The Geology ofMiddle-earth

WilliamAntonySw1th1n Sarjeant

Abstract: A preliminary reconstructionof the geology of Middle-earthis attempted,utilizing datapresented in text,maps and illustrations by its arch-explorer J.R.R. Tolkien. The tectonic reconstructionis developed fromearlier findings by R.C. Reynolds (1974). Six plates are now recognized, whosemotionsand collisions have createdthe mountainsofMiddle-earthand the riftstructuredownwhich theRiver Anduin flows. The stressesinvolved in theplate collisions have producedpattemsoffaults,whoselines have determined the courses of the other rivers and the occurrence of the richest ore deposits.However, the time of Bilbo and Frodo is a period of tectonicquiescence. Volcanic activity is at aminimum and confined to four “hot-spots", all at some distance from plate margins, while seismicactivity is minor. Tolkien’s paintings, in particular, show how glacial and riverine erosionhave shapedMiddle-earth’s topography.

Keywords: earthquakes, erosion, faulting, Middle-earth geology, tectonics, topography, volcaniceruptions

The periodof the rise ofgeology, in the late eighteenthand earth was Margaret Howes (1967), in her surveyof “Theearly nineteenth centuries, coincided with the epoch during Elder Ages and the Later Glaciations Of the Pleistocenewhich this Earth ofours was being fullyexplored for thefirst Epoch”. In this, she strove to trace the successivetime. Most of its explorers were able to fumish quite geographies from the overthrow of Morgoth to a periodaccurate accounts of the geography of the lands they had beyond the time ofAragom’srule in Gondor- indeed, intovisited, but few were trained geologists. The geological the late Pleistocene Epoch, when the geography ofMiddle-informationthoseexplorers brought back tended therefore to earth had been reshaped into present-day Eurasia and northbe incidental and imprecise. Even so, the geologists of their Africa. I-Ierworkwas original and imaginative, but itstrayedhomelanddid their best to utilize these scraps of data, to far from Tolkien, utilizing data of such questionablebegin formulating a picture ofgeologyon a globalscale. authenticitythat,in the last analysis,her conclusionsmustbeIn seeking to elucidate the geology of Middle-earth, our setaside.

task is similar. We have a good general picture of its The truly seminal work on Middle-earth geology wastopography, drawn by Christopher Tolkien on the basis ofthe written by RobertC. Reynolds for The Swansea Geographerinformationfumished by his father,as prime explorer ofthat in 1974. Though entitled “The Geomorphology of Middle-special world. We have also the excellent paintings done by earth", it is much more thanthat, for itapplies the conceptsthe explorer himself, representing his vision ofMiddle-earth of plate tectonics then current to the whole geography ofand published in the 1973 and 1977 Tolkien calendars and Middle-earth (Figure 1).subsequent compilations. In addition,we have the scrapsof Four plates were recognized - the Eriador Plate in thegeological information to be found in The Hobbit and The west, the Rhovanion Plate in the north, and the Harad andLord of the Rings - incidental observations only, but Mordor Plates in the south. The River Anduin wasnevertheless helpful. considered as flowing throughwhat was then styled anIn contrast,the supplementarymaterial broughttogetherin aulacogen and would now be regarded as a rift valley.

the successivevolumes ofThe History ofMiddle-earthmust Reynolds viewed the bounding faults as being transformbe viewed as the equivalent ofa geologist’s field notes - faults, i.e. faults alongwhich movementhad been essentiallyunrevised and not to be trusted; so thismust be discounted. lateral butoccurringat different times in contrarydirections.(In any case, the additional geological information to be He considered the region south ofthe Emyn Muil and northfoundthereinis quiteremarkablymeagre.)Moreover, though of the line oftheWhite Mountains to be a tectonic basin, theit is possible to determine the sequence of tectonic events, Nindalf Basin, while Rohan constituteda stable block oflack of informationconcemingfossilsprecludes any precise ancient rocks - a craton.determination ofthesequence ofstrataand geochronology. lt is Reynolds' work that forms the basis for my ownThe first person to attempta geological historyofMiddle- analysis of the geology of Middle-earth. However, our

THE GEOLOGY OF MIDDLE-EARTH 335

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336 J.R.R. TOLKIEN CENTENARY CONFERENCEknowledge of plate tectonics has grown, and the concepts Basin -itincorporates the Dead Marshes, the Wetwang andhave changed greatly, since Reynolds’ work was published.” the many mouths ofthe Entwash - indicates that this basinMoreover, in my view hepays too small a regardto thenorth oncecontaineda lake, sincesiltedup.andnorth-westofMiddle-earthand to the many major faults, However, the complex interaction of the plates has alsomost ofthem normal faults with a trend from south-westto produced three horsts (fault-bounded, elevated blocks)north-east- usually, indeed, from west-south-westto east- within the rift.Two of these - the Emyn Muil and Emynnorth-east-thatcontrolso much ofMiddle-earthgeography. Amon - respectivelydeterminethe northemand southemMy modifiedconcepts(Figure 2) recognise not four, but limitsof the Nindalf Basin; they control the Anduin’s course

six plates (or in modern terminology, as applied to American and character, producing such dramatic features as TolCordilleran tectonics, six terrans) as being involved in the Brandir, with its “grey faces" of stone (Tolkien, 1954a, p.shaping of Middle-earthgeography. The most ancient of 412) and the Rauros Falls. The third occurs at the rift’sthese are the Forlindon Plate and the Eriador Plate, whose southwestemmost end, forming the mountainous island ofcollision causedthe orogeny-themountain-buildingphase- Tolfalas, beyond thedepressionmarkedby the many mouthsthat produced the Ered Luin or Blue Mountains. Since that oftheAnduin.time, the Forlindon Plate has been largely subsumed; that is, Though no doubt there was much volcanic activityduringdrawn down into a subduction zone at the continental the earlier orogenies, the only recently active region wasmargin, its materials reincorporatedinto the earth’s mantle. associated with the crumpling of the Mordor Plate afterIndeed, only two blocks west ofthe Ered Luin - the regions collision, causing fissure vulcanism and some explosiveof Forlindon and Harlindon - still persist. Moreover, both activity aroundits rims. The spoilingofthelandscape that soplates have moved north, producing the many strike-slip distressed Frodo and Sam was, I suspect, largely afaults that have fumished courses for westward-flowing consequenceoftheinitial vulcanism andnot just ofthe spoil-rivers. heaps produced by mining. (The solfatara fields aroundThe collision ofthe Eriador Plate with two otherplates,the Namafjall, Iceland, affordjust as grimaprospect.)It is likely

Rhovanion Plate to eastward and the Harad Plate to that the Udrin Basin of northwestemmost Mordor is ansouthward, caused two furtherorogenies that, no doubt, enormous crater, a caldera, the product of a cataclysmicoverlapped in time. Between the Eriador and Rhovanion eruption like that ofKrakatoain 1883. (Reynolds’ altemativePlates, there arose the Misty Mountains and between the suggestion, that itis an independentsmall plate, seemsmuchEriador and Harad Plates, the White Mountains, the three less probable in view of its positionand shape.) However,plates forming a triple junction against the stable basement the only volcano recently active in this region is Mountrocks oftheRohan Craton. Doom - Mount Orodruin - which, by its great height inA second triple junction was formed by the collision ofthe proportion to its basal diameter (cal., 1977), must have been

Eriador and Rhovanion Plates with the Forodwaith Plate. built up rapidly by basic lava, scoria and ash.The consequent orogeny produced the Ered Mithrin, the Mount Doom is indeed one offourisolatedvolcanoes,eachGrey Mountains, together with their westward extension representing a “hotspot” at some distance from a platethrough the region of Angmar toward the Ice-Bay of margin and all of them associated with evil-doing - DolForochel; Mount Gundabadsurely representsa rotatedblock Goldur in Mirkwood, Orthanc in Isengard and Erebor, theof erosion-resistant rocks at the exact position of the Lonely Mountain. Isengard, with its black rocks (Tolkien,junction. Unfortunately, we know too littleof the geology of 1954b, pp. 159-160), was certainly a vast volcanic crater,thesemountains to speculate further. while Orthanc itself(cal., 1977)musthave beenan aiguille -The mostrecentmajor tectoniceventhas been the collision a column ofsolidifiedlava thrustup from the vent in a lastof therapidlymovingMordor Plate with thenorthempartof spasm of an enlption within the crater of Isengard, to bethe Harad Plate and the southemmostpart of the Rhovanion afterward shaped by human hand or magic. (The so-calledPlate. The Mordor Plate is bounded on north and south by “spine”

produced in the last phases ofthe eruption ofMonttransformfaults,their motionat firstwestward and then, Pelée, Martinique, is comparable.) The Lonely Mountain,more prolongedly, eastward.A major consequencehas been fromits shape and with its“grey and silent cliffs”(Tolkien,the formation of the Anduin Rift Valley, caused by the 1951, p. 215) within a landscape “bleak and barren”, wasresultant tearing-apart of the crust. Despite the claims of certainly a volcano (see cal., 1977); there are many presentReynolds (1974), this riftis boundednot by transformbutby volcanoes of closely similar outline, e.g. La Tungar,

I normal faults. At its southem end, it has buckled against the Argentina. The huge cave in which the dragon piled his ill-stable Harondor Craton and has been tumed westward. gotten gains within the Lonely Mountain was surely a lava-

I Essentially this riftis, of course, a region of subsidence, tube ere the dwarves reshaped it,and so must have been themost markedly in its northem portion -the“Gladden Basin” smaller tunneldown which Bilbo unwillingly went to seek

I of Reynolds - and in the triangle between the Emyn Muil, the dragon. (A comparable structure is the Thurston lava tubethe White Mountains and the Ephel Driath - the Nindalf ofKilauea Volcano, Hawaii.)Basin. As Reynolds noted,the marshy natureofthe Nindalf Yet of these recent volcanoes, only Mount Doom was still

' The laterstudyby Pat Mclntosh(1973)treatsonly surfaceoutcrops,while theshortpapers by Duncan McLaren (1985) and MikePercivalIII

(1985) deal with Numenor.

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THE GEOLOGY OF MIDDLE-EARTH 337

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Figure 2: The principaltectonic featuresofMiddle-earth:a new interpretation.

338 J.R.R. TOLKIEN CENTENARY CONFERENCEactive in the time of Bilbo and Frodo. Moreover, the only gravel-covered pediplaned surface (Tolkien, l954b, p.“seismic events” recorded in the chronicles are those caused 232). Extensive piedmont glaciation ofthe lowlands inGandalf’s throwing-downofthe balrog(Tolkien, 1954b)and thesouthseems unlikelyfrom theirlatitude,but valleyGollum’s fall with the ring into the tires ofMount Doom glaciation in the White Mountains has been very(Tolkien, 1955). Of other earthquakes,we have no record. important. Over-deepenedglacial troughs abound -All in all, this time must have been one of unusual tectonic Morgul Valley (Tolkien, 1954b, p. 319), Morthondquiescence. Vale (Tolkien, 1955, p. 62), Harrowdale (Tolkien,However, in the present topography ofMiddle-earth,the 1955,p. 64); with overflow channels(Tarlang’s Neck; »

effects of earlier tectonic events are patent. Rivendell, for Tolkien,1955, p. 63) from one trough to another, andexample, is positioned where the MistyMountain foothills other classical glacial features such as arétes andare intersected by thegreatGwathlo Fault. The entryto the pyramidal peaks (Starkhom and Irensaga; Tolkien, '

valley (see cal., 1977) is through a canyon reminiscent ofthe 1955,p. 68). Periglacial conditions are suggestedin the ‘Black Canyon of the Gunnison River, Colorado, but the lowlands and mountain fringes from unconsolidated .-

valley broadens beyond (cals., 1973, 1977). Helm's Deep materials incorporatingcoarse regolith (Tolkien, 1954b,(cal., 1977) must also be a canyon, within a terrain p. 258). Northwards, glacial processes become moreessentially of limestones;its situationand fortifications are severe. Piedmont glaciers fed from the Misty ‘comparable to those ofthe castle ofAigle, Switzerland.The Mountainsstrippedlarge areas ofEriador, producingitstroll-hauntedEttenmoors are a block of resistant rocks bleak ill-drainedandstoney landscape(Tolkien, 1954a,displacedbetween the Evendim andMinhiriath Faults. The pp. 294,313)with ungradedtumblingstreams(Tolkien,richmineralveinsofMoria, with theirpricelessmithril,were 1954a,pp. 295, 299). Caradhras is a fine pyramidaldeveloped where the Tharbad and Hollin Faults intersected peak at the head ofaU-troughwhose snows still feedthe Misty Mountains. (Mithril itself, crystallizingout at so an icy stream, and the lake Mirrorrnere is an ice-high a temperature that it is only found in veins at great scoopedhollow (Tolkien, 1954a,p. 296) . _ .depths, may well be a naturally-occurring alloy ofplatinum Reynolds noted also that the Long Lake on the Riverand another metal, perhaps palladium.) The almostequally Running (Tolkien, 1951, p. 194), Lake Evendim and therich mineralization of the Mordor Plate resulted from the hollow occupiedby theMidgewater Marshes are probably offaultmovements along its rims, while the much less rich glacialorigin.He considered that the extensive tluvio-glacialmineral deposits ofthe Iron Hills, worked by Dain and his sands and gravels of the Shire (Tolkien, 1955, p. 296 anddwarves, are associatedwith the North Rhiin Fault. cal., 1973) were deposited under periglacial conditions andElsewhere, economic deposits are not common. There is with localised lowering of groundwater base-level,

iron in the Ered Luin; coal somewhere in the Shire (see consequent upon erosion by the Gwathlé and BaranduinSarjeant, 1993, p. 64); limestone to be quarried for the valley ice-tongues.The erosional deepeningofthevalleys onbuildingsofGondor in theWhite Mountains,chalk to be had the chalk downsofthe Shire (Tolkien, 1954a,pp. 126,147)in the Shire’s White Downs and good building stones of was another consequence. In addition, as he remarked (p.other kinds in Amor, Hollin and many other regions. (As 70):Gimli said (Tolkien, 1954b,p. 137): “This country has tough Post-glacial eustatic changes have affected the wholebones.”) Ofthe occurrences ofprecious stones, we have no coast, creating rias and small fiords and flooding low-details; perhaps the dwarves have kept that information to lying basins (Belfalas) although delta formation by thethemselves! Anduin has kept pace with this. Alluviationby theThe shaping of the landscape is, ofcourse, dependent on rivers has also occurred; the peats and clays of the

the interplay of structureand rock type with erosion. It is Baranduin _ _ . being famous fortumipsbutespeciallyglacial erosionthat has shaped the northem mountains and mushrooms (Tolkien, 1954a, p. 100), as also is thethe highestmountainsofthe south. The varied rocksofthe Marish (Tolkien, 1954a,p. 112).Misty Mountains,as seen by Gandalf,Bilbo and the dwarves In the north, areas oflithologicallycontrolledhighfrom the eagles' eyrie (cals., 1973, 1977), are strikingly relief occur abutting glacially stripped lowlandscomparable to the Nepal Himalayas of today. The volcanic (Tolkien, 1954a, pp. 211-212) occupied by bogsEphel Dtiath, theAsh Mountains, as seen fromnear Shelob's (Midgewater Marshes; Tolkien, 1954a, p. 194) andLair by Frodo and Sam (cal., 1977),have also been reshaped; mis-titstreams in glacially enlarged valleys (Tolkien,the result is quite comparable to the Grand Tetons of 1954a, p. 212). The WeatherHills (Tolkien, 1954a,p.Wyoming, even though their rocks are dissimilar. Moreover, 197) are a rugged escarpment and the Trollshawsthe effects ofglaciationhave also modified the lowlands. As (Tolkien, 195421, p. 213) a deeply dissected uplandReynolds (1974,p. 70) pointedout: which includes rocks of probably red-bed facies

. . . largeareas ofRhovanion eastofthe Anduin . . . (Tolkien, 1954a, p. 225)., have been sculptured by these processes for The Carrock,by whichBeom once dwelt (Tolkien, 1951,

considerable periods: the Iron Hills may be monadnock p. 125), is surely an especially massive erratic blockremnants ofa fomierhigher land surface, as may also transportedto itspresentpositionby a since-vanishedglacierbe the hills near the Sea of Rhiin. Dagorlad, from its Elsewhere, riverine erosionhas predominated. Subsurfaceveneer of quartzitic regolith, could be a fossilised erosion has produced the troll-hole in the Trollshaws

l

THE GEOLOGY OF MIDDLE-EARTH 339

(Tolkien, 1951, p. 53), the “goblin-holes” in the Misty the surface by earth movements and exposed by erosion.Mountains where Gandalf, Bilbo and the dwarves (The Great Whin Sill of northem England is an example.)encounteredtrouble (Tolkien, 1951,p. 70), and the cave that The staircase below the East Gate (cal., 1973) surelyserves as palace for the King of the Wood-elves (Tolkien, traverses a series of beds dipping westward at a low angle1951, p. 178). Striking products are the underground lake like steps, producing the Stair Falls (Tolkien, 1954a,p. 314).once haunted by Gollum (Tolkien, 1951, p. 82), very like Bree-hill, “tall and brown” (Tolkien, 1954a, p. 193), andthat underlying Australia’s Nullarbor Plain today, and the bleak Weathertop appear to be monadnocks, isolated hillsGlittering Caves ofAglarondthat so much delighted Gimli withina landscape reduced by prolonged riveraction almost(Tolkien, 1954b, pp. 152-154)and would put even the to theconditionofapeneplain. Bree-hill is lower and formedCarlsbad Cavems toshame. probably of sandstone,Weathertop much higher and formedMany other deductions are possible. The West Gate of ofmore ancient induratedrocks, perhapsslates.

Moria appears, from the illustration (cals., 1973, 1977), to All in all, in geological terms,Tolkien’s descriptions andhave been cut througha massivevolcanic sill - a sheet of pictures ofMiddle-earthare ofa world that,geologicallyatlava intnidedbetweenstrata underground,to be brought to least, is very like our own.

Acknowledgements

I amdeeplyindebtedtomy colleagueDr. Mel R. Stauffer(University ofSaskatchewan) forhis ideas on the applicationofplate tectonicsto Middle-earthgeology. Dr. John Senior (University ofSaskatchewan) and an anonymous participantin theTolkienCentenaryConferenceatKeble College,Oxford,made helpful suggestions conceming the probable nature ofmithril.

References

References to Tolkien’s illustrations, appearing initially in calendars, are cited as “cal., 1973" or “cal., 1977"; all have been subsequentlypublishedelsewhere.

cal. 1973.The JRR. Tolkien Calendar 1973.New York: Ballantine Books, 1972.

cal. 1977.The Lord ofthe Rings 1977Calendar, illustrationsby J .R.R. Tolkien. London: GeorgeAllen & Unwin, 1976.

Howes, Margaret M. 1967. “The ElderAges and the later glaciationsof the Pleistocene Epoch" in Tolkien Journal, vol. 3, no. 2, pp. 3-15,figs. 1-6.

Mclntosh, Pat. 1973.“The geologyofMiddle-earth"inMallorn, no. 7, pp. 3-7, 1 fig.McLaren,Duncan. 1985.“Geographical observationsonNtimenor" in Anor, no. 7, pp. 2-4.Percival, Mike. 1985.“On Niimenor" in Anor, no. 8, pp. 4-6,figs. l-2.Reynolds, Robert C. 1974.“The geomorphologyofMiddle-ea|1h"in The Swansea Geographer, vol. 11,pp. 67-71, 1map.Sarjeant, William A. S. 1992. “Where did the dwarves come from?"inMythloreVol. 19 No. 1 (Winter 1993),pp. 43,64.Tolkien, J . R. R. 1951.TheHobbit: or, There and Back Again, secondedition. London: Allen & Unwin.

Tolkien, J. R. R. l954a. The Fellowship ofthe Ring. London: Allen & Unwin.

Tolkien, J. R. R. l954b. The Two Tower. London: Allen & Unwin.

Tolkien, J . R. R. 1955.The Return ofthe King. London: Allen & Unwin.