336 J.R.R.

TOLKIE N CEN TEN ARY

CONFERENCE

knowledge

of

plate tectonics

has grown, an d th e c on ce pt s Ba si n

-it

incor porate s the Dead Marsh es, the Wet wan g and have changed greatly, since Reynolds’ work was published.” the many m ouths

of

the Entwash - indicates that t his basin Moreover, in my view he pays toosmall a reg ardt o thenort h onc e con tai ned a lak e, since siltedup. andnorth-west

of

Middle-earth

an d to the ma ny ma jo r fa ul ts, Ho we ve r, th e com pl ex in te ra cti on

of

the plates

h as als o most

of

them normal f aults with a trend from south-we st to produced thre e hor sts (fault-bounded, eleva ted blocks ) north-east - usually, indeed, from west-south-west to ea st - wi th in th e

rift.

Two of

these - the Emyn

Muil

an d Emy n

north-east-that control

so much

of

Middle-earth geography. Amon - respectivelydeterminethe northem

and southe m

My

modiﬁedconcepts (Figure 2)

reco gni se not fo ur, but

limitsof

the Nindalf Basin; they control the A nduin’ s cours e six plates (or in mod ern ter min olo gy, as appl ied to Ame ric an and cha rac ter , producing such dra mat ic features

as

Tol

Cordilleran tectonics , six terra ns)

as

b ei ng inv ol ve d in th e Br an di r, wit h its “grey faces"

of

stone (Tolkien, 1954a, p. shaping

of

Middle-earth

geography. Th e mos t anc ien t

of

412 ) and t he Ra uro s Fal ls. The third occurs at the

rift’s

these are the Forlindon Plat e and the Eri ado r Pla te, who se sou thw este mm ost end , formi ng the mou nta ino us islan d

of

collis ion cause dthe oroge ny

-the

mountain-building phase - Tolfalas, bey ond thedepressionm arkedby the many mouths that produced the E red Lui n or Blue Mou nta ins . S inc e tha t

of

theAnduin. tim e, the For lin don Pla te

ha s been lar gel y sub sum ed; tha t is, Tho ugh no do ubt the re was muc h vo lca nic

activity

during drawn dow n in to a su bd uc ti on zo ne at th e co nt ine nt al th e ea rli er or og en ie s, th e onl y re ce nt ly acti ve reg ion was margi n, its materials reinco rpora tedinto the earth’ s ma nt le . as so ci at ed wit h th e c ru mp li ng

of

the M or do r Pl at e af te r Indeed , only two blocks west

of

the Ere d Luin - the reg ion s col lis ion , cau sing ﬁss ure vul can ism and som e exp los ive

of

Forlindo n and Harlind on - still persist. Mo reo ver , bot h act ivi ty a rou ndi ts rim s. The spo ili ng

ofthe

lan dsc ape tha t so plates ha ve mo ve d no rt h, producing th e m a ny st ri ke -s li p di st re ss ed Fr od o a nd Sa m wa s, I su sp ec t, la rg el y a fa ul ts tha t ha ve fu mi sh ed co ur se s

for

westward-ﬂow ing

consequence

of

theinitial vulcanism andnot just

of

the spo il- rivers.

heaps produced

by min ing . (The solfata ra ﬁelds

around The collis ion

of

the Eriad or Plate wit h tw o oth er plates, th e Na ma fj al l, Ic el an d, a

!

ord just

as

grim a prospect.)

It

is

likely

Rh ov an io n Pl at e to ea st wa rd an d th e Ha ra d Pl at e to th at th e Ud ri n Ba si n of northwestemmost Mo rd or is

an southward, caused

two further

or og en ie s tha t, no doub t, en or mo us cr at er , a ca lde ra , th e product

of a

cataclysmic overl appe d in time. Betw een

th e E ri ad or an d R ho va ni on er up ti on like that

of

Krakatoa in

1883. (Reynolds’ altemative Pla tes , the re aro se the

Misty

Mountains

an d bet we en th e su gg es ti on , th at

it

is an independentsmall plate, seems much Eria dor and Har ad Pla tes , the W hit e Mou nta ins , the thr ee

less probable in view

of

its position

and shape. ) Howeve r, plates for min g a triple junction aga in st the sta ble ba se me nt th e on ly vo lc an o re ce nt ly active in thi s re gi on is Mou nt rocks

ofthe

Rohan C r a t o n . D o o m - Mount Orodr uin - wh ic h, by it s great he igh t in A sec ond triple junction was for med by the col lis ion

of

the proportion to its bas al diamet er (cal., 1977), must have been Eri ado r and Rhova nio n Pla tes wit h the Fo rod wai th Pla te. bui lt up rap idly by bas ic lav a, sco ria a nd ash . The consequent oroge ny produced the Er ed

Mithrin,

th e Mo un t D oo m i s in de ed on e

of

four

isolatedvolcanoes,each Gre y Mou nta ins , tog eth er with the ir wes twa rd ext ens ion representing a “hotspot” at so me di st an ce f ro m a plate through th e reg ion

of

Ang mar towar d

th e Ice -Ba y

of

margin

a nd al l

of

them associated with evil- doing - Dol Foroc hel; Mount Gunda bad sur ely rep res ent sa rot ate dblo ck Gol dur in Mir kwo od, Ort han c in Iseng ard a nd E reb or, the

of

erosion-resistant ro ck s at th e ex ac t position

of

th e L o n e ly Mountain. Isengard, wit h it s blac k ro ck s (Tolkien, junction. Unfortunately, we know too

littleof

the geology

of

1954b, pp. 159-1 60) , was certa inl y a vas t vol can ic cra ter , these m o u n t a i n s t os p e c u l a t e f u r t h e r . w h i l e O r t h a n c

itself

(cal., 1977) mustha ve beenan aigui lle - The mostrecent major tecto nic event

has been the col lision a colu mn

of

solid iﬁedlava th rust up from the vent in a last of th e rapid ly movin gMo rdor Pla te with the north em part of

spasm

of

an enlption

within

the crater

of

Isengard, to be th e Ha ra d Pl at e an d th e southemmost part

of

the R ho va ni on af ter wa rd sha ped by hu ma n h an d or magi c. (The so-called Pla te. The Mor dor Pla te is bound ed on north a nd sou th by “spine” produced in the last phases

of

the erupti on

of

Mont transformfaults,their motion

at

ﬁrst

wes twa rd and the n, Pel ée, Ma rti niq ue, i s co mpara ble.) The Lonely Mounta in, more prolongedly, eastwa rd.A major con sequen ce

has been

fromits

shap e and

withits “grey

and silent

cli

!

s”

(Tolkien,

the forma tion

of

the Anduin

Rift

Valley,

ca us ed by the 1 95 1 , p. 215 ) within a landscape “bleak and b arr en” , was resultant tearing-apart

of

the crust. Despite th e cla im s of ce rt ai nly a vo lc an o (see cal., 1977) ; there are many present Reynolds (1974), this

rift

is bou nde d notby tra nsf orm butby vol can oes

of

c lo se ly si mi la r ou tl in e, e.g . La Tu ng ar , I normalfaults.

At

its so uthem end,

it

has bu ck le d ag ai ns t the Ar ge nt in a. Th e hu ge ca ve in wh ic h th e d ra go n piled his

ill-

stable Haro ndor Crato n and has been tumed westwa rd. gotten gains wit hin the Lon ely Mou nta in was sure ly a lav a- I Essent ially this

rift

is,

of

course, a region

of

s ubsi den ce, tube ere the dwar ves re sha ped

it,

and so must h ave been the most markedly in its northem portion

-the

“Gladden Ba si n” sm al le r tu nn el down which Bilbo unwilli ngly went to seek I

of

Reynolds - and in the trian gle betw een the Em yn

Muil,

the dragon .

(A

com parabl e struc ture is the Thur ston lava tube th e Wh ite Mo un ta in s an d the Ephe l Dr ia th - the Nindalf

of

Kilauea Volcano, Hawaii.) Basin. A s Reyno lds note d,the marshy nature

of

t h e N i n d a l f Y e t

of

these recen t volcan oes, only Mount Doom was still ' The laterstudyby Pat Mclntosh (1973) treatsonly surface outcrops, while the short

papers by Duncan McLar en (1985) and

Mike

Percival

III