indicates a quarry on the south side of the hills, to the east of Scary. Prologue No mention is provided as to what is being quarried, although it seems likely the product was building stone of some type.
“a little fall where the water fell a few feet over an outcrop of grey stone” FR-I-3: 71 An outcrop! The “grey” color does not provide conclusive evidence as to the type of rock involved, as many rocks are “grey.” Possibly limestone?
The path to Tom Bombadil’s house is bordered with stones. FR-I-6: 119 Naturally occurring stones are often used, but not exclusively, as building materials in glaciated areas, where such field-stones are frequently encountered.
“A white, chalky path…” FR-I-7: 127 Chalk: a fine-grained, often white or gray variety of limestone, formed from the deposition of the remains of the tests (shells) of microscopic-sized foraminifera, coccoliths, and other marine organisms.
“Eastward the Barrow Downs rose, ridge behind ridge into the morning…” (133) description of hills on the west side of the Barrow-downs. FR-I-8: 133 Hardly conclusive geologic evidence, but the use of the term “ridge” suggests a linear feature extending in a preferred orientation. The underlying geologic structure of a region often informs its geographic expression. Were the ridges seen by the Hobbits ranging east-west, north-south, or some other orientation? The wording suggests a north-south orientation.
Stone houses in Bree FR-I-9: Again, stone houses may suggest a surfeit of stones in a glaciated area, readily available for construction purposes. Both Bombadil’s house and Bree are located in the northern part of Middle-earth, perhaps indicating a glacial history.
“a cheerless land,” & mention of a wide, shallow valley FR-I-12: 195
“a single pale-green jewel…It is a beryl, an elfstone” as stated by Aragorn, and was found on the bridge over the Mitheithel by Aragorn. FR-I-12: 196 The beryl was apparently left by Glorfindel, and is probably not native to the area. Beryl is composed of beryllium (Be) and aluminum (Al), along with a basic silicate component (Silicon [Si] and Oxygen [O]), having the chemical formula Be3Al2Si6O18. It is a member of the cyclosilicate group, and crystallizes in the hexagonal crystal system, with a Hermann-Mauguin notation of 6/m 2/m 2/m. Further description of beryl can be found in Chapter 6.
“rocky ground;” A southeast-wards running valley. At the southern end of the valley is a perpendicular ridge. On the top of this ridge, Aragorn & the Hobbits “lit a small fire under the gnarled roots of an old pine, that hung over a shallow pit: it looked as if stone had once been quarried there.” FR-I-12: 198 “Shallow pits” may be dug for any one of a number of reasons. The fact that it is shallow suggests that nothing of great value was found there, and the lack of any further geologic information precludes making any predictions about what had, perhaps, once been quarried at this location. The orientation of the southeastwards running valley and a perpendicular ridge suggests a northwest-southeast and northeast-southwest (orthogonal) structural grain.
“A rocky shoulder of the hill.” FR-I-12: 199 Suggests steeper relief.
“And the seas and lands may change.” (Gandalf at the Council of Elrond) FR-II-2: 260 Indeed. The first edition of the LoTR appeared in 1954, pre-Plate Tectonics. Even so, Tolkien had some idea that geologists accepted the notion of rock cycle with its concomitant erosive cycle, deposition, lithification, followed by metamorphism, and remelting (anatexis) to form new magma. He may also have been aware of the concept of peneplanation, where surfaces are reduced to a relatively flat, level landscape over time.
The lands on the west side of the Misty Mountains: “At the Ford of Bruinen they left the Road and turning southwards went on by narrow paths among the folded lands…The Country was much rougher and more barren than in the green vale of the Great River in Wilderland on the other side of the range…” FR-II-2: 274 Is Tolkien referring to structurally folded rocks resulting from tectonic movements, or is he simply descriptive of the geographic features present in this area? If the folded lands are tectonically formed, they would not be out-of-place on the flank of a large mountain range, in which case, the folds are probably running parallel to the Misty Mountains, that is to say, north to south. The land on the east flank of the Misty Mtns. is much gentler, perhaps suggesting that the Misty Mtns were thrust from the east.
Caradhras is described “a mighty peak, tipped with snow like silver, but with sheer naked sides, dull-red as if stained with blood.” (279) Silvertine and Cloudyhead are less colorful…gray, white. FR-II-3: 279 The appearance of a reddish hue to Caradhras is suggestive of the presence of Orthoclase (potassium (K) feldspar) in the rock. Orthoclase has a typical pink color that can be darker, and is most often found in granitic igneous rocks. The absence of K-spar in Silvertine and Celebdil may account for their gray and white appearance. It is also possible that the red coloration is due to the presence of iron compounds in sedimentary rocks.
The country to the west of Moria is described as “a barren country of red stones,” and the Sirannon flowed in a stream bed marked by the “brown and red-stained stones.”
Durin’s door is located on “the grey face of the rock.”
FR-II-4: 292
FR-II-4: 296
The brown and red-stained stones suggest a lot of iron (Fe) in the water draining the mine. The presence of Fe (the fourth most abundant element in the Earth’s crust), is not uncommon in the many minerals that comprise granitic igneous rock, such as the feldspars, biotite, and hornblende, along with some pegmatitic minerals, including tourmaline, spodumene, and beryl. Pegmatites more rarely occur in igneous rocks of a more basic composition, such as diorite or gabbro, but are far less common in those rocks. The lighter color of the Misty Mtns supports a granitic composition.
The text states that the TOTAL DISTANCE from Westgate to Eastgate is only 40 miles.
Sam notes that Moria is built in “hard rock.”
FR-II-4: 302
FR-II-4: 307
This is an exceptionally short width for a mountain range that Tolkien indicates had massive, snow-covered peaks. This is discussed further in this chapter. Perhaps the mountains are not as high as Tolkien reported?
Mines of Moria FR-II-4: 309 “Mithril” was mined here, as well as iron (Fe).
A small tributary empties into the Silverlode, and then both plunge “over a fall of green-hued stone.” FR-II-6: 326 Chromium (Cr), iron (Fe), and manganese (Mn) commonly give minerals and/or rocks a greenish hue. Common green minerals that appear in metamorphic rocks include chlorite, actinolite, and epidote, and perhaps talc. Such metamorphic rocks may be associated with igneous rocks. If a granite is enriched in Amazonite, a green variety of feldspar, it could form green-hued stones.
The approach to the Emyn Muil from the north passes through a “hilly, rocky land,” and the banks of the Anduin are marked by “low crumbling cliffs, and chimneys of grey weathered stone….and beyond these again there rose high ridges..” The text refers to the “grey hill-country of the Emyn Muil.” FR-II-9: 376 This passage suggests that the Anduin is deeply incised into its valley as it passes through the hilly region of the Emyn Muil. “Grey weathered stone” is too vague to allow for a geologic interpretation. This is reinforced by Tolkien’s description of the Argonath, where the Anduin swiftly flows through a very steep-walled valley incised into the rock, suggestive of a mountain stream defile.
Aragorn says there are “rocks and stony eyots in the stream.” “rocky banks” FR-II-9: 376,378 An “eyot” is a strictly English term that refers to sandbar-type islands in the middle of a stream, and that are commonly found in the Thames River. The term “eyot” may be replaced by the term “expansion bar” to indicate that it is formed where a stream may widen, lose velocity, and dump its load of sediment because it has lost the power to transport the sediment. The presence of rocks in the Anduin here, however, suggests a shallow reach of the stream. The fact that the bars include rocks suggests that the Anduin is a fairly active river system, with high stream power, so the eyots may be rock-preserved.
“A tumbled waste of grey limestone boulders” FR-II-9: 382
At last! An incontrovertible geologic reference.
West side of Anduin.
Nen Hithoel is “fenced by steep grey hills whose sides were clad with trees, but their heads were bare, cold-gleaming in the sunlight.” FR-II-9: 384 Given the clue cited above, it appears that the gray hills on either side of the Anduin here consist of limestone or dolomite, sedimentary rocks of marine origin, most commonly formed from biologically-derived sediments.
The Two Towers: refer to the Ballantine Books 23rd Printing of 1970
Geologic "Clue" Text Reference
& Page Number
Geologic Comments or Notes
A small rill trickles out into Anduin from a spring in Parth Galen. TT-III-1: 24 A normal geologic occurrence, since Parth Galen lay not far above the Anduin, adjacent to the lower parts of Amon Hen. Groundwater might seep to the surface in such a place.
“a stony land” TT-III-1: 26 As noted above, stony land often occurs in glaciated areas. However, this is not the only place they may appear; another alternative might be colluvial deposits from slow, continuous downhill creep.13
“Here the highlands of the Emyn Muil run from North to South in two long tumbled ridges. The western side of each ridge was steep and difficult, but the eastward slops were gentler, furrowed with many gullies and narrow ravines.” “bony land” TT-III-2: 27 This is quite significant. The ridges of the E.M. run north-south, with a steeper side on the western slopes, and a gentler side on the eastern slope. This is suggestive of low-angle thrusting from east to west. Compare to the Misty Mountains, whose eastern slopes were gentle, and the western side (slopes) were rough and tumbled. This seems to confirm a regional trend to the structures in the Wilderness and the Misty Mountains.
“The dale ran like a stony trough between the ridged hills, and a trickling stream flowed among the boulders at the bottom.” TT-III-2: 27 The “ridged hills” must have had steep sides, that led to downward movement of the boulders found at the bottom. A “trickling stream” would not likely transport boulders.
Shelly Shapiro map (1988) suggests (small scale map) at least one north-south ridge to the west of Rauros. This would confirm the trend noted above. However, “hills” as opposed to “mountains” are not well depicted on this map. Furthermore, the Shapiro map does not accurately show north-south ridges as described in the LoTR text.
Larger-scale map (4) in the text suggests wider hills to the north, as does the small scale map -- plus the Entwash with its big delta is not too far away. This spot is 30 leagues (90 miles) or more from the White Mountains (to the SSW)
TT-III: 12-13
(maps appear before Chapter 1)
The western ridge of the two above mentioned ridges is 20 fathoms (180 feet), or more, higher than “a wide and rugged shelf which ended suddenly in the brink of a sheer cliff: the East Wall of Rohan. So ended the Emyn Muil, and the green plains of the Rohirrim stretched away before them to the edge of sight.” TT-III-2: 30 Again, the mention of a western ridge suggests a north-south trending structure, in line with the tectonic orientation of the Misty Mountains and the overall Emyn Muil. It is reported that the Three Hunters had difficulty finding a way down this slope, and had to follow the trail established by the Orcs. This is in consonance with a model of thrusting from the east to the west that resulted in the tectonic grain of the region. The ridges tend to gently slope towards the Entwash, to the south.
Aragorn, Legolas, and Gimli have been going north on the ridge, they then go due west down a “deep cleft” onto the “level plains” (p.18) of Rohan. TT-III-2: 30 See above. The ridges and valleys seem to slope gently towards the south, towards the very broad and flay-lying mouths of the Entwash before they drain into the Anduin.
Now northwest on the 3rd day of pursuit, land is now rising towards northwest, towards Fangorn. Ground is “harder and the grass shorter.” TT-III-2: 36 Not unexpected. Fangorn is located on the east side of the Misty Mountains, and as noted previously, the east side is gentler than the west side, but the land would still be sloping upwards towards the mountains.
As Merry & Pippin approach Treebeard’s Hill: “They found it was further than they thought. The ground was rising steeply still, and it was becoming increasingly stony…soon they saw that there was a rock wall before them: the side of a hill, or the abrupt end of some long root thrust out by the distant mountains.” TT-III-4: 81 Land slopes tend to increase exponentially towards a mountain range; hence, it is not to be unexpected that the slopes would be steeper as one approaches the foothills of the Misty Mountains. Later, in Ch. Five of Book III, it is noted that this rock wall has “rough steps” leading up to the top. Perhaps these rough steps are developed by weathered fractures in the rock that allow for easier weathering. There is no mention of fracture orientations that would allow for a Wulff Net analysis.
The Forest of Fangorn slopes steadily upwards towards the northwest. TT-III-4: 87 As above.
The Glittering Caves of Aglarond: “gems and crystals and veins of precious ore glint in the polished walls.” TT-III-8: 193-195 No end to the geologic possibilities here. Given that the “caves” are located within a mountain range, it might be logical to assume a granitic or dioritic composition, but such rocks are not prone to develop caves.
The Ring of Isengard: “Shafts were driven deep into the ground…” TT-III-8: 203 Suggest mining operations at the southern end of the Misty Mountains. Important to note here that Tolkien considered the Misty Mountains to “end” at Isengard, although interpretation of the various maps in the text suggest it could also be linked to the White Mountains further to the south and east.
Emyn Muil described as a “strange twisted knot of hills.” The rock is weathered. TT-IV-1: 265,267 The dell in which Frodo and Sam rest contains weathered rock, surround by the jagged peaks of the Emyn Muil.
The ridge the Hobbits run into forms a great “grey cliff.” TT-IV-1: 268 Dolomite? Harder limestone? A bioherm? (An accumulation of reef and shelly material)
The bottom of the gully that Frodo & Sam climb down “lay along the edge of a rock-fault.” “great fissures” TT-IV-1: 268 No further information is given, but it is suggestive that the southern border of the Emyn Muil in this area may represent a fault scarp.
Frodo and Sam have just left the Emyn Muil. “But here, over the desert and the reeking marshes…” TT-IV-1: 274 Marshes are not often found in desert areas. This is an interesting combination of landforms. Perhaps Tolkien meant to suggest that these were “deserted” areas.
Small rivers and streams from the Emyn Muil flow into the marshes. TT-IV-2: 287 As an upland area relative to the Dead Marshes, it is likely that streams flow cold from the Emyn Muil into the marshes.
A reeking miasma lies over the Dead Marshes. TT-IV-2: 294 Not surprising.
“The gasping pools were choked with ash and crawling muds, sickly white and grey, as if the mountains had vomited the filth of their entrails upon the lands about. High mounds of crushed and powdered rock, great cones of earth fire-blasted and poison-stained…” TT-IV-2: 302 The presence of mud suggests at least occasional episodes of rainfall, as well as the reference to “pools.” This places this region in the southernmost parts of the temperate zone, probably north of 30o North. See chapter text for further explanation. Furthermore, the land as depicted resembles closely a volcanic landscape that contains still active volcanoes, like the “paint pots” at Yellowstone N.P., U.S.
The Ered Lithui, on the north side of Mordor, are described as “grey as ash.” TT-IV-3: 308 Ash is a common product blown out of volcanoes, consisting of rock fragments, mineral crystals, and volcanic glass, created during the eruption of a volcano. Ash measures less than 2 mm (0.079 inches) in diameter, specifically. It is also used loosely to denote any eruptive products. Ash color is often gray, but can be reddish, brown, or almost black.
Gollum states that the path he wants to take, the road to Minas Morgul passes through “black rock.” TT-IV-3: 315 Volcanic (basaltic) mountains often display black rock due to the enrichment of the black to dark-green minerals olivine, pyroxene, and hornblende, along with biotite.
“a barren stony country” TT-IV-4: 324 Probably colluvial deposits from the Ephel Duath.
“…a long cutting, deep, and sheer-sided in the middle, by which the road clove its way through a stony ridge.” TT-IV-4: 326 A possible dike exposed through erosion of surrounding material, or perhaps a lava flow emanating from the Ephel Duath.
The road to Minas Morgul does pass through “black and forbidding rock.” TT-IV-8: 396 Enrichment of dark-green to black olivine, pyroxene, hornblende, and biotite. These rocks may also include calcium plagioclase, a gray to white mineral. (Commonly found in basalt)
Shelob’s Lair. TT-IV-9: 414 Shelob’s lair might represent a lava tube, formed by lava flowing from a volcanic vent underneath hardened lava. If the tube is emptied of its lava, a cave could result. This interpretation is strengthened since the tunnel system seems to extend east-west completely beneath the crest of the Ephel Duath. Perhaps the natural “cave” was enhanced by the borings of orcs.
The Return of the King: refer to the Ballantine Books 70th Printing of 1983
Geologic “Clue” Text Reference: & Page Number Geologic Comments or Notes
“To his left lay a sea of mist, rising to a bleak shadow in the East, but to his right great mountains reared their heads, ranging from the West to a steep and sudden end, as if in the making of the land the River had burst through a great barrier, carving out a mighty valley to be a land of battle and debate in times to come.” RK-V-1: 24 Pippin describing the land as he approaches the Great Gate of Gondor, with Gandalf. It is difficult to imagine a great mountain range so abruptly ending against the Anduin River, and the Ephel Duath. One wonders about the geologic history of the River Anduin. Did it carve the valley between the southeastern end of the White Mountains (Ered Nimrais in Gondor) complex and the Ephel Duath, or was the valley already tectonically established? In geologic terms, is the Anduin an antecedent stream or a superimposed stream?
The dark door Dimholt. RK-V-2: 69 The Ered Nimrais (White Mountains) are likely igneous, metamorphic, or migmatitic – a combination of the two types. It is unlikely for caves to naturally form in such an environment, although it is implied that the Dark Door led to a mined tunnel built by the Forgotten People before they were cursed by Isildur. Their relationship with the Misty Mtns is moot.
At the end of the “living lands:” “marshes and the desert” RK-V-10: 199 Another reference to an odd occurrence north of Ithilien, near the Black Gate.
“…there were smokes and fumes that rose out of the earth…” and “great heaps and hills of slag and broken rock and blasted earth…” RK-V-10: 200 This description suggests, again, a volcanically active area, such as the Valley of Ten Thousand Smokes14 on the Katmai Peninsula of Alaska. However, such areas are not usually mined for ore, although the rocks could be used for building materials. The word “slag,” however, is problematic. Slag is almost always a by-product, or waste material, from the smelting of ore. Ores are not usually found in volcanic deposits.
The “shadowy defile” beyond the Morannon “was bored and tunneled by teeming broods of evil things.” RK-V-10: 201 Adds credence to the notion that Shelob’s Lair was also tunneled and bored by the evil things that dwelt there, namely, orcs and their ilk.
The field before the Morannon was “a great mire of reeking mud and foul-smelling pools.” RK-V-10: 201 Volcanic gases include sulfur dioxide, that has a sometimes sickening odor of rotten eggs.
Eastern faces of the Ephel Duath are “sheer, falling in cliff and precipice;” boulders abound. RK-VI-2: 236, 238 Certainly possible on the flank of a volcanic belt.
Mt. Doom is described as a “huge cone.” RK-VI-2: 245 Volcanic cones are often developed by explosive volcanoes, that produce great quantities of ash, as well as liquid lava. A volcanic cone would be a likely candidate for being responsible for the presence of so much ash in the vicinity.15
The Plain of Gorgoroth is “pocked with great holes, as if, while it was still a waste of soft mud, it had been smitten with a shower of bolts and huge slingstones.” RK-VI-3: 259 Not a bad description of what such a plain could look like: explosive volcanoes can spew sometimes large blocks of rock away from the cone, and if the surrounding ash and volcanic debris is not yet hardened, such blocks could cause the features observed by the Hobbits.16
“…,fuming, barren, ash-ridden land.” RK-VI-3: 262 As Frodo and Sam turn south from the east-west road connecting the Barad-dûr with Minas Morgul, and head towards Orodruin.
“Sam felt a tremor in the ground beneath him, and he heard or sensed a deep remote rumble as of thunder imprisoned under the earth.” RK-VI-3: 266 Earthquakes and tremors are often associated with volcanic activity, and in many cases, offer a harbinger of an eruption to come. Geologist look for increased earthquake/tremor activity as a sign of increasing threat of an eruption.
Orodruin is described as a sheer-sided cone. RK-VI-3: 267 The cinders flanking a volcanic cone volcano usually have an angle of repose between 25 and 32 degrees. Anything greater than 15 degrees is considered a steep slope for a mountain. “Sheer” slopes are defined as nearly perpendicular. Such a slope is unlikely for the flank of a volcano.
Mines and forges RK-VI-2-6 Mentioned in northwest corner of Mordor.

Additional Geological Evidence

The Hobbit, published in 1937 by George Allen & Unwin, London, provides several geologic references in addition to the three books of the LoTR. Since The Hobbit takes place in the very same world as the LoTR, using geologic references from it meets the criteria for inclusion in this chapter, as discussed above. Supplemental information and its geologic significance from both the LoTR and The Hobbit is included in this section to support the geologic conclusions that will be made subsequently. As a start, there are many references to the use of iron for the manufacture of swords and other implements of war in both the LoTR and The Hobbit, and the production of iron requires the use of coal. Additionally, there are frequent mentions of “jewels” in both the LoTR and The Hobbit, and the geologic origin of “jewels” is discussed here.

Some Basic Metallurgy

There were seven metals known in early human history. Gold occurs frequently in its pure form, as a native element.17 Copper (Cu) is also a native element, but is found in this form to a lesser extent than gold. The other early metals known to humankind included: lead, silver, tin, iron, and mercury. These metals most often occur in combination with other elements in the form of minerals. To obtain the “pure" metal, it is necessary to smelt18 the ore material to remove the impurities, such as other oxides, sulfides, and carbonates. "Roasting" the carbonate and sulfide minerals in air reduces them to oxides, which in turn can be smelted into the desired metal. The “reducing” agent for the oxides is typically carbon monoxide, obtained from the fire in which the ore is smelted. Along with sufficient temperature, the metal ore can be converted into usable metal. The carbon monoxide reacts with the oxygen to form carbon dioxide, that is released to the atmosphere.

The earliest ores to be smelted were those rich in tin (Sn) and lead (Pb). Evidence from the Çatal Höyük site in modern-day Turkey suggests this event occurred about 6,500 BCE. Tin and lead can be successfully smelted employing the heat of a wood fire. Tin has a melting point of about 232o C (449oF) and the melting point of lead is about 328o C (622oF). Copper, however, melts at a much higher temperature (1,085oC, 1,985oF). It has been noted that Neolithic19 pottery kilns were capable of producing sufficient heat to smelt copper ore. These kilns have been discovered as far back as 6,000 BCE, and could have produced temperatures greater than 900oC ((1,652oF). Bronze, an alloy much harder than copper, is produced by mixing copper with tin and/or arsenic. Evidence suggests that bronze was developed about 3,500 years BCE somewhere in Asia Minor (Georgia, Armenia, Azerbaijan, Turkey, and adjacent parts of Iran, Iraq, Syria, and Greece (across the Bosporus and the Dardanelles).

Iron is “a whole ‘nother story.” Iron (Fe) is the fourth most abundant element in the Earth’s crust, after, in order, oxygen (O), silicon (Si), and aluminum (Al). It is the most abundant element in the Earth overall. Unfortunately, iron has a rather high melting point, around 1,538oC (2,800oF). Furthermore, the smelting process for iron ore is far more complex than that for copper, tin, or lead, for example, requiring the use of some relatively advanced metallurgical techniques. The first record of iron production in human history dates from around 2,200 to 2,000 BCE. Charcoal, produced by the heating of wood in reducing (oxygen poor) conditions, is not sufficient as an energy source to smelt iron, but coal is, and coal is a fairly accessible geologic commodity.


The paragraphs above suggest that iron, frequently mentioned as the metal-of-choice for the fashioning of swords, shields, plowshares, and other accoutrements of both war and peace, requires the availability of coal for its smelting. Coal, the lithified remains of ancient plants that accumulated over long periods of time in a swampy environment, depleted in oxygen, and then deeply buried, is a readily available geologic commodity.20 Although coal frequently outcrops at the surface, better quality coal can be obtained through the use of mining. As recently as the dawn of the 20th Century, coal was most often obtained in underground mines, however, the advent of large earth-moving and mining equipment led to a surge in surface, or open-pit mining starting in World War Two and continuing on to the present day. Converting high-grade bituminous coal into “coke,” the coal-equivalent of charcoal, is accomplished in coking ovens. Coke is used in the iron smelting process. Unfortunately, coal is a rather “dirty” sedimentary deposit, frequently including layers of ancient soil, and the plants that constitute the coal itself often serve as a repository of unwelcome heavy metals, sulfur, and other contaminants. Furthermore, the burning of coal releases huge amounts of carbon (C) into the atmosphere, with detrimental effects on the climate through global greenhouse warming.21 Coal is a sedimentary rock, and sedimentary rocks are most frequently deposited in both on- and off-shore (near-shore) depositional environments, or alongside large river floodplains as they approach the shoreline. Coal in particular carries a geochemical signature of its origin in brackish water (mixture of seawater and fresh water) environments very close to the shoreline, since the presence of the mineral pyrite (“Fool’s gold”) in coal suggests an origin where iron carried to the shoreline in fresh-water solution can combine with the sulfate anions present in seawater to form pyrite through the action of sulfate-reducing bacteria. Furthermore, the accumulation, burial, and lithification (hardening) of the sediments that can form sedimentary rocks occurs in what geologists refer to as “basins.” During periods of uplift, deeply buried rocks, such as the lithified sedimentary rocks that were buried most often in near-shore areas, can be brought back to the surface, and the basins that include sedimentary rocks are often adjacent to other uplifted areas, such as mountain ranges. Occasionally the sedimentary rocks themselves can form mountain ranges, as evidenced in mountain ranges such as the relatively youthful Himalaya Mountains and the much older, and more highly eroded mountains of the Appalachians in North America. Most coal that is mined today by either underground mining or surficial mining is found in sedimentary basins that are now exposed at the continental surface of the Earth.

Iron Ore

It was noted above that iron was one of the first metals known to modern humans. Iron can occur as a native element,22 and can be found at the surface in the form of meteorites that have landed on the Earth. Kamacite is the name applied to this mineral of extra-terrestrial origin. Native iron has also been found in basalt (an igneous rock), and in carbonaceous sedimentary rocks, although these occurrences are extremely rare.

Although the ancients had probably observed meteorites, they probably did not understand their origin, but they were more familiar with the occurrences of the iron-bearing mineral goethite in what is called “bog ore.” The goethite is formed by the mixing of iron-rich groundwater with surface water. Bacteria that use sulfur as an energy source concentrate the iron in these wet, boggy conditions, where the iron can accumulate as goethite. Initially used as a black pigment, goethite (named for the German poet Johann Wolfgang von Goethe, 1749-1832) is iron-rich and can be easily collected and utilized. As recently as the American Revolutionary War and the Napoleonic Wars, bog iron was the major source of iron ore. Another source of iron for early metal-workers were lateritic soils that concentrate aluminum and iron.

These supplies were soon depleted in those areas were iron was being used, and iron makers turned to hematite, with an average iron concentration of 70%, as a source of iron ore. These ores are referred to as “natural ores,” or “direct shipping ores,” since they were rich in iron and could be directly used in the iron-making process. Although direct shipping ores are still being actively mined, they underwent fast depletion, and most iron ore produced today comes from three other sources: Banded Iron Formations (BIFs), magnetite ores, and magmatic magnetite ore deposits.

Banded Iron Formations were formed worldwide during essentially one period in geologic time, the Paleo-Proterozoic Era (1.6 to 2.4 Ga, or billion years ago) of the Precambrian. These deposits record the earliest evolution of the cyanobacteria, that used the energy of the sun to power their photosynthetic systems, producing oxygen as a by-product. As these organisms first began to produce free oxygen, it immediately reacted with the iron in the sediments, forming a deposit of black, dark-gray colored, magnetite-bearing sediment. As soon as the oxygen was used up, further deposition resulted in the accumulation of reddish-colored chalcedony, not too enriched in iron. This process cycled back and forth, over and over again, over the course of hundreds of millions of years, until most of the then-available free iron was “used up,” and the remaining oxygen being produced by the cyanobacteria could enter the atmosphere, setting the stage for the development of our present atmosphere that contains 21% oxygen. There are many conflicting hypotheses concerning the origin of the BIFs; the model presented here is a simplified version of only one of these models. It should be noted that BIFs contain, on average, only 15% iron. In North America, the BIFs that produce iron ore are referred to as taconite. The chief taconite production of North America is centered around the western portion of glacial Lake Superior in Ontario, Minnesota, Wisconsin, and Michigan. The famous Mesabi Range is actually only one part of a long range of low-lying mountains that begins to the northeast, in the Gunflint Range of Ontario, and extends southwestward through the Vermillion Range, the Mesabi Range, and the Cuyuna Ranges. On the south shore of Lake Superior, iron ore is, or was, recovered from the Gogebic Range, the Marquette Range, the Iron River Range, and the Menominee Range.

A somewhat richer source of iron ore is provided by magnetite ores, that can also be found in BIFs, if there were suitable conditions for their formation at the time of deposition. As noted, most BIFs have an iron concentration of only 15%, but magnetite ores can contain between 33% and 40% magnetite, which upon concentration yields an effective iron content of 64% iron by weight.

Finally, and of most interest for the geology of Middle-earth, some iron ore can be found in granite and other ultrapotassic (potassium-rich) igneous rocks, which will be discussed in more detail below. Some of these rocks segregate magnetite crystals, forming an economically viable concentration of iron ore. Occasionally, these bands of segregated magnetite crystals are weathered out of the host rock, and are carried downslope by stream (fluvial) processes, and then deposited in lag deposits (like gold) when the stream power falls below the threshold required to move such relatively “heavy” (dense) crystals.

Dwarf Mining in the LoTR and The Hobbit

There are many references to the mines delved by the Dwarves in both the LoTR and The Hobbit. These will now be discussed to inform the geologic significance of these mining operations in terms of Middle-earth. Establishing the location of Dwarven mines in the LoTR is fundamental to understanding the geology of the Middle-earth landscape. No discussion of the location of Dwarven mining projects in Middle-earth would be complete without some discussion of the history of the Dwarves.

In anticipation, perhaps impatient, of the arrival of Eru’s Firstborn on Arda, and in his desire to have someone to teach his skills to, the Vala Mahal (Aulë the Smith) created the Seven Fathers of the Dwarves. The location of their “birth” is not established in the Legendarium, but Eru was aware of Aulë’s action, and reprimanded Aulë for overstepping his bounds. Unlike Melkor, Aulë had no great pride and was repentant of his deeds, so Eru took pity on the creation of his vassal, Aulë, and adopted the Dwarves as his own, but forbade their awakening before the arrival of the Elves, Eru’s Firstborn. The Dwarves created by Aulë were placed inside a mountain and slept there until the Elves awoke in Cuiviénen. After their own awakening, the Dwarves, divided into seven “clans,” settled in various parts of Arda. Durin’s folk, the Longbeards, settled in Khazad-dûm early in the First Age. The Firebeards and the Broadbeams settled in the Ered Luin (the Blue Mountains), while the Ironfists, Stiffbeards, Blacklocks, and Stonefoots all settled in the East. The two famous dwarven cities of Belegost and Nogrod, that figure prominently in the legends of the Silmarillion, were settled during the Years of the Trees in Valinor, before the arrival of the Elves in Beleriand.

The Dwarves of the Blue Mountains forged chain mail, swords, and other accoutrements of war, as well as aiding the Elf Thingol of Doriath in the creation of his home, the Thousand Caves of Menegroth. Meanwhile, Telchar of Nogrod forged the knife Angrist and the sword Narsil, as well as the Dragon Helm of Dor-Lómin. All three of these storied items held great import in the legends of the First Age, and the sword Narsil was reforged into Andúril and carried by Aragorn at the end of the Third Age, as he led the forces of the West against Sauron in the LoTR.

The chaos and destruction created by the War of Wrath at the end of the First Age of Middle-earth resulted in the destruction of Belegost and Nogrod, but interestingly, according to the legends of the Silmarillion, the Ered Luin (the Blue Mountains) were the only small part of Beleriand that survived the First age. Formerly the legendary east edge of Beleriand, the Ered Luin now form the western edge of Middle-earth, before arriving at the shores of the Great Sea to the west. The refugees from Belegost and Nogrod found their way to Khazad-dûm. At the same time, some residents of that city traveled north to the Iron Hills and the Grey Mountains. It is interesting to note that Tolkien himself names one of these “ranges” as the “Iron Hills,’ no doubt reflecting the rich sources of iron ore found there…perhaps mimicking the Mesabi Range of Minnesota.

There is little mention of significant Dwarf activity during the Second Age. The Dwarves of Khazad-dûm formed perhaps the most famous of the friendships between the Elves and the Dwarves when they befriended the Elves of the Gwaith-i-Mírdan formed by Celebrimbor. In response to a question from Sam concerning what the Dwarves actually did in Moria, Gandalf replies that “The wealth of Moria was not in gold and jewels, the toys of the Dwarves; nor in iron, their servant...but they did not need to delve for them: all things that they desired they could obtain in traffic. For here alone in the world was found Moria-silver, or true-silver as some have called it: mithril is the Elvish name.” (FR-II-4) In this same chapter, Gandalf tells the Fellowship that “It cannot be less than forty miles from West-door to East-gate in a direct line.” Many pundits have sought to determine the nature of mithril, without conclusive success. Mithril itself is described by Gandalf, saying it could be “beaten like copper, and polished like glass; and the Dwarves could make of it a metal, light and yet harder than tempered steel. Its beauty was like to that of common silver, but the beauty of mithril did not tarnish or grow dim.” (FR-II-4) Also known as “true-silver,” suggestions for a modern-day equivalent include platinum and iridium, but both of these elements are extremely “heavy” elements and do not fit the lightweight description of mithril. A closer equivalent might be titanium, that is a light metal, and is relatively strong, with a silvery-color and corrosion resistance. Aluminum and magnesium could also serve, but they are not silvery, and are not as strong as titanium. It is important to note that mithril was always rare in the world of Middle-earth, and the fact Gimli rebuilt the Great Gate of Minas Tirith after the War of the Ring with mithril suggests that he may have found new deposits of mithril ore in the White Mountains, in the Glittering Caves of Aglarond.

The Doors of Moria, on the west side of the Misty Mountains, were jointly built by the Dwarves and the Elves in support of their mutual work and friendship.23 It was at this time that Annatar, Sauron in disguise, befriended the Elves of Hollin, and helped them in the shaping of the Rings of Power. Sauron retained all of the rings thus created, except for the three rings that were made by Celebrimbor alone. Sauron doled out these rings to Men (nine rings) and to Dwarves (seven rings), and these rings were generally alike in power, except that their effects on Men and Dwarves were somewhat different. Men became wraiths, slaves to Sauron’s will, while the Dwarves were not reduced to thralldom…the only effect the rings had on the Dwarves was to increase their greed. When the Elves became aware of Sauron’s intentions, they took their own three rings off, and hid them away. Angered at the Elves’ intransigence, Sauron initiated a war against the Elves. When Sauron marched against them in Middle-earth during the Second Age, he destroyed most of Eriador in the process. Dwarves issued from Khazad-dûm and attacked the rear of Sauron’s forces, however, they were too late to the battle, and could not prevent the destruction of Hollin and Sauron’s capture and torture of Celebrimbor. Elrond Half-elven was dispatched by Gil-galad from Ered Lindon, with elvish troops, to interdict Sauron’s advance, but Elrond’s forces were routed, and forced to take shelter in a well-protected valley on the west side of the Misty Mountains that became the foundation of Imladris. Elrond and his surviving troops remained there, until the Númenoreans sent by the 11th King of Númenor, Tar-Minastir, defeated Sauron and relieved the siege of Rivendell. The Dwarves did not heavily participate in the War of the Last Alliance at the end of the Second Age, and a few actually fought on Sauron’s side, although most of the Dwarves who did fight in that war did so on the side of the Elves and Men.

While deep-mining in Khazad-dûm during the Third Age (1980 TA), the Dwarves awakened a Balrog who had been sleeping there since probably sometime in the First Age. The Balrog drove the Dwarves out of Khazad-dûm, and it was repopulated with orcs, becoming a dark place, and being renamed Moria -- the “Black Pit.” Durin’s folk went to the Grey Mountains and established a mining enterprise there shortly thereafter. The Grey Mountains settlement prospered until 2300 (+/-) TA, when dragons appeared in the North. Other Dwarves left Khazad-dûm and settled in the Iron Hills. Thrór traveled to Mount Erebor, and established a colony there that thrived for over 200 years, until the arrival of Smaug the Dragon in 2770. In The Hobbit, Thorin relates to Bilbo that his grandfather, Thrór, was forced to retreat to Mt. Erebor after being driven from the North (Grey Mountains). Reentering The Lonely Mountain, Thrór and his fellow-dwarves “found a good deal of gold and a great many jewels too,” (Unexpected Party). Erebor itself was mined for gold and jewels, as mentioned above. The cavern in which Smaug resides is an old chamber excavated by the Dwarves. The Dwarves driven out of Erebor moved to the Iron Hills, while a colony was also established in Dunland, a region on the western side of the Misty Mountains, between the northern reaches of Rohan and the Glanduin River to the north, before the Glanduin flows westwards into the Greyflood near the crossing at Tharbad.

In 2790 TA, Thrór attempted to re-enter Khazad-dûm and was killed by Azog, the chieftain of the orcs in Moria. This act initiated the War of the Dwarves and Orcs, a merciless battle in which the Dwarves were ultimately the victors, but were too wounded in the process to resettle Moria. Following the victory at Khazad-dûm, the Battle of Azanulbizar, Thráin II went to the Blue Mountains to reinvigorate the dwarven mine workings there, and to establish his realm. It is specifically stated in the LoTR (Fellowship) that active Dwarf mines were located in the Ered Luin. It is also mentioned in the LoTR and The Hobbit that the Dwarves regularly traveled the Great East-West Road between their mines in the Blue Mountains and their other workings in the Iron Hills and Erebor.

Summary of Dwarven Mine-works in Middle-earth

The following table summarizes the locations and significance of extant and extinct Dwarf iron-works in Middle-earth as mentioned in The Hobbit and the LoTR. The historical events noted in the “Active” column are a highly simplified recounting of the history of these various mining areas.

Dwarven Mining Activity in Middle-earth
Locality Active References Mined Comments
Khazad-dûm FA; SA; TA to ~2000 LoTR Mithril, Iron, Gold, jewels Founded by Durin. Dwarves were forced to flee in 1981 TA. Quite possibly resettled after the War of the Ring in the FO.
Erebor: The Lonely Mountain TA, 2000 to 2770; reestablished in 2941 The Hobbit, LoTR Gold and jewels Settled after the destruction of Khazad-dûm
Ered Luin (The Blue Mountains) FA, destroyed in War of Wrath. Reactivated TA by Thráin II and his son Thorin. LoTR Iron Dwarves first settled here after their awakening. We are certain that iron was a major mining activity, but since the Dwarves were given gifts of jewels from Tirion (by Finrod Felagund), it may be assumed there was a dearth of jewels here.
Ered Mithrin (The Grey Mountains) FA -- limited mining. Orcs took control after War of Elves and Sauron in the SA. Resettled by Dwarves fleeing K-d. in 1981 TA until the arrival of Scatha in 2569 TA. Orc infested by 2941 TA LoTR, Unfinished Tales Iron? There is no specific mention of other metals or jewels. There was some limited mining in the FA. Orcs took control of the Grey Mtns after the War of the Elves and Sauron in the SA. Not actively again worked until the loss of Khazad-dûm forced many Dwarves to settle there in 1981 TA; they were routed by Scatha the Worm about 1900 SA. Fram (Lord of the Éothéod) slew Scatha around 2000 TA.
Iron Hills (Emyn Engrin) FA; no mention of work in the SA, resettled by Dwarves in 1981 TA. LoTR Iron, other non-specified minerals Initially settled by Longbeards, no mention of what happened to the Dwarves in the SA. The area was resettled in 1981, and was active thereafter.
Glittering Caves of Aglarond FO
Jewels, mithril(?), precious ore Settled by Gimli son of Gloin, at the behest of King Elessar. “Gems and crystals and veins of precious ore glint in the polished walls.”
Note: FA = First Age, SA = Second Age, TA = Third Age. FO = Fourth Age, as per J.R.R. Tolkien. K-d. = Khazad-dûm.

The Coal Mining Connection

Having established the location of important mining-complexes in Middle-earth, it is now time to consider how these deposits provide some evidence for the existence of coal-mining activity. It has already been pointed out that coal is a necessary component of the process for working iron ore, and is also used in other metallurgical applications. One might wish that there exists somewhere a description of the plant fossils found in the coals of Middle-earth!

In The Hobbit, there are several references to coal or coal mining. In “An Unexpected Party,” (Ch. 1, The Hobbit), Gandalf tells Thorin & Company “Just let anyone say I chose the wrong man or the wrong house, and you can stop at thirteen and have all the bad luck you like, or go back to digging coal.” Later in the same chapter, Thorin informs Bilbo that following the destruction of Erebor by Smaug the Dragon, surviving Dwarves “had to earn our living as best we could up and down the lands, often enough sinking as low as blacksmith-work or even coalmining.” Unfortunately, there is no specific mention of where this coalmining was taking place, but perhaps it can be reasonably deduced that the Dwarves lived close to the areas they mined, suggesting that coal deposits may have been found around the Dwarf settlements at the end of the Third Age.

This suggests that coal deposits were probably found in relatively close proximity to the mining areas cited above, that is to say, Rhovanion (and areas to the east), Dunland (west side of the Misty Mountains), or adjacent to the Ered Luin. It should be noted that the map of Middle-earth in the LoTR shows the Sea of Rhûn occupies a large area to the east, and may represent a geographic “low-spot” in the middle of a geologic sedimentary basin. Coal, as noted above, is a sedimentary rock, and is associated with thick depositional packages of sedimentary rock found in basinal areas, often adjacent to mountain ranges. This is a typical feature of the coal mining district in the United Kingdom, where coal is located south of the metal ores found in the Caledonides of northern England and Scotland, and the sedimentary Appalachian Basin to the west and north of the Appalachian Mountains in eastern North America. The fact that the Dwarves were actively mining metal ore (iron, mithril, and other metals) in Moria, the Grey Mountains, the Iron Hills, and also in the Ered Luin, suggests that there were sedimentary coal deposits not too far away. That coal and metal ore had to have existed in fairly close proximity to each other is based on the fact that the world of the LoTR is pre-industrial. Railroads and other modern conveyances were simply not available to the Dwarves and other metal-workers in the LoTR. There were few roads available as well, so the long-distance transport of coal to the iron-mining areas (or vice-versa) was not a realistic option.

An Important Piece of the Puzzle: Gems and Jewels

The key word is jewels. There are many references to “jewels” within the Legendarium as a whole, but Tolkien provides few specifics, other than his frequent mention of beryl, an “elfstone.” An understanding of the geologic occurrence of “jewels,” or perhaps better described as well-formed, pure crystals of certain minerals, serves as one part of any consideration of the geology of Middle-earth.

There are three defining characteristics of a gem (jewel), namely, its color, hardness, and rarity. “Precious” gemstones possess all three of these characteristics, while semi-precious possess only two of the three characteristics. For example, the four “precious” gemstones include diamond, ruby, sapphire, and emerald. They all exhibit beautiful (1) colors (except diamond, which is famous for its brilliance, or ability to disperse light), are (2) rare, and (3) hard. Gems of quartz are considered semi-precious, because they display many beautiful colors (1), are indeed hard (durable, 3), but quartz is not particularly rare, although high-quality quartz gems are quite valuable. The crystal form of any mineral is a reflection of its internal atomic structure, and can be beautiful in its own right, but most jewels are faceted (cut) by gemsmiths, to enhance their natural beauty. What is important to a geologist is that the gems and jewels of the world often tell a unique story about their origin. Most gems occur in unique geologic environments and are usually, but not always, associated with igneous and metamorphic rocks. Furthermore, most quality gems and mineral crystals are found in rocks that have been directly formed from or in contact with high-temperature fluids, called hydrothermal fluids, that slowly cool over time allowing for the slow growth of discrete mineral crystals in the cooling fluid. The unique chemistry of these fluids has a direct impact on the color of the various minerals they are likely to produce. Minute changes in the chemistry of a mineral can result in brilliant differences in its color.

Some Igneous Petrology

Igneous rocks are classified by igneous petrologists,10 into four compositional groups, that are gradational into each other. Igneous rocks in appearance can also be fine-grained, with individual mineral grains not discernable to the naked eye, or coarser-grained, with visible mineral particles, some of which may be euhedral, that is, displaying their true crystal form. Without going into too much detail, the four igneous groups consist of felsic, intermediate, mafic, and ultramafic. Each of these groups also consists of both a fine-grained and a coarse-grained end-member, with different grades of grain size between. There are thus eight basic igneous rock types.

The abundance of elements in the Earth’s crust heavily influences the composition of the igneous rocks that make up the crust. The eight most abundant elements, by weight percent, include oxygen (46.6%), silicon (27.7%), aluminum (8.1%) iron (5.0%), calcium (3.6%), sodium (2.8%), potassium (2.6%), and magnesium (2.1%). These eight elements together make up 98.5% of the Earth’s crust. ALL of the remaining elements make up only 1.5% of the crust. Nevertheless, the Earth is large enough that there are, fortunately, considerable amounts of these remaining elements for us to use! After the first eleven elements (in order of abundance), the abundance of an element is usually reported in terms of parts per million, or ppm, and include titanium (5,560 ppm), hydrogen (1,400 ppm), phosphorous (1,050 ppm), manganese (950 ppm), and fluorine (585 ppm). Notice that some of the common elements with which we are familiar, and have been mentioned above, such as the metals copper, lead, tin, silver, and gold, are not even included among the common elements in the crust. We are far less familiar with some of the more common elements in the crust, such as strontium and zirconium, that are, respectively, four times and three times more abundant than nickel, the material used in American coinage. Similarly, the elements cerium, neodymium, lanthanum, and yttrium are far more abundant than the familiar elements tin, tungsten, molybdenum, mercury, silver, and gold. Geologists have noted this fact with interest, and classify the elements into two geologic groups: dispersed and concentrated elements.24 Dispersed elements are found everywhere, but in generally low concentrations, whereas concentrated elements are not found in most places, but are “concentrated” in certain unique geologic environments, allowing them to be economically extracted and used. A kilogram of zirconium, with a crustal abundance of 165 ppm, is currently about $150 per 10 kilograms, while copper, at a concentration of only 60 ppm, costs about $83 per 10 kilograms. Another example, and of great current interest due to its importance in the manufacture of cell phones and magnets, is praseodymium, with a crustal abundance of 9.2 ppm. The going price of praseodymium is $85 per kilogram, whereas you can get tin, at 2.3 ppm in the crust, for $20 per kilogram.

We are fortunate that in the course of geologic time, a lot of the elements that we use in our everyday lives have been concentrated in ore deposits through the chemical differentiation and evolution of the Earth’s crust. The study of the distribution of the elements in the crust, and in the Earth as a whole, is a fascinating investigation into the chemical evolution of our world.

What is important for the geology of Middle-earth, however, is that the presence of these less-common elements is responsible for the staggering array of mineral and gem colors that we see. Consider again the elfstone, beryl. The chemical formula of the mineral beryl is Be3Al2Si6O18, (beryllium-aluminum-silicon-oxygen) and is an economic source for the lightweight metal beryllium. Pure beryl is colorless; however, very small amounts of iron will yield aquamarine, and similarly tiny amounts of chromium or vanadium produce the brilliant green color of an emerald. The addition of manganese to the beryl chemical formula yields morganite, otherwise known as “pink beryl.” In the way of passing interest, the largest naturally occurring, single crystal of any variety at the surface of the Earth is a crystal of beryl that measures 18 meters in length and 3.5 meters in diameter. It weighs approximately 840,000 pounds, and was found, in 1972, in the Malakialina district of Madagascar (Rickwood, 1981).

Given the fact that most of the crust is made up of just eight elements, the minerals that contain these elements are also the most common, known as the rock-forming minerals, and the igneous rocks that are the cooled remains of magma reflect the distribution of these minerals. Felsic igneous rocks have proportionately a great deal of oxygen and silica, potassium, and aluminum, with much lesser amounts of heavier elements, such as iron, magnesium, and calcium. The word “felsic” denotes that rocks in this group contain significant amounts of different types of feldspar (orthoclase and sodium plagioclase), along with quartz (a combination of silicon and oxygen), and muscovite mica. Smaller amounts of biotite and hornblende also appear in felsic rocks. Intermediate igneous rocks contain many of the same minerals, but reduced amounts of quartz and muscovite mica, and an increase in the proportion of biotite, hornblende, sodium plagioclase, and more calcic forms of plagioclase. These minerals contain more iron, sodium, magnesium, and calcium than the felsic minerals. Mafic igneous rocks, although still containing about 50% oxygen and silicon combined, are highly enriched in the heavier elements mentioned above.

Felsic igneous rocks include granite, that contains crystals visible to the naked eye (phaneritic), and rhyolite, where the texture is aphanitic, and the grains are not visible to the eye. Intermediate igneous rocks include diorite (phaneritic), and andesite (aphanitic), while mafic rocks include gabbro (phaneritic), and basalt (aphanitic). The rarer ultramafic rocks include peridotites (phaneritic) and komatiite (aphanitic), and contain, proportionately, the least oxygen and silicon of the igneous rocks.

Mention was made earlier of hydrothermal fluids. Since the eight most abundant elements of the Earth’s crust readily react and form most of the minerals found in igneous rocks, the remaining, high-temperature fluids in the magma that produces the igneous rock are enriched in unusual elements. These fluids are “left-over” as the magma cools, and are under great pressure. These fluids are frequently forced upwards by the pressure surrounding them, and can be injected into a wide variety of cooler rocks at higher, cooler levels in the crust. These fluids will then interact with the rock into which they are injected or simply remain in the crack or crevice into which they were forced. As they slowly cool, individual mineral grains get a chance to grow, and, as noted above for beryl, the size of some of the crystals so produced is staggering.

There are six different kinds of hydrothermal deposits.25 It is far beyond the scope of this chapter to include a discussion on the origin and significance of hydrothermal deposits, except as they relate to Middle-earth geology. Hydrothermal deposits often form a “porphyry.” The word “porphyry” applies to igneous rocks that contain two different sizes of minerals. The larger grains, that are easily visible to the naked eye are called phenocrysts. The finer-grained material surrounding the phenocrysts is called the groundmass, and its crystallinity is poor to non-existent. Occasionally there are porphyrys that contain two different sizes of phenocrysts, This may represent an early, slow-cooling period in which the larger crystals formed, followed by a more rapid cooling that only allowed for the growth of the smaller phenocrysts. Eventually, the hydrothermal fluid that remains was rapidly cooled to form the aphanitic groundmass.

Pegmatites that contain large crystals are a special-type of porphyry deposit, in that there is no real groundmass: the hydrothermal fluid that nourished the pegmatite cooled slowly throughout, and each of the minerals that formed had the chance to express their crystal form, interlocking with adjacent crystals. A pegmatite represents the last remaining hydrothermal fluids contained within a magma, and often is full of rarer elements. Pegmatites are most often associated with felsic to intermediate composition igneous rocks, such as granite, granodiorite, or diorite. Pegmatites can contain huge crystals (Shigley and Kampf, 1984), and in addition to the huge beryl from Madagascar, mentioned in the text above, the Etta Mine from South Dakota, USA, has produced a spodumene crystal that was over 14 meters in length, and almost 1 meter in width. Large garnet crystals about 1 meter (or more) in height and width have been found in Gjølanger, W. Norway, Kristiansand. S. Norway, and the Barton Deposit, Gore Mountain, Adirondacks, USA. Shigley and Kampf (1984) also discuss the Harding pegmatite in New Mexico, USA, and note that it has produced spodumene crystals up to 5 meters in length.26

As noted earlier, since pegmatites are enriched in rarer elements, the minerals produced in a pegmatite are also frequently of a rare variety. To reiterate, the key point is that pegmatites are generally found in felsic (granitic) to intermediate (dioritic) environments. There are mafic and ultramafic pegmatites, but they are quite rare, and are not usually known for producing gemstones. The felsic and dioritic rocks that host gem-bearing pegmatites are often found in the core of a mountain range, as in, for example, the Sierra Nevada Range of the Western Cordillera of North America, the Himalayas, the Appalachians and Caledonides, or the Andes (American Museum of Natural History, 2022). Thus, the dwarven mining of mithril, iron, other metals, and gems and jewels in the Mines of Moria is not unexpected, since iron ore can be found in granite (felsic) and other ultrapotassic (potassium-rich) igneous rocks.

Other Geologic References in The Hobbit and the LoTR

When the Dwarves and Bilbo were enroute to Erebor, it is noted in The Hobbit that the Elves of Mirkwood live in “a great cave within the edge of Mirkwood on its eastern side” (Flies and Spiders). This cave also served as the treasury of the King of the Elves (in Mirkwood). “If the elf-king had a weakness it was for treasure, especially for silver and white gems; and though his hoard was rich, he was ever eager for more, since he had not yet as great a treasure as other elf-lords of old. His people neither mined nor worked metals or jewels, nor did they bother much with trade or with tilling the earth.” This suggests, perhaps, a dearth of pegmatites in eastern Mirkwood (or that Elves were poor miners!).

In the LoTR (Fellowship), the map of The Shire depicts two east-west trending groups of hills -- The Green-Hill Country, and the hills north of Scary, near the Brockenborings and the quarry (FR-I-1, map at start). These two trends occur at a roughly perpendicular orientation relative to the Ered Luin and the Misty Mountains. Since they are noted as being “hills” and not “mountains,” perhaps they represent older uplifts that have been eroded down over time. Such deep erosion and geologic age of the country rock would lend itself to the development of the “good tilled earth” emblematic of The Shire.

As the Hobbits journey through the Old Forest, they climb the top of a hill and see that the land to the southeast of their position falls rapidly. This slope proceeds downwards towards the valley of the Withywindle, and thus the hill that the Hobbits are standing on may be part of the drainage divide between the Baranduin and the Withywindle in this part of the forest. As the Hobbits attempt to travel north from this hill, they are constantly directed southeastwards, towards the Withywindle, aligning their path with the slope direction towards the Withwindle valley. This tendency for a hiker to land up following the slope of the ground is not unexpected, especially in areas that lack well-developed trails and their associated trail blazes.

The Ered Mithrin (Grey Mountains) also occur almost perpendicular to the trend of the Misty Mountains, as do the Iron Hills further to the east. Again, this may suggest that these “ranges” of mountains and hills and represent the older, more eroded remains of earlier mountains.

The map of Middle-earth drawn by Shelly Shapiro (1988) suggests the presence of at least one north-south ridge to the west of the Falls of Rauros, although the text suggests there are several ridges more or less parallel to this north-south trend. The eastern slopes of these ridges tend to be relatively smooth, while the western face is more rugged, and the “deep winding valley” between the ridges is filled with boulders at the bottom. These roughly parallel features may represent upturned sedimentary beds forced upwards by the development of the Misty Mountains to the west. Similar features should be found on the west flank of the Misty Mountains, and this may be hinted at in Tolkien’s description of the land south of Rivendell along the mountains. These ridges would have the same appearance, but here the western sides of the ridges would be smoother, while the eastern edges would be more rugged and steep. Such related structures suggest that as the Misty Mountains were uplifted, they forced the overlying sedimentary rocks into their current structural configuration, with the subsequent erosion of these beds over the top of the Misty Mountains as they were being uplifted. Slightly to the north of Rauros, “the highlands of the Emyn Muil run from North to South in two long tumbled ridges. The western side of each ridge was steep and difficult, but the eastward slopes were gentler, furrowed with many gullies and narrow ravines.” These features are similar to the ridges described above, and would confirm the impact of the Misty Mountains orogeny on the adjacent sedimentary rocks. This will be further discussed below, when considering Middle-earth in terms of Plate Tectonics.

This general rise in the level and ruggedness of the landscape is echoed by Merry and Pippin’s approach to the Old Forest, as Tolkien notes that “The ground was rising steadily” as Merry and Pippin enter Fangorn; and they see “before them, but some distance off, there stood a green hill-top, treeless, rising like a bald head out of the encircling wood.” Not an unexpected feature as one approaches a larger mountain range.

As Merry approaches Edoras in the company of King Théoden and the Riders of Rohan, he is “borne down by the insupportable weight of Middle-earth.” Many geologists feel this at times, as they survey their years of labor in furthering the understanding of our own Arda. What a delightful turn of phrase for any student of the Earth!

In his description of the vertical wall of rock that divides Minas Tirith in two, and juts out from the eastern side of Mount Mindolluin, Tolkien does not provide, as usual, any clue as to the nature of this striking outcrop. It may represent a dike of some type, perhaps resulting from the intrusion of a granodioritic magma into the core of the Ered Nimrais (the White Mountains), from which the adjacent country rocks have been eroded away. Without any further specific geologic information, the above interpretation is speculative. Tolkien does state, however, that this outcrop is tall: he notes that the peak of the rock dividing Minas Tirith is 700 feet above the first level of the City, in which the Great Gate is built (RK-V-1). Mt. Mindolluin is stated to be the easternmost peak of the Ered Nimrais.

Of equal importance is the fact that Tolkien describes the “deep purple shadows” of the high glens of Mt. Mindolluin. Mountains that expose granite or granodiorite outcrops that contain orthoclase often appear purplish from the distance, as in “the purple mountain majesty” of the Front Range of Colorado, overlooking the western portion of the Great Plains Province, as noted in the song “America the Beautiful",27 and that was originally entitled “Pike’s Peak,” a prominent peak west of Colorado Springs, Colorado, in the Front Range. Robert Foster, in The Complete Guide to Middle-earth (2001) confirms the bluish appearance of Mount Mindolluin by noting that its meaning in Sindarin is minas + dol + luin, or “towering-head-blue.”

Mt. Orodruin could, as described by Tolkien, “pour forth rivers of molten rock from chasms in its side.” Tolkien also notes the presence of “a long cave or tunnel that bored into the mountain’s smoking cone.” As noted earlier, this tunnel could be the remnants of a natural lava tube, perhaps enhanced by Sauron’s minions in his quest to forge a path to the Cracks of Doom inside the cone.

A discussion of igneous activity in and on the crust of the Earth often requires one very long chapter (or several shorter chapters!) in an introductory-level textbook in geology. For our purposes here, it is only important to note that igneous activity is conveniently divided into two types: extrusive and intrusive. Volcanoes and their associated geologic features are extrusive, in that the magma forming the volcano rises to the surface where it is expelled from the ground in a variety of volcanic landforms, largely dependent on the chemical nature of the magma (felsic-intermediate-mafic) and the geologic setting in which the volcanism occurs. Intrusive igneous activity never reaches the surface, but has an extremely important role in the formation of mountains, and is volumetrically more significant. As a result of their geologically very rapid expulsion from the Earth, extrusive igneous rocks tend to be finer-grained, or aphanitic, with no discernible crystals visible in the cooled rock. Intrusive igneous rocks, on the other hand, cool slowly, as their cooling is retarded by the overlying mantle of rock that insulates and retains the internal heat of the magma for longer periods of time, allowing for individual crystal growth. In very general terms, extrusive igneous activity is usually common for mafic magmas, but can develop with intermediate or felsic magmas. Intrusive activity is more common for felsic to intermediate rocks, although again, there are occurrences of intrusive mafic igneous rocks. What is important here is that Tolkien’s descriptions of Mount Doom, the Ered Lithui (Ash Mountains), and the Ephel Dúath are indicative of a mafic to intermediate magma, which in turn suggests that the origin of the magma may be typical of a continental volcanic arc, in which subducting oceanic crust remelts and the magma produced, being less dense than the surrounding environment, is forced upwards to extrude on the surface. The Andes Mountains of South America are a continental volcanic arc, as are the Cascades of the northwestern United States and adjacent Canada. That Mount Orodruin is still in an eruptive cycle implies that the volcanism of Mordor is of fairly recent geologic origin. It is reported that the Ash Mountains extend about 500 miles from the Morannon to their terminus in Rhûn.

Some Geologic Puzzles

The “Fence” Around Mordor

While the overall origin of volcanism in Mordor may be similar to that of a continental volcanic arc, the orientation of the volcanic ranges surrounding Mordor is problematic. The Ered Lithui and the Ephel Dúath meet at an almost right angle at the Morannon, the gate into Mordor in the northwest corner of that land. Similarly, the range of mountains on the south side of Mordor, identified as part of the Ephel Dúath, also meets the north-south trending segment of the Ephel Dúath at a near-right angle, suggesting that this range makes a 90 degree turn. This is a highly unusual configuration of mountain ranges, and Mordor, as depicted on the various maps of Middle-earth, is “surrounded” by volcanic ranges. This is hard to explain in terms of modern Plate Tectonic Theory, as described below.

The Geographic Extent of the Misty Mountains and the White Mountains

Another “puzzler” is the length and width of the Misty Mountains Range, also known as the Hithǣglir (Sindarin, “mist” and “range”). Some commentators suggest that the northern terminus of the Misty Mountains is Mount Gundabad, one of the ancestral homes of the Dwarves, and extends southwards (more or less) to Methedras, that overlooks Isengard, and lies between Eriador and Rhovanion. However, the maps attached to the LoTR show that the range actually extends further north than Mount Gundabad, bending slightly towards the northwest. There is near unanimous opinion, based on Tolkien’s words themselves, (TT-III-4) that the Misty Mountains end at Methedras. It should be noted that Tolkien states not once, but two times in the same chapter that Methedras is at the southern end of the Misty Mountains. Merry tells Pippin that the peak that they see in the distance is Methedras, and that the Ring of Isengard “lies in a fork or a deep cleft at the end of the mountains.” This statement, however, may apply to the geographic, not geologic terminus of the Misty Mountains. A little later, Pippin, sitting in the arms of Fangorn, sees “the great cleft at the end of the mountains,” namely, the Misty Mountains. The distance from Mount Gundabad to Methedras is reportedly 800 miles (almost 240 leagues), and would be greater if one considers the northwestward extension of the mountains from Mount Gundabad.

There is mention in both The Hobbit and the LoTR of the “High Pass” that crosses the Misty Mountains above Rivendell, and serves as a passage for the Great East-West Road between Rhovanion and Eriador. Legend states that the High Pass was created by the Vala Oromë, sometime before the First Age28. Be that as it may, and lost in the mists of legend, the High Pass is frequently described as snow-covered, particularly in the winter, and is so depicted in many illustrations. There is no extant reference that states that the mountains are always snow-covered. This would suggest, but does not ensure, that the High Pass lies above the treeline of the Misty Mountains, although this is not required for the pass to be seasonally snow-bound. If this is the case, then one must wonder why the passage through the Mines of Moria from the West Gate to the East Gate only extends a distance of 40 miles (about 11 leagues, FR-II-4). This is an incredibly short distance for such a major mountain range, and there are no modern geologic analogues. Comparing the Misty Mountains to other snow-capped mountain ranges on Earth today shows that the latter have widths measured not in tens of miles, but in hundreds of miles. One would expect foothills on either side of a major mountain range, and this is, in fact, suggested in the LoTR (FR-II-3, TT-III-4), As noted above, there is mention of several north-south ridges paralleling the Misty Mountains west of Rauros, and the description of the trail the Fellowship took upon leaving Rivendell indicates that there were foothills on the west side of the Misty Mountains as well. Even so, including associated foothills, the stated width of the Misty Mountains begs incredulity, considering their purported height.

As noted above, the Misty Mountains are clearly stated in the LoTR to terminate at Methedras. That is somewhat confusing, in that the published maps of Middle-earth suggest a clear connection between the White Mountains east of Isengard and the Misty Mountains. A look at the LoTR maps shows that there is indeed a spur of the White Mountains that extends northwestward, towards the Misty Mountains. This northwestwards trending spur could suggest that there might be some geologic (structural) connection between the Ered Nimrais (White Mountains) and the Misty Mountains. The Gap of Rohan does appear to lie on a saddle between the Misty Mountains and the northern spur of the White Mountains to the south. The stronghold of Helm’s Deep, originally constructed by the Men of the West (Númenoreans who settled in Gondor), was maintained by the Rohirrim after they were granted the lands of Calenardhon by the 12th Ruling Steward of Gondor, Cirion, in 2510 T.A., is located in this northwestwards spur of the White Mountains. There are several spurs of the White Mountains that extend southwestwards from the main range on the southern side of the mountains. If the Misty Mountains and the White Mountains are, in fact, structurally connected, then the extension of the geographic White Mountains to the west of Isengard may represent an older orogenic event that was located to the west of the suture zone that formed the Misty Mountains.

Some commentators have noted that the White Mountains were perpetually snow-covered, but were not as high as the Misty Mountains. Again, there is no firm evidence for this in the LoTR, but it is noted that available maps of Middle-earth show no passes over the Ered Nimrais. One must simply go around them, or under them (in one day), as did Aragorn, Gimli, and Legolas along with Halbarad and the Dúnedain of the North, Elladan, and Elrohir. If the White Mountains were always snow-covered, their height would have been at least 4,000 meters (approximately 13,000 feet). However, Aragorn and his party managed to walk through the White Mountains in the matter of only one day on their epic journey through the Paths of the Dead. Again, this leaves one with a similar “Misty Mountain Problem:” it is difficult to conceive of such a tall mountain range possessing such a relatively narrow width.

Misty Mountains and Modern-Day Mountain Ranges on Earth
Range Length (Mi) Width (Miles) Width (Km) Leagues
Misty Mountains, Middle-earth 796 40 64 11
Ered Nimrais, Middle-earth 600 The passage of the Paths of the Dead is only one day
Appalachian Mountains, N.A. 2,000 100-300 160-482 29-86
Rocky Mountains, N.A. 3,000 70-300 110-482 20-86
Cascades, N.A. 260 100 160 29
Zagros (Iran, Asia) 990 150 241 43
Himalaya Mountains, Asia 1,550 125-250 201-402 36-71
Caledonides (Europe) 1,625 75 115 21
Tien Shan (Asia) 1,550 300 482 86
Kunlun (Asia) 1,250 125 202 36
Atlas (Africa) 1,600 75 115 21
Alps (Europe) 750 120 200 34
N.A. = North America

Additional Meteorological Evidence

The atmosphere of the present-day Earth includes several large cells that dominate the weather patterns on the surface. Broadly speaking, in the equatorial regions of the Earth, warm, moist air rises from the oceans and lands in this zone, and as the moist air rises, it cools, producing huge amounts of rain that fall back to Earth and provide the rainfall needed to support the lush jungle forests typical of the equatorial area. As this warm, moist air mass rises, the water is ”wrung out” of the air mass, and the dryer, now somewhat cooler air begins to move laterally away from the Equator, that is, towards the north and south. The rising air mass creates an almost perpetual low pressure zone, accompanied by large amounts of rainfall. This now cooler air descends around 30o North and 30o South; however, this air mass is now very dry, since it lost its contained moisture as it was rising over the equator and surrounding area. As a result, the area surrounding 30o North and 30o South contains most of the world’s present-day deserts, and lies in an almost perpetual high-pressure area, as the downward moving air mass forces itself towards the Earth’s surface. Low pressure areas are associated with rainfall, while high pressure areas, at the Earth’s surface, tend to be dry. Thus, the equatorial regions are in a low-pressure zone, and the deserts of the world are located in a high-pressure zone. The two cells of moving air that rise at the Equator and sink around 30o North and 30o South are known as Hadley Cells.

A similar process is at work to the north and south of the Hadley Cells. A low-pressure area exists around 60o North and 60o South, marked by high amounts of precipitation as moist air is carried aloft, and quickly cools. As these air masses rise, they are deflected both to the north and to the south. Known as Ferrel Cells, these air masses converge with the Hadley Cells around 30o North and 30o South, adding to the dry air moving downward towards the Earth’s surface. Approximately half of the rising air masses of the Ferrel Cells are deflected either further north (for the northern hemisphere Ferrel Cell) or further south (for the southern hemisphere Ferrel Cell). These dry air masses sink back to the Earth’s surface at both the North and South Poles. The polar regions of the Earth are therefore, ironically, actually deserts in terms of annual precipitation: the only reason we associated them with snow is that the limited amounts of snow that fall in the polar regions essentially never melt, and accumulate over time.

Complicating this picture is the fact that the Earth itself is rotating through the air masses that constitute the Hadley and Ferrel Cells. The frictional drag of the Earth’s surface through these air masses produces prevailing winds that have been well-defined over time. Between the Equator and 30o North and 30o South exist the “trade winds” that in the northern hemisphere flow from northeast towards the southwest, and in the south flow from the southeast towards the northwest. Between 30o and 60o North and 30o and 60o South are the prevailing westerlies, that flow from the southwest towards the northeast in the northern hemisphere, and from the northwest to the southeast in the southern hemisphere. The equatorial region itself, where there is little wind, is known as the Intertropical Convergence Zone (ITCZ), and the narrow belt around 30o North and South is known as the Doldrums, or, to a mariner, the Horse Latitudes. This belt is also devoid of significant wind, and sailing vessels tried to avoid becoming caught in the Doldrums. The name “Horse Latitudes” is derived from the fact that during the days of sail, mariners stranded in the Doldrums might be forced to send their precious horses over the side, to reduce the need for water onboard, while waiting for a wind to blow them back to safety. Modern steam vessels, fortunately, have obviated the need for such dire action.

This bit of meteorologic information helps locate Middle-earth in terms of the present-day Earth, a relationship Tolkien tried to establish in creating his national myth for England. The land of the Hobbits, The Shire, is in the “northwest of the old world,” just like England is today. In terms of latitude, The Shire is approximately 750 miles north of Gondor’s latitude, and about 1,000 miles north of South Gondor, on the borders of Harad. This equates to the Shire lying approximately 215 leagues north of Gondor, and 286 leagues north of South Gondor, and a bit further to the latitude of Harad. On a map of today’s world, the southern United Kingdom is 1,332 miles north of Gibraltar, and only about 1,425 miles north of the North African deserts. On Earth today, 30o latitude is approximately 2,070 miles north or south of the Equator. If the deserts of Near Harad are located at about this distance from the equator of Middle-earth, then The Shire would be located at approximately 47o North Latitude, not too far off the latitude of London, the U.K., at 51o North, on the Earth of today. Thus, when Tolkien talks about rains from the Great Sea watering the lands of Eriador, he is talking about the prevailing westerlies that drop rain (and snow) from the North Atlantic Ocean on the lands of Europe to the east. Harad is probably a dry desert because it lies at about 30o North on Middle-earth. Thus, Middle-earth of the LoTR preserves the prevailing wind and climate regimes that occur on our own world, today. This would be in line with Tolkien’s desire to create a national myth for England: a writer cannot stray too far from the realities of this world, our Arda, to realistically link it to a legendary land of yesteryear, such as Middle-earth. Within the world of geology and climatology, Middle-earth becomes similar to our Arda, and the reader is comforted by the fact that the world of the Middle-earth is not too different from her/his own.

III: Putting it All Together

It is essential to understand the evolution of Plate Tectonics on Earth before tackling the plate tectonic architecture of Middle-Earth. As noted earlier, the Theory of Plate Tectonics became widely accepted by geologists in the 1960s through the 1970s, and has since developed into an over-arching “Theory of Everything,” geologically speaking. However, our understanding of the process itself has evolved over time, as has the process itself, as we look at the start of Plate Tectonics in terms of geologic time.

The Earth today can be differentiated into several well-defined layers. The Earth’s layers can be divided on the basis of their chemical composition, or their mechanical (physical) properties. In terms of chemical composition, the Earth is divided into the crust (both oceanic and continental), the mantle, and the core. In terms of mechanical, or physical, properties, the Earth contains four discrete layers: the crust (both oceanic and continental) and the uppermost solid mantle, called the lithosphere, overlying the asthenosphere (essentially the mantle), and the outer and inner core. The well-known “Moho” separates the lithosphere from the underlying asthenosphere. Each of these zones possesses unique geophysical properties that makes them different from each other. This was not always the case, however.

The young Earth was essentially molten at the outset. Several factors were operating simultaneously to heat the Earth, including the friction caused by the coalescing of the planetesimals that formed the Earth, the prodigious amount of heat by radionucleotides throughout the coalescing Earth, and the constant bombardment of the Earth’s surface by other planetesimals. One of these collisions resulted in the formation of the Earth’s moon, when a Mars-sized body called Theia obliquely struck the early Earth. The debris flung out by this impact created a ring of debris surrounding the Earth that later gravitationally coalesced to form the Moon. Theia itself merged into the core of the Earth, resulting in the Earth’s iron-nickel core being larger than that of its sister planet Venus, Mars, or Mercury, the other “terrestrial” planets.

During this early molten phase, the physical and chemical differentiation of the Earth began.

Viktor Goldschmidt29, a brilliant mineralogist and petrologist, is considered the “father” of modern geochemistry, and divided the naturally occurring elements of the Earth into four chemical categories. These categories include (1) the “siderohile,” or iron-loving elements, (2) the “chalcophile,” or sulfur-loving elements, (3) the “atmophile” elements, those that accumulate in the atmosphere as gases due to their volatility, and (4) the “lithophile,” or rock-loving elements, because they readily react with oxygen, forming “lighter” compounds that do not sink into deeper levels of the Earth, and are therefore common in the rocks of Earth’s crust and on its surface. Remember that the lithosphere (the continental and oceanic crust along with the uppermost mantle) is the “rocky” skin of our planet. This is a robust classification scheme, and holds up pretty well, but as with everything geologic, there are many irregularities and odd-occurrences. Uranium, for example, is the heaviest naturally occurring element at the surface of the Earth today. Geophysical considerations would suggest that Uranium, like most other “heavy” elements, would sink to the inner parts of the Earth during its chemical differentiation, but this is not the case. For physio-chemical reasons, uranium (and other similar “heavy” elements) frequently forms compounds with oxygen, and is therefore found more abundantly at the surface that would be normally assumed. In fact, uranium is forty times more abundant than silver in the Earth’s crust. Uranium is more plentiful than antimony, tin, cadmium, mercury, or silver, and has about the same abundance as arsenic or molybdenum…all due to the fact that uranium is classified as a lithophile element. Many other oddities are evident in Goldschmidt’s classification as well, nevertheless, the scheme “holds water” as a general guide to the distribution of the elements in the overall.

The Hadean30 Eon refers to the first slightly-less-than 600 million years of the Earth’s history. During this time, chemical differentiation of the Earth resulted in an accumulation of lighter minerals at the surface, that gradually began to cool over time. This was a slow process, and the early crust was extremely thin, and easily broken into small pieces, or remelted altogether. Frequent volcanic activity resulted in the “outgassing” of the Earth, and volcanoes provided lots of noxious gases, including sulfur dioxide, hydrogen sulfide, carbon dioxide, hydrogen halides, methane, and water vapor, among others. These gases formed Earth’s “second” atmosphere, the “first” atmosphere consisted of the naturally occurring gases and volatiles that were present in the solar system at the time of the Earth’s formation. This early atmosphere was rapidly volatilized and driven off by the Earth’s high heat. As time passed, these small, thin plates began to coalesce to form larger plates. These early plates are today exposed on the shields of a continent. The term “shield” is derived from the nearly circular (shield-like) shape of the Canadian Shield of North America, and represents an area where these ancient continental rocks, usually igneous and metamorphic, are exposed at the surface. Thus the shield represents a region that contains numerous early, small “micro-plates” that amalgamated to form a larger continental mass. The term “craton”31 refers to a larger area, where sedimentary rocks partly cover this older terrain, but the crust remains relatively undisturbed by later tectonic events (mountain building) in the Phanerozoic Era. The shield areas of today’s Earth contain the oldest rocks and minerals yet found on the surface. Modern cratons today are surrounded by “mobile belts” that contain the orogenies that have occurred since the end of the Precambrian, and since the formation of Rodinia, as discussed below.

Gradually, over time, the crust began to thicken, as continuing chemical differentiation provided more and more “light” minerals to be accumulated at the crust. Geologists generally agree today that the crust was thick enough to form longer-lasting “plates” around 3 billion years ago (3 Ga). The heat flow of the Earth was still very high however, and these early, small plates, were jostled around relatively rapidly (in geologic terms), and the resulting collisions resulted in the formation of many small mountain ranges, that were quickly eroded down, and the evidence of their presence is locked up in the interior shields of the continents. These early tectonic collisions affected smaller areas, and can be found worldwide, exposed on shield areas, where Earth’s oldest rocks, formed during the Precambrian, are found.

The European Example

The European continent represents a good example of the growth of a continent over geologic time. The old core of the continent contains two former, smaller cratons that merged together to form what is today called the Russian Platform. To the north, the Baltic Shield that underlies much of eastern Norway, Sweden, Finland, and very northeastern Russia is itself an amalgamation of five, even older Precambrian micro-continents. These smaller plates include the Karelian, Belomorian, Kola, Svecofennian, and the Sveconorwegian terranes. The first three crustal fragments are dated at 3.1 to 2.5 Ga, in the Archean. The Sveconorwegian terrane (Caledonian) is dated at 1.2-1.1, Ga, that corresponds to the Grenville Orogeny in North America. In the south, the Ukraine Shield exposes Archaen and Proterozoic rocks. These two shields fused together to form old Europe. Over time, this continental mass grew through the later collision of Europe with other continental plates. Some of these later mountain-building events included the Hercynian, and the Alpine orogenies.

The North American Example

Like Europe, North America also represents the amalgamation of numerous smaller plates. Prior to the formation of the core of modern North America, there were six small cratons that came together to form the core of modern-day North America. These cratons include the Wyoming, Hearn, Rae, Slave, Nain, and Superior cratons. The Wyoming craton consists of 2.8 to 3.1 Ga gneisses and migmatites (metamorphic rocks) and slightly younger granite (igneous) intrusions, about 2.5 to 2.8 Ga. The Wyoming craton fused with the Hearne, Slave, and Rae terranes to form a western “sub-continent.” The Nain terrane collided with the Superior craton to form an eastern “sub-continent.” The Superior is the largest province within the core of North America, containing rocks dated at about 2.7 Ga. The collision of the greater Wyoming and Superior terranes formed a mountain range known as the appropriately-named Trans-Hudson Suture Zone, in an event known as the Algoman Orogeny. This mountain building event is dated at around 2.0 to 1.8 Ga. The result of these collisions was the formation of what is now called “Laurentia,” the innermost core of the North American continent. Many geologists are currently investigating the formation of an early supercontinent,32 although research is still underway. This first potential supercontinent is poorly delineated and documented, but has been dubbed “Columbia,” and possibly included the proto-cratons of Laurentia, Baltica, Ukraine, Amazon, and Australia. Some geologists have suggested that the Siberian, North China, and Kalaharia proto-cratons were also involved. This supercontinent is dated between 2.1 to 1.8 Ga.

The Mesabi Range of Minnesota was mentioned earlier in the text, and this range represents a somewhat later collision between Laurentia and a volcanic island-arc, known as the Penokean Orogeny (mountain building episode). This orogeny is essentially the last mountain-building episode in this part of the continent.

Modern Plate Tectonics

The first demonstrably “modern” Plate Tectonic orogeny is considered by many geologists to be the Grenville Orogeny, from 1.4 to 1.1 Ga, that is exposed in eastern North America and parts of Scotland, Australia, Antarctica, and Baltica, suggesting that they were all connected at that time. Funny how those plates move about the surface of the Earth! The Grenville Orogeny, that produced the “supercontinent” of Rodinia, was far larger than previous orogenies, as it involved the cores of Earth’s modern plates, and is documented world-wide in scope. Reaching heights at least as great as those of the present-day Himalaya Mountains, and a length of 10,000 km., the Grenville Range must have been an impressive sight...but which is exposed in North America today, with the exception of the Adirondack Mountains of New York, USA, in relatively flat, low landscapes. The Grenville Orogenic Event is represented in Europe by the Caledonian Mountains of Scotland and Scandanavia. Although clearly a product of “modern,” large-scale plate tectonics, outcrops of the Grenville in North America, such as the Adirondacks, are still considered part of the Canadian Shield and the North American craton due to their igneous/metamorphic petrology and intimate relationship with the rest of the Canadian Shield. This is despite the fact that the orogenic events that formed the older parts of the Canadian Shield and Baltica were much smaller.

It should be pointed our here that the later orogenies that produced the Taconic, Acadian, and Alleghenian events in North America are matched by similarly timed orogenies in Europe and Africa. The Hercynian/Variscan Orogeny in Europe was formed simultaneously with the Alleghenian Orogeny in North America, during the late Paleozoic Era.

It is extremely important to note, however, that even though they are geologically old and “stable,” large “intra-cratonic” basins can form within the bounds of a craton. These basins, with their accumulated sedimentary rock “packages,” are usually no more than 16,000 feet deep (4.9 km). Examples in North America would include the Michigan Basin, the Illinois Basin, and the Williston Basin of the Northern Great Plains. Many of these intra-cratonic basins contain coal beds. Sedimentary basins also exist on the cratonic side of a mobile belt flanking the Precambrain core of a continent, such as the Appalachian Basin of eastern North America.

This has great significance for the geology of Middle-earth, and with this short burst of geologic discussion behind, we can focus on Middle-earth, remembering, that like “our” Earth, Arda has a long geologic history.



To begin with, Tolkien’s Middle-earth is a continent-sized world. The maps included in the LoTR suggest that the continent is over 2,000 miles in width at its greatest extent in the North, from Forlindon to western Rhûn. The north-south length of Middle-earth, as shown on the map, is a little less than 2,000, but the continent probably extends further to the south and to the east than is illustrated in the LoTR. The continental size of Middle-earth, similar to the size of Australia, allows for the amalgamation of many smaller plates and “micro-continents” over the course of geologic time.

Most importantly, since Tolkien himself considered his Middle-earth to be a legendary part of our extant Earth today, the tectonic events that have impacted Middle-earth are, in this chapter, correlated with the major geologic events that have created the Earth.

The geologic data presented in the LoTR has been tabulated above. The key mineral localities from that table and the discussion of dwarven mining activity in Middle-earth are recapitulated here.

  (1) Khazad-dûm: mithril, iron, gold, jewels (Misty Mountains)
  (2) Erebor: gold and jewels (isolated)
  (3) Ered Luin (Blue Mountains): iron
  (4) Grey Hills (Ered Mithrin): iron
  (5) Iron Hills: iron
  (6) Aglarond: jewels, precious ore, possibly mithril (White Mountains)

The evidence suggests that Khazad-dûm hosts many pegmatite veins. As noted earlier, pegmatites are most often associated with felsic to intermediate composition igneous rocks, such as granite, granodiorite, or diorite. Pegmatites can contain huge crystals (Shigley and Kampf, 1984), odd mineral assemblages, and often yield a source for many of the rarer elements. The possible presence of mithril in this environment is supported by the latter condition. This further suggests that the core of the Misty Mountains is a felsic, granitic-granodiorite rock, indicative of continent-continent collision, overthrusting, associated metamorphism, and anatexis (remelting) resulting in the origin of felsic intrusions, along with, perhaps, some ophiolites and oceanic crust.

There are two possible explanations for the Glittering Caves of Aglarond in the Ered Nimrais, the White Mountains, each of which poses some geologic “problems.” The LoTR suggests that the Glittering Caves of Aglarond are enriched in crystallized minerals. It is never specified what the mineralogy of Aglarond is, but the two geologic possibilities include calcite or dolomite mineralization, that might be found in a limestone- or dolomite-rich area, or some other mineralogy, perhaps indicative of pegmatite formation.

Limestone deposits in mountainous areas are not unheard of, one example would be the limestone rocks of the Dinaric Alps in Croatia, or the Dolomites of northern Italy, that were probably known to Tolkien. Limestone readily lends itself to the production of what geologists call karst topography, marked by the presence of caves, disappearing streams, springs, sinkholes, and underground drainage. Calcite mineralization can be associated with caves formed in karst, and may give rise to the glittering crystals found at Aglarond. Tolkien probably knew that the Italian Dolomites contained many caves, some of which were abundantly mineralized. Such karst-related caves, however, are usually not “glittering,” but contain typical stalactites and stalagmites, often with a somewhat muddy appearance. Furthermore, other gems and ores are not often found in limestone/dolomite caves.

However, as noted in the text above, it is specifically stated in the LoTR that after the War of the Ring, Gimli the Dwarf rebuilt the Great Gate of Minas Tirith at the request of King Elessar. This gate was rebuilt using mithril. Since the mines of Khazad-dûm were not in operation at this time, and mithril was, as always, exceedingly rare, it is likely that Gimli located additional ores of mithril in the Glittering Caves of Aglarond or somewhere nearby. Furthermore, the crystallization present in the caves suggests the presence of beryl, tourmaline, quartz, topaz, and other semi-precious gems and minerals. All of these factors are suggestive of a felsic intrusion. It this is the case, then the origin of the mithril in the White Mountains is pegmatitic, and the core of the Ered Nimrais has a geologic origin similar to that of the Misty Mountains, that is, continent-continent collision. This also, however, is problematic, in that “caves” are rarely found in granitic or granodioritic, pegmatite-rich areas. This is a clear case where some further “geologic indications” from Tolkien would be deeply appreciated.

The Tectonic Framework of Middle-earth

The Figure below presents the large-scale tectonic architecture of Middle-earth, based upon the arguments presented in the paragraphs above. According to the interpretation presented in the Figure, Middle-earth at the end of the Third Age represents the amalgamation of several smaller “micro-continents,” or plates, that were themselves composed of still smaller continental terranes. The orientation and overall tectonic grain of the continent suggests the operation of both large-scale and smaller-scale Wilson Cycles operating over the course of geologic time. The Misty Mountains represent the culminating orogeny that gave form to “modern” Middle-earth as depicted on the maps provided in the LoTR.


Sedimentary basins are circled in yellow. “M” = Mithlond Basin. “A” = Arnor Basin. “B” = Bree Basin. K.D. = Khazad-dûm. Agl = Glittering Caves of Aglarond. “G” = Esgaroth Basin. Other basins are labelled on the map. The red lines represent approximate suture zones, as the Misty Mountains, for example, is where the Eriador and Rhovanion Plates collided. A similar situation exists for the Ered Nimrais suture zone. The structure and tectonic relationships of the Gap of Rohan are problematic.

To the west of the Misty Mountains, the smaller Mithlond Basin and both the Arnor and Bree Basins are separated by the Emyn Uial, and the Arnor Basin is bounded on the southeast by the North Downs north of The Shire. There may be several small basins, or one larger basin, between the Bruinen (Loudwater) to the east and the North Downs uplift to the west. These basins are bounded on the southwest by the Weather Hills, and a structural high extending eastward towards the the Mitheithel (Hoarwell) and the Trollshaws. Tolkien specifically states that Aragorn and the Hobbits found a southeastwards-trending valley between two hills that took them in the right direction (southeast), but “towards the end of the day they found their road again barred by a ridge of high lands;” (FR-I-12). This suggests an orthogonal ridge(s) trending southwest-northeast, in line with the structural high. This high may also represent the northeastern edge of the Dunland Basin. It is to be noted that Tolkien specifically mentions “the sullen hills” that the Hobbits and Aragorn must travel through after they crossed the Mitheithel on the Last Bridge. The Dunland Basin, located further south on the former Eriador Plate (the Eriador, Beleriand, and Gondor Terranes combined), is a sedimentary basin that contains sediments from the Misty Mountains to the east and the erosion of the older Blue Mountains to the northwest and the Weather Hills-North Downs-South Downs complex to the north. In this regard, it may be geologically similar to the Appalachian Basin of eastern North America, that lies on the cratonic side of the Appalachian Mountain orogenic belt, and contains abundant coal beds (Pennsylvanian age) among other sedimentary rocks. In addition to the sedimentary basins discussed above, there are probably several smaller basins on both the Gondor Plate and the Rhovanion Plate.

The origin of Dol Guldur, near the southwest edge of the Mirkwood Basin, is problematic. The origin of the name gives one clue as to its nature, but not a particularly conclusive one. It is stated that in Sindarin, Dol Guldur means “Hill of Dark Sorcery,’ but its former name, Amon Lanc, is translated as “Bald Hill.”33 Without any further information on its lithology or structural relationships, it is difficult to explain this one hilly/uplifted area in the middle of a sedimentary basin. It is entirely possible that the east-west trending Mountains of Mirkwood, roughly parallel to the Iron Hills and the Ered Mithrin, represent a rejuvenated, older mountain range, that records an old orogeny, possibly related to similar geologic events that led to the uplift of the of the latter. It would be nice to be able to say the same for Dol Guldur, but the fact that the maps clearly show Dol Guldur to be a single, isolated structure argues against a connection with the orogenies further to the north. One possibility may be that it represents a record of hot spot volcanism, although there is no mention in the LoTR or The Hobbit regarding the rocks or other geologic features present at Dol Guldur that would allow for such a conclusion. Another possibility is that it is an inselberg, or a monolith, made up of one type of rock, described as an isolated hill that stands up above the surrounding plain.

Earlier in the text, the importance of coal availability for the smelting of metal ores was considered. The existence of the basins labelled in the figure above, plus the possible existence of other small basins adjacent to major uplifted areas, suggests that coal might have been readily available to miners and metallurgists in the Third Age of Middle-earth. The areal extent of a given basin is not the deciding factor in whether or not a basin contains coal beds, as can be seen by the enormous coal deposits in the relatively small (areally) coal basins of southeastern and south-central Wyoming, USA, such as the Hanna Basin, and the Carbon Basin. Given that low-volatile bituminous coal is required for the production of the coke needed for iron (and other) smelting, it is suggested that the coal in the various basins adjacent to the dwarven mining areas is of Pennsylvanian (Upper Carboniferous) age, that has provided almost all of the present-day Earth’s deposits of suitable bituminous coal required for coking. Sedimentary basins adjacent to orogenic zones and intra-cratonic sedimentary basins both can contain excellent reserves of coal.

Given the geologic tableau illustrated in the figure above, the tectonic evolution of Middle-earth reflects the continuous amalgamation of smaller plates into larger tectonic plates. It is considered here that the Misty Mountains and the White Mountains (Ered Nimrais) are in fact one mountain range formed during the latest major orogenic event in Middle-earth geologic history. Consideration of the tectonic map above suggests that Middle-earth was formed by the collision of two large, continent-sized plates, the Eriador Plate and the Rhovanion Plate, forming the relatively young Misty Mountains-White Mountains mountain range. This further suggests that both of these large plates represent collisions of several earlier terranes, three of which, the Beleriand, Gondor, and the Mordor plate, are indicated on the map.

It may be easiest to consider the formation of both the Eriador and Rhovanion Plates separately, before looking at the collision between them that created the tectonic architecture of Middle-earth.

On that basis, the Table below provides one possible hypothesis concerning the geologic evolution of Middle-earth. The Table keeps events on the Eriador and Rhovanion Plates separate until their collision during the ongoing Alpide-Himalayan orogenic cycle, the last major orogenic event on modern Earth.

Ga stands for giga-years as in billions of years. Ma stands for millions of years.

Geologic Timeline of Orogenic Events on Middle-earth: Age Ga
Age (Ga) Eriador Plate Rhovanion Plate Super-Continent Cycles
3.1 Weather Hills orogeny -- the old core of Eriador “Ur” Supercontinent
2.8-2.12 Subduction of ocean crust beneath Eriador forms the North Downs, some associated continental crust attaches to Eriador from the west A small continental plate collides with Rhovanion to form the mountains to the west of the Sea of Rhûn and the Mountains of Mirkwood.
Kenorland Supercontinent
Banded Iron Formations (BIFs) abundant.
2.0-1.8 Another small plate collides with Eriador forming the Emyn Uial. At the same time, the Dor-en-Ernil & Pinnath Gelin are formed on the Gondor Plate. Collision of an old Forodwaith shield with Rhovanion to form the Ered Mithrin & Iron Hills. Erebor is a granitic intrusion formed simultaneously.
Columbia Supercontinent
BIFs abundant.
1.3-.7 The Beleriand Plate collides with Eriador, forming the Blue Mountains (continent-continent collision) Formation of the Emyn Muil through continent-continent collision between Rhovanion and an unnamed plate.
Rodinia Supercontinent
Formation of Grenville Mountains
Geologic Timeline of Orogenic Events on Middle-earth: Age Ma
Age (Ma) Eriador Plate Rhovanion Plate Super-Continent Cycles
650-500 Collision of the Gondor plate and Eriador. Formation of the mountains to the north and west of the River Lefnui, labelled on LoTR map as the Ered Nimrais, but actually a separate range. Mordor Plate with oceanic and continental crust attaches to Rhovanion, forming the Ered Lithui (continental volcanic arc). Pannotian Supercontinent
335-200 An unnamed plate attaches to Rhovanion south of the present-day Sea of Núrnen. Contiental Island arc volcanism. Pangea
63-30 Collision of the Eriador and Rhovanion Plates to form the Misty Mountains-Ered Nimrais complex. Oceanic crust to the east of the Eriador Plate is subducted to form the still active continental volcanic arc of the Ephel Duath. The collision began in the north, and moved southwards. Alpine and Himalayan Mountain Ranges form, ongoing

As per the Wilson Cycle, when the Eriador craton (including the amalgamated Gondor and Beleriand plates) moved eastward, the oceanic crust to the east of the craton was subducted and formed an early continental volcanic arc that was consumed in the larger continent-continent collision that sutured Eriador to Rhovanion, the last culminating major mountain building episode on Middle-earth. The operation of continent-continent collisions over the course of geologic time provides a source for the numerous pegmatitic, felsic intrusions found throughout the Misty Mountains (Khazad-Dûm, Aglarond), and the collision of Eriador and Rhovanion may have provided the origin of Erebor, another felsic intrusion somewhat isolated from other mountain ranges. It is possible that a Farallon Plate subduction process beneath North America that led to the uplift of the Front Range of Colorado may be operative, and that Erebor represents a distal event related to the formation of the Misty Mountains. The age of the Ered Mithrin-Iron Hills (Archaen-early Proterozoic) complex suggests that this orogenic events occurred prior to the establishment of relatively thick continental crust, and it may represent a sequence of banded iron formations, without felsic magmatism. The Blue Mountains (Ered Luin) are most likely Grenvillian, and may contain felsic and migmatitic zones within their metamorphosed cores, as well as enriched iron deposits.

Middle-earth was no doubt affected by Pleistocene glaciation, as is evidenced by the abundance of field stones used for the construction of homes in the northern parts of Eriador, such as Bree. After his mother, Mabel Tolkien, took her two sons to Birmingham for a family visit in 1896, Tolkien’s father, Arthur Tolkien, died in South Africa. Tolkien was raised in the village of Sarehole, a small village in the countryside only four miles from Birmingham. It has since been subsumed into Birmingham, which itself is the largest city and metropolitan borough in the West Midlands Region of England. The Devensian ice sheet reached a maximum about 27,000 years ago, during the Last Glacial Maximum. This ice sheet reached as far south as the English Midlands, and glacially derived features are present in Birmingham (Gibson, Gibbard, Bateman, and Boreham, 2014). It is entirely possible that the young Tolkien saw buildings and stone walls constructed out of the small boulders and other rocks associated with glacial deposits, including morraines and outwash, and incorporated his memories into his descriptions of The Shire and the neighboring Bree-lands. Pleistocene glaciation also affected the Misty Mountains-Ered Nimrais mountain range, and sculpted some of the passes and other associated features, such as cirques, aretes, horns, and glaciated valleys including paternoster lakes. There is insufficient evidence in the LoTR to suggest evidence for Pleistocene glaciation elsewhere in Middle-earth, but given that The Shire, Bree, and other associated areas were glaciated suggests that a terminal moraine of sorts probably extended across Middle-earth from the Blue Mountains to the Misty Mountains. Alpine glaciation originating in the Misty Mountains moved both east and west, and affected areas adjacent to the mountain range. A second terminal moraine probably extended from the eastern slopes of the Misty Mountains towards the east, and may be observed in Mirkwood and points east. The Gulf of Lhún may represent a drowned glacial valley (estuary) formed by the latest Pleistocene glacier.

IV: Conclusion

As noted in the Introduction to this chapter, specific geologic detail is lacking in the LoTR. Rather than try to create a geologic map of Middle-earth, with detailed lithologic and structural information, including formation names and structural symbols, this chapter has attempted to create an overview of the tectonic architecture of Middle-earth as presented in the LoTR. As Aragorn says to Gimli and Legolas as they consider the evidence concerning the whereabouts of Merry and Pippin after the battle between the orcs and the Rohirrim near Fangorn, “There, that is my tale. Others might be devised.” (TT-III-5). Indeed. Far from being conclusive, this chapter is presented in the hope that the ideas provided above encourage further work and exploration into the geology of Middle-earth.

V: Review of Extant Literature

There exist a sufficient number of articles dealing with the geology of Middle-earth to already require several reviews of the extant literature. A relatively recent blog by Tennant (2012) notes that Howes (1967) analyzed Middle-earth from a purely geomorphologic perspective, but that her analysis was “too far adrift” from the reality of Tolkien’s creation. Tennant (2012) then discusses the work of Reynolds (1974) who presented several detailed maps of Middle-earth that described the geology in terms of Plate Tectonics. Further refinement of Reynolds (1974) work is provided by Sarjeant in 1996. It should be noted that these authors focused on the lands depicted on the maps that accompany the Lord of the Rings, that is, the Middle-earth of the Second and Third Age.

In reconstructing the geology of Middle-earth, Ingles and Orthia (2016) observe that there was a sudden rash of geologic studies about Middle-earth in the early 1970s, followed by a relative dearth of such studies until a reblossoming of interest in the 1990s, and then again starting in the second decade of the 21st Century (2012 on), as mentioned by Tennant (2012). They note with some dismay that most extant investigations of Middle-earth geology avoid inclusion of the greater Arda presented in the Silmarillion and the Ambarkanta, with traditional geologists consigning the history of the lands of East and West Beleriand to the realm of “geologic myth.” While noting the arguments of Ingles and Orthia (2016), this chapter, for the reasons described above, follows the traditionalist view of describing the geology of Middle- earth, and considers only the created geology of the maps that accompany the Lord of the Rings. It is hoped that this chapter will add one more perspective on the geology of Middle-earth that will encourage further research into this matter.



1The exact location of Thangorodrim is equivocal. Tolkien made a drawing of Thangorodrim that suggested it had an elevation of 35,000 feet if it was produced to scale. Tolkien also once stated that Thangorodrim was 150 leagues north of Beleriand, which would have been 450 miles on the Númenorean scale. Both of these values are suspect, as a distance of 150 leagues away from Beleriand would have effectively limited Morgoth’s ability to attack the Elves and Men of that region, and a height of 35,000 for surficial volcanic peaks is very high by current geologic standards. The total height of the Hawaiian volcanic arc (from seafloor to its highest surface expression) is about 33,500 feet (Mauna Kea), that makes it “taller” than Mt. Everest (29,029 feet). There are only four volcanoes in the world that have an elevation of over 22,000 feet. They are the Ojos del Salado, Monte Pissis, Nevado Tres Cruces, and Llullaillaco, all located in the Andes Mountain Range of South America, a continental volcanic arc.

2A detailed account of the history of the publication of the LoTR is provided by Wikipedia, and a portion of the article is given below:

“Although a major work in itself, The Lord of the Rings was only the last movement of a much older set of narratives Tolkien had worked on since 1917 encompassing The Silmarillion, in a process he described as mythopoeia.
    The Lord of the Rings started as a sequel to Tolkien's work, The Hobbit, published in 1937. The popularity of The Hobbit had led George Allen & Unwin, the publishers, to request a sequel. Tolkien warned them that he wrote quite slowly, and responded with several stories he had already developed. Having rejected his contemporary drafts for The Silmarillion, putting Roverandom on hold, and accepting Farmer Giles of Ham, Allen & Unwin continued to ask for more stories about hobbits.”

3Humphrey Carter, in his authorized biography of J.R.R. Tolkien J.R.R. Tolkien: a biography, does not mention any courses in geology as part of Tolkien’s curriculum at Oxford, although this absence does not preclude the possibility that he did, indeed, have one or more courses in that subject. It is interesting to note, however, that Tolkien provides the reader with a very geologic quote, when Gandalf relates Gollum’s story to Frodo. As the hunted Smeagol, now called Gollum, searches for a dwelling after being sent away from this home alongside the Anduin, he looks up at the Misty Mountains and thinks to himself: “The roots of those mountains must be roots indeed; there must be great secrets buried there which have not been discovered since the beginning.” (FR-I-2???) Indeed. Geologists are always searching for the great secrets buried at the roots of mountains, and this quote has found its way to many geologic theses and dissertations.

4Gold (chemical symbol Au, atomic number 79) is one of the densest naturally occurring elements, with a specific gravity of 19.32. For comparison, lead (Pb) has a specific gravity of 11.34, and tungsten (W) has a specific gravity of 19.25. The fact that gold is so relatively dense results in its accumulation in lag, or placer deposits, where the force of a flowing stream is insufficient to move the gold particles downstream. Gold placer deposits are a valued mineral deposit, and are actively sought after, although most of the available gold placer deposits have already been “mined out,” although flakes of gold can still be found in numerous streams originating in the Colorado Rockies, or the Appalachian Mountains of North Carolina, where the panning or sluicing thereof provides an enjoyable summer activity for many. Furthermore, gold is a member of the “native element” family, meaning that it occurs in a pure form in the natural environment, hence the presence of gold nuggets in stream beds. Current geologic investigation for gold deposits focuses more on the appearance of gold in metamorphic and igneous terranes, usually, but not always, of Precambrian age. In addition to its rarity, gold has some amazing characteristics. One ounce of gold can be beaten out to 187 square feet (17 square meters) in gold leaf. Gold can be found along with tellurium, selenium, and bismuth, as well as lead, zinc, tin, and silver.

5The story of Noah’s Flood is so universally known, that it can be considered a part of the human sub-conscious. There is ample evidence that the story that appears in the Book of Genesis in the Hebrew Bible was possibly based on the older Sumerian and later Akkadian epics regarding a god-inspired world-wide flood that had a catastrophic impact on all living things. An excellent account of the origin of the Noah Flood story can be found in the book by Albert Clay and Paul Tice (2003), entitled Atrahasis: An Ancient Hebrew Deluge Story. The Sumerian version of the story includes appearances by Anu, Enlil, and Enki, the gods of sky, wind, and water, respectively, and also discusses the origin of human-kind.

6Alred Wegener was a German meteorologist (primarily), with additional interests in geology, climatology, geophysics, and polar research. He is best remembered for his controversial hypothesis expounded in his book Die Entstehung der Kontinente (The Origin of Continents, 1912) and later republished in his better-known Die Entstehung der Kontinente und Ozeane (The Origin of Continents and Oceans, 1922). At the time of its publication, Wegener’s hypothesis was largely rejected by mainstream geologists, however, interest in his ideas were stimulated in the 1940s and 1950s.
Wegener’s studies in Greenland focused on polar air circulation, and his findings stimulated the discovery of the jet stream. Wegener tragically died while on an expedition to Greenland in November, 1930.

7Consider the Western Interior Seaway that appeared in the western half of North America during the end of the Cretaceous Period (see below) of the Mesozoic Era into the Paleocene Epoch of the Tertiary Period. Also known as the Cretaceous Seaway, or the Niobrara Sea, the sea resulted from the in-flooding of waters from the ancestral Arctic Ocean to the north and the Gulf of Mexico to the south. Over the course of geologic time, this flooding of the low-lying continental areas of the Great Plains and adjacent lands to the west proceeded from the north and south, with the inrushing seawaters eventually meeting in the central Great Plains, and forming a continuous seaway that separated westernmost North America from its eastern half. At its greatest areal extent, the Western Interior Seaway areas reach from easternmost Nebraska, South Dakota, and North Dakota to as far west as easternmost Utah and Idaho. The basal sandstone that marks the beach that was deposited as the seas flooded the land is known as the Dakota Sandstone, of Cretaceous age, and outcrops of this sedimentary unit can be found in eastern Nebraska and throughout the present-day Great Plains as well as the uplifted areas now exposed in Colorado, Wyoming, Montana, and Utah. The information provided above is meant to demonstrate that while flooding of continental areas does occur in the geologic record, it is of limited duration, and affects only already low-lying areas. Mountainous and hilly areas to the east, in “Appalachia,” and to the west, in “Laramidia,” were never inundated by seawater. The uplift of the Black Hills, a mountainous area within the Great Plains, occurred during the general uplift that caused the retreat of the Western Interior Seaway and the uplift of the modern Great Plains to their present elevation. The location of the Black Hills, during the incursion of the Western Interior Seaway, was not a mountainous area at that time, but was part of the greater, flat-lying region of central-western North America. The Black Hills were uplifted in a mountain-building episode, known as the Laramide Orogeny, that affected most of the western United States and adjacent Canada. Further information about the history and evolution of the Western Interior Seaway can be found in Flores and Kaplan (1985).

At Varda's request, further information on Flores and Kaplan (1985):
The Cenozoic Paleogeography of the West-Central United States, ed. by Romeo Flores and Sanford S. Kaplan, 1985, published by the Rocky Mountain Section of the SEPM (It used to be called the Society of Economic Paleontologists and Mineralogists, but is now known as the "Society for Sedimentary Geology," although it still keeps the logo SEPM.) This volume was the third in a series of works, beginning with "The Paleozoic Paleogeography of the West-Central United States," and "The Mesozoic Paleogeography of the West-Central United States." All three volumes were immediately sold out, and can be found in most reputable geology libraries today, used copies may be available as well. The "West-Central United States" includes the Great Plains and the Rocky Mountains, from Montana south to New Mexico. I was the Chairman of the professional paper symposium at which most of the papers in the book were presented orally at the Colorado School of Mines back in the Fall of 1985, shortly after my wife passed away. I have one copy still in my possession.

8Geologic time scale, provided by the U.S. National Park Service, Washington, D.C.

9The Piezoelectric Effect was first demonstrated directly by Pierre Curie and his brother Jacques Curie in 1880. First noted in the mid-18th Century, the effect was studied by, among others, Carl Linnaeus, whose system of nomenclature for living things in the biologic world became known as the Linneaen System. The Curie brothers, using their more refined knowledge of crystal structure, were able to show that certain crystals, such as those of quartz, topaz, and tourmaline, could produce an electric potential if heated or struck. Other crystals (non-geologic) that exhibit the same effect include crystals of cane sugar and Rochelle salt. Quartz displays some of the most pronounced production of electricity, and this phenomenon is the basis for the use of quartz crystals in wrist-watches, hence, quartz watches. Just as quartz will produce a small electric current when struck, it will also vibrate if an electric current is passed across a tuning-fork shaped piece of crystal quartz. It is this latter effect that allows for great accuracy in quartz watches, the power for the electric field causing the quartz to vibrate is produced by a small, replaceable battery.

10As noted in the text, geologists commonly divide rocks into three broad-based categories, namely igneous, metamorphic, and sedimentary. Petrology, literally the study of rocks, can therefore be subdivided to include igneous petrology (the study of igneous rocks), and so on. The word “petrology” is a combination of the old Greek words for “rock” (petros) and “study, or account of” (logos). Igneous rocks are those derived from the cooling and solidification of liquid magma. Metamorphic rocks are rocks (including igneous, sedimentary, and even pre-existing metamorphic rocks) that have been altered by heat and pressure over time. Sedimentary rocks are derived from the solidification of pre-existing particles through the deposition of sediments, followed by compaction and cementation (lithification) with burial. Obviously, there is a continuum between these types of rocks, that is well-represented by the “Rock Cycle” that constitutes an early introduction to the study of geology for most students even today. Further discussion of igneous, metamorphic, and sedimentary rocks is included in the text above.

11A fathometer is an instrument that uses sonar to determine depths to the seafloor. The word “fathom” is derived from the Old English word “fǣthm,” and represents the distance between the fingertips of outstretched arms. The verb sense of “fathom” originated in the 1600s, and was shortly extended to mean probing, or testing, hence its modern usage as a verb meaning to understand something, or get to the bottom of something.

12This meeting was written up by a graduate of Princeton University, J.I. Merritt, who in the Princeton Alumni Weekly summarized how Heezen’s paper may have inspired Hess to think in terms of an alternative model to provide a reasonable model that could support Wegener’s earlier suggestion that the continents had once been joined together.

13Colluvial deposits are those sediments that are accumulated at the base of a slope through the processes of slow, continuous downhill movement due to gravity, rainwash, and/or sheetwash. Alluvial deposits are those deposited by active stream activity, and are associated with river or stream beds. Eluvial deposits are those that are near their point of origin,where they are formed, and have not been moved through colluvial or alluvial processes.

14A modern example of such a volcanic area might be The Valley of Ten Thousand Smokes in the Katmai Nation Park and Preserve, located in Alaska. At this site, the eruption of the volcano Novarupta in 1912 (June 6-8) resulted in numerous ash flows filling the valley. Once the eruption had ended, smoke continued to vent from the many fumaroles in the ash deposits. A fumarole is simply a crack, vent, or any kind of fissure, through which water vapor and volcanic gases, such as sulfur dioxide, or carbon dioxide, can vent to the atmosphere. There are many other examples of such fumarole-rich areas, including The Geysers in Sonoma County, California, or the Salton Sea, also in California.

15Geologists classify volcanoes in three distinctive forms, although, as in many things geologic, the three forms exist on a continuum, and a particular volcano may lie anywhere along this continuum. Nevertheless, the three basic types of volcanoes include cinder cones (explosive), shield volcanoes (“quiet volcanoes,” at least as far as volcanoes go!), and composite volcanoes, that contain both explosive episodes and periods of lava flow. Of the three basic types of volcano, composite volcanoes are most apt to produce lateral vents that could produce lava tubes, as was mentioned in the textural discussion of Shelob’s Lair. The presence of a combination of ash, solidified lava rock, and the potential for lava tubes, suggests that the Ephel Duath might be composed of composite volcanoes. Mt. Orodruin (Doom), however, is specifically mentioned to be a “cone,” suggesting it is explosive in nature, but could still have a magma internal core that produces lava flows, as Orodruin certainly does.

16Volcanic ejecta is classified as ash (less than 1/10th inch), lapilli (“little stones” that range in size from 1/10th inch up to 2.5 inches), and bombs (greater than 2.5 inches). Very large bombs are often called “blocks,” and can be quite large. In 1924, Kilauea (Hawaii) ejected blocks weighing up to 14 tons, and Mount Vesuvius in Italy has ejected blocks that weighed as much as two to three tons, over a distance of up to 200 meters!

17The list of native elements, those chemical elements that can occur in a “pure” form by themselves, is a long one. Metallic native elements include: aluminum (Al), bismuth (Bi), cadmium (Cd), chromium (Cr), copper (Cu), gold (Au), indium (In), iron (Fe), iridium (Ir), lead (Pb), mercury (Hg), nickel (Ni), Osmium (Os), palladium (Pd), platinum (Pt), rhenium (Rh), rhodium (Rh), silver (Ag), tantalum (Ta), tin (Sn), titanium (Ti), vanadium (V), and zinc (Zn). Of these, gold, copper, and silver are most frequently found as native elements. Occurrences of the other elements listed are few and far between. Other elements that can occur as native elements include the metalloids antimony (Sb), arsenic (As), silicon (Si), and tellurium (Te), and the relatively well-known carbon (C, occurring as graphite or diamond), selenium (Se), and sulfur (S).

18The English word “smelt” is a very old word, and is derived from the Proto-Germanic root “smeltana,” to melt. The Old English word “meltan” gave rise to both modern-day “melt” and “smelt,” cf. Dutch “smelten” (to melt), or German “schmelzen,” to melt/smelt.

19The technological advance of humans has been divided into three broad periods of time. The earliest period, dating from about 3.5 Ma (million years ago), is called the “Stone Age,” and is marked by the widespread use of stone tools by early modern humans. The Stone Age was replaced by the “Bronze Age,” when the smelting of copper was developed, and adding various amounts of tin to copper would produce the alloy bronze. The Bronze Age was replaced by the Iron Age, once the smelting of iron ore was achieved. The early part of the Stone Age is referred to as the Paleolithic (“early stone”) and the latter part of the Stone Age is the Neolithic (“new,” or “recent”).

20Igneous petrology has been previously mentioned. The same study applies to sedimentary rocks (“sedimentary petrology,” or, more commonly, “sed pet”). Given its historically significant role in the course of world (and geologic) events, coal has its own field of study within the wider world of sedimentary geology, and its practitioners are known as coal petrographers. The study of coal has revealed that coal is formed within the framework that applies to all sedimentary rock, that is, deposition, burial, dewatering, and lithification, but that coal possesses its own unique lithification process due to the nature of its parent material: plants and associated organic debris. Coal petrographers divide coal into several categories located along what is called the “coal series.” Beginning with peat, the turf-like material found at the surface of the Earth, and consisting of wet, partially decayed plant and/or organic material, the coal series contains steps that reflect the amount of burial dewatering, and lithification that this organic material undergoes. After peat is formed and undergoes initial burial, the increased pressure leads to the formation of lignite (“brown coal”), then sub-bituminous C, B, and A, followed by bituminous C, B, and A. After bituminous A, the next step is semi-anthracite, followed by the final stage of coalification: anthracite coal. Each step of the series is noted by an increase in the energy content of the coal, as more and more water and other volatile gases are removed from the lithifying material. All coal beyond lignite is referred to as black coal. Furthermore, both sub-bituminous and bituminous C and B coals are often referred to as steam coal, or thermal coal, since it is most often used for power generation at electric power plants. Bituminous A, often combined with semi-anthracite, is used for the manufacture of the coke used in the iron and steel-making process. The highest energy content, measured in British Thermal Units (BTU) is found in bituminous A and semi-anthracite coal. The removal of too much of the volatiles in coal, at the anthracite stage, results in the loss of some inherent energy, although anthracite was formerly a highly-sought after rock, due to its usually low sulfur content. Such coal was nicknamed “blue coal” due to the blue flame that was produced when it was burned.

21It is far beyond the scope of this chapter to consider present-day global greenhouse warming, nevertheless, coal plays a big part in the release of carbon dioxide to the atmosphere, and its continued use as an energy source should not be encouraged. Coal is a fascinating material geologically speaking, and our remaining, huge reserves of coal should be left for more appropriate uses in the future than simply be burned to produce electricity today, especially when there are better alternatives available.

22Only nineteen (19) of the Earth’s 91 naturally occurring elements appear at the surface as Native Elements. They are divided into three groups: (1) Metals – platinum, iridium, osmium, iron, zinc, tin, gold, silver, copper, mercury, lead, and chromium, (2) Semi-metals – bismuth, antimony, arsenic, tellurium, and selenium, and (3) Non-metals – sulfur and carbon.

23In discussing the West-door of Moria, Gandalf told the Fellowship of the Ring: “Those were happier days, when there was still close friendship at times between folk of different race, even between Dwarves and Elves.” The “Doors of Durin” were built by the Dwarf, Narvi, and the lettering above the door was inscribed by Celebrimbor of Hollin himself.

24Perhaps this is going a stretch, but in order to properly understand how the mineralogy of the different igneous rocks (and all other rocks, for that matter), it is important to know the abundance of the various elements that make up these minerals. The table below provides the abundance of a select group of the elements that constitute the Earth’s crust.

Abundances of Selected Elements in the Earth’s Crust
Element Weight
ppm Element ppm Element ppm
Oxygen 4.61x105 461,000 Cesium 3.0 Iodine 0.45
Silicon 2.82x105 282,000 Hafnium 3.0 Antimony 0.2
Aluminum 8.23x104 82,300 Beryllium 2.8 Cadmium 0.15
Iron 5.63x104 56,300 Uranium 2.7 Mercury 8.5x10-2
Calcium 4.15x104 41,500 Bromine 2.4 Silver 7.5x10-2
Sodium 2.36x104 23,600 Tin 2.3 Selenium 5x10-2
Potassium 2.34x104 23,400 Tin 2.3 Selenium 5x10-2
Magnesium 2.33x104 23,300 Tantalum 2.0 Bismuth 8.5x10-3
Titanium 5.56x103 5,560 Arsenic 1.8 Helium 8x10-3
Hydrogen 1.4x103 1,400 Germanium 1.5 Neon 5x10-3
Phosphorous 1.05x103 1,050 Holmium* 1.3 Platinum 5x10-3
Manganese 950 Tungsten 1.25 Gold 4x10-3
Fluorine 585 Molybdenum 1.2 Osmium 1.5x10-3
Barium 425 Terbium* 1.2 Rhodium 1x10-3
Strontium 370 Thallium 0.85 Tellurium 1x10-3
Sulfur 350 Lutetium* 0.8 Iridium 1x10-3
Carbon 200 Thulium* 0.52
Zirconium 165 The remaining elements are not listed due to their extreme rarity and lack of definitive data regarding their abundance. The key point of this chart is to show how some familiar, “common” elements are really much “rarer” than what we call the “Rare Earth Elements” (REEs). Most of us are aware of the elements gold, silver, platinum, cadmium (think batteries), tin, tungsten, helium, and molybdenum, to name a few. Yet these elements are LESS abundant than unfamiliar elements like cerium, neodymium, yttrium, lanthanum, and erbium. Barium and strontium are fairly common elements - who would have thought? What is truly amazing is that we can find economic silver and gold deposits!
Chlorine 145
Rubidium 90
Nickel 84
Zinc 70
Cerium* 66.5
Copper 60
Neodymium* 41.5
Lanthanum* 39
Yttrium** 33
Cobalt 25
Scandium** 22
Lithium 20
Niobium 20
Nitrogen 19
Gallium 19
Lead 14
Boron 10 Rare Earth Elements are indicated by an asterisk (*). Yttrium and scandium are considered REEs even though they are not members of the Lanthanide Series on the Periodic Chart. Yttrium and scandium are denoted by a double-asterisk (**).
Thorium 9.6
Praseodymium* 9.2
Samarium* 7.05
Gadolinium* 6.2
Dysprosium* 5.2
Argon 3.5
Erbium* 3.5

For those with an interest in matters financial, the role of the REEs in the modern global economy is tantamount to geopolitical influence. These elements are increasingly used in the production of magnets, cell phones, automobiles (gas and electric), and other high-tech applications. At the present time (2022), the People’s Republic of China is the world’s major supplier of REEs. The REEs are: neodymium, yttrium, cerium, scandium, dysprosium, europium, lanthanum, praseodymium, samarium, terbium, gadolinium, thullium, ytterbium, erbium, holmium, lutetium, and promethium. For what it is worth, a mnemonic device for remembering the REEs that has been popular with college students is “Lately college parties never produce sexy European girls that drink heavily, even though you look.” This is not to say that REE deposits are not found elsewhere, but that the deposits in China are at present the most economically efficient to utilize, and the environmental regulations regarding mineral extraction in China are less stringent than they are in other places where the REEs are found, resulting in lower production costs and greater profitability for the mine operators. Remember that REEs are members of the “dispersed” group of elements, and as a result, areas in which they are enriched are of great economic value. Geologists have a good idea about where additional sources of REEs can be obtained, however, these deposits may not be as economically viable as those in China. Hence, there is a debate about the development of these deposits in the interest of national security for the United States and other Western Nations. In addition to the formerly producing Mountain Pass Mine in California, other notable REE deposits are found in Idaho, Wyoming, Nebraska, Colorado, New Mexico, Missouri, and New York. Some of these deposits can be quite rich, however, the extraction of REEs from the tight bonding of their usual silicate mineral hosts requires extensive (and expensive) separation techniques, along with adequate protection for the environment.

25Hydrothermal mineral deposits come in six varieties: porphyry, skarn, volcanogenic massive sulfides (VMS), sedimentary exhalative deposits (SEDEX), epithermal, and Mississippi-Valley type deposits. Porphyry, skarn, epithermal, and Mississippi-valley type (MVT) deposits are epigenetic, that is, they are formed AFTER the rock in which they are currently located was formed. VMS and SEDEX deposits are syngenetic; they were formed at the same time as the host rock was formed. Porphyrys are commonly found in volcanic island arcs, where they are enriched in gold and copper in andesitic-composition rocks. They are also found on continental volcanic arcs, in a rhyolitic host rock, and are enriched in copper, molybdenum, gold, along with some tin and tungsten. Skarn deposits represent a change in the chemical composition of a rock with the addition of hydrothermal fluids. They are common in felsic to intermediate magmas that are rich in volatiles (chemically reactive elements). Skarn itself occurs in marble and other metamorphosed carbonates, and is enriched in tungsten, tin, molybdenum, copper, iron, lead, zinc, and gold. Epithermal hydrothermal vein deposits are derived from a deeply buried felsic magma body (called a pluton, that serves as a source for the fluids. These deposits can occasionally be formed in mafic rock associations, such as the greenstone belts of the Canadian Shield. Massive sulfide mineral deposits form from an abundance of sulfide minerals that contain chalcopyrite (copper mineral), sphalerite (zinc mineral), galena (lead mineral), acanthite and argentite (silver mineral), and gold. SEDEX deposits form in marine shales, and include ores of zinc, lead, silver, copper, tin, and tungsten. The Mississippi-Valley-type deposits are famous for producing one of the richest lead-zinc mining districts in the world, the Tri-State District of Missouri, Kansas, and Oklahoma. MVT type mineralization also produced the rich fluorite deposits along the Ohio River in southernmost Illinois (Rosiclaire). MVTs form only in limestone or dolomite on shallow marine platforms.

26The world of geologists is still a small one, and with a little work, most students of geology can trace their geologic ancestry through their teachers. When I was an incoming Freshman at Lafayette College, in Easton, Pennsylvania, my first geology professor was Dr. Arthur Montgomery. He was the mineralogy and petrology teacher at the time, and also helped teach the introductory-level course in geology, in which I was enrolled in Fall, 1967. As he was, at that time, approaching retirement after a long career at Lafayette, beginning in 1951, one of his former students, Dr. Raymond Grant, was hired on to serve as the mineralogy instructor, although Dr. Montgomery remained active in the Department. Towards the end of my freshman year, my father arrived to pick me up (I was not yet old enough to drive!), and I took pleasure in showing him the mineral display set up in Van Wickle Hall at the college. As we were looking at the display, Dr. Montgomery came upon us, and presented me with my very first Estwing geologic hammer, that I still have to this day. He explained to my father that I was showing great aptitude for geology, and he hoped that I would remain a major in geology. My Father was somewhat skeptical…he had hopes for me following in the family tradition, and becoming a M.D., or an attorney…but I convinced him. Dr. Montgomery was instrumental in finding, with his partner Ed Over, the Harding Mine in New Mexico, while working for the Titanium Alloy Manufacturing Company (TAMCO), in 1939-41. TAMCO turned down the property, so Dr. Montgomery bought the mine himself…a mine that produced the strategic war element tantaluma, and lithium, that was crucial to the war effort. Over the next few years mining tantalum ore, and then beryl (a source for beryllium), from 1949 to 1959, Dr. Montgomery returned to academia and earned a Ph.D. in Geology under Dr. Clifford Frondel, at Harvard University, in 1951. The mine was eventually closed for economic reasons, but Dr. Montgomery donated the mine to the University of New Mexico in 1978, to be preserved as a museum and point of geologic interest. A deeply religious man, Dr. Montgomery brought aid and comfort to the residents of Dixon, N.M., where many of the mine workers lived. His magnanimity towards his students was legendary, although, as I well recall, his mineralogy final exam, identifying 100 mineral specimens, was one of the hardest tests at Lafayette that I ever took. (Grant, 2019, Ewing, 2000). I was not able to take Dr. Grant’s final mineral identification exam due to a conflict with my Naval Reserve service, so Dr. Montgomery agreed to give me the exam at a slightly later date. In the Fall of my Senior year at Lafayette, Dr. Montgomery invited me and a few of my classmates to travel with him to visit the Franklin-Sterling Hill mine dumps, in order to participate at the 14th Annual Franklin-Sterling Mineral Exhibit (10-11 October 1970) where Dr. Frondel was the featured speaker at the mine dumps. The dumps were open for collecting, of course, and I was able to supplement my earlier collection of the mineral franklinite from inside the New Jersey Zinc mine with some good specimens on this second visit.

aTantalum usually occurs with niobium, however, niobium is about ten times more abundant than tantalum, having an average crustal abundance of 20 ppm, while tantalum has an abundance of only 2 ppm. Still, tantalum is more abundant than Antimony, cadmium, mercury, silver, bismuth, helium, neon, platinum, gold, tungsten and molybdenum. Tantalum is used in the manufacture of electrical capacitors and resistors. Tantalum capacitors are preferred for use in electronic equipment, such as cellphones, computers, cameras, and automobiles.

27The poem “America the Beautiful” was written by Katharine Lee Bates in 1893, and was originally entitled “Pike’s Peak,” the prominent 14,000 footer located to the west of Colorado Springs, Colorado. There were many musical versions prepared, but that composed by Samuel A. Ward became the standard by which the hymn is known today. Interestingly, the tune written by Ward was originally set (1892) to a standard church hymn, however, in 1910 Ward’s melody was attached to the Bates’ poem, and the rest is history, The musical inspiration for Ward occurred as he was on a ferryboat trip from Coney Island, New York, back to his home in Newark, New Jersey.

28Funny....Tolkien states in Return of the King that S..A. = Second Age, T.A. = Third Age, and F.A. = Fourth Age. No mention of First Age. Therefore, this text follows Tolkien’s abbreviation scheme as provided in the Appendices to the LoTR.

29Viktor Moritz Goldschmidt. Born in 1888 to a distinguished Jewish family in Zürich, Switzerland, Goldschmidt’s father, a physical chemist at the Eidgenössisches Polytechnikum, moved to Amsterdam in 1893, Heidelberg in 1896, and finally Oslo, Norway, in 1901. Goldschmidt’s forbears included rabbis, judges, lawyers, and military officers. Completing his dissertation on “The Contact Metamorphism in the Kristiana Region” under the famous Waldemar Christofer Brøgger at the age of 23, Goldschmidt became a docent (Associate Professor) at the University of Oslo in 1912. In 1929, Goldschmidt moved to the University of Göttingen, but the rise of the Nazis in Germany forced Goldschmidt to return to Norway in 1935. The wartime history of Goldschmidt is, to say the least, incredible. On the verge of being transported by the Germans to Auschwitz, he was removed from the transport about to take him to Germany, and then later was aided by the Norwegian underground to escape to Sweden. He later moved in England, in 1943, where he remained for the duration of the war. Although a few scientists in Norway were not happy about his return, since they considered him a traitor for leaving Norway, most were happy to see him in his home once again. However, his health problems dating to the years before the war were exacerbated by his imprisonments, interrogations, and flight during the war years. Although he enjoyed a relatively secure and happy time in England, his health was broken by the war, and he died, in Norway, at the relatively young age of 59. Considered a father of modern geochemistry, The Geochemical Society sponsors a yearly Goldschmidt Conference.

30The Hadean Eon derives its name from the Greek underworld, and ruled by the Greek god Hades. As this period of Earth’s earliest history was marked by extreme heat due to gravitational compression, widespread volcanism, and impacts with asteroids, the Earth’s mostly molten surface did display hellacious appearance. Most of the Earth’s heat of formation is still retained in its inner portions, covered by the insulating blanket of the uppermost Mantle, oceanic, and continental crust (the Lithosphere). The earliest minerals yet found are dated at 4.4 Ga, and there is some evidence that there was, at times, some water present on the surface. No evidence for life on Earth has been found this early in its history, and the earliest recorded appearance of life is contained in rocks that are dated at 3.5 Ga.

31The Craton is defined as that part of a continental plate that is “stable” and has not been subjected to orogenic (mountain building events) since the Late Proterozoic Grenvillian orogeny. While the Grenville certainly represents the first “modern” Plate Tectonic event, its present-day exposure on the Canadian and the Baltic Shields (Sveconorwegian Province) in northwestern Europe relegates it to forming a part of those respective shields. This area has been little modified by subsequent geologic orogenies, although parts of the older Grenville have been exhumed by later tectonic events. The Berkshire Mountains of Massachusetts, the Hudson Highlands of New York, and the Reading Prong of New York, New Jersey, and Pennsylvania (all in the USA) represent exhumation of older Grenvillian rocks at the surface. Still, most of the rocks of the Grenville Orogeny and the even older Archaean rocks exposed on the Canadian Shield are today covered by a veneer of sedimentary rock that forms the craton of North America. In Africa, the entire continent is pretty much a craton, overlying four older “micro-continents” that coalesced to form modern Africa. These four shield areas at the West African, Congo, Kalahari, and Tanzania shields, that are covered by sedimentary rocks between them. As a result of Plate Tectonics, the West African shield has a "mirror image” in the Amazonia Shield of South America, and the Congo Shield is represented by the São Francisco Shield in Brazil. The Kalahari Shield in Africa was connected to the Rio de la Plata Shield in Uruguay and southern Brazil. It is important to note that although the cratons are generally geologically “stable,” large relatively shallow basins can and are found on cratons. Examples in North America include the Michigan Basin, Illinois Basin and the Williston Basin, among others.

32A “supercontinent,” such as Rodinia, is defined to be an amalgamation of most of the extant continental plates at the same time. Including the proposed “Columbia” Supercontinent (also referred to as the Nuna or Hudsonland), there have been four supercontinents assembled on Earth. The first, Columbia, is dated at 2.5 – 1.5 Ga, and broke up around 1.5 – 1.35 Ga. The next supercontinent, Rodinia, is dated at about 1.3 – 0.9 Ga, and, as noted in the text above, is represented by, among others, the Grenville Orogeny. Following the breakup of Rodinia in 750 – 633 Ma, the Pannotia supercontinent was assembled around 600 – 550 Ma, and covers the very beginning of the Paleozoic Era, in which we can well document the development of life through fossil remains. The Pannotia Supercontinent broke up around 500 Ma, and was followed by the formation of Pangea, around 335 Ma, and is the latest, and therefore youngest, of the supercontinents. The present-day Earth is still involved in the breakup of Pangea. Interestingly enough, Pangea was the first supercontinent recognized by geologists, and its name was given to it by none other than Alfred Wegener. “The name "Pangaea" occurs in the 1920 edition of Die Entstehung der Kontinente und Ozeane, but only once, when Wegener refers to the ancient supercontinent as ‘the Pangaea of the Carboniferous’” (Wikipedia, 2022).

33Here is an intriguing thought: J.R.R. Tolkien was probably familiar with the highly popular musical composition composed by Modest Petrovich Mussorgsky (1839 – 1881). Entitled “Night on Bald Mountain,” the piece depicts a nocturnal gathering of witches, sprites, and other devilish creatures on the summit of Bald Mountain in Russia, who dance until the first light of dawn. This piece is similar in concept to the piece written by Camille Saint-Saens (1835 – 1921) who composed “Danse Macabre” in 1874, but the Mussorgsky title is so much more apropos of Dol Guldur. What better inspiration could there be for the devilish activities of the Necromancer in his fortress of Dol Guldur, the ”Naked Peak?”