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Article 8: The Geology of Middle Earth PDF Print E-mail
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Written by monks   
Monday, 14 August 2006 06:18

Much of the following is paraphrased from Sarjeant’s paper:
‘The Geology of Middle-earth’ presented at the .
Apart from the detailed breakdown of the plates (diagrams) and their movements Sarjeant (and Reynolds) offer specific geomorphologies and explanations.
 In this article I presume to have absolutely no knowledge of geology.

bold: M-E locations
italic: more specialised geological terms
bold italic: Real World References


A great internet resource can be found here at the School of Earth Sciences (now part of the School of Earth and Enviroment), Leeds University, UK (incidentally Tolkien had a Professorship at Leeds in the 1920s).

The first thing one notices about the north-west of Middle-Earth, is the abundance of rivers flowing north-east to south-west (or east-north-east to west-south-west) such as the Baranduin and Gwathlo. These indicate the presence of major faults. As much of the visible consequences of plate interaction involves the production of faults (and other deformations such as folds and strain), that’s a good place to start.

There are three (or four) basic types of faults. They are classified according to their direction of movement in relation to the orientation of the fault. Bear in mind that in reality, plate interactions consist of somewhat more complex interactions.

Normal Fault
 The movement of the plates follows the gravitational influence on them with respect to the fault plane.  The exposed upward block forms a cliff-like feature known as a fault scarp. A scarp may range from a few to hundreds of meters in height and their length may continue for 300 or more kilometers (around 200 miles).

For a real world example:
The Grand Teton range is a fault scarp, hence it’s abrupt rise from the surrounding plain. The first image below shows the steep eastern face of the Grand Tetons and another small fault scarp slipping along its flank. Imagine the edge of the downthrown fault block crumpling as it slips causing ‘mini’-scarps along its length. The Tetons have undergone considerable erosion of course, while the more recent, active scarp has not.

Reverse Fault (also known as a thrust fault) Thrust Fault
When thrust faults are exposed on the surface overburden material lies over the main block. They are normally associated with areas of folded surfaces and or mountaineous regions. The dip angles of thrust faults are normally not as steep as a normal fault. Basically the reverse of the normal fault. This forms a thrust fault type expression on the surface with material overlaying other material.



For a real world example:

For a real world example:


Transcurrent (Strike-slip) Fault
 It is called a strike-slip because the strike is the plane running along the length of the fault (as opposed to the dip), and the plates slip along this plane. On the surface, scarps form as hills crossing the fault zone are torn apart by movement over time. Actually anything crossing this fault zone is either slowly torn apart, or offset. Rivers crossing the fault line are called offset streams and are classic signatures of fault activity along the San Andreas. These faults can be very long, the San Andreas is nearly 600 miles long.
 The direction that the plates are moving relative to each other are described as sinistral () or dextral().It’ important to determine this because it impacts on the features produced at the bends on the fault. Here’s a basic summary:
For a more in- depth discussion:

For a real world example:


Fault contacts:  may give rise to the following visual features:
* Typically cut bedding or other features on both sides of the fault.
--compare with unconformities.
* May show abundant small-scale faults.
* May show exposed fault surfaces.
* May contain fault gouge. (Rock that has been ground to a fine powder or clay along faults is known as "fault gouge").
* May show other accompanying "fault rocks" such as breccias (Rock composed of sharp-angled fragments embedded in a fine-grained matrix. Breccia commonly results from processes such as landslides or geologic faulting, in which rocks are fractured. It can also be of igneous explosive origin (e.g., a volcanic breccia) or cataclasites.
* May show increased fracturing.
* May show evidence of hydrothermal alteration.

For more information



There are supposed 6 plates (terranes)[]: Forlindon, Eriador, Forodwaith, Rhovanion, Mordor, Harad.


The Forlindon and Eriador plates are the most ancient of this group and produced the Ered Luin orogeny resulting in the Forlindon plate being subducted beneath the Eriador plate at the continental margin. Forlindon and Harlindon represent the last remnants of the Forlindon plate. In the process, both plates moved north producing many strike-slip faults which have channelled the paths of many rivers, such as the Baranduin and Gwathlo.

Both plates have moved south producing strike-slip faults

[](photo ref)[](technical)[]which give rise to the westward flowing rivers across Eriador.



The Eriador plate collided with the Rhovanion plate producing the Misty Mountains.

Tolkien described the landscape west of the Misty Mountains as:

At the Ford of Bruinen they left the Road and turning southwards went on by narrow paths among the folded lands. Their purpose was to hold this course west of the Mountains for many miles and days. Chapter 3 The Ring Goes South

Folding and crumpling of the land at plate margins is one the results of orogeny.
Depending on how the rock acts to tectonic forces, two types of mountains are formed: block mountains or fold mountains.
Block mountains are created when large areas are widely broken up by faults creating large vertical displacements. The uplifted blocks are block mountains or horsts (See Anduin Rift Valley below). The intervening dropped blocks are termed graben: these can be small or form extensive rift valley systems. This form of landscape can be seen in East Africa, the Vosges, the Basin and Range province of Western North America and the Rhine valley.
Where rock does not fault it folds, either symmetrically or asymmetrically. The upfolds are anticlines and the downfolds are synclines; in asymmetric folding there may also be recumbent and overturned folds. The Himalayas are an example of folding. Over time, erosion can bring about an inversion of relief: the soft upthrust rock is worn away so the anticlines are actually lower than the tougher, more compressed rock of the synclines.

The Eriador plate collided with Harad plate to produce the White Mountains. These two orogenies probably overlapped in time. These three plates form a triple junction []against the stable Rohan Craton.
the 3 plates form triple junction against stable basement rock (Craton)[] of Rohan.

Craton: (kratos; Greek for strength) A craton is a stable continent eroded down to just above sea level. Because continental cratons are composed of light weight rock such as granite they are like a boat resting in water, neither rising nor sinking on their own. They are said to be in isostatic equilibrium. Conversely, mountains of any kind must be held up by something, like heat or a root zone, or they will sink right back into the earth.

The Eriador and Rhovanion plates collided with the Forodwaith plate forming another triple junction. The orogeny produced both the Ered ?Mithrin and their westward extension through the Angmar egion and on towards the Ice-Bay of Forochel. It’s suggested that Mount Gundabad sits at this exact juncture, being a rotated block []of resistant rocks.

Most recently in the region, the rapidly moving Mordor plate has collided with the northern part of the Harad plate and the southernmost part of the Rhovanion plate.
The Mordor plate is bound on the north and south by transform faults,[] their motion initially westward but latterly, and more prolongedly, eastward. Thus the Anduin Rift valley[][Great Rift Valley: ] has formed by the crust being torn apart in an easterly direction. It is bounded by normal faults. [USGS: TECHNICAL: PHOTOS:]At its southern end, the rift valley has buckled against the Harondor craton, turning westward as a consequence.

 There is a problem for me at least with some parts of the plate analysis. Not being a geologist of any description, we should certainly defer to Sarjeant and accept his analysis, but I’m not able to give a narrative of events concerning the plate movements in the area. That’s because I see contradictions, that, as a layman, I cannot explain. Indeed, the contradictions are no doubt nothing of the sort to a geologist.

Anduin Rift Valley

 The rift valley is primarily an area of subsidence,[ ] [IN DETAIL :]especially in the areas of the Gladden Basin and the Nindalf Basin. The Nindalf Basin incorporates marshy areas such as the Dead Marshes, the Wetwang and the numerous mouths of the Entwash. This indicates that this basin []once contained a lake that is now silted up. The interaction of the plates has also produced three horsts (fault bounded elevated blocks) []within the rift. The limits of the basin are determined by horsts; the Emyn Muil to the north and the Emyn Arnon to the south. They control the course, character of the Anduin and dramatic features such as the ‘grey faces’ of Tol Brandir and the Falls of Rauros. Beyond the depression marked by the delta of the Anduin appears the third horst: the mountainous island of TolFalas.


Volcanic Activity.

Volcanos overview[]

Earlier orogenies would have produced volcanic activity. The most recent in the region is associated with the crumpling of the Mordor plate after it collided with the Harad and Rhovanion plates. This has caused fissure vulcanism and explosive activity around it’s the plate’s rim, c.f the landscape that Frodo and Sam experienced attributed in part to mining in the area. For a glimpse of this, one such place is the Namjfall solfatara fields in Iceland.[PHOTOS   MORE PHOTOS]

While Reynolds posited that Udun was a small plate distinct from Mordor, Sarjeant suggests Udun is a vast caldera.[] It’s size relates it to a volcanic event of considerable magnitude such as that of Krakatoa in 1883.[] The only recent volcanic activity in the region is Orodruin. It’s great height in proportion to its basal diameter suggests it was built up rapidly by ‘basic, lava[], scoria [] and ash[]’

There are four hotspots (volcanic activity away from plate margins[] []): Orodruin, Dol-Guldur, Isengard (Orthanc), and Erebor. Note, all are associated with the forces of darkness.

Isengard and Orthanc

To the centre all the roads ran between their chains. There stood a tower of marvellous shape. It was fashioned by the builders of old, who smoothed the Ring of Isengard, and yet it seemed a thing not made by the craft of Men, but riven from the bones of the earth in the ancient torment of the hills. A peak and isle of rock it was. black and gleaming hard: four mighty piers of many-sided stone were welded into one, but near the summit they opened into gaping horns. their pinnacles sharp as the points of spears, keen-edged as knives. Between them was a narrow space, and there upon a floor of polished stone, written with strange signs, a man might stand five hundred feet above the plain. This was Orthanc, the citadel of Saruman, the name of which had (by design or chance) a twofold meaning; for in the Elvish speech orthanc signifies Mount Fang, but in the language of the Mark of old the Cunning Mind.

 The drawings which most closely resemble the final conception in the text are Isengard & Orthanc, plate 164, p 168 J.R.R Tolkien: Artist and Illustrator. And of course the illustration on the dust jacket designs for The Two Towers. 
  Isengard’s black rocks and topography suggest that it is a huge volcanic crater []; Orthanc itself could have been an aiguille (a column of solidified felsic (felsic is a term used in geology to refer to silicate minerals, magmas, and rocks which are enriched in the lighter elements such as silica, oxygen, aluminium, sodium, and potassium.) lava expelled from the vent []during the last eruptions) []. This was found by the Numenoreans and shaped by hands or magic into the tower of Orthanc.

Tolkien’s description is reminiscent of  the volcanic spire produced during the eruption in the Etang Sec crater of Mont Pelee, [,en/
]Martinique []

In October [1902], a lava dome began to rise out of the crater floor. It grew for a solid year into a gigantic shaft in the form of an obelisk. It has been described by many as the most spectacular lava dome produced in historic times. It was 350 to 500 feet thick at its base and it soared to over 1000 feet above the base of the crater floor. It sometimes rose at a remarkable rate, up to 50 ft/day. The huge spine of lava became known as the "Tower of Pelée." At night the sides of this magnificent monolith was marked by traces of red incandescent cracks from the still hot lava in its interior.
At its maximum size, the Tower of Pelée was twice the height of the Washington Monument and equal in volume to the Great Pyramid (Cheops) of Egypt. It finally became unstable and collapsed into a pile of rubble in March 1903, after 11 months of growth. No geologist had ever witnessed the emergence of such an object before.


For more information on these formations see also:


 ‘The land about them grew bleak and barren, though once as Thorin told them, it had been green an fair. There was little grass, and before long there was neither bush nor tree, and only broken and blackened stumps to speak of ones long vanished. They were come to the Desolation of the Dragon, and they were come at the waning of the year.

They marched under the grey and silent cliffs to the feet of Ravenhill. Here the river, after winding a wide loop over the valley of Dale, turned from the Mountain on its road to the Lake, flowing swift and noisily. Its bank was bare and rocky, tall and steep above the stream, and gazing out from it over the narrow water, foaming and splashing among many boulders, they could see in the wide valley shadowed by the Mountain’s arms, the grey ruins of ancient houses, towers, and walls.
“There lies all that is left of Dale”, said Balin. "The mountain's sides were green with woods and all the sheltered valley rich and pleasant in the days when the bells rang in that town." He looked both sad and grim as he said this: he had been one of Thorin's companions on the day the Dragon came.
 They did not dare to follow the river much further towards the Gate; but they went on beyond the end of the southern spur, until lying hidden behind a rock they could look out and see the dark cavernous opening in a great cliff-wall between the arms of the Mountain. Out of it the waters of the Running River sprang; and out of it too there came a steam and a dark smoke. Nothing moved in the waste, save the vapour and the water, and every now and again a black and ominous crow. The only sound was the sound of the stony water, and every now and again the harsh croak of a bird. Balin shuddered.
 The Hobbit: chapter 11, On the Doorstep.

From the description it’s clear that Erebor could have been of volcanic origin. There are a number of volcanoes of similar outline, eg La Tungar of Argentina. Moreover, Smaug’s repose and Bilbo’s tunnel were probably the remains of a lava tube (or braided lava tube complex judging from the multiple exits from Smaug’s cavern in the illustration ‘Conversation with Smaug: The Hobbit) []which the dwarves of the mountain developed. Most convincing of all are Tolkien’s drawings of Erebor, specifically the original dust jacket for The Hobbit, ‘The Front Gate’, and ‘The Lonely Mountain’. Grey was certainly the overriding tones, indeed the final illustration of the Font Gate in the Hobbit loses some of the grey wash that Tolkien applied to the river and the mountain above the gate. ‘which in the block making process became black. The dark wedge on the hill at the left, also solid black in the published illustration, in the original is a grey wash over hatching.’ J.R.R Tolkien Artist and Illustrator pp 135.


Volcano, Hawaii is a prominent example:for more general information of the geomorphology of lava tubes and caves see;

Of course, Erebor was not always like this, but this would represent its pristine geologic state.

Earlier effect of tectonic events abound throughout the north-.west.



Rivendell is situated at the intersection of the Great Gwathlo Fault and the foothills of the Misty Mountains.

"Here it is at last!" he called, and the others gathered round him and looked over the edge. They saw a valley far below. They could hear the voice of hurrying water in rocky bed at the bottom; the scent of trees was in the air; and there was a light on the valley-side across the water. Bilbo never forgot the way they slithered and slipped in the dusk down the steep zig-zag path into the secret valley of Rivendell. The air grew warmer as they got lower, and the smell of the pine-trees made him drowsy, so that every now and again he nodded and nearly fell off, or bumped his nose on the pony's neck. Their spirits rose as they went down and down. The trees changed to beech and oak, and there was a comfortable feeling in the twilight. The last green had almost faded out of the grass, when they came at length to an open glade not far above the banks of the stream.
"Hrnmm! it smells like elves!" thought Bilbo, and he looked up at the stars. They were burning bright and blue. The Hobbit, Chapter 3, A Short Rest.

Tolkien drew two views of Rivendell probably in the early 1930s in pencil crayon which follow the text (notwithstanding the placement of Elrond’s house) closely. They were titled: Rivendell Looking West and Rivendell Looking East. The latter became the final view in the ‘Rivendell’ illustration for the Hobbit. Entrance to the valley is through a precipitous and narrow gorge. Sarjeant compares this entrance to the entrance to the Black Canyon on the Gunnison river, Colorado:


 Tolkien’s depiction of ‘Rivendell Looking West’, is strikingly similar to the above landscape. The rock cleft really is that severe and narrow, levelled off with flat grass covered tops. For more Black Canyon images:

Unlike the Black Canyon, Rivendell, broadens into a fertile valley. We know that the Lauterbrunnen []was Tolkien’s original inspiration.


In his letter to his son Michael he wrote: ‘I am….delighted that you have made the acquaintance of Switzerland, and of the very part that I once knew best and which had the deepest effect on me. The hobbit (Bilbo’s) journey from Rivendell to the other side of the Misty Mountains, including the glissade down the slithering stones in the pine woods, is based on my adventures in 1911…’
‘…but leave many vivid pictures as clear as yesterday…We went on foot carrying great packs practically all the way from Interlaken, mainly by mountain paths, to Lauterbrunnen  and so to Mürren and eventually so to the head of the Lauterbrunnenthal in a wilderness of moraines.
 Studying his drawings, it is patently obvious the Rivendell Looking East, the study for the Hobbit illustration ‘Rivendell’ is based on the Lauterbrunnen.

 Tolkien also states that his inspiration for Celebdil was the Silberhorn (not to be confused with Mount Silberhorn in the Southern Alps of New Zealand) of the Bernese Alps:
 ‘I left the view of the jungfrau with deep regret: eternal snow, etched as it seemed against eternal sunshine, and the Silberhorn sharp against dark blue: the Silvertine (Celebdil) of my dreams.’
TLoJRRT, p391-392.



Helm’s Deep

 The hills drew near, but the tall peaks of Thrihyrne were already dim against the darkening sky. Still some miles away, on the far side of the Westfold Vale, lay a green coomb, a great bay in the mountains, out of which a gorge opened in the hills. Men of that land called it Helm's Deep, after a hero of old wars who had made his refuge there. Ever steeper and narrower it wound inward from the north under the shadow of the Thrihyrne, till the crow-haunted cliffs rose like mighty towers on either side, shutting out the light.
At Helm's Gate, before the mouth of the Deep, there was a heel of rock thrust outward by the northern cliff. There upon its spur stood high walls of ancient stone, and within them was a lofty tower. Men said that in the far-off days of the glory of Gondor the sea-kings had built here this fastness with the hands of giants. The Hornburg it was called, for a trumpet sounded upon the tower echoed in the Deep behind, as if armies long-forgotten were issuing to war from caves beneath the hills. A wall, too, the men of old had made from the Hornburg to the southern cliff, barring the entrance to the gorge. Beneath it by a wide culvert the Deeping-stream passed out. About the feet of the Hornrock it wound, and flowed then in a gully through the midst of a wide green gore, sloping gently down from Helm's Gate to Helm's Dike. Thence it fell into the Deeping-coomb and out into the Westfold Vale.

Helm’s deep is detemined to be another canyon, but set in a limestone landscape []. Sarjeant suggests castle Aigle [] in Switzerland to have a similar situation and fortifications. I’ve never been to castle Aigle but I’m not convinced from the above images. I don’t think there is any obvious real world analogs of Helm’s Deep. As Hammond and Scull say ‘The geography of Helm’s Deep, the stronghold of the Men of the land of Rohan, required even more careful planning.’ because of the details of the battle to be fought there. Therefore the whole locale is more of a set piece rather than a typical place to build a fortification. Peter

Jackson’s movies are reasonably faithful to Tolkien’s sketches, so they’re one reference one could use.
Tolkien’s  pencil sketch ‘Helm’s Deep and the Hornburg’ (J.R.R Tolkien Artist and Illustrator, plate 161, p165) is the most reliable indicator, certainly of the kind of precipitous terrain in the area. Coupled with the existence of the Caves of Aglarond, limestone is the obvious choice.

Gimli speaks of them:

'You have not seen, so I forgive your jest,' said Gimli. 'But you speak like a fool. Do you think those halls are fair, where your King dwells under the hill in Mirkwood, and Dwarves helped in their making long ago? They are but hovels compared with the caverns I have seen here: immeasurable halls, filled with an everlasting music of water that tinkles into pools, as fair as Kheled-zaram in the starlight.
'And, Legolas, when the torches are kindled and men walk on the sandy floors under the echoing domes, ah! then, Legolas, gems and crystals and veins of precious ore glint in the polished walls; and the light glows through folded marbles, shell-like, translucent as the living hands of Queen Galadriel. There are columns of white and saffron and dawn-rose, Legolas, fluted and twisted into dreamlike forms; they spring up from many-coloured floors to meet the glistening pendants of the roof: wings, ropes, curtains fine as frozen clouds; spears, banners, pinnacles of suspended palaces! Still lakes mirror them: a glimmering world looks up from dark pools covered with clear glass; cities. such as the mind of Durin could scarce have imagined in his sleep, stretch on through avenues and pillared courts, on into the dark recesses where no light can come. And plink! a silver drop falls, and the round wrinkles in the glass make all the towers bend and waver like weeds and corals in a grotto of the sea. Then evening comes: they fade and twinkle out; the torches pass on into another chamber and another dream. There is chamber after chamber, Legolas; hall opening out of hall, dome after dome, stair beyond stair; and still the winding paths lead on into the mountains' heart. Caves! The Caverns of Helm's Deep! Happy was the chance that drove me there! It makes me weep to leave them.'
'Then I will wish you this fortune for your comfort, Gimli,' said the Elf, 'that you may come safe from war and return to see them again. But do not tell all your kindred! There seems little left for them to do, from your account. Maybe the men of this land are wise to say little: one family of busy dwarves with hammer and chisel might mar more than they made.'
 'No, you do not understand,' said Gimli. 'No dwarf could be unmoved by such loveliness. None of Durin's race would mine those caves for stones or ore, not if diamonds and gold could be got there. Do you cut down groves of blossoming trees in the spring-time for firewood? We would tend these glades of flowering stone, not quarry them. With cautious skill, tap by tap - a small chip of rock and no more, perhaps, in a whole anxious day - so we could work, and as the years went by, we should open up new ways, and display far chambers that are still dark, glimpsed only as a void beyond fissures in the rock. And lights, Legolas! We should make lights, such lamps as once shone in Khazad-dum; and when we wished we would drive away the night that has lain there since the hills were made; and when we desired rest, we would let the night return.'



 In his letter to P.Rorke,S.J in 1971, Tolkien writes: It may interest you to know that the passage [in reference to the Caverns of Helm’s Deep] was based on the caves in Cheddar Gorge and was written just after I had revisited these in 1940 but was still coloured by my memory of them much earlier…I had been there during my honeymoon nearly thirty years before.TLoJJRT, p407

During the last one million years (the Pleistocene Epoch) Ice Ages gripped most of Britain.  During the cold Glacial phases, sheets of ice up to two miles thick reached as far south as the Mendip Hills.  During the warmer interglacial periods torrents of water were released as the ice melted and escaped south along existing river beds.

 Each torrent of water swept along with it boulders and gravel which scoured out a deep channel, eventually cutting a Gorge 400 ft deep and 3 miles long out of the Hill. 
 The Carboniferous Limestone rock of which the Mendip Hills is formed contains many cracks which also allowed the river to work its way underground, enlarging the cracks into caves.
 The Gorge is a Site of Special Scientific Interest because of the calcareous grassland, Karst limestone butresses and Horseshoe Bats.  Peregrin falcons nest on the cliff face and soay sheep keep the scrub in check.


 The Cheddar Yeo in Gough's Cave is Britain's biggest underground river. The Cathedral-like Caves and Britain's biggest Gorge are million-year-old Ice Age river beds. 
Below: Gough’s Cave:


For some beautiful images of Cheddar Gorge, Somerset and the caves see here:

 Gimli’s ‘glades of flowering stone’, evokes the many speleothems that exist in limestone caves, especially Aragonite crystals. Stone Flower Cave 

[]in Beijing, China is certainly a candidate for visual inspiration, France’s Grotte De Clamouse []and Lechuigilla, Carlsbad, New Mexico, USA []are others. Recently, David Attenborough historically received permission to take a camera crew into Lechuguilla for the BBC’s Planet Earth series. Perhaps Tolkien’s imagination stretched as far as the Chandelier Ballroom, perhaps Gimli’s  ‘groves of blossoming trees’ stretched to this:




 The Ettenmoors lie to the north of the Mithiethel (Hoarwell). Sarjeant describes them as a block of resistant rocks displaced between the Evendim and Minhiriath Faults’.

 The O.E.D defines a moor as: an area of open uncultivated land on acid peaty soil, usually high-lying and covered with heather, coarse grasses. Also known as a heath. A heath is defined as an area dominated by ericaceous shrubs. (erics: a hardy shrub of the genus Erica, with small leathery leaves and bell-like flowers: a heath, or heather).

 The underlying rocks are resistant. While not necessarily having the same geologic evolution as the Ettenmoors, Dartmoor, UK shares similarities as a raised moorland of granite.
Dartmoor, rises to a height of 619m (2,039ft) above sea level. At 248 sq.miles it is the largest of the 6 granite regions which form the spine of the Westcountry. Many of Devon's major rivers rise on the granite uplands, in the bogs high on the moor..

"I am afraid we must go back to the Road here for a while,' said Strider. 'We have now come to the River Hoarwell, that the Elves call Mitheithel. It flows down out of the Ettenmoors, the troll-fells north of Rivendell, and joins the Loudwater away in the South. Some call it the Greyflood after that. It is a great water before it finds the Sea. There is no way over it below its sources in the Ettenmoors, except by the Last Bridge on which the Road crosses.' TFotR, Book I, Chapter 12, Flight to the Ford

 The Ettenmoors may also be what Tolkin refers to as the ColdFells. Fonstad has them as a separate area to the east. The Ettenmoors are not the TrollShaws, they are geographically distinct, as the TrollShaws are wooded and rocky hills.…Gandlaf describes his flight from the Nine'I reached here at last by a long hard road, up the Hoarwell and through the Ettenmoors, and down from the north. It took me nearly fourteen days from Weathertop, for I could not ride among the rocks of the troll-fells, and Shadowfax departed. TFotR, Book II, Chapter 2, The Council of Elrond.



Mineral Deposits (Economic Geology)[]

Mineralisation along plate fault lines is a result of a process called lateral secretion. Ore deposits formed by lateral secretion are formed by metamorphic reactions during shearing, which liberate mineral constituents such as quartz, sulfides, gold, carbonates and oxides from deforming rocks and focus these constituents into zones of reduced pressure or dilation such as faults. This may occur without much hydrothermal fluid flow.
 Correspondingly, the richest mineral deposits in the region are located in Moria, where the Tharbad and Hollin Faults intersect the Misty Mountains, and the shear zones of the Mordor plate; considered to be almost as rich in mineralization as The Dwarrowdelf.

`The wealth of Moria was not in gold and jewels, the toys of the Dwarves; nor in iron, their servant. Such things they found here, it is true, especially iron; 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. The Dwarves have a name which they do not tell. Its worth was ten times that of gold, and now it is beyond price; for little is left above ground, and even the Orcs dare not delve here for it. The lodes lead away north towards Caradhras, and down to darkness. The Dwarves tell no tale; but even as mithril was the foundation of their wealth, so also it was their destruction: they delved too greedily and too deep, and disturbed that from which they fled, Durin's Bane. Of what they brought to light the Orcs have gathered nearly all, and given it in tribute to Sauron, who covets it TFotR, Book II,.Chapter 4, A Journey In The Dark.

Mithril clearly was only found at great depths, probably crystallising out at high temperatures. It may have been a naturally occurring alloy of platinum and another metal, possibly palladium.

Platinum and palladium are metals generally found in ultramafic rocks.
 The source of platinum and palladium deposits is ultramafic rocks which have enough sulfur to form a sulfide mineral while the magma is still liquid. The Earth's mantle is considered to be composed of ultramafic (high mafic content) rocks. The majority of ultramafic rocks are exposed in orogenic belts.
 Mafic minerals are usually dark in colour. Common mafic rocks include basalt and gabbro. In geology, mafic minerals and rocks are silicate minerals, magmas, and volcanic and intrusive igneous rocks that have relatively high concentrations of the heavier elements. The term ‘mafic’ is a combination of "magnesium" and ferrum, the Latin word for iron [ma(gnesium) + f(errum) + ic].
Below left: basalt, below right, gabbro.


For more information on ore deposition processes see:
Ore genesis:


In addition, the following are sites of economic/mineral deposits:
Ered Mithrin:
But Thorin I his son removed and went into the far North to the Grey Mountains, where most of Durin's folk were now gathering; for those mountains were rich and little explored. But there were dragons in the wastes beyond; and after many years they became strong again and multiplied, and they made war on the Dwarves, and plundered their works.
TLotR Appendix A, III Durin’s Folk.

Iron Hills: less rich in mineralization than the Hithaeglir fault deposits. The associated with

North Rhun Fault. It certainly had iron, hence its name but also other ores as their folk traded ores with Erebor.
Also, See Erebor below.

Most of these that escaped made their way into the North, and Thrain I, Nain's son, came to Erebor, the Lonely Mountain, near the eastern eaves of Mirkwood, and there he began new works, and became King under the Mountain. In Erebor he found the great jewel, the Arkenstone, Heart of the Mountain.

but Thror, Dain's heir, with Borin his father's brother and the remainder of the people returned to Erebor. To the Great Hall of Thrain, Thror brought back the Arkenstone, and he and his folk prospered and became rich, and they had the friendship of all Men that dwelt near. For they made not only things of wonder and beauty but weapons and armour of great worth; and there was great traffic of ore between them and their kin in the Iron Hills. Thus the Northmen who lived between Celduin (River Running) and Carnen (Redwater) became strong and drove back all enemies from the East; and the Dwarves lived in plenty, and there was feasting and song in the Halls of Erebor.
So the rumour of the wealth of Erebor spread abroad and reached the ears of the dragons, and at last Smaug the Golden, greatest of the dragons of his day, arose and without warning came against King Thror and descended on the Mountain in flames. It was not long before all that realm was destroyed, and the town of Dale near by was ruined and deserted; but Smaug entered into the Great Hall and lay there upon a bed of gold.
TLotR Appendix A, III Durin’s Folk.

As we know Erebor certainly had gold, and probably other precious metals:
It was therefore perhaps partly by the malice of the Ring that Thrain after same years became restless and discontented. The lust for gold was ever in his mind. At last, when he could endure it no longer, he turned his thoughts to Erebor, and resolved to go back there.

Ered Luin had iron but very little precious metals.
So Thrain and Thorin with what remained of their following (among whom were Balin and Gloin) returned to Dunland, and soon afterwards they removed and wandered in Eriador, until at last they made a home in exile in the east of the Ered Luin beyond the Lune. Of iron were most of the things that they forged in those days, but they prospered after a fashion, and their numbers slowly increased.48 But, as Thror had said, the Ring needed gold to breed gold, and of that or any other precious metal they had little or none.

Shire: coal

White Mts: limestone for building in Gondor.

Shire's White Downs: chalk []R-W REF: Chalk Downs, England []
The word 'down' derives from a medieval germanic or norse word - "dun", a hill.
We can certainly base these down lands on those found in Britain, especially southern England. Tolkien went on a walking holiday in Berkshire and sketched the villages and climbed the downs in his first year as an undergraduate.
Downland is formed when chalk formations are raised above the surrounding rocks. The chalk slowly erodes to form characteristic rolling hills and valleys. As the chalk layer is generally tilted, chalk downland formations typically have a marked scarp slope on one side, which is very steep, and a dip slope on the other, which is much shallower. {link]Where the downs meet the sea, characteristic white chalk cliffs can be formed, such as the White cliffs of Dover and on the Isle of Wight.

Chalk deposits are very porous, so the height of the water table in chalk hills rises in winter and falls in summer. This leads to characteristic chalk downland features such as dry valleys or coombes, and seasonally-flowing streams or winterbournes. The modern practice of extracting water from this 'reservoir', in order to satify demand for water, may be putting some of these streams under extreme stress.
In the valleys below the downs there is typically a clay soil, and at the interface between the two a springline can occur where water emerges from the porous chalk.

Compare the hobbits appraching the Barrwo Downs, there is eveidence of a springline:The afternoon was wearing away when they scrambled and stumbled into a fold that was wider and deeper than any they had yet met. It was so sleep and overhung that it proved impossible to climb out of it again, either forwards or backwards, without leaving their ponies and their baggage behind. All they could do was to follow the fold - downwards. The ground grew soft, and in places boggy; springs appeared in the banks, and soon they found themselves following a brook that trickled and babbled through a weedy bed. TlotR chaper 6, The Old Forest.

 Along this line, settlements and farms were often built, as on the higher land no water was available. This is demonstrated very clearly beneath the scarp of the White Horse Hills, above the Vale of White Horse. In many chalk downland areas there is no surface water at all other than artificially created

Steep slopes on chalk downland develop a ribbed pattern of grass covered horizontal steps a foot or two high. Although subsequently emphasised by cattle and sheep walking along them, these terracettes (commonly known as sheep tracks) were formed by the movement of soil downhill, a process known as soil creep .See picture below


Eastward the Barrow-downs rose, ridge behind ridge into the morning, and vanished out of eyesight into a guess: it was no more than a guess of blue and a remote white glimmer blending with the hem of the sky, but it spoke to them, out of memory and old tales, of the high and distant mountains. Chapter 8, Fog on he barrow Downs.

Their way wound along the floor of the hollow, and round the green feet of a steep hill into another deeper and broader valley, and then over the shoulder of further hills, and down their long limbs, and up their smooth sides again, up on to new hill-tops and down into new valleys. There was no tree nor any visible water: it was a country of grass and short springy turf, silent except for the whisper of the air over the edges of the land, and high lonely cries of strange birds.

Arnor, Hollin, many other regions: good building stone of other kinds.
 Of Hollin:
'That is true,' said Legolas. `But the Elves of this land were of a race strange to us of the silvan folk, and the trees and the grass do not now remember them: Only I hear the stones lament them: deep they delved us, fair they wrought us, high they builded us; but they are gone. They are gone. They sought the Havens long ago.'

Guided by Aragorn they struck a good path. It looked to Frodo like the remains of an ancient road, that had once been broad and well planned, from Hollin to the mountain-pass. The Moon, now at the full, rose over the mountains, and cast a pale light in which the shadows of stones were black.

Many of them looked to have been worked by hands, though now they lay tumbled and ruinous in a bleak, barren land.
Chapter 3, The Ring Goes South.

Shaping of the Landscape:
 The shaping of the landscape is determined by the ‘interplay of structure and rock type with erosion.’ Sarjeant.

The Northern Mountains and the highest mountains of the south, such as the Ered Nimrais have been shaped by glacial erosion [
Below is the Upper Grindelwald Glacier advancing down the Schreckhorn in in the Bernese Oberland, Switzerland. This was the region that Tolkien drew so much of his inspiration for the mountains of Middle-Earth, especially the Misty Mountains The Lauterbrunnen is in the Bernese Oberland, see Rivendell above).


Rocks and sediments are added to glaciers through various processes. Glaciers erode the terrain principally through two methods: scouring and plucking.
As the glacier flows over the bedrock's fractured surface, it softens and lifts blocks of rock that are brought into the ice. This process is known as plucking, and it is produced when subglacial water penetrates the fractures and the subsequent freezing expansion separates them from the bedrock. When the water expands, it acts as a lever that loosens the rock by lifting it.

This way, sediments of all sizes become part of the glacier's load.
Abrasion occurs when the ice and the load of rock fragments slide over the bedrock and function as sandpaper that smoothes and polishes the surface situated below. This pulverized rock is called rock flour. This flour is formed by rock grains of a size between 0.002 and 0.00625 mm. Sometimes the amount of rock flour produced is so high that currents of meltwaters acquire a grayish color

According to Sarjeant, the Misty Mountains are composed of varied rocks, visible in the .Misty Mts:varied rocks:R-W REF:
Nepal Himalayas.
Ephel Duath (Ash Mts) R-W REF: reshaped, result comparable to Grand Tetons, Wyoming (though rocks are disimilar).
Lowlands: glaciation has modified.more info

Sarn Gebir:
The task proved hard indeed, yet in the end it was done. The goods were taken out of the boats and brought to the top of the bank, where there was a level space. Then the boats were drawn out of the water and carried up. They were far less heavy than any had expected. Of what tree growing in the elvish country they were made not even Legolas knew; but the wood was tough and yet strangely light. Merry and Pippin alone could carry their boat with ease along the flat. Nonetheless it needed the strength of the two Men to lift and haul them over the ground that the Company now had to cross. It sloped up away from the River, a tumbled waste of grey limestone-boulders, with many hidden holes shrouded with weeds and bushes; there were thickets of brambles, and sheer dells; and here and there boggy pools fed by waters trickling from the terraces further inland.
One by one Boromir and Aragorn carried the boats, while the others toiled and scrambled after them with the baggage. At last all was removed and laid on the portage-way. Then with little further hindrance, save from sprawling briars and many fallen stones, they moved forward all together. Fog still hung in veils upon the crumbling rock-wall, and to their left mist shrouded the River: they could hear it rushing and foaming over the sharp shelves and stony teeth of Sarn Gebir, but they could not see it. Twice they made the journey, before all was brought safe to the southern landing. Chapter 9, The Great River.

REYNOLDS (quoted and summarised)

'...large areas of Rhovanion east of the Anduin...have been sculptured by these processes for considerable periods:' Iron Hills: may be monadnock remnants of a former higher land surface,Hills near the Sea of Rhun. same as Iron Hills.
Dagorlad:veneer of quartziticregolith, could be a fossilised gravel-covered pediplaned surface.Lowlands in the south: Extensive piedmont glaciation seems unlikely due to lattitude.

White Mts: valley glaciation very important. Overdeepened glacial troughs abound:-
Morgul valley
Morthond Vale
-with overflow channels from one trough to another:Tarlang's Neck

other classic glacial features:

Aretes and Pyramidal Peaks (Horns): Starkhorn, Irensaga.
Lowland and Mountain fringes: Periglacial conditions suggested from unconsolidated materials incorporating coarse regolith.

Northwards: glacial processes become more severe.
Misty Mts: piedmont glaciers fed by Misty Mts stripped large areas of Eriador, producing ill-drained and stony landscape with ungraded tumbling streams.

Caradhras: fine Pyramidal Peak at head of a U-trough whose snows still feed an icy stream, and the

Mirrormere in an ice shaped hollow.

Glacial origin:
Long Lake on River Running
Lake Evendim
hollow occupied by Midgewater Marshes

Shire: extensive fluvio-glacial sands and gravels deposited under periglacial conditions and with localised lowering of groundwater base-level, consequent upon erosion by Gwathlo, Baranduin valley ice-tongues. Erosional deepening of valleys of chalk Downs of Shire: another consequence.

Coast: affected by post-glacial eustatic changes: creating rias, small fjords, flooding low-lying basins (Belfalas)- although delta formation by Anduin has kept pace with that.
Rivers: alluviation:
Baranduin: peats and clays: being famous for turnips and mushrooms.

North: areas of lithologically controlled high relief occur abutting glacially stripped lowlands occupied by bogs
more bogs: Midgewater Marshes and mis-fit streams in glacially-enlarged valleys.
Weather Hills: rugged escarpment
Trollshaws: deeply dissected upland: includes rocks of probably red-bed facies. [Hence Rhudaur; Land of Roaring Red Gold? I presume]

The Carrock: Large erratic.(glacial)
After a good while the eagles must have seen the point they were making for, 'even from their great height, for they began to go down circling round in great spirals. They did this for a long while, and at last the hobbit opened his eyes again. The earth was much nearer, and below them were trees that looked like oaks and elms, and wide grass lands, and a river running through it all. But cropping out of the ground, right in the path of the stream which looped itself about it, was a great rock, almost a hill of stone, like a last outpost of the distant mountains, or a huge piece cast miles into the plain by some giant among giants. Chapter 7 Queer Lodgings Hobbit
Elsewhere riverine erosion predominates.

Subsurface erosion:
Goblin holes (Misty Mts),
Thranduils realm,
Underground lake of Gollum: R-W REF: underlying Australia's Nullarbor Plain.
Glittering Caves of Aglarond: R-W REF:Carlsbad caverns with knobs on! Other deductions:
West Gate of Moria:been cut through a massive volcanic sill-asheet of lava intruded between strata underground, to be brought to the surface by earth movements and exposed by erosion: R-W REF: The

Great Whin Sill, Northern England.
East Gate: staircase below it: traverses a series of beds dipping westward at a low angle like steps, producing the Stair Falls.

Bree-Hill, Weathertop: monadnocks: isolated hills within landscape reduced by river action- almost to a peneplain.
Bree-Hill: lower, sandstone
Weathertop: much higher:more ancientindurated rocks,perhapsslates.


Dr. Mel R. Stauffer and Dr. John Senior (University of Saskatchewan)


Pat McIntosh(1973) on surface outcrops.

Duncan McLaren(1985) and Mike Percival(1985) deal with Numenor

1973. The J.R.R Tolkien Calendar 1973. New York: Ballantine Books, 1972.

1977. The Lord of the Rings 1977 Calendar, illustrations by J.R.R. Tolkien. London: George Allen &

Unwin, 1976.

Howes, Margaret.M. 1967. "The Elder Ages and the later glaciations of the Pleistocene Epoch" in

Tolkien Journal, vol 3, no. 2, pp 3-15, figs. 1-6.

McIntosh, Pat. 1973. "The geology of Middle-earth" in Mallorn, no. 7, pp. 3-7. 1 fig.

McLaren, Duncan. 1985. "Geographical observations on Numenor" in Anor, no. 7, pp. 2-4.

Percival, Mike. 1985. "On Numenor" in Anor, no. 8, pp 4-6, figs. 1-2.

Reynolds, Robert C. 1974. "The geomorphology of Middle-earth" in The Swansea Geographer, vol 11,

pp. 67-71, 1 map.

Sarjeant, William A.S. 1992. "Where did the dwarves come from?" in Mythlore Vol. 19 No. 1 (Winter

1993), pp 43,64.

Last Updated on Monday, 22 January 2007 14:59