MEM IR OF T HE GE L GICAL UR VEY O S O O S , C TLAND S O .

THE GEOLO GY

FANNIOH MOUNTAINS

COUNTRY AROUND UPPER LOOH MAREE AND STRATH BROOM . (EXPLANATIO N OF SHEET

. . P E A H L L D J HO R E L L F R . D . . . S . B N C , . . , N , . , TH L T G U G M A . H O U . . E A E W NN C . T. CL , , E E G E Y F . R . . G S . AND NL , WIT H CO NTR I B UTI O NS B Y

L . . H I N X M A B I . M A W N A P K . T . O O . , . . , C C , B A M R M P E . C . . O M . . C . AND C T N, , A N D PETR O L O G ICAL N O TES

D J H E A L L . J . D . . F . R . S O . S . . T LL, . , , _

’ P U B LI S H B Y O R R O F T H E LO R S CO I SS I O N R S O F H I S J ST Y S T R A SU R Y ED DE D MM E MA E E .

E D IN B U R G H P R IN TE D F O R H I S M AJE STY ’ S STATIO N E R Y O FF IC E B Y M O R R ISO N G I B B LIM ITE D A T NF I L TA E D .

A nd to be purchased from S N F O R D 1 2 1 3 1 4 O NG A C R O N O N E . TA , , L E , L D ; W S R E B R G E D 2 S T . R A K. JO H N S O N I M I N U I N U H W. . T , L T , A D E Q A E , D , R S R B I G IS I M I E D 1 04 G F TO N T T D U LIN . H O D G E S F G C O . , , L T , A EE , l n nce S u e M a F rom any Agent for th e sa e o f O rd a rv y ps . F I S H E R N IN 1 P H I R R C O r ou an B ook e lle f o . U L thr gh y s r, r m T W , ADE TE A E , N N w h e ole ole ale e n to th e ade ou de th e O O W . C . h o t L D , , is s Wh s Ag t Tr tsi C oun of ond on ty L .

1 9 1 3 .

d ix ence P rice T wo S hillings a n S p .

P R E F A C E .

THIS M emoir describes the geology of the area included in Sheet 9 2 - S of the one inch map of cotland . It comprises the mountainous ground bounding the upper part of Loch M aree and extending north G annich wards to ruinard Bay and the head of Loch Broom , the F - t i mountains in the south east quadrant , and that par of the ma n th e S m watershed of Highlands situated to the east of trath Broo . R This elevated region forms part of the county of oss , but formerly O f m a it contained small outlying portions of the county Cro rty . The belt of complication due to the post - Cambrian movements crosses the sheet from Loch Broom to the alluvial plain at the head M of Loch aree . To the west of this belt lie large tracts of Lewisian G neiss and T orridon S andstone overlain unconformably by the n m Cambrian formatio . To the east there is a great develop ent of the E S t astern chists , which give rise to some of the wildes scenery in

B - - Central oss shire . In the north west corner of the map there is a an d small patch of Triassic Liassic strata, let down against the

T orridon Sandstone by a large fault . P J S . The heet was surveyed geologically by B N . each , . Horne , the H inxm an M E G G ...... late W . unn , C T Clough , L W , H Cadell , reenly ,

P . . . T . I . ocock , and C B Crampton The largest part was done by the M r G n late . unn , whose area extended from the Fionn Loch orth to G d A n T e alla ch S ruinard Bay , thence eastwar s by , trath Beg , and S B e inn D O f trath Broom to earg , and southwards to the watershed P M . the F a nnich mountains . essrs each and Horne took part in the mapping of th e belt of complication due to the post - Cambrian movements from S trath na Sh e allag to the southern margin of the D r P E S Sheet . . each also surveyed the astern chists around Fionn D m B he inn r. , and Ho e the development of these rocks along e n M r the southern slope of the F n ich range . To . Clough was assigned the complicated tract of Lewisian G neiss stretching from ’ m C hais e in M r G M . Loch aree to Bei u a g Beag ; to reenly , some S h e alla h isolated areas near Loch na g, the Heights of Kinloc ewe , and M M H inxm an P on either side of Loch aree ; to essrs . , ocock , and E S - Crampton , parts of the astern chists in the north east and south th e B e inn nan R am h east corners of map , and on near the head of F i h M r T orrid on S ann e . Loch ; and to Cadell , a patch of andstone

- along the north east shore of Little Loch Broom . D etailed descriptions of the Lewisian , Torridonian , and Cambrian

rocks , and of the tectonics of the belt of complication , have already appeared in the M emoir on “ The G eological S tructure of the North ” d m West Highlands, which are here reproduced in a condense for n A s E S with some of the horizontal sectio s . regards the astern chists iii iv P re a ce f . the various officers have furnished descriptions of their respective P th e areas . erhaps most interesting feature connected with these rocks is the account O f the remarkable geological structure of th e F nnich a range . A lmost the W hole of the petrology O f the rocks within this S D r A heet has been done by . Teall . few specimens have been D r examined and reported on by . Flett .

P . D r . . The memoir has been edited by . Horne lates I to V have M r been prepared from photographs taken by . Lunn . We are indebted r R R R e v M . to the . obertson of annoch for the excellent photograph - in P n A n T e allach . of the corrie rock basi on , represented late VI The Bibliography given in the A ppendix has been prepared by M r . Tait . E A J J . . . H T LL , D irector . G S O eological urvey ffice , 28 J rm n S e . y treet , London 2 1 st 1 9 1 2 November . C N T E N T O S.

T E CHAP R I .

P AG E IN T R O DUCTIO N A rea P hysical Features

H C APTER II .

F oR M A T I O N s A N D R O CK G R O U P s G eneral G e ological D escriptio n P revious Literature

T ER CHAP III .

LEWI S IAN G N E I ss G eneral D e sc ription T h e Fundamental Complex U ltrabasic R ocks B asic R oc ks A c d R c s i o k . P re - Torridonian Intrusion s U ltrabasic D ykes Basic D ykes S y enite D yke

P egm atites . T h e Loch M aree S eries and some A ssoc1ated S chi st s M c - S c 1 . i a hist 2 M c - A c - S c . i a tinolite hist G a e - c 3 . r phit S hist 4 . Kyanite G neiss R 5 . G ranular Q uartz ock ua c i 6 . Q uartz S chist and Q rtz M agnetite S h st

- 7 . Q uartz Hornblende S chist

8 . Limestone l l 9 . Ca careou s B iotite Hornb ende S c hist 1 0 l . Ch orite S chist 1 1 H l d c a nd Ho n le d C hIO I ite S c . ornb en e S hist r b n e hist 1 2 l M c a nd P r e . Hornb ende S chist with brown i a y it s CHAPTER IV

T H E T O R R ID O N SANDS TO NE G ene ral D escription D iabaig G roup A pple cross G roup A ultbea G roup

TE CHAP R V .

CAM B R IAN FO R MATIO N A o c L a aidh S h S he alla rea fr m Lo h g to trat na g . A rea from S trath na S h e allag to Kinlochewe Forest

TE CHAP R VI .

P O S T CAM B R IAN M O VEMENTS A m c S tratli S h e alla rea fro Lo h Broom to na gb A rea from S trath na S h e allag to Kinloch e we Forest

CHAPTER VII .

T H E E AS TER N S CH IS TS Area north O f th e F annich Watershed A rea south of th e F annich NVa te rsh e d

TE CHAP R VIII .

G R T - HO R B L - R O C S I M O I S R I S D S O F A NE N ENDE K N NE E E , AND YKE M ICA - TR AP A N D LAMPR O P HY R E

TE CHAP R IX .

M ESO ZO IC R O C R S Trias Lias

CHAPTER X .

FAULTS

CHAPTER XI .

P LEI S TO CENE AND R ECENT D EPO S I TS G lacia tion a nd G lac ial D eposits I ce - worn R ock S urfaces Boulder Clay and M oraines E rratic B loc ks Fluvio G lacial Sand s and G ravels Freshwater Loch s R aised B eaches Fr eshwater A lluvia P eat Blown Sand

TE CHAP R XII .

E CO NO MIC G EO LO GY Iron- O re Lim estone Building S tone R oad M etal l us V e & c M . eta lifero ins, P lan tations R ainfall R eturns

APPEN D IX .

BIB LIO G R APHY LIS T O F WO R KS R EFE R R ING T o TH E G EO LO GY O F TH E A R EA INCLUDED IN T HIS M EM O I R

IN D EX L IST OF ILL U TR ATI N S O S.

G R E S E X FI U IN T T .

P A C F. ’ 1 . S c u c c M B e inn C hais e in e tion from near F rna e, Lo h aree, to a g M or

2 . S c c A cl C h orcurach e tion a ross nti ine near Creag , east D u d ll d l c of n onne Lo ge, Litt e Lo h Broom ’ 3 S c A M h a i hde an . e tion from g by M ullach Coire M hic F h e arch air to C re ag R ainich ’ 4 S c l c n . e tion from S io h by B e in a M h hinidh to Abh uinn B 1 uach aig ’ S c l n ru i al 5 . e tion from G e G d e by Me l a G h iubh ais to C ro masa s u K l ch g, o th of in o ewe 6 D c c h e . iagrammati Se tion from near t Heights of Ki nlochewe by Fionn B h einn and A n Cabar to th e eastern edge of S heet 9 2 a d 7 . M p showing irection of I c e flow in A rea Included in S heet 92 8 M l and s . a s R s n p of part of Centra West o s hire , showi g distribution of boulders of A ugcn G neiss an d O ld R e d Sandstone

P A E S L T .

f rr c G L T 1 . E sc m s c o S ii P A E arp ent, ea tern fa e g nan Cla h eala, F annich Forest F rontispiece c c s th e F annich M ouhtains II . Se tions a ros ’ A S c B e inn A C h aille ach and ( . ) e tion from Bheag by S gurr nan Clac h G eala to A n C oileach an ; ’ m R ainich A C h ailleach B . S c ( ) e tion fro CreaDg by , A n S hm an and T orrau R uadh th e G rudie g , to R iver (to face) 76 G o us M u c B G ss l cl III . arnetifer s ovite iotite nei with enti es of P e m atite S i1rr l c G F a nnich c 78 g , g nanC a h eala, Forest (tofa e) V F S l c us S c c S hrr l c I . laggy i i eo hists , east fa e of g nan C a h G a F annich c 80 eal , Forest (to fa e) V c s F annich M u l u . View of rest of ea t part of o ntains p atea

- in ac u d c frost debris terr es (foregro n to right) , orries to left in north - east face of chain ; Loch F annich in m iddle distance (to face) 98 V ch ll an L och ain m u m c - in T orridon I . Lo To , a ro k basin S ds e s s d A n T e allach ce 10 2 an ton , ea t i e of (to fa ) THE GEOLOGY OF THE FANNIC H NT IN ET M U A S C . O ,

TE CHAP R I .

R O D O INT UCTI N .

A R E A .

T H E S 432 area included in this heet amounts to square miles , of which 426 are occupied by the mainland and the remainder by sea, the latter comprising th e head of Loch Broom with parts of Little Loch

Broom and G ruinard Bay . The land area forms part of the county R O SS of , but formerly it embraced several isolated portions of the

county of Cromarty . This tract of country is defined on the east by a line drawn from the slopes of Seana B hraigh in the north - east F a nnich corner of the map, to a point near the mouth of Loch on the ionn B h einn south . The southern boundary traverses the crest of F ’ and runs westward to B einn a C h earcaill ; the western margin crosses Loch M aree near G arbh E ilean and stretches northwards to Sand on the shore of G ruinard Bay ; while the northern boundary extends from G ruinard Bay east by Leckmelm on Loch Broom to M eall e nam B han .

P HY S IC AL FE ATU R E S . o The ground through ut this extensive tract is mountainous , and f d the most O it is occupied by eer forests . The only cultivated areas S lie along the seacoast, also in the lower parts of trath Beg and S trath Broom , and along the alluvial plain at the mouth of the R Kinlochewe iver . A glance at the geological map will S how that four dominant rock groups are represented within the area , namely , the Lewisian G T orridon S neiss , the andstone , the Cambrian formation and the ”e E s S chists a tern . These furnish the key to the topography of the n regio and to the development of the characteristic mountain forms .

- In the north west part of the map , the ground occupied by the Lewisian G neiss to the west of the Little G ruinard R iver and the 1 0 00 ft Fionn Loch forms a plateau under . , with steep , rocky hills somewhat rounded in outline , but comparatively free from glacial E drift . astwards this plateau rises into prominent ridges or hills , ’ ’ B einn C hais ein M or 2802 B e inn C hais ein as , for example , a g ( a g “ ” T h e term E aste rn S chists is h e re used to include th e M oine S e rie s of th e G e l cal S u e and th e ac d and a c n e e e e l n e e n o ogi rv y, i b si g iss s, r s mb i g typ s of L wisia G ne th e e th e - C a an u t iss to w st of post mbri thr s s . 2 I ntroduction .

’ 2234 A M hai hde an 2800 Beag ( ft . ) and g (over whose rocky features are largely determined by the north - westerly trend of the

. l es gneiss and the basic dykes In places the p are smooth , and n covered with debris of local rocks . The intimate con ection between mountain form and geological structure is well illustrated in the tract between the southern portion of th e Fionn Loch and Loch M E . E S . . aree , where a great escarpment runs in an direction from B e inn Airidh 259 3 M e all M h einnidh B e inn Charr ( ft . ) by to Lair 281 7 G a ( This escarpment , overlooking leann T lacha, is one of the remarkable topographical features of the region . In the sequel it will be shown that it is due to an intrusive sheet of hornblende A schist associated with the sedimentary schists of rch aean age . The second type of scenery is characteristic of the T orridon S ff andstone , whose mountain forms di er completely from those met with among the metamorphic rocks to the west and east . They i present lofty escarpments w th terraced outlines, due to the outcrops of beds of sandstone and grit which are traceable for miles across the G plateau of Lewisian neiss . Under the influence of denuding agents , C O I rie s they give rise to huge precipitous with lateral ridges , and they tend to form detached masses with rounded buttresses , crossed by innumerable joints and small faults along which erosion proceeds M O f more rapidly . ost the distinctive outlines of Torridonian scenery — are exemplified in A n T e alla ch perhaps the most picturesque

- mountain of this system in the North west Highlands . Situated O f S S h e alla between the head Loch Broom and trath na g, it forms a conspicuous feature in the landscape when seen from the surrounding 30 00 heights . In this mountain five peaks exceed ft . in altitude . 0 f O n 30 0 t. the eastern side three prominent ridges or spurs , all above , an project from the central mass . The two highest points reach

4 4 . P elevation of 34 83 ft . and 3 7 ft respectively (see late S outh from Loch na Sh e allag this scenic type is continued in r 2 R u D B einn D M hO 9 4 . earg ( 7 ft ) and ein earg Bheag , and along the ’ great western escarpment of B einn a C hlaidh eim h and Sgii rr Ban to n - th e B einn T arsuin . Beyond Lochan Fada we encounter buttresses and dip slopes of Slioch ( 321 7 where this pile of sediments rests S on a highly uneven floor of Lewisian G neiss . outh from Loch M G R aree , between the rudic iver and the western margin of the S B einn heet , these mountain forms reappear , culminating in an ’ ll 23 6 - B inn C he arcai . E Oin ( 280 1 ft . ) and e a ( 7 ft ) in the south west corner of the map .

The third type , though of limited development, is , nevertheless , r distinctive . It is due to the presence of the Camb ian quartzites , which give rise to a prom inent escarpment resting on the T orridon

S . S andstone ometimes they form long , glaciated dip slopes , as , for S urr r i instance , on g Ban , north f om Lochan Fada ; somet mes they are c thrown into a compli ated system of folds , as in the tract south from the head of Loch M aree . d E S The fourth type of scenery is presente by the astern chists , which occupy the eastern half of the region under description . This area forms part of the Highland plateau , running along the main h a s watershed of the country , which been deeply trenched by river E systems developed since ocene time . It is observable that these crystalline schists give rise to less rocky contours than the Lewisia n P h sica l F ea tures y . 3

G neiss to the west . In the lower portion of the plateau numerous ribs of schist project through peat and glacial deposits . But in the mountainous region rising above the limits of the drift the hilltops S and lopes have frequently a thin veneer of grass , turf , peat or loose debris of local rocks . In this region also there are lofty escarpments and precipitous corries illustrating the features characteristic of the fiaggy siliceous schists and the massive muscovite - biotite - gneiss O f P I M S . the oine eries (see late , Frontispiece) . - O f In the north east corner the area , occupied by the E astern S chists , there is a belt of high ground stretching from B einn B hrai h D earg (3 547 ft. ) to Seana g with five peaks exceeding 3 00 0 T h e O f ft . in altitude . most prominent mass elevated ground , F a nnich however, is the group of mountains to the north of Loch F annich E , extending for a distance of seven miles in an S E . and

. . . 30 00 . W N W direction , and containing eleven peaks over ft in height . In the sequel it will be shown that some of the prominent topo graphical features oi this mountain group are due to the remarkable O f geological structure the chain . In this connection reference ought to be made to the exposure by denudation of topography belonging to ancient geological periods . Thus along the tract bordering the western limits of the T orridon S G andstone the present outlines of the Lewisian neiss are , to a - d n considerable extent, a renewal of the pre Torri o ian land surface which can be shown to have been one of high relief . The most ff S conspicuous instance is that a orded by the slopes of lioch , where the nearly horizontal beds of T orridon Sandstone are seen to envelop G — 2000 three prominent hills of Lewisian neiss one over ft . in A height with intervening valleys . nother eminence of pre Torridonian age rises to a great altitude between B e inn D earg M hor B einn D Sh ea lla and earg Bheag , south from Loch na g, which are mainly composed of T orridon Sandstone and are linked with each O f S M other by a narrow bridge that material . outh from Loch aree the tops of at least three gneiss hills are seen to protrude through the Torridonian strata in the Srath L ungard district in the south A O f west part of the map . gain , the disposition the Torridonian sediments on the south - west side of Lochan Fada shows that the G T illach a deep valley of leann and of Lochan Fada, together with the great escarpment that bounds the B e inn Lair chain to the

- south , must have been developed in pre Torridonian time and have been laid bare by the removal of the overlying strata .

G . B . N . P J . H . w . ,

lo w Furthermore , it is highly probable that the plateau of Lewisian G neiss along the western limits of the area may be in

- part a restoration of the pre Triassic land surface . This plateau , 6 ft 00 . whose general level is over , rises eastwards , as already

2 0 300 . 00 0 . indicated , up to lofty ridges from to ft in height But to t S 9 1 the west and nor h it extends into the areas included in heets , 1 0 0 1 0 1 J and , where outliers of Triassic and urassic strata are distrib uted over it in such a m ann er as to suggest that the plateau is in great part a renewal of that upon which the M esozoic strata were laid down . If the strata composing the faulted inlier of Triassic and Liassic rocks in th e north - west corner of the m ap were restored to roduction 4 I nt .

their original level ( th e amount of downthrow being about 1 000 they would be th ick enough not only to cover the lower plain but l e S also to abut against the p of the higher plateau . O f The main watershed the country, between the streams that S e a A flow eastwards into the North and westwards into the tlantic , traverses the region under description in a highly sinuous manner

- (Fig . 7, p . In the high ground in the north east part of the S map it runs from north to south near the eastern limits of the heet, but to the south of Loch D roma it bends westwards for a distance of F annich eleven miles along the crests of the mountains , thence B h einn 3 6 it curving eastwards to beyond Fionn ( 0 0 ) . This great westward deflection of th e watershed round the head of Loch F a nnich basin has O bviously a direct relation with the evolution of n the river systems , as will now be show . O f In consequence of the position the main watershed , as regards S O f this heet , the streams flowing eastward , with the exception those i h F ann c . in the area, are not important Those in the extreme - S B h rai h north east corner , north from eana g , are tributaries of the R O O f a iver ykell , and those to the south th t mountain are sources of R D the iver Carron , both of which rivers enter the head of the ornoch B e inn D h A h Firth . The streams on either side of earg and t e b uinn ’ ‘ G hiubh ais L I D a , south of Loch roma , help to form the Black Water f R A an a fluent of the iver Conan . nother tributary of the Conan issues from Loch F annich . To the west of the main watershed the R iver D ouch ary is the R hidorroch R principal branch of the iver, which enters the sea at R “ Ullapool on Loch Broom . The Broom iver is formed by the ‘ junction of the two streams that rise near Sgti rr M or and the head ’ B i D hra o n . n R of Loch a respectively The undon ell iver , which n R ini h a c . e ters little Loch Broom , finds its source near Creag The G R Sh ealla ruinard iver , issuing from Loch na g and discharging into G A bh uinn S Se al a ruinard Bay, is formed by two streams , rath na g A bhuinn G M and leann na uice , which unite just above the head of G R G the loch . The Little ruinard iver , which also flows into ruinard th e A bh uin . n Bay , has its sources near the head of Fionn Loch The

— - B ruach aig a tributary of the Kinlochewe R iver drains a wide O f a fli ue nts O f district by means three , the first rising in the valley G T ulach a O f M leann , the second on the southern slopes ullach Coire M F he a rch air - hic , and the third on the north east declivity of Fionu B h inn F anni h e c . , south from the head of Loch These are some of the more important lines of drainage in the region described . O bse rv In connection with the trend of these river systems , it is able that the behaviour O f the main watershed in this region is in accordance with the evidence presented by the Highland plateau north of the Caledonian Canal . Throughout this extensive tract we find that , in the through valleys , the watershed of the tribu taries of th e rivers flowing east lies to the west of that O f the main rivers themselves . The phenomena point to the conclusion , that th e headwaters of the main streams flowing east have been - fl owin captured by the westward g rivers , and that the latter have become O bsequent in valleys previously carved out by an eastward drainage system . Hence it arises that the high plateau is traversed from west to east by comparatively low passes at the watershed . P h sica l ea tures y F . 5

R D ouchar For example , the iver y , which was evidently at one time a tributary of the O ykell through the hollow now partly occupied by Loch an D a im h ( Sheet h as been captured by the R hidorroc h R 820 iver, the resulting pass being only ft . above sea A c ons icious R level . more p instance is furnished by the iver Broom , which first stole the waters O f the A bh uinn C uile ig and afterwards cut backwards into the valley excavated by the G lascarnoch R iver S 93 — ah I ( heet ) affluent of the Black Water branch of the Conan . n the course O f this recession the Broom tapped in turn some of the burns draining the northern S lopes of the F annich range and some - D d to the north west of Loch roma , till the watershed now coinci es

1 5 . with a pass (9 ft ) to the east of that loch . In the sequel it will be shown that these passes have been covered by ice moving westward during the maximum glaciation , and that lochs have been left at or near the actual watershed . The evidence relating to minor cases of capture is perhaps more Ur apparent . Thus the burns flowing eastwards from Sg r Ban and M ullach Coire M hic F h e arch air evidently formed at one time the ’ hr i headwaters of the stream that now flows into Loch a B ao n . These have been deflected and led away by the A mh ainn Loch an

Nid through Loch na Sh e a llag into G ruinard Bay . In like manner the rivulet draining the southern declivity O f M ullach Coire M hic Fhear chair runs south - eastwards for about three miles in th e direction of ’ ’ A bh uin h B h ui h — f F annich n a C adh d e a tributary O Loch . But the waters of this rivulet have been stolen by the burn flowing through G T a na aidh— an A bh uinn B ruach ai leann g affluent of g, which drains R into the Kinlochewe iver . A gain , it is highly probable that the valley in which Lochan Fada now lies was once occupied by a stream that drained into G leann na M S C h rom buill R annich uice , and thence by the rath iver , the F depression and the G rudie R iver into the Conan . This system has M been tapped by two separate streams flowing into Loch aree . Thus the waters of the G leann na M uice and Srath C hrom buill portion have been captured by the A bh uinn B ruach aig at the n Heights of Kinlochewe , while Lochan Fada has been drai ed by A bh uinn F i h M an h asa g and led directly into Loch aree , there being 1 000 a a fall of about ft . in the course of the latter stre m within a distance of three miles . The examples above adduced of the modification of former drainage systems point to the conclusion that the steep gradient of the westward - flowing streams has been an important factor in the deflection and capture O f the headwaters of the rivers fl ow1ng

r B . N . P J. H . towa ds the east.

M f th e any O the smaller streams , especially in district of the E S astern chists , run in deep and narrow gorges diversified by water

n , falls , and a few of the larger streams also have formed ca ons, as for D R r D instance , the undonnell ive above undonnell , and the two T h e branches of the R iver Broom south of Braemore . beautiful ravine on the eastern branch of the latter is a typical example of this kind of scenery produced by river action in the fl aggy sch i sts of M i the oine Series . In several instances these ravines run along l nes of fault or joint planes . 6 I ntroduction .

It is worthy O f note that the best - developed gorges are situated mainly on the rise between the inland portions of the continental 1 0 00 shelf and the intermediate plateau , varying in height from to

1 5 0 f - 0 . n t above sea level . The deepest ca ons occur in the main w valleys crossing this slope , especially here the rise coincides with M S the outcrop of the siliceous schists of the oine eries . The gorges in such situations were probably initiated and largely developed n during the retreat of the confluent glaciers , when the cutti g power of the streams was intensified by the escape of water from the melting D ice front . uring this stage of the glacial period the main valleys draining westwards received more ice than the normal outflow from their respective catchment basins . The great displacements that traverse this Sheet have in S Om e i i r cases given r se to consp cuous surface features . The st aight north oi M east side Loch aree coincides with a line of fault or shatter belt, and the trend of the Loch Broom valley is attributed to the same G R and cause . The course of the Little ruinard iver of the lower part of the I nve rianvie stream are additional examples . The outcrop M - of the oine thrust , the most easterly of the post Cambrian dis S placements, which crosses the heet from north to south , gives rise ,

- in some places , to a well marked hollow . It is mainly due to the soft Cambrian strata (Fucoid Beds) that overlie the strongly resisting quartzites at their base and are overlain in turn by thrust materials . A c lip slope of quartzite is established on the west , and an escarpment M of displaced masses capped by oine schists on the east . This escarpment is best seen on the east side O f A m h ainn Loch an Nid D in the undonnell Forest . The level of the stream just below its exit from Loch an Nid is about 900 ft from which the ground rises steeply up to the top of Creag R ainich (2646 about a mile to the east . There are several large freshwater lochs in the region under description , and a great number of small size . The largest is Loch

M . aree , thirteen miles in length , with richly wooded islands The western portion of the lake is beyond the limits of this map . The next F annich in size is Loch , seven miles long , which is closely followed D ra cti by the Fionn Loch and the ubh Loch , these two forming p S cally one sheet of water . Lochan Fada , north from lioch , and Loch ’ She alla na g are each three and a half miles in length , and Loch a B h S raoin two and a half miles . mall lochs are numerous on the O f G rocky plateau Lewisian neiss west of the Fionn Loch , and on 0 8 0 . G R 4 00 . either side of the Little ruinard iver , between ft and ft th e above the sea . They are also very abundant on the plateau of E S S astern chists between the Loch Broom and trath Beg valleys ,

1 50 . 1 000 0 . where the ground is between ft . and ft in altitude M in - n e nded any of the lochs lie rock basi s , some are p by moraines , and a large number rest in drift and peat . In the sequel it will be shown that the topography of the whole region has been largely modified during the G lacial period . In addition to the general erosion of the solid rocks there is evidence n pointi g to the conclusion that , by ice action , cols have been U - lowered , valleys have been deepened and made shaped , rock basins have been excavated , and corries developed out of shallow depressions at the heads of streams . The confluent and valley P h sica l ea tures y F . 7 glaciers have left their S poor in the form of numerous lateral and terminal moraines . O f The population is small , and consists mainly crofters who cultivate land mostly adjoining the sea . The principal arable land S embraces a stretch of three miles in the lower part of trath Beg , and another area , four and a half miles long , in the Loch Broom valley . The areas now under sheep are comparatively small ; the O f G R chief being the ground west the Little ruinard iver , a strip along the south side of Little Loch Broom , all the ground between ’ G A llt C hairn reat and Little Loch Broom , southward to a , and a E N E n limited tract . . . of Kinlochewe . The remai der of the region is

O B N P . G . . J H ccupied by deer forests . W. , . . , . C H AP T E R I I .

M A R P S FO R TIO NS A N D R O CK G O U .

T H E geological formations occurring within the region under de sc rip

tion are presented in the subjoined table . These are arranged in m stratigraphical succession , except in the case of the etamorphic

rocks , where the order given in the table does not necessarily imply

sequence in time .

B l n and ow s . P e a t . F e llu u — e el r shwate r a vi m riv r grav s . M n ll — a ed e c e ari e a uvi um r is b a h s . l G lacial sand and grave . lde - l M orainic drift with som e bou r c ay .

e ne Lim sto .

White and mottle d sandston e with re d clay and i . Tr as c n l a e o g om e r t .

n Lime sto e . S e ul e G rp it rit Z n 0 lenellus o e . n F uc d B e d C ambria . oi s } P ip e R ock .

- B asal or F alse b edde d Quartzit e .

A l e u u tb a G ro p . A le G u T do n c . orri nia . pp ross ro p

D iabaig G roup .

M ne P c and el c c and ne e and oi sammiti p iti s hists g iss s,

S e e "und ffe en e d c . ri s. i r tiat s hists

M e and l a e d e n c o n lend c and assiv fo i t , pyrox i , h r b i

micace ous rocks . e an L wisi e d S e rp en tine and p ri otite . G nerss . u - c ca - c a e - c and Q artz s hist, mi s hist, gr phit s hist

lim e stone (Loch M ar ee S erie s) .

e Lamprophyr .

S ye nite . - e M uscovite p gmatite . I n M oine l n - H n e de c . S e e or b s hist ri s . " H n le nde - c or b s hist . I n Lewisi n a H n l nd e e . G ners or b it s. S e rpentine and p e ridotite .

G E N E R AL G E O LO G I C AL D E S C R IPTIO N .

In Chapter I . brief reference has been made in connection with the topography to the distribution of the four important rock groups

which enter into the geological structure of the district . 8

1 0 F orm a tions a nd R ock G roups.

S S Shealla other closely ; indeed , between trath Beg and trath na g the E astern Schists overlap all underlying thrust materials and rest S m directly on undisturbed Cambrian strata . outh fro Loch an N id O f the belt widens , till at the Heights Kinlochewe it is three miles O n R broad . the rocky plateau north from the Kinlochewe iver the structure is extremely complicated . The plane of the Kinlochewe thrust has been folded , and the displaced materials overlying it have been so denuded as to expose the imbricate structure of the Fucoid R f r n S G . e e e c e ou h t Beds , erpulite rit and limestone beneath j g to be made here to one of the remarkable tectonic features of the region , G T orridon S namely , the outlier of Lewisian neiss and andstone on ’ M e all a G hiubh ais which has been isolated by denudation from the main mass of thrust materials overlying the Kinlochewe thrust - plane

5 . (Fig . , p The planes of disruption , except where they are folded , i are incl ned to the like the strata above and below them . A s E S t already indicated , the astern chis s occupy the eastern half of the area included in the map . They comprise ( 1 ) mylonise d rocks ; (2) granulitic quartzose schist and muscovite - biotite - gneiss or schist representing the psammitic and pelitic types of the M oine Series and ( 3) a limited development of micaceous and hornblendic rocks , resembling , in some particulars , Lewisian types to the west . M - Near the oine thrust plane , and generally in the large area that S ul embraces trath Beg and Loch Broom , the dip is fairly reg ar , at low angles of from 1 0 ° to and in some cases The direction

‘ - is mostly towards the south east , and there are few signs of any l A plication , only some occasional undu ations and contortions . long

certain lines , however, the schists have been much ridged up and f E E O . N . O ne . contorted . these runs in an direction , crossing Loch A Broom between rdcharnich and Leckmelm , and , though a compara

tiv e l . y narrow band, may be traced for several miles In the eastern S r portion of the heet , beyond the thirteenth milestone f om Ullapool ,

the str ucture is complicated . The strata strike generally north and

south at high angles , and there is much overfolding and puckering , the high eastern dip being an inverted one in relation to the gentle

dip of the same rocks about Braemore .

From the point of view of tectonics , the most interesting part of the area of the E astern S chists is that embracing the F annich

mountains and the tract immediately to the north of it . In that

region , several bands of rock with more or less distinctive lithological

' O ne n characters have been mapped out . of these bands contai s i micaceous and hornblendic rocks , some of wh ch resemble Lewisian

types to the west . When traced in the field these bands behave as O f if they were synclinally arranged , but if the correlation one of the

groups with Lewisian types to the west be correct , it would follow that the rocks form a great recumbent fold with an amplitude of

several miles . The Triassic and Liassic rocks occupy a very small area in the - hi e north west corner of the map . The former consist of w t and red inte rstra tifie d sandstones , near the top with green and mottled shales i or marls , and as yet have not y elded organic remains . The latter , so O - far as bserved , are composed of thin bedded argillaceous limestones

with fossils .

h les ne a u a le and a ua e e B e e d e T is mi to is bo t mi q rt r abov ra mor Lo g . P rec ious L itera ture . 1 1

P R EVIO U S I E R A U R E L T T .

“ In the memoir on The G eological S tructure of the North - west Highlands of Scotland ” a detailed account is given of the literature bearing on the controversy between Sir R oderick M urchison and P rofessor Nicol regarding the succession of the rocks in that

region . It is desirable to recall certain points in that historical

sketch on account of their bearing on the ground now being described . ’ It was there shown that Nicol s main concl usions had been confirmed G S m : 1 by the work of the eological urvey , na ely ( ) that the quartzite limestone series (Cambrian) rests unconformably on the T orridon Sandstone ; ( 2) that the limestone is the highest member of the quart zite - limestone series ; ( 3) that the so - called Upper Quartzite and Upper Limestone of M urchison ’ s sections are merely the repetition of the lower quartzite and limestone due to folds or faults ; (4) that there is no conformable sequence from the quartzites and limestones into the overlying schists ; ( 5) that the line O f junction is a line of

fault, indicated by proofs of fracture and contortion of the strata . In this connection reference ought again to be made to the im portant O bservations by P rofessor Bonney on the sections in A bhuinn B ruachai th e g near Heights of Kinlochewe , within the limits of the

. so map He pointed out that, with the exception of some dykes , the “ called intrusive syenite of G len Logan (G len B ruac haig) is merely a granitoid variety of the Hebridean G neiss . He showed that its junction with the quartzites , Fucoid Beds and limestone is a faulted

. O D r one , and indicated the direction of the fault In pposition to . Hicks h e contended that the newer series (E astern S chists) in G len B ruac hai g belongs to the metamorphic rocks , as they consist of dark ae - - l uartzite s. green schists , dull coloured mica schists and micaceous q

D r. With reference to the work of Hicks in this region , it may be sufficient to state that he regarded the schists of Ben Fyn (Fionn B h e inn S 92 r in heet ) as forming a group in the metamo phic series . - i n r 1 He classified the pre Cambrian rocks th ee divisions . ( ) lower , i M 2 consisting of mass ve gneisses (Loch aree) ; ( ) middle , comprising S 3 more banded gneisses (Loch hiel) ; ( ) upper, composed of crystal line schists (Ben The occurrence of small patches of red sandstone on the shores G M acC ulloch of Loch ruinard was recorded by , who considered it to “ ” be the equivalent of the R e d M arl of E nglish ge ologists i S ub S M sequently this deposit was referred to by edgwick and urchison , R e d S E who indicated its resemblance to the New andstone of ngland, i S and also to some beds seen below the Lias n kye . § R e d S G In his paper on the Newer andstone near Loch ruinard , P con lom e r rofessor Nicol notes an interesting point , namely , that the g ate belonging to this series contains fragments O f quartzite and lime th e stone , which he identified with the quartzite and limestone of

J r l . ua t ur Ge l oc vo . 9 3 . o . o S Q . . . , xxxvi . p

4 1 . a r J l . t. ur. G o 1 u o e l. S oc v o . . f Q , xxxix p “ ” l 65 and 9 9 I vo . . I D e scription of th e We ste rn sle s of S cotland . ii pp , and ol i v . 5 4 ii . p . . “ § O n th e S truc ture an d R elation s of th e D e posits c on ta in e d b e twe e n th e ” P a R n d h e l c S e e in th e N S c land T rans. Geol . rim ry ocks a t O o iti ri s orth of ot ,

S oc. S e c nd e 1 5 S e ol . . . 6 . ( o ri s) , v iii p orm a ti ns a nd ou F o B ook G r ps.

* neighbouring mountains (Cambrian) . He discovered Lias boulders T inafuline E we P J on the shore near T opposite Isle , and rofessor udd collected Lower Lias fossils from boulders at the same plac a i Both in situ O ff regarded these blocks as derived from rocks not far , but they were not aware that th e Lower Lias occurs in place at three o r four localities farther to the north in the neighbourhood of Sand and

close to G ruinard Bay . 1 880 Sir A G In , . eikie suggested that the hummocky contours of e G G h the L wisian neiss , especially in the neighbourhood of airloc , bear a striking resemblance to the surface which geologists now always

associate with the action of glacier ice . He contended that these rocks would never have assumed s uch a contour if exposed merely

to ordinary subaerial disintegration . He also compared the basal

- Torridonian breccia of that district to moraine stuff. § 1 8 6 M r O 9 J . G G In , . . oodchild advanced the pinion that the desert conditions now obtaining in the Sinaitic peninsula are the exact counterpart of those that prevailed in pre - C a rnbrian time in S R utherland and oss . In his opinion , the felspars in the Lewisian G O f - neiss , instead of being slowly kaolinised by the action rain water c harged with carbonic acid , gave way under the strain set up by e n xtreme expa sion and contraction , due to rapid changes of tempera - m th e ture . The ferro magnesian inerals of gneissoid rocks , having different coefficients of expansion from those of the other con stitue nts S , plintered into fragments so small that they were easily P blown away as dust by the wind . ossibly in the case of the Torri donian strata these materials from the old gneissic mountains may

now and then have been distributed by the agency of lakes , but the action of water may have been there limited to the distribution of the disintegrated materials by the transient torrents after the heavy

rains which occasionally deluge such regions . ” 1 89 P P e In 7, rofessor en k gave an account of his visit to the

- North West Highlands , during which he examined typical sections in A ssynt and in the Loch M aree districtfl] R egarding th e hummocky structure of the Lewisian G neiss and the overlying T orridon

breccias , he inferred that they did not imply submarine , lacustrine

or glacial conditions . In his opinion the phenomena could only be c O f ac ounted for by supposing the existence a dry continental climate , the main erosive agents being large changes of temperature , wind and occasional torrential rains . S ubsequently , from an examination of the felspars collected from h T rri D r M t e o don S . andstone at Kinlochewe , ackie concluded that a glacial or subglacial climate prevailed during Torridonian “ time . J ua rt. r Geol oc l . 1 8 ou . S . vo . . 6 . Q . , xiv p ’ i 0 . c t 1 9 . 1 p . p . 6 i l c t. v o . . 660 . I xxxiv. p a ture ol i l c l S e c e H e and v . . 400 al n G e a , xxii p . so o ogi k t h s at om A d ” 1 882 a 16 7 . bro , , p . “ ” D e l 1893 e C nd n i B s E i e l oc vo . d n . G o . S . II n a n T ra n . s rt o itio s rit i , , vii ( 22 1 p . . “ ” TI G e l c e P roble m s a ns N e d - e S c land Zeitschri der omorpho ogis h r w st hott , fl G llsc a i lcu — 1 ese h t tr E rd n de e u B 1 1 9 . lin B nd N o 3 . 46 er a . f j , xxxii . , pp “ T h e F e lspa rs P re sen t in S e dim e nta ry R ocks as I ndicators of th e ” l C nd n v . C n e ane u c o . l a e T a E d Geol. S o . C r ns. in o itio s of o t mpor o s im t , . , vii 1 8 3 443 . ( 9 p . P revious L iter u a t re. 1 3

In the course of the Bathymetrical Survey of the freshwater lochs O f Scotland carried out under the direction of Sir John M urray P M r. S and Laurence ullar , several of the lakes included in this heet

XI . were sounded . In the sequel (Chapter ) special reference will be * W O . G . J . H . made to the results btained . ,

“ B a e cal S u e th e S c F e wa e c und e th e thym tri rv y of ottish r sh t r Lo hs, r d e c n of S ir J n M u a and a u e nce P ulla du n th e e a 18 9 ir tio oh rr y L r r, ri g y rs 7 l i — vo s . . vi . TE CHAP R III .

H A E * T E LE WIS I N G N ISS .

E N E R D E S C R IP IO N G AL T .

T H E G Lewisian neiss , as already indicated , forms about half of the M area lying to the west of the oine thrust . The largest tract extends from the sea near the north - west corner of the map southwards to M Loch aree , where it is truncated by a great fault striking north

I i - west along the loch . we place the one inch maps 9 1 and 92 together in proper position it may seem as if the Lewisian rocks on the south - west S ide of the Loch M aree fault have been shifted

- laterally towards the north west for a distance of about nine miles . A s - , however , the pre Torridonian land surface was extremely uneven M on both sides of Loch aree , and consisted of steep mountain slopes w ith an intervening hollow in which ran a line of fault, it is quite possible that the straight cliffs in which th e Lewisian rocks now end

- - on the north east side of the loch are of pre Torridonian age , though they have also been affected by fault - movements of post - Torridonian " tim e r Various detached masses O f Lewisian G neiss occur along the

central region between Kinlochewe and Loch Broom , one of which M is an inlier , north from the head of Loch aree , partly bounded on the east by the F a sagh fault t The others have been carried west - T he ward by post Cambrian thrusts . largest of these displaced the R masses , extending from Loch an Nid to Kinlochewe iver , is d more than eight miles in length , and is of consi erable interest in the so- history of geological research , as it includes the called syenite of G P 1 879 len Laggan , § which was recognised by rofessor Bonney in as

a faulted mass of Hebridean (Lewisian) gneiss . ” O n the south - west side of the Loch M aree fault the gneiss west of the post - Cambrian dislocations forms three small inliers within the T orridon S an d O f t e andstone area , also the eastern extremity h large “ tract which extends from Loch M aree through one - inch map 9 1 to G S th e S the sea at airloch . everal small thrust stripes occur on ides ’ M e all G hiubh ais of a , the hill two miles west of the head of Loch hi r a e e .

“ F or u e a cula e e e n ce be m ade T h e G e l cal S uc u e f rth r p rti rs , r f r may to o ogi tr t r ” f h N - e l nd M ol r O t e H a em Ge . S a a 190 7 a cul a l . a orth W st igh s , , , p rti r y to p rts of

c a e v . . and h pt rs iv . , vi , xi , xii . " T h e -T orridon aul d e c e d in C a e X 1 post f t is s rib h pt r . d l ca n d e d i X T h e c a 3: This is o tio is e scrib n C hapte r . ott ge from which this aul a e na e n ot a e d in th e ne w e d n S e e 2 I o f t t k s its m is m rk itio of h t 9 . t stood n h e S e c M a e e ne a th e u A bh uinn a n F h asai h t . hor of Lo h r , r mo th of g “ ” le n an of P He ddle th e le n in c A bh uinn G . B ruach ai l Log rof , g whi h g f ows . “ P e l i cal N e on th e V c n of th e U e P a c M a e e tro og ot s i i ity pp r rt of Lo h r ,

l . J Ge l o vo . . 9 3 ua rt our o . S c . Q . . , xxxvi p 1 4 G enera l D escri tio p n . 1 5

In many localities , perhaps particularly on the sides of Fionn ’ B e inn C hais e in M or Loch and the slopes of a g , the rock is thickly ff covered with drift , but where the solid gneiss is exposed it o ers a striking contrast to the adjacent Torridonian rocks . Its face is stamped with the signs of much greater age , of many different movements and episodes of intrusion which were all completed before n the Torrido ian formation began to accumulate .

m - The earlier bands of gneiss , and also any later pre Torridonian

- dykes , strike in most places nearly north west , or in some direction

- between north west and west , and they are steeply inclined , while the Torridonian rocks have com monly a gentle easterly dip or are rolling

A - about at low angles . band of hornblende schist forms the summits

O f B einn B einn A iridh - Lair and Charr , making at its north eastern margin a long range of magnificent crags stretching for about six

- h - miles in a north westerly direction . Near t e south eastern end ff the cli s diminish in height, become partially hidden under

Torridonian outliers , and are finally completely covered by the mountain masses of Slioch . - S L un ard The inlier of hornblende schist in rath g , close to the

- south western margin of the map , is greatly obscured by morainic drift , and possibly extends over a much larger area than that L o hm ar represented . The area west of the c e e Hotel is one of the most accessible , and is also almost free from drift . A s in - the North West Highlands generally , the chief rocks com posing the gneiss are divisible into two series , namely

1 A n . intricately arranged mass of ultrabasic, basic and acid

rocks , partly massive and partly foliated , which has been

called the Fundamental Complex . 2 A . series of later intrusive dykes , chiefly basic and ultrabasic , n which are ofte foliated , and which usually strike between

- west and north west .

In addition to the above two groups, the district to be now described contains also another, namely

3 A - - . series of beds including limestone , mica schist , graphite schist

- and quartz schist , which are believed to be of sedimentary M S origin . They may be termed the Loch aree eries ,

- O f as they are well seen on the north east side this loch . S 3 eries is of special interest , as , if it is really of sedimentary origin , it is probably as old as any known sedimentary series either in S cotland or any other part of western E urope . It was the belief O O G of the lder bservers that the Lewisian neiss , like the primitive gneiss everywhere , was on the whole of sedimentary origin . In later th e h ad years , after igneous character of many of these rocks been D r n recognised, . Hicks was the first to mai tain that some of the M G - schists near Loch aree and airloch , in the adjoining one inch * f 91 . O map , were metamorphosed sediments The work the G S eological urvey has helped to confirm this view , and has also disclosed , in the northern part of the map , another zone of highly sheared rocks striking from B e inn D earg Bheag in a north - westerly

“ ” - - P r e and C e n al R e Geol. M a . T h e e C ambrian R ocks of W st tr oss shir , g ,

104 1 880 . p. , 1 6 T he L ewisi a n G neiss .

h - U idh e direction to Loch na , which may also possibly be of sedimentary origin . The original relations of the Loch M aree beds to the more for orth o ne isse s massive gneisses , the most part g or gneisses of ri i r igneous o g n , are by no means clear . The fo mer are only found r in specially shea ed belts , and their boundaries with the massive T orridon gneisses are in most cases , if not all , lines of pre thrust or fault . S M r G . th ome observers , including the late unn , have favoured e view that the Loch M aree beds belong to a higher and newer series than the massive gneisses , upon which they probably lay at one O f time unconformably , the absence any clear unconformity being due to the amount of metamorphism and shearing which the two series have experienced in common . M r O n . thers , i cluding Clough , are more impressed by the fact — n that some of the supposed sediments for instance , the kya ite

- gneisses near Carnmore , rather more than four miles north east of the M and cluster of islands in Loch aree , the limestone rather more than a mile and a quarter north - east O f the outlet of Loch Bad an S alai - 9 1 — O f g g, one inch map lie within massive gneisses common type and seem to pass gradually into them . It is suggested , ara ne isse s therefore , that many of these massive gneisses may be p g , — — gneisses of sedimentary origin , there being much more sediment ary material in the Lewisian G neiss than our present knowledge u ff enables s to di erentiate . There is no evidence of the intrusion of any of the massive gneisses into the supposed sediments , but this may possibly be accounted for by the great pressure under which the supposed intrusions took place . The broadest band of the Loch M aree beds stretches from A bh uinn F h asai h Letterewe to the foot of an g , and may be called

- - the Furnace band . Its length from south east to north west is about

five miles , and its greatest breadth , including various bands of

- - A hornblende schist, nearly three quarters of a mile . nother , the G T irlach a G n leann band , can be traced from Lochan Fada along lean T irlach a Srath an B uidh e to the foot of , and thence round the north B e inn Airidh and west sides of Charr . Between the Furnace and G len T irlach a belts several others of less breadth can be followed north - west from the west S ide of Loch G arbh ai O ne — B e inn Airidh — g. the Charr band is visible on the - — F olais a south east side of that mountain , and a second the b nd in a north - and - south b urn from two - thirds of a mile north to 1 50 * F olais yds . west of . Both these bands are folded by a common - olai system of folds with axial planes striking north west . The F s band contains the Letterewe limestone , formerly quarried near l A F o ais . , which is traceable for several miles considerable fault SS W G arbh ai runs in a . direction from the foot of Loch g to Loch M - - aree , and on its south east side a band of mica schist occurs near the limestone and can be traced south - east until it coalesces with the

- mica schist of the Furnace band . The tectonic relations O f the different bands described are O T h e G T irlacha B einn A iridh F olais bscure . leann , Charr and bands

N ot n ed on th e on e nc A u ua e le no o am i h map . bo t a q rt r of a mi rth fr m e e e e L tt r w .

e w i eiss 1 8 T h L e is a n G n .

the - movement , sediments and associated hornblende schists may have been folded so as to be flanked by the more massive gneisses on either side . M any broken pieces of the thick hornblende - schists associated with the sediments are found in the mylonites just referred to , and it is certain that these hornblende - schists must have been foliated before the mylonites were formed . There may have been two periods of fl e x ure later than the foliation of these hornblende - schists and separated from one another by an interval during which certain rocks were mylonised. It also seems probable that the movements which plicated the mylonites in the Folais area were later than the broad fl e x ure which affects the basic dykes near ff Carnmore , for certain mylonites near this place seem una ected by the fl e xure . The G leann T irla ch a sediments dip steeply away from the massive

- gneisses on their north east side , but it is not improbable that they

- are separated from these gneisses by a thrust plane . In a section

- rather less than a mile above the head of Lochan Fada , a pale grey rock , a few feet thick , comes between the sediments and the reddish ff n gneiss . The grey rock di ers from the red gneiss in containi g long prisms of hornblende and few or no parallel quartz streaks : the quartz and felspar are granulitic , and the individual grains are in a state of strain , but many of the hornblende prisms have idiomorphic terminations , are quite free from deformation , and O f contain inclusions quartz and felspar . In the field it seemed as if the grey rock might perhaps be an altered sediment in which hornblende had been developed by metamorphic action , but possibly it may be a sheared form of the red gneiss . The boundary between 4407 the pale rock and the red gneiss is not sharp , but a specimen ( ) of the latter , taken at a distance of two or three feet from the grey rock , is granular rather than granulitic . A - quarter of a mile south east of Furnace , and also between the headland a mile nor th - west O f Smiorasair and the foot of Abh uinn hasai h - th e loch side an F g , the mica schists are separated from O f - Lewisian rocks by gneiss with many bands hornblende schist , most of which certainly represent basic dykes . The line between

- - the gneiss and the mica schists is a pre Torridonian dislocation . S - outh east from the headland referred to , the gneiss and the dykes become more and more crushed as they are traced away from

- - the loch in a north east direction towards the mica schists . The gneiss is first crossed by many strings of a compact purplish - brown

flint - y felsitic looking material . Then the external aspect becomes ff fl in t a ected , the rock weathers white and the y material becomes

. f general The dykes are similarly af ected , but to a less extent . Both in the gneiss and dykes the flinty rock can O ften be seen to follow planes of dislocation . The fault which bounds the gneiss on

- d h as u - the north east si e probably an pthrow to the south west , but whether the crush phenomena O bserved in the gneiss are due to this u P d line of movement is doubtf l . erhaps it is a later islocation along an A u - ra air 0 . S m i s old line of weakness . bo t 6 0 yds south east of o

- burn , at a place where a marked feature appears at the north east loch side fl a margin of the gneiss , the gneiss seems to pass into ggy - m brown mica schist, and the latter ight be held to have been formed nera l D escri tion 1 9 G e p .

d from the former by mechanical eformation . But perhaps a portion of the schist has been caught on the upthrow side of part of the fault and has been so crushed with th e gneiss that the rocks cannot

now be distinguished . The zone of highly sheared schist extending from B einn D earg n a h U idhe I s Bheag to Loch possibly of sedimentary origin in part , 1 1 . but the evidence s inconclusive Its length s about seven miles , and 200 or 30 0 its breadth in some places is yds . , but it is very variable

in development , and sometimes consists of several parallel bands at

considerable distances from one another , separated by large intrusive n dykes which form a great part of the total width of the zone . O both flanks the zone is bounded by gneiss which retains its original coarse -r characters . The rocks within the zone comprise quartz ock , quartz

S - lrornble nde - t - - chist , quartz schis , hornblende biotite schist , garnet

if r us fin - u e o e . amphibolite , and grained micaceo s gneiss Their n - appeara ce , especially that of the finer biotite schists , is sometimes D r h as suggestive of a sedimentary origin , and , as . Teall pointed out , the association O f quartz and hornblende without felspar is unknown * in igneous rocks . In the field , however , the siliceous members of A t the series O ften seem to merge into ordinary quartz veins . Creag l h m h e a l M e adh onac S S E . , about a mile and a quarter of Creag

m h e all - fine - Beag , the hornblende schist and grained gneiss are in r - many places penet ated by quartz veins , and also by quartz rock and

- quartz schist , which appear to have been formed by the coalescence

of quartz veins and subsequent shearing . Further , at the head of a small burn that flows off the north e ast S lope O f Creag na Sgoinne A llt G hiubh sa chain th e into Loch , quartz bands seem to merge into

thin quartz veins that traverse the gneiss in all directions . The

- - f quartz hornblende rocks dif er much in composition , and the more S S iliceous varieties are almost pure quartz . ome rocks within the

- sheared zone are garnetiferous hornblende schists , and appear to be

portions of the Fundamental Complex . Whether any are of sedi

mentary origin or not , the rocks within the zone are of special - T orridon interest , because , unlike most of the sheared pre rocks in

- other parts of the North West Highlands , they have been sheared

before the intrusion of the basic dykes . This is seen , for instance ,

near the head of the small burn just referred to , where the foliated quartzose bands are well developed along the north side of a dyke of hornblende - schist which clearly crosses the foliation O f the a Y t b nds . e these dykes have been locally converted into horn

- blende schist , either totally or partially , by renewed shearing movements . A well - developed linear foliation or rod structure is to be found in the pink gneiss and basic dykes occupying the centre of the B inn a n d S S W . e . Letterewe syncline , a mile a third from Lair In these rodded rocks the constituents are in the form of rods , not a an d n th e S lamin e, sections at right angles to the le gths of rods how r no pa allel arrangement . The structure is evidently of secondary r i w ff r o ig n , and due to causes hich have a ected diverse va ieties of th e c rocks over considerable districts . When dykes (whi h are th e folded) strike N . rods are usually almost at right angles to

“ H land O f S c land T h e G e ological S tructure of th e N orth We st igh s ot , M em Geol S ure . . 79 p . . T he L ewisia ne 20 n G iss. t hem and incline south - east about I n parts of the syncline the phenomena suggest that the rods may represent portions of foliation planes which have been cut up into narrow strips by strain - slips developed during folding of earlier foliation planes . But in other t ale distric s this explanation does not seem satisfactory . A ll the shearing and mylonising movements so far referred to are — f of pre Torridonian age . It is di ficult to be certain of the sequence of events , but there were at least three distinct shearing movements, which are indicated below, beginning with the earliest .

1 S ea n of th e uartz h ornblende - c and e oc in th e B e inn . h ri g q s hists oth r r ks

n h - idh e n e D earg B heag an d Loch a U zo . 2 S e n e of th e c d e c was cc an e d n en e . h ari g of som basi yk s, whi h a omp i by i t s c u l n and ea n of th e c th e F unda e n al C le r mp i g sh ri g ro ks of m t omp x , u t did not ule le d an e de n ld n th e d e b as a r a to y vi t fo i g of yk s . F ld n c duce d de but c a a e l en le f ld uc th e 3 . o i g whi h pro wi omp r tiv y g t o s, s h as l h l e an cl e n e e L e tte re we sy nc in e and t e arg ti in e ar C arn more . Th s fold s pli cate d th e alre ady partly -foliate d dyk e s and le d to th e furthe r l a n o f e d e c e e n ot al e ad c l e e l l a e d fo i tio som yk s whi h w r r y omp t y fo i t . The y d o n ot n e ce ssarily in dicate th e disposition of th e rocks o f th e F unda e n al C le for e e c e e in an ca e al e ad m t omp x , th s ro ks w r , m y s s, r y in a highly con torte d c ondition b e fore th e late r fl e xure s we re e l e d de v op .

In the above table no mention is m ade of mylonites— those crushed rocks which still show cataclastic structure as well as partial

S - - recrystallisation . ome of those in the north and south burn near F olais f , T Letterewe , were formed be ore the Letterewe syncline , but others in the Carnmore district seem later than the Carnmore

anticline . S ome of the mylonites are very compact and black , and look so fl in much like flint that they have O ften been called ty crush rocks . 2 0 S W B inn E 0 S . e ast of the burn a mile and yds . of Lair , a mylonite , 40 about yds . wide , has been formed from an acid gneiss containing

O f . basic streaks and lenticles , some which probably represent dykes The m ylonise d rocks formed from the acid gneiss have a conchoidal

fracture and are of dark brown or black colour when fresh , but they W “ weather with a dirty white crust , speckled with hite or pink eyes v of felspar . Those stripes which ha e been produced from the basic O f streaks are , in fresh fractures , much the same appearance as the

above , but they weather with black or dark brown surfaces . S 4774 pecimen , from a similar striped mylonite on the west side of

- u the burn , shows under the microscope well marked a gen of felspar S in the pale stripes and of hornblende in the dark stripes . ome of S S the augen how igns of crush . They are surrounded by fine streaks

of the cryptocrystalline material , and these streaks are themselves M r m icrO S C O ic . sometimes contorted and crushed by p faults . Barrow has analysed a portion of this specimen with the following result

We m ay suppos e also tha t rodding can be prod uced in any cube of rock by u e c n e ual e u e u d e in O e a lea n th e s bj ti g it to q pr ss r s from fo r si s pposit p irs , vi g con stit ue nts to be stre tch ed out towards th e oth e r t wo sid e s on whi ch th e “ ” re ssure le G u e n D f 10 6 n a n ie K r stallin e n S c e e . . is ss ( r b m , y hi r p G u en nn e dd n n h e ddle r . r b ma stat s th at ro i g is cha racte ristic of rocks i t mi l ld but th e e d en ce in th e N -We st H land not in cc d imbs of fo s , vi orth igh s is a or nce O n n a with this pi io ) . A u ua e le n e e e e bo t a q rt r of a mi orth from L tt r w . era l escri tion G en D p . 2 1

The percentage of silica must be much higher in some stripes than in others . Besides these black m ylonise d rocks which Show clear indications m lonise d of crushing, we frequently find , in or near the y zones , dark brown , grey or black strings , rarely more than an inch thick , which bulge out in rounded projections , or end bluntly and look like S intrusive felsites . uch strings are , however , confined to zones h m w ich have been crushed , and it see s probable that many of them are isolated on all sides by the adjoining rocks . It is difficult to see i how they can be intrusions of true gneous rock , though some specimens that have been sliced bear a close resemblance thereto . G ood examples of these felsite - like strings are seen in the wood on — L ochm a re e the north west side of Hotel , and just below the summit M l m i r ir e al R S o asa . of iabhach , In the latter locality the gneiss may be clear , fresh and granular up to the edge of the veins , but A 4 281 there are dislocations near by . specimen ( ) of one of the S fl ux ion strings hows a microlitic groundmass and signs of , and the fragments O f quartz and felspar included in the groundmass S how P n strongly marked cataclastic structures . erhaps by the inte sity of crushing in some of the m ylonise d zones sufficient heat may have been generated to fuse small portions of the rock , which then behaved as intrusive

- The post Cambrian thrusts will be described in Chapter VI . , but th e G character of the large mass of displaced Lewisian neiss , of which . the southern end lies between A bh uinn an F h a saigh and A bh uinn B ru h i ac a G . g (in len Logan) , may be mentioned here Its most - w characteristic rock is a coarse granitoid biotite gneiss , hich in places shows no banding and bears a strong resemblance to parts of the Fundamental Complex near the mouth of the Little G ruinard R ff iver . It has not been much deformed , and is quite di erent from the Lewisian rocks— largely composed of the Loch M aree Series which are found a little farther west in the unthrust area . The basic dykes in the thrust mass also S how their intrusive character perfectly

“ - clearly, and have in no case been converted into hornblende schism" though all the dykes in the adjacent unthrust area have been so . These strik ing contrasts may be explained by the difference betwee n the general strike O f the larger masses of unthrust gneiss and the

S om ewhat similar flinty cr ush rocks b e h avin g lo cally a s i ntrusion s occur in e d c n an ce al n th e c cula aul a un d th e ca uld n oth r istri ts, for i st , o g ir r f t th t bo s ro “ fe and E B B a le T h e u de n H M au . . f l e l u B . ce o G e nc C . C . . s bsi o . T o gh , , i y , ” - C auld n S u de n c l c and th e A c a e d I ne u P e n e na ua rt. ro bsi e of G e n o e sso i t g o s h om , Q J our . Ge l c l l o S o . vo . xv . . , . p ' e d e ua rt. 1 P rofe ssor B onne y n otice d th e occ urre n ce of som e of the s yk s . Q J our Geo 0 5 . l S ea v ol . . 1 . . , xxxvi . p 2 2 T h e L ewisia n G neiss .

O f - u direction of movement the post Cambrian thr sts , which is con side rabl f y nearer west than the strike O the gneiss . We S hall now proceed to describe the main rock types in more O f detail , taking first those the Fundamental Complex , next the pre

. Torridonian dykes , and , lastly , those rocks which belong to , or are M S closely connected with , the Loch aree eries . It will be understood from what has been already said that it is not intended to imply by t M th his order that the Loch aree beds are e youngest .

T H E F UN D M E N C O M P E X A TAL L . The portion of the Fundamental Complex most free from folia tion and most near its original condition occurs in the northern area P near Little G ruinard . articularly good exposures are found at f G B e a - G adha gf about a quarter of a mile north west of Little ruinard , P and portions of these are represented on lates VI . , VII . , and VIII . “ in the memoir on The G eological S tructure of the North - West ”

P . Highlands . In late VI the darker and paler constituents are th e very imperfectly separated , and bulk of the rock may be taken n to represent the magma, of intermediate compositio , from which more distinctly basic and acid rocks are in process of formation . A nother view is to regard the bulk of the rock as a mixture rock , - fl uid formed by the mingling , probably while in a semi state, of P basic and acid portions . In lates VII . and VIII . the rock types are more distinct , and the basic and ultrabasic parts are in the form of rounded lumps, chiefly composed of dark hornblende or horn - an d O blende gneiss , which are surrounded ften injected by more acid

- quartzo felspathic material . These dark lumps must have solidified before the paler material , and in certain localities it may be seen that some of these lumps must also have possessed a banded structure before the acid material was introduced . Similar basic inclusions are common in many other districts, but are apt to occur u sporadically in groups . They vary in size from little kernels p to S great lenticles more than a hundred yards long . ome of the larger will be referred to again . P In lates VII . and VIII . of the above memoir the basic lumps S how no clear elongation , but it will be understood that , if a similar rock were subjected to shearing, some deformation and parallel elongation into lenticular forms would be developed . In many dis tric ts where the rocks are foliated the smaller lumps are elongated h th e wit their long axes parallel to one another and foliation , but it is a common experience to find the lumps , particularly the larger ff l ones, much less a ected by the fo iation than the surrounding more O acid gneisses . The shearing movements seem ften to have pro c e e de d around their margins and to have had very little effect on the main central portions . It must be remembered , also , that in areas which are almost free from granulitic structures and the ordinary indications of shearing , we often find parallel bands and lenticular f stripes o basic rock mixed in with the more acid gneisses . The parallelism in these cases may perhaps be attributed to flow motion before complete consolidation .

- N ot nam ed on th e one inch map . e u nda m e nta l C o m lex T h F p . 2 3

O G ccasionally in the northern area , near Little ruinard and other places , the banding , or broad early foliation of the gneisses ,

- - - O f - strikes north east or east north east instead north west, as is l i most com mon . This unusua direction may poss bly indicate the original arrangement , for such an arrangement is found in the least S - S 1 07 altered areas in the courie district , one inch heet , where it

- certainly existed before the development of the north west strike . O n G the other hand , the Little ruinard gneisses , unlike those in the S S f courie district , how no dif erences of character which can be con n c e te d with the changes of strike . It cannot be asserted that in the former district the gneisses which strike north - west are generally

- more granulitic than those which strike north east . Neither the ultrabasic nor basic rocks are always shown

- separately on the one inch map from the more acid , but the localities of some of the more important exposures will be given in the following detailed descriptions — Ultra ba sic R ocks The largest ultrabasic mass in the district is a massive dark hornblende - rock which is situated a little south - west

- G . O f of Little ruinard It is nearly two thirds a mile in length , trends

- - out north easterly , and , as shown in the one inch map , is almost at right angles by three epidiorite dykes . This mass is penetrated by irregular bands and strings of quartzo - felspathic material which is M similar to much of the crude acid gneiss of the district . asses and lumps of hornblende - rock of the same character as th e large mass occur in abundance in the surrounding gneiss , which , near the large mass , has a vertical foliation nearly parallel to the long axis of the latter . S “ mall masses of dark pyroxenite or hornblendite , and of grey G R peridotite , appear at several places east of ruinard iver and ‘ l south of Lochan na C airi l . They include such varieties as O livine - I nve ri nvi augite rock (wehrlite) and lherzolite . Between the a e and G R Little ruinard ivers , also , several bands and oval masses of

- peridotite and hornblende pyroxenite make their appearance, often n associated with basic rocks containing felspar , which also belo g to the Fundamental Complex . A - - brown weathering rock , resembling peridotite , forms eye like O f masses in the gneiss on the west side Loch Fada , two miles south of 1 00 G . . west Little ruinard The largest is nearly yds long , and lies more than half a mile from the south end of the loch and 1 50 yds . from the side . O n th B e inn D the nor east side of earg Bheag, close to the margin of the basic gneiss where it alternates with stripes of acid gneiss , two masses of a soft , unctuous , light coloured rock make their appearance . The rock is probably chiefly composed of talc - S O f or chlorite , together with another light coloured mineral . ome it is purple penninite) , probably from oxidation . The gneiss on each side has a peculiar appearance , probably from the presence in O f O f it some this mineral . In a burn a quarter of a mile north - east of Carnmore old

r 1 0 . house , va ious lenticles , the largest measuring yds in length , consist in large part of pale green actinolite . They are of consider n e scalés able i terest , because th y contain of graphite more than a O f quarter an inch long . 24 T he L ewisia n Gneiss .

A small outcrop of serpentine and peridotite occurs three - quarters E N E . E . . F ra o h i nn of a mile of ilean c in the F o Loch . B a sic R ocha— These rocks contain felspar , but are connected with those just described by insensible gradations and occur in a very

S imilar way . The chief varieties in this district are massive and

foliated diorites and basic gneisses . In hand specimens they are

often indistinguishable from certain dyke rocks , but in field ex posure s they usually S how a more variable composition and many

irregular quartzose strings . M any of the small lumps included in the acid gneiss , in the manner already mentioned in the introductory description O f the

Fundamental Complex , are of basic character . They are very liable

- to decompose , and have thus often given rise to small pot holes in

the gneiss which once surrounded them . This is well seen near the O S - m h e all - rdnance tation on Creag Beag , two miles north west of all Loch na S h e ag. Larger basic masses are very well exposed in the area between Sh e alla G hiubh sach ain Loch na g and Loch , where they strike north or - A ll east in some direction between north east and east . round their margins the gneissose foliation bends so as to conform with ° O fl them , but, a little distance the margins , the gneiss strikes north

west , so that they seem to have acted as centres of resistance to the fl ux ion b general flow of the acid gneiss , whether this be due to efore

solidification or to subsequent mechanical movement . The mass of which the relations are best exposed crops out about a quarter of a E E hiu h ch in . G b sa a . N . mile from the north end of Loch , and forms an 5 2 - l 3 . 5 0 0 . irregu ar oval yds long by yds broad . It is a well foliated ,

- - rather evenly banded hornblende gneiss . ’ A 3 - M h daidh M OI ‘ O f 00 ds. a bout y north west of Loch a , a band - 60 fairly well foliated basic gneiss , yds . wide and crescentic in shape , seems to form a great part of the circumference of a circle of which the centre is a very fresh coarse massive diorite with large white

- . 500 felspars The diorite lies about yds . north west of the loch and 1 is 30 yds . long . A O f O f R D quarter of a mile east the summit einu earg Bheag , one of the lines of intense shearing which have granulitise d the acid

gneisses subsequently to the intrusion of the basic dykes , passes through a basic gneiss belonging to the Fundamental Complex and

- converts it into a feathery hornblende schist . Basic rocks are well seen near the crag - tops half a mile north ’ east oi Carnmore and on the west and north - west sides of R e inn a C hais e in M or g . In the latter locality the basic material is much

- mixed with pale grey acid gneiss , either in broad masses or thin

irregular strings, which may cross the foliation of the basic rock .

Large basic lumps are also enclosed in the acid gneiss . The felspar is generally subordinate to the hornblende and in smaller i gra ns .

- In the centre of the Letterewe syncline , about three quarters of G arbh a i O f - a mile west of Loch g, various bands hornblende schist have been mapped which differ somewhat from th e normal dyke r ocks and may belong to the Fundamental Complex . The margins : 3

of some of these have been engraved on the one inch map . A n evenly banded hornblende - gneiss with much epidote is often

26 T h e L ewisia n G neiss .

It contains more quartz veins than the gneiss farther off the dyke , S - and hows various thrust like lines parallel to the dyke . It probably became finely foliated in consequence of movements which took place near the dyke before it was folded into its present form . The north - west part O f the thrust gneiss in the centre of the Letterewe syncline is chiefly composed of an acid gneiss with biotite

- and felspar augen . The gneiss at M e a ll R iabhach at the south east end of this thrust mass is a regularly banded acid gneiss without the lenticular wavy structures which are common in the strip of gneiss along the loc h side between the headland north - west O f S m iorasair and A inn F h a ai h the foot of bh u an s g . It is as a rule granitic rather than O f granulitic , but displays strong indications cataclastic action in certain parts

P R E - O R R ID O N I N IN R U I T A T S O N S . The most important intrusions are the basic dykes striking north west , but another series of dykes , of rather more basic composition than the above, is also well developed in the northern area between G B e inn D - Little ruinard and earg Bheag . The last mentioned dykes , which may be called the “ green dykes from their general olive green tint , strike as a rule nearly east and west, but must be dis tinguish e d from the east - and - west picrite dykes of the Lochinver - 1 0 1 1 0 7 district, one inch maps and , which are later than the north “ ” west basic dykes , while the green dykes are for the most part “ ” O lder than the latter . The green dykes are basic amphibolites consisting mainly of acicular green hornblende , with some chlorite , but often nearly free from felspar . They have been classed with ultra e basic dykes in this district . O n partially foliated syenite dyke h as C o ach been found , and near Carnmore and pp y there are a number of pegmatites which are believed to be later than the basic dykes . — Ultra ba sic D ykes Half a mile south of the outlet O f Lochan na B earta a dark green foliated ultrabasic dyke has been traced for

- about three quarters of a mile . For most of its course it closely

h - follows a thick dyke of ornblende schist , but diverges near the

- O f south east end . The rock , being a more perishable nature than the contiguous schists , has given rise to a slack or valley . There is evidence that the intrusion is later than the contiguous hornblende A t. schis nother , or possibly the same , dyke is seen farther east , a h di E B einn D M Or. mile and a half S S . of earg In the splaced mass of gneiss about three - quarters of a mile north of the Heights of O f Kinlochewe a few small dykes sheared ultrabasic rock , at present in the form of unctuous schist , have been noticed . They are only a

- - little below one O f the great post Cambrian thrust planes . “ The green dykes are most numerous south of Creag - m h e all ’ M h adaidh M OT Beag and Loch a . They are comparatively soft, weather rather like the other ultrabasic dykes , and frequently contain large plates of biotite . In direction and thickness they are more but irregular than the other dykes , the general strike is nearly east and west . They are coarse and quite massive at the centre and not very schistose even at the margins . The margins are chilled and show clear intrusive junctions , which prove that they belong to real a nd dykes not basic knots , such as are so frequently found in the

Fundamental Complex . P re T orridonia n I ntrusions. 27

B a sic D kes — - y The north west dykes , though numerous , are by no O n means evenly distributed . the eastern and southern slopes of ’ B einn a C haisge in Beag they occupy nearly as much ground as the

gneiss , while , on the other hand , certain belts are comparatively free S 1 0 0 . from them . ome of the larger examples are more than yds n wide , and adjacent dykes which run early in the same direction M occasionally combine and form even broader masses . any of the

dykes form projecting outcrops , but others weather into hollows or I a air s S S W . slacks , as near Loch an g , three and a half miles of th e n G . t Little ruinard In norther part of the district , for a wid h of

three miles or more , all the dykes are massive epidiorites except in W a narrow zone of shearing , here they have been converted into

- * S D r. hornblende schist, like the dykes near courie described by Teall . Consequently in this northern area the evidences of intrusion are

very abundant and clear . This is also the case , as already stated , in G B ruac h ai G the gneiss of len g ( len Logan) , which has been carried

- P forward by the post Cambrian movements . late II . , in the memoir ” G S - on the eological tructure of the North West Highlands , a , representing , portion of this displaced mass shows two of these epidiorite dykes intersecting the rudely foliated gneiss near th e

A t C a dh a , Heights of Kinlochewe . Beag , a quarter of a mile north of G B e inn D west Little ruinard , and again near earg Bheag, the gneisses of the Fundamental Complex strike north - east nearly

at right angles to the dykes . In the above areas the dykes are but - th e approximately vertical , south of the quartz hornblende zone dykes are usually in the form of hornblende - schist and incline to the

- north east nearly parallel to the prominent foliation in the gneiss . E ven in the well - foliated dykes the form of some of the original G arbh ai O f minerals is still preserved . Thus between Loch g, north

S - - lioch , and the north and south burn rather more than a mile west

- of that loch , various bands of hornblende schist contain porphyritic O ne forms composed of granules of felspar . of these bands , about 1 0 0 ff 0 . . . . e yds W N W of the outlet of the loch , is composed of di er nt S O layers , some of which how the porphyritic forms , ften about half an

inch long , so crowded together as to equal in bulk the rest of the 1 A 000 . rock , while other layers contain hardly any . gain , about yds

- - north east by north of Furnace, certain parts of a hornblende schist f - are full of porphyritic orms of felspar , giving lath shaped and squarish sections . Near the sides and along certain bands in the interior these forms have been sheared out into thin parallel streaks .

In most of the foliated dykes the foliation is parallel to the sides .

The margins are more closely foliated than the interior , and , in the O broad dykes , are ften finely schistose , while the central parts remain in a massive condition . That the foliation is so often parallel to , and most perfectly developed near , the margins , is , no doubt, due to the fact that most O f the shearing movements have in this district h ad proceeded along the dykes . These movements have often com ara tiv l p e y little influence on the contiguous gneiss . A u large dyke , which contains free q artz , and appears to be more acid than the usual type , crosses the south part of Loch Fada , on the

“ - T h e M e a D le e n H n le nde S c ua rt. J our . t morphosis of o rit i to or b hist, Q G eol. S oc. l li vo x . 13 3 . . p . 28 T h e L ewi ia n Gn eis s s.

G E E S . L o hain west side of Little ruinard , and continues past c na a h C p c . ’ A little north - east O f B e inn a C haisge in M Or certain foliated dykes contain such abundant inclusions of pale - grey acid gneiss that r they can be eadily distinguished and traced . From the evidence obtained it seems probable that most of these dykes are earlier than A O f the neighbouring dykes without inclusions . good example one i n r of these dykes , which the lenticula inclusions form perhaps half 300 the mass , may be seen yds . W . N . W . of the south end of Lochan C na a p ch . S ome of the foliated dykes in the gneiss in th e centre of the Letterewe syncline still show their original intrusive character dis tinc tly . This is seen best about half a mile west and half a mile rbh ai south of the outlet of Loch G a g. These dykes are distinctly

- foliated , and some of them strike north east for several hundred yards and are inclined at gentle angles . In addition to the above , all or nearly all the foliated dykes which occur near the D ubh Loch of ’ S rOn L oc hm are e Carnmore and a Choit , west of the Hotel , must have been foliated before they were plicated , for the foliation planes share in the folding of the outcrops . f 00 E E . O f O D The folded dyke 7 yds . S the head the ubh Loch of

- 1 2 Carnmore dips gently north east and contains a quartz vein , f rom 2 0 . to ft thick , which is, almost parallel to the base , and lies rather nearer the base than the top . The portion of the dyke above the vein consists O f hornblende - schist with foliation planes parallel to n the top of the band, but the part below is biotite acti olite schist w ith disturbed foliation planes dipping steeply south , so that it is i clear that the quartz vein occup es a plane of discordance . In addition to the quartz , the vein contains scattered hornblende crystals ,

- - streaks of biotite actinolite schist , and irregular patches , as much as a foot thick , of a coarsely crystallised carbonate which contains some I t diopside . is suggested that the schist below the vein may once

- have been in the form of hornblende schist like that above , but that the movements along the vein have converted some of its hornblende into biotite , and in doing so have set free some carbonate .

— - Syenite D yke A bout a third of a mile south east of Carnmore - 5 8 . old house a coarse grained dyke , from to ft thick and chiefly O f nricrocline 1 60 composed hornblende and , can be traced for S . . N E . yds in a N direction ome parts are massive , but others ,

r r n . particula ly on the south east side , are foliated pa allel to the margi — P e ma tites. P g egmatites , which are believed to be of later age than D the basic dykes , are abundant near the ubh Loch of Carnmore , and C o a ch M narrower bands are also common near pp y , Loch aree , but m lonis d are generally in a y e condition . The unfoliated pegmatites are harder than most of the rocks in which they occur and often form prominent exposures or crags in areas which are to a considerable M extent covered with drift . any of them are rather irregular in O ff direction and give short branches , but near Carnmore the general

- trend is perhaps north west , irrespective of the foliation of the gneiss

1 500 . which they traverse . In the crags yds south of Carnmore , O f - where the strike the gneiss varies between east and north east , the transgression across the foliation is quite clear . The Carnmore pegmatites are frequently found quite free from P e o ridonia n I ntrusions 9 r T r . 2 foliation even in places close to well - foliated dykes of hornblende 9 1 schist , and in the adjoining one inch map similar unfoliated n pegmatites frequently cross foliated dykes . The common c o stit u nts e of the unfoliated pegmatites are plagioclase , orthoclase and

m i roline i . c felspar , quartz , biotite and muscov te In the crags north east of Carnmore muscovite O ften occurs in idiomorphic crystals 1 1 3 . . from to ins long and from a }A to in broad , measured across the basal cleavage . In the tumbled blocks from a white pegmatite a mile and 200 yds . west of south of Carnmore some of the mica plates are 4 O f th e 3 . . e n 1 0 . ins long and or ins broad In most pegmatit s, both ear C o ach Carnmore and pp y , white felspar is more common than red . North - east of Carnmore the white felspar is sometimes enclosed G O f within the red . raphic intergrowths quartz and felspar have

- been noticed in the crags south , north and north east of the same place . O S N pegmatites how clear evidence of folding , but the movements which plicated many O f the m ylonise d rocks in the Letterewe syn cline M lon is d are probably later also than the pegmatites . y e pegmatites C o a ch Smiorasair are common , but , excepting near pp y and , are rarely more than a foot or two thick : at the former place they have more O m lonise d m lonise d ften been y than the adjacent rocks, and the y - O f examples contain numerous eye shaped pieces pink or white felspar , ’ n some of them as large as a he s egg , in which one cleavage plane r S are r crosses the entire breadth . C ystals of such a ize ra e in any of M the other Lewisian rocks . ost of the pieces have rounded outlines , and look like corroded phenocrysts embedded in a streaky pale - grey

- or greenish grey felsitic matrix . The subparallel streaks composing in n the matrix vary tra slucency , and are often so thin that thirty can be counted in the thickness of half an inch . They wind round the felspar augen and are sometimes sharply folded .

fin - 5 - m The greenish e grained rock 0 yds . north east of the ica schist on the south - east S ide of S m iorasair is probably a m ylonised pegmatite . It is hard , sharply jointed , very fresh , weathering only M in a dirty white film , and possesses a conchoidal fracture . icro scopic examination shows the m atrix to be cryptocrystalline and O f the grains in it to be composed felspar and epidote . The felspar m someti es shows plagioclase striation and gives definite extinction . A n M r analysis of the rock by . Barrow gave the following result

S ili ca A lu mina F e rric O xide Lim e M agn e sia P otash S oda Loss on ignition

T H E O C H M R E E S E R IE S A N D S O M E SS O I E D HI L A A C AT S C STS . The distribution and general relations of these beds have been n dealt with in the introductio to this chapter . Tourmaline is not uncommon both in the mica - schists and in veins in the thick horn

- blende schists which are associated with them . These veins must 30 T h e L ewisia n nei G ss.

have been in existence before the formation of some of the m ylon ise d th e rocks in the Letterewe syncline . In more detailed description

of lithological characters , etc . , which now follows , the rocks will be taken in the following order ( 1 ) M ica - schist ; ( 2) M ica - actinolite - schist ; (3) G raphite - schist ;

- - — (4) Kyanite gneiss ; ( 5) G ranular quartz rock ; ( 6) Quartz schist and

— - quartz - magnetite - schist ; (7) Quartz hornblende schist ( 8) Limestone ( 9) Calcareous biotite - hornblende - schist ; ( 1 0) Chlorite - schist ; ( 1 1 ) Hornblende - schist and hornblende - chlorite - schist ; ( 1 2) Hornblende

schist with brown mica and pyrites . No further description will be given of the rocks in the highly B e in n D h - U idh e sheared zone between earg Bheag and Loch na . 1 M ica - chist — fl a - S . . The ggy brown mica schist which so closely resembles the Findlater Castle rock of Banffshire is not so common M G . O on the north side of Loch aree as in airloch We ften find , h instead , bands which are of a rat er more siliceous type or which are so intimately mixed with thin seams of graphite - schist that they can N O e lastic hardly be separated . grains have been detected in any A - O f the beds . broad band of the somewhat siliceous mica schist runs for about three miles close to the path that leads from near

- Letterewe in a south east direction , and other exposures occur at the S ide of the thick hornblende - schist east of Furnace and near

C o h - O ppac y . These schists weather with a pale grey crust and ften

- project somewhat from the other associated mica schists . Fractures across the foliation are conchoidal , and present a somewhat vitreous lustre . ‘ In G leann T II lacha a dark brown foliated rock is seen on both sides of the limestone in the burn two - thirds O f a mile above the head of Lochan Fada , also in a section rather less than a mile above fia m the head , and in other places . It is less ggy and ore felspathic than the Findlater Castle schist , and contains epidote crystals , sometimes half an inch long , as well as calcite in certain bands .

Biotite is generally in considerable excess of white mica , and small grains of black iron - ore and prisms of tourmaline can often be seen h with t e unaided eye . In the section rather less than a mile above Lochan Fada the mica - schist is irregularly mixed with a peculiar s coarse gneissose rock , of uncertain origin , which contain large crystals of green actinolite , epidote , pink and white felspar and O quartz . The dark and pale constituents are ften separated into sub parallel folia , and the actinolites in the acid parts are sometimes arranged in radiating groups as much as an inch in breadth . The - O mica schist ften occurs in parallel bands with the gneissose rock , but , in some places , parts appear to be included in this rock . It sometimes shows a structure , resembling bedding , which is crossed by a foliation parallel to the banding in the gneissose rock . The more micaceous or pelitic mica - schists never spread over large areas , and they have not been separated from the others . They m a often contain many garnets , as y be seen on the shore of Loch 1 I ni h la M 50 . s ss aree , yds slightly west of south of g , and also in the burn running south - east across the Lewisian inlier on the east side S T h e of lioch . schist in the last locality has a silvery lustre , and the matrix is composed almost entirely of colourless and pale - green

- mica , reddish brown biotite and epidote . T he L och M a ree S eries a nd some A ssocia ted S chist s. 3 1

O wing to the fineness of grain it is often difficult to discern to m lonise d m icroscO ic what extent the mica schists have been y , but p examination shows that in various places the granulitic consti tuents have been strained and crushed down into streaks of still finer S th e - material . ome of the brown flaggy schists on south east side R A iridh of einu Charr should perhaps be regarded as mylonites , in

O f - the composition which other rocks share as well as mica schists . Near the south - west side of the thick hornblende - schist a mile - a n south e st of the hilltop , the brown schist co tains lenticles and

- M eyes of hornblende schist like those of the thick band . any of 2 3 the lenticles are or ft . long , and their folia end abruptly at

the margins , while the folia of the brown schist wind round the

margins . 2 - n l te - chist — M - M ica A cti o i S . . ica schists with brown mica and A needles of actinolite are not uncommon . ccessory constituents

frequently found are garnet , pyrites and some ferriferous carbonate ,

in irregular streaks . The pyrites is often in sufficient abundance to S give a rusty colour to weathered surfaces . chists of this type form a considerable proportion of various bands which run from near the B e inn Airidh G arbh a i top of Charr towards the west end of Loch g. E xamples may also be seen in the burn that flows into Loch M aree M half a mile east of Isle aree , and at the edge of the thick horn blende - schist rather more than two - thirds of a mile slightly south O f east Furnace . While I n some of these schists the hornblende crystals a re small and r sparse, in othe s , only a few yards distant , they may be half an r inch thick and two inches long , and may p eponderate over the matrix , combining into radiate forms with arms nearly parallel to M the foliation . icroscopically they are dark green or black , but in thin slices often nearly colourless and evidently crowded with small M granulitic inclusions . ost of the garnets have round edges or th e occur in lumps with the long axes parallel to foliation . In the - - B einn band three quarters of a mile south west of Lair, the large th e m garnets have round outlines and coats of biotite , while s aller have no such coats and are idiomorphic . The calcareous seams in these schists vary from the thinnest streaks up to bands a foot or two thick . They often cross the foliation or enclose rounded pieces of schist . In a thin band within the thick hornblende - schist half a mile south - west of M eall M heinnidh , the transgressive appearance of the calcareous streaks and the inclusion of hornblendic lumps within them are well seen . S ome of the hornblendic lenticles appear to have been derived from a schist which was first sharply folded and then broken along the fl x u r A r limbs of e e . considerable part of the calcareous matter appea s to have been int roduced into its present position either at the time u m lonisin of , or subsequently to , vario s thrusts and y g movements .

The rocks were probably originally calcareous , and the ready solu bility O f the carbonate enabled it to travel from one part of the rock

th e . to another, and to collect in lines of thrust G ra hi e - c — h d 3 . t h ist u S . p This type sually forms t in ban s , from

- a few inches to a few feet thick , which are mixed with mica schist

- - - A t or mica actinolite schist . a locality nearly a mile south west of B e inn Lair a dozen lam in ae of more or less graphitic schist are some 32 T h e L ewisia n G neiss .

O f - times visible in the breadth half an inch . The graphite schists and th e intermixed mica - schists O ften weather with a rusty colour in

consequence of disseminated pyrites . Nearly all the rusty schists Sm iora sair between Letterewe and contain graphitic bands , and ,

- including thin hornblende schists , they form an outcrop between

300 4 50 . and yds wide, which lies between hard siliceous mica schists on the south - west side and a thick hornblende - schist on the

- - - north east . Bands of graphite schist also occur north west of Loch ‘ ‘ G arbh ai SS W oi B inn G T II h . e lac a g, Lair , in leann and other

places .

In many localities , for instance , in the burn a quarter of a mile - - O f - north east of Furnace , the graphite schist is so full black leaded p lanes O f movement that no clean fracture can be procured though the adjoining schists are but little crushed .

The graphite in these schists never occurs in distinct scales , but in irregular shreds and small patches , which sometimes exist as inclusions in other minerals . These inclusions prove not only that the graphitic rocks existed as schists , but also that these schists had been contorted and crushed before the formation of the minerals O ne which contain the graphite . of the enclosing minerals is actinolite in feathery and radiate forms . This is seen well in slice 442 O - 7 , btained from a hard graphite schist that rings under the E B inn A 1 500 . SS e hammer , yds of Lair . schist a mile and f . f 30 0 ds . O o y W N . W . the head Lochan Fada contains a white mica which must have been developed after the parallel arrange ’ ment of the chief graphitic portions . In a microscopic section , 442 1 , from this locality , there are also various patches of felspar ,

O D r . ften twinned , and a mineral supposed by Teall to be probably andalusite , which is of later origin than the present distribution of the graphite .

- iss — - 4 K a nite Gne . . y Three bands of kyanite gneiss have been noticed near Carnmore (head of Fionn Loch) . They strike north

- west , and are all more than a mile and a half north east of the h nearest sediments in G leann T irla c a . The band east of the O ld

- house has been traced for a quarter of a mile , dips north east about 1 20 - and varies in thickness from 6 to ft . It is pale grey in colour and rather coarser than the contiguous gneiss , which is reddish and contains subparallel streaks of colourless quartz . In

- the landscape , however , the kyanite gneiss generally appears dark , u probably on account of the ro ghness of the weathered face . The folia tion o in the immediately adjacent reddish gneiss dips the same

- O ff as in the kyanite gneiss , but farther it becomes more irregular , and it is suggested that possibly the latter hand may occur along 2 T he . a plane of movement . kyanite crystals , sometimes ins long, usually project on the weathered face and have their long axes rudely parallel to the biotite flakes and the margin of the band , O ne variety of the rock contains little else but kyanite and biotite , the u an latter in large cr mpled plates half inch long , together with quartz ud veins which incl e unusually large kyanites . In the more common O type quartz is abundant , and both ligoclase and orthoclase also

occur .

- — - E E . N 5 . Gra nula r ua rtz R oc Q h Three quarters of a mile . . I nish lass - M of g (north east shore of Loch aree) , and also three

3 4 T he L ewisia n G neiss .

1 6 thick respectively , are separated by ft . of fine hornblende

schist . They contain crystals of dark green actinolite , some of which 3 4 are or ins . long , and combine into radiate forms . Idio

morphic garnets , half an inch in diameter , occasionally occur in

some micaceous portions . The quartz is usually subordinate in

amount to the actinolite , and occurs in granulitic streaks edging 51 0 9 that mineral . In a thin slice, , the actinolite is seen to contain A 20 many inclusions of quartz . band of similar schist , about yds .

- — wide , is seen a little more than two thirds of a mile south east of

the top of R einu Lair . * 8 L im estone — . The Letterewe Limestone has long been known , n 200 and was formerly quarried on the west side of the bur yds . north - west of the ruined house of F olais T The limestone and the accompanying calcareous beds appear repeatedly in the burn north th e ° e x o ure s 700 . s of the quarry for about yds , p being separated by

fi l - - B inn ne e . y foliated hornblende schist , like that of Lair Here the rocks occupy the apex of a compound syncline , the axial planes of

- which strike north west . In some exposures the thickness of the 21 S - F olais - limestone is about ft . outh east of , in the south western m u li b of the syncline , the limestone and calcareo s beds can be traced for nearly three miles , but they form only a thin outcrop , and

- are much interrupted at the south east end by lines of movement . A long the north - east lim b of th e syncline the horizon cannot be

traced as far as a mile .

In the quarry the limestone is compact and creamy , and contains n S lumps of gree actinolite . ome of the bands contain more biotite , h c lorite and hornblende than carbonate , and also thin streaks of

white talc Some of the actinolite lumps are 2 or 3 ins .

in diameter , and all have smooth round surfaces coated with flakes - O f of biotite , chlorite and white mica . In cross sections some them S how centres from which the actinolite crystals have grown out in

diverging rays , while many others are broken by small faults . A soft greenish rock which appears to be a calcareous mylonite in a plane of m ov enrent is seen between the thick limestone and the hornblende - schist on the east side of the burn near the end of the

old tramway . It is finely striped , and contains many inclusions A with their long axes parallel to the striping . mong these '

inclusions have been noticed lumps of limestone , round pieces

- composed of actinolite fibres , rounded pieces of quartz tourmaline

- ff vein stu , and scattered prisms of tourmaline . A ll th e impure calcareous rocks which accompany the thick m lonise d limestone seem to be y , but they are not all of the type m l nis d of the green rock described . The y o e rock in the burn two - thirds O f a mile slightly west of north of FO lais includes no

O f d O f fine l - lumps ra iate actinolite , but many small pieces y foliated - m lonise d hornblende schist . The plane of junction between the y - O rock and the thick hornblende schist is ften a crush line , at the

’ I n d ca e d in M acc ullo ch s G e l cal M a o f S c lan d and d e c e d b t is i i t o ogi p ot , s rib y “ I M u c n a nd S ir A G e e in e a e O n th e A l e e d R c ir R . . S . r hiso iki th ir p p r t r o ks f h e e n I land o f S c la nd a nd th e N - We e n a nd C e n al H o t e W st r s s ot , orth st r tr igh l 1 1 l oc . o . . 7 . t J ur Geo S v . l nd ua r . o . . a s Q , xvii p , “ h - n m a A u a ua e of a le n I N ot n am e d on t e one i ch p. bo t q rt r mi orth of e w L e tte r e . T h e L ree e es a nd som e A ssocia ted chists och M a S ri S .

side of which the foliation planes of the hornblende - schist are h a s truncated , and it seems certain , consequently , that this schist contributed material towards the formation of the mylonite . In the

- F olais burn two thirds of a mile slightly west of north of , besides the

- pieces of hornblende schist , fragments of a slightly calcareous dark

- grey mica schist , rich in biotite , appear in the crushed material . ‘ The G leann T rrlach a Limestone may possibly be on the same ff horizon as the Letterewe bed , but in a di erent limb of fold . It ff a h di ers considerably in ppearance , but this is per aps mainly due to the great amount of deformation the limestone at Letterewe has ‘ A G T II la ch a undergone . good exposure of the leann bed is seen

O f . rather less than a mile W . N . W . the head of Lochan Fada The and fresh rock is almost white , but the weathered face is brownish , is crowded with projecting fibres of pale green tremolite arranged in fans or radiate forms . Individual fibres of this mineral penetrate far f o . into the matrix , and show no signs crushing Those of longest dimensions lie along parallel planes , and give rise to a banded A “ appearance . train of boulders of a very similar limestone extends in a south - westerly direction from the south side of Lochan th e Fada a mile and a half below head , so that it is probable that the limestone crop extends in a south - easterly direction in the bed of the

A . . 300 . . loch for a considerable distance . bout yds W N W of the m O good exposure referred to , a boulder of li estone was bserved to be

- crowded with prisms of pale green augite , but this mineral has not th e in situ been found in limestone . Limestone appears in various localities just at the north margin

B e inn - O n M e all of the Lair hornblende schist . the north side of M héinnidh four bands of limestone or calcareous rock can be observed ; the bottom band contains streaks and lenticles O f lime stone embedded in a chloritic or micaceous schist which overlies B einn A iridh gneiss . In one of the exposures in the burn W . N . W . of

Charr the limestone contains reddish streaks , represented in specimen 347 1 o we , which their colour to the presence of crystals of reddish brown rutile : a plagioclase felspar and quartz are also present . In a second exposure in the locality the rock consists of almost n pure white saccharoid dolomite which gives more than 9 6 per ce t .

of mixed carbonates of lime and magnesia , as is shown by the following analysis

I nsol

S iO 2

A 12 0 3

F 6 2 0 3 F e O M nO C a o M gO

0 0 2

In striking contrast to the last rock , another exposed farther east contains m any silicates concentrated along certain layers which perhaps represent bedding . The original rock was probably a ff d H C l cherty carbonate . It e ervesces freely with col dilute , and the analysis of one O f the purer calca reous bands shows that it h as 3 6 T h e L e wisia n neiss G .

only been partially dolomitised . The analysis , which was executed M r J S . . G n by . rant Wilso , is as follows

I n l so .

S iO 2

A 12 0 3

F 6 2 0 3 F e O M n O C aO M gO

0 0 2

S G r p. .

O f reco nis The insoluble portion consisted mainly silica , which is g in able the thin slice as microcrystalline quartz . 9 C a lca reous B iotite- H ornblende- S chist — . S . ome of the limestones are flanked by calcareous schists or calcareous gneisses, in which biotite , or a green mica and hornblende , seldom radiate , occur in A E S E F olais abundance . bout a third of a mile of , a calcareous

- - 50 0 - biotite hornblende gneiss occurs or 7 yds . north west of the F olais calcareous horizon , and is flanked by more acid gneiss on both sides .

- — 1 0 0 hlorite S chist. . Bands composed almost entirely of chlorite are seen in the following places : a quarter of a mile south - east of O f Furnace , the burn by the road about a mile and a quarter north

- Letterewe , and the more easterly of the two burns three quarters of M E . N . N . a mile . of Isle aree 1 H ornblende S chist a nd H ornblende C hlorite c ist 1 . S h . The hornblende - schists occupy a much larger area than the sedi ments with which they are associated . The most prominent band forms R B inn i h n the mountain masses of einu Lair and e Air d Charr . O the latter hill hornblende - schist is exposed continuously for a distance of two miles across a synclinorium , with axial planes

- striking north west . The base of the band changes its course in the - M north west side of the hill and curves southward to Loch aree, while the hornblende - schists in the south - east slopes are repeatedly

- folded with a band of mica schist . There can be little doubt that the hornblende - schists now under n consideration were originally intrusive ig eous rocks . Their general uniformity O f composition and the absence of inclusions are incon

sistent with the supposition that they are altered subaerial lavas . O n n the other hand , they have owhere been observed to transgress S - of the sediments . outh east of Letterewe one the hornblende schists keeps close to a thin band of siliceous mica - schist for nearly A a mile . similar want of evidence of intrusion is , however , also found at the S ides of dykes which have been sheared and dragged u to an nusually great extent . O It is improbable that these schists are lder than the basic dykes ,

for they are never seen to be intersected by them , even in areas P where the adjoining gneisses repeatedly are . ossibly they represent

intrusive sills which were fed by the dykes . Before the dykes were the foliated gneiss probably contained but few divisional planes , and a mass of molten rock which had come up through it in vertical ssocia e s 3 T h e L och M a ree S eries a nd som e A t d S chi ts. 7

fissures might, perhaps , on reaching the sediments , find more ready passage between the bedding planes and take the form of sills . The most common type of these hornblende - schists is more P finely foliated than most of the dykes . arallel to the foliation we O a ff - r can ften discern thin lamin e of di erent colours , black , dark g een — a or dirty white . These lamin e may possibly have been derived from ff parts which di ered originally , or they may be due to segregation G proceeding during shearing . arnets are abundant in certain places , and are often bordered with granules of white felspar . In this one inch map no parts have been observed free from foliation , though in th e G - 9 1 airloch district, in one inch map , the central parts of the O n broader bands are sometimes so . the other hand , the shivery O chloritic type , which is also ften slightly calcareous , is rarer than G h in the airloc area . Thin zones in which the hornblende forms augen may be seen in the Beih u Lair schist half a mile slightly north of east of th e foot G arbh ai i B e inn of Loch g, a third of a m le slightly north of west of A 11 Lair, and at other places . exposure by the east side of a small burn rather more than three - quarters of a mile east of the head of Lochan Fada shows a good many imperfect lath - shaped sections of felspar about half an inch long . O n B einn Lair and M eall M héinnidh certain zones containing lenticles O f dirty - white saussurite may be noticed at frequent E N . O f B inn i E . e A ridh intervals from a third of a mile . of the top

- W O f SS . Charr to three quarters a mile of the head of Lochan Fada . O ne P XX of the best exposures , represented in late VIII . in the “ ” - M . G S O f emoir on The eological tructure the North West Highlands , 2 0 N . 0 . N E . is yds . east of the path nearly two miles of Letterewe O f pier . Here a considerable number the lenticles are more than a foot long , and some exceed three feet . Their long axes are parallel , and indicate a direction of stretching which 1 s nearly at right angles to the strike O f the foliation . The lenticles vary greatly in I n ff I n abundance di erent localities , and some places are very sparse ;

6 0 . indeed one example was found isolated yds from any other , a mode O f occurrence hardly explicable on the supposition that th e lenticles have been produced by the breaking up of a once M continuous band . ore probably they represent segregations which O existed in the rock before its conversion into schist . riginally h they may ave been nearly spherical ; occasionally , indeed , as in a locality a third of a mile slightly east of south O f the head of

Lochan Fada , examples give nearly circular sections . M any of the thin quartz veins in the hornblende - schist contain tourmaline in very thin needles , which are often combined into S heaves . It usually forms only a small proportion of each vein , the

. S rest consisting of quartz , or of quartz , axinite and epidote uch M M héinnidh 1 50 veins are well seen on call , from yds . west of the - 0 7 0 . top to rather more than a quarter of a mile south east , also yds - G arbh ai O f south east of the long island in Loch g, where some the tourmaline needles are an inch long . The fragments of tourmaline vein - stuff which occur in the calcareous m ylonise d rocks already described may well have been derived from similar veins . Near Torridonian rocks the hornblende - schists are often crossed a nd by thin epidotic strings , and the foliation planes the sides of 38 T he L ewisia n G neiss .

the veins of quartz and pegmatite are also stained with h aematite . The pebbles in the basal Torridonian breccias are sometimes crossed b y epidotic strings , which , as they do not pass into the matrix , must have existed in the Lewisian rocks before the formation of the

- b breccias . They were doubtless formed in pre Torridonian times y

- decomposition near the rock surface . 1 2 H ornblende- chist with B rown M ica a nd P rites —M . S y . any of the thin bands of hornblende - schist which occur within the area chiefly occupied by the altered sediments , closely resemble portions

- - of the actinolite mica schists . They contain calcareous streaks , brown mica and pyrites , together with hornblende crystals which are frequently grouped into radiate forms and are of a stouter build O f than those usually found in the thick bands . The thin bands hornblende - schist in the mica - schist half a mile E S E of C oppachy finel - are of the y foliated type , so common in the thick bands , and th enr ul probably some , if not all , of represent folded and fa ted M O f portions of these bands . any the other bands farther west , C o ach likewise most of the thin bands between pp y and Letterewe , C o ach and half a mile W . N . W . of pp y , belong , entirely or in part , to f S 4 3 O O . 77 the type schist under description pecimen , btained from O f M I nish la 350 . ss the side Loch aree yds west of g , proved on microscopic examination to be in a m ylonise d condition : one portion with rounded outline and less calcareous than the rest is - fin l - G composed of hornblende schist of the e y foliated type . In leann T irlach a pyritous hornblende - schists appear again near the base of B einn - the Lair hornblende schist in several places .

w G . E G . 0 . c . . T. , , . CHAPTER IV .

T R R I D N SA D E T H E O O N STO N .

D R I G E N E R AL E S C P T O N .

E R E F E R E N C has been made in a previous chapter (p . 9) to the G uneven floor of Lewisian neiss on which the Torridonian rocks rest . O f These strata , which occupy about half of the region west the M O f - oine thrust , consist mainly of a great series false bedded grits , or arkoses , with some finer sandstones and thin shales . In the largest area of these rocks , running from Loch Broom southwards to the head M of Loch aree , they generally dip eastwards , but near the northern

- end , where the breadth is greatest , they dip north west in one locality , and thus give rise to a geological basin composing the hill of san M hOr A . long the western margin of this tract the members of this t formation rest on the Lewisian rocks with a striking unconformi y , which is further indicated by the presence of various Torridonian outliers lying on the Lewisian G neiss in the vicinity of Little G ruinard , near the northern margin of the map , and farther south at ’ A M hai hdean and near the hill called g . A G nother Torridonian tract, west of Little ruinard , extends in a nearly southerly direction through part of one - inch map 9 1 to E we M O f Loch and the foot of Loch aree , and is considerable interest , as it is the only area in this map which contains the highest group (A ultbea) of the T orridon S andstone . The stra ta belonging to this subdivision are found on the north - west or downthrow S ide of S W S . a large fault which strikes from the village of First Coast , and on their north - west side they are bounded by another nearly parallel * dislocation , which also throws down in the same direction , and brings a patch O f M esozoic rocks into the extreme north - west corner of the map . Between these two lines of fracture , and for some

- O f distance south east the First Coast fault, the dip is often towards

- the north west . — — A nother large parallel fa ult the F a sagh fault crosses the O f M Torridonian and other rocks near the head Loch aree , but E S E throws to , in the opposite direction to the two other faults just referred to . The outcrop of this fault appears to be shifted

- for . a distance of three miles towards the north west , by a powerful dislocation which strikes north - west along Loch M a re e rl' O n - S M the south west ide of the Loch aree fault, Torridonian strata extend along the side of the loch for nine miles to the western margin of the map , excepting a space of half a mile a little north

ul are d e c e d in C a e X Th e se two fa ts s rib h pt r . ° d e c e d in a e X 1 This fault is s rib C h pt r . 89 4 0 T he T orridon a ndstone S .

e u v west of Noa , where they are co ered unconformably by n Cambrian quartzite . O this side of the loch they form a much G larger area than any other rock . The Lewisian neiss emerges , however , from beneath them in a few places , chiefly near the west m ar rn g . ’ The Torridonian strata which have been afl e cte d by the great

- post Cambrian movements do not form large masses , but they occur at intervals along the line of complication . The largest forms an ’ M e all G hiubh ais outlier on the hill called a , about two miles west M - O f the head O f Loch aree . The thrust plane beneath the displaced materials can be traced in an almost circular crop round the mountain . The most striking features in the lithological character of the unthrust Torridonian beds are their unaltered condition and the O f e lastic S freshness of many the grains of felspar . econdary a enlargement of the quartz gr ins , and the development of minute h scales of mica in the felspar , are the only important c anges that ° afl e cte d O f have the original constituents . The great bulk the

- formation consists of very false bedded , rather coarse felspathic sandstones (arkoses) with occasional intercalations of finer sand stone and micaceous sandy shale . Coarse angular breccias , chiefly O f vi made up pieces of Lewisian rocks like those exposed in the cinity ,

are common at the local base , but perhaps particularly so where this base occurs below a certain stratigraphical horizon , that is the top of D A the lowest or iabaig group to be described in the sequel . bove

- this horizon bands with well rounded pebbles are frequent , but the pebbles are to a large extent composed of vein - quartz and of other

rocks , such as grit , quartzite , chert , jasper , felsite , and quartz * G porphyry , which are quite unknown in the Lewisian neiss , and have doubtless been derived from some other pre - Torridonian forma

- tion, not as yet recognised in the North West Highlands , which

intervened between the Lewisian G neiss and the T orridon Sandstone . In the sandstones which make up the bulk of the formation the D r — a prevalent felspar is stated by . Teall to be microcline felspar which seems uncommon in the Lewisian G neiss except in the area

- . L a x ford between Cape Wrath and Loch , where granite gneisses and O f pegmatites are largely developed . Clastic grains quartz are h abundant in all except t e finest argillaceous deposits . The larger 1 grains are well rounded , but the smaller , less than mm . in length , O but are angular . The quartz is ften rather cloudy and opalescent , D r - . Teall has ascertained that the minute hair like inclusions so characteristic of the blue quartz of the Lewisian pyroxene - gneisses

are very rare . From the nature of the Torridonian rocks it may be inferred that they were accumulated rapidly in an area subject to violent currents

and the influx of floods . The remarkable freshness of the felspars seems to indicate that decomposition due to chemical action advanced

slowly in comparison to denudation , and from this again we may

perhaps infer that the climate was cold or arid . With the exception of the basal breccias the rocks in the bottom r group of the formation , and also those in the top g oup, are some fine rn l r what grain , and include a considerab e p oportion of sandy l S om e of th e se pebble s will be furth e r de scribe d 1 11 th e se q ue .

42 T he T orridon a nd to e S s n .

- I n a rather bright red colour . places , however , below or alternating - e A ll with these bright red b ds , coarse pebbly sandstones are seen . these strata dip gently eastward under the coarse grits or arkoses O f A n T e allach A , which are placed in the pplecross group . O n th e south side of Loch na Sh eallag a series O f hard bright - red fl a ggy sandstones , without pebbles , separates the basal shales from fl a the overlying arkoses . Below these ggy re d beds black shales r make their appearance , followed by blue , black , and fer uginous greywacke , and sandy seams in shale , the whole succession having a 25 A thickness probably of about 0 ft . fine section has been laid bare B e inn D 4 0 due north of earg Bheag, where almost ft . of black shale can be seen . These shales are full of black streaks and blotches O f which are strongly suggestive a possibility of discovering fossils , d but up to the present they have yiel ed none . ’ A M hai hdean 3 5 The Torridonian outlier on g (Fig . , p . 7) is of interest, because the most abundant pebbles therein are not composed O f of siliceous gneiss like the adjacent Lewisian rock , but hornblende

S chist of the B einn Lair type . The pieces are often 5 or 6 i n situ hi ins . long , and no schist like them is now known wit n a A - mile and a half. bout half a mile north west of the hilltop the - t hornblende schist pebbles are often above an inch in leng h , and indicate by the direction of their inclination that they have probably

- come from the south west . The breccia bands on the north side O f M Or 1 2 f u . O F ar Loch also contain pebbles , or ins long , the R - einu Lair type of hornblende schist , and are still farther from the nearest exposure of such schist . O n - S the north west side of lioch , an outlier , consisting mainly of G a rbh ai coarse breccia , extends from near the foot of Loch g far up - A the high ground to the north west . s it ascends it divides into irregular arms which S how well the steepness of the surface on which the breccia was deposited . Four other small outliers of similar rock still high er up indicate how th e hornblende - schist has A . O f here been encased in Torridonian sediments gain , the patch coarse breccia which rests on the steep hillside of hornblende G arbhai schist on the north side of Loch g, half a mile east of the ff outlet , shows clearly that its di erent beds have been deposited almost horizontally against a steep face of the schist . Where no

- breccia is now left , the planes of the hornblende schist are frequently a a stained with h ematite , and are streaked with thin veins of h ematite , a brindant while the quartz veins are reddened , and epidotic strings have been developed , the epidote being sometimes in distinct crystals E embedded I n quartz veins . xamples of these phenomena may be B einn found to the west , south west and east of the top of Lair , in 25 one case at a height of more than 0 0 ft . O n the south side of Loch M aree th e D iabaig beds are well exposed in the section cut by the R iver L ungard at T alladale (see 1 2 M G S Fig . in the emoir on The eological tructure of the North 1 0 0 . West Highlands The top beds , about ft thick , consist of hard

- compact brick red grits , with no pebbles , and below these comes a series of black and grey shales , greywackes , reddish grits and shales , r 250 A amounting togethe to about ft . nother fine section of black grits and dark and grey shales is also visible in the wooded glen a

f T a lladale . m S S . E . O ile . ecross rou T he A ppl G p . 43

In the outlier of thrust T orridon Sandstone that forms most of ’ — M e all a G hiubh ais the hill two miles west of the head of Loch M aree— the strata are not much deformed save near the thrust planes . In such positions the grits are sometimes rendered somewhat schistose , and the shales are slightly cleaved .

E E R S R T H APP L C O S G O U P.

The sandstones and arkoses O f this group are coarser in grain than O f D t f the top sandstones the iabaig group , and weather wi h dif erent

- colours , purplish or brownish red instead of foxy . The former O f colours seem due , partly to the original colour the fresh grains of t O f felspar , par ly to the red staining the more altered felspars or fragments of felsite , and partly to thin pellicles of iron oxide which l i coat the individual e ast c grains . These pellicles may be regarded as the result of subaerial decomposition of the old land surface from which the materials were derived . In many of the beds , grains of felspar are as abundant as quartz , and include a considerable pro

- portion of microcline and microcline microperthite , which are in a very fresh condition .

- False bedding is extremely prevalent, so much so that the true fi r dip is often dif cult to asce tain , excepting by the help of intercalated

a - beds of finer sandstone . The minor lamin e in the false bedded O * layers are ften curved into a vertical or even reversed position . ff w They di er in grain as ell as colour , and do not , therefore , represent ff lines of staining merely . Their upper ends are often cut o abruptly by the - even base of the overlying bed without the least indication of shearing or slickensides . S uch curved and reversed laminae are

- often seen many miles away from the post Cambrian complications , ff and it is certain that they have not been a ected by them . The phenomena must be due to some cause which was operative again and again in Torridonian times . In many cases it affected a bed i t before was covered up by the overlying layer , and probably , there fore , before it was in a completely consolidated condition . Intercalated with this series of arkoses are a great number of thin O - seams , ften only an inch or two thick , which contain well rounded

2 3 - pebbles , as much as or ins . in length , of vein quartz ,

- quartzite , felsite , quartz felsite , and chert or jasper . When the fl a ttish pebbly beds decay , the pebbles are left behind on rock surfaces , while the fine sand is blown or washed away . The pebbles of vein- quartz are white and identical in character with that which occurs so commonly in disturbed regions . The quartzite pebbles are

- - - either light grey , pale red or liver coloured . They are not sheared , but represent sandstones which have been indurated by the deposition of secondary Silica on the original grains . D r The felsites are chiefly of a purplish colour , and are stated by . Teall to be identical in all respects with the felsites of the Uriconian S 0 eries of Shropshire . N organic structures have been discovered in fi the cherts . It is dif cult to draw a line between the cherts and h jaspers , and it is quite possible t at some of the latter may represent

- e al e e dd n n ce d S ir A . G e e a e a e c This typ of f s b i g is oti by iki , who g v sk t h “ ” f - l 4 o G e 9 . T h e e a n e x ample of it in his T e xt B ook of o ogy p . 7 sam u and ne type is O ccasionally obse rve d in th e C arbonife ro s s sto s. T h e T orridon S a ndstone 44 .

ili ifi d A s c e . D felsites collection of pebbles made by r. Horne in S L un ard L ochm are e f rath g , south of the Hotel , contained dif erent pebbles in the proportions indicated below :

Ve in - quartz Q uartzite C he rt an d Jaspe r G rit F elsite and F elspar - porphyry

ff The proportions in di erent localities vary , however , considerably . The pre - Torridonian surface of the Lewisian G neiss east and - S south east of lioch was in places of a very steep, rugged character , A as already indicated , and where the pplecross rocks abut against it O o they ften pass into coarse breccias , which do not , h wever , extend l 80 1 00 . O d far , perhaps rarely more than or yds from the surface 1 1 M “ G (see Fig . in the emoir on The eological S tructure of the North - West A t the north end O f the inlier pieces of

ff - breccia are seen sticking to the cli s of hornblende schist , and sandstone veins fill up thin cracks in the schist . The basal A bh uinn F hasai h Torridonian beds near the mouth of an g , also , consist O f coarse breccias containing pieces O f Lewisian rocks like those found in the immediate vicinity . The disintegration of the sandstones I n exposed positions some times gives rise to effects that are usually thought in this country to ’ O n be confined to our coasts . the high plateau between the peaks of ’ A n T e allach M ac M ath air and us , to the north , the sandstone is decomposed to great depths , and the loose sand blown about by the wind forms dunes comparable to those ordinarily seen on the sea S O u S shore . imilar phenomena occur the top of lioch . Between Loch na Sh e allag and the summit of A n T e allach th e thickness of the beds of the A pplecross group still preserved is prob 1° A t 4 000 ft. 0 ably or more , but no remains of the highest ul bea b A group exist , and it is impossi le to say what thickness of pplecross d beds has been removed by enudation . It is to this great thickness of beds of almost uniform character that we owe the characteristic n mou tain features already described . The extensive area occupied by the A pplecross group on the south - west side of Loch M aree is divisible into two parts by an im

N E . portant fault, striking N and with a large downthrow to the N E east , which is supposed to be the continuation of the Fasagh N . t fracture , its outcrop having been shif ed for three miles by the Loch M u O n aree wrench fa lt . the east side of this dislocation the rocks are di much broken by parallel joints and generally p eastwards , very 2 00 . steeply for yds or more next the fault , but more gently farther off O n S . the west ide the beds are rolling about at gentle angles and O are ften nearly flat . A rkoses belonging to this group , sometimes much deformed , occur at intervals along the line of complication between Loch Broom and Kinlochewe . T H E U B E G R O U P A LT A .

In the north - west corner of the map the beds referred to this

E . N . group are found on the west or downthrow side of the N . fault A ultbea rou The G p . 4 5

. which comes to the shore at First Coast These beds are , however , in most places so much jointed , shattered and veined with quartz that they cannot always be distinguished from the lower portions of the Torridonian Series . Just along the course of the fault on the south side of B e inn C hailleach O f 9 D . earg Bad , a wedge limestone , about ins thick , is

- hand . seen in one place , and also a dirty white or grey siliceous These are probably parts of the Cambrian Series crushed down in the

G . C . T c . B . N P . E G fault . w . , . , . , . . C H AP T E R V .

A M R A O R M A O C B I N F TI N .

I N th e - the area to the west of post Cambrian displacements , the

Cambrian strata, as already indicated , form a narrow belt traceable from the northern margin of the map to the shores of Loch M aree E and the Kinlochewe Forest . verywhere along this belt they rest T n unconformably on the orrido S andstone . In the central part of the belt near Loch an Nid the discordance between the two forma tions is clearly seen , bed after bed of the red sandstones being trans S re sse d . g by the basal quartzites outh of Lochan Fada , however , where a strike section is exposed for two miles , the unconformability is not very apparent , though the boundary between the two is dis tinctly traceable .

The quartzites have the largest development , as they range from * T h e - O f P 5 6 00 . . R 00 . ft to ft in thickness five sub zones the ipe ock , O f based on the peculiar forms the pipes due to burrowing annelides , have been identified in the area under description . But the most important members of the series are the Fuc oid Beds and S erpulite G O f - rit, owing to the occurrence in them trilobite bearing bands , which , O f J prove that they are Lower Cambrian age . . H .

H A AI D H T O R T H N A H EA L L A AR E A F R O M LO C L G ST A S G .

Between the northern edge of the map and Strath na Sh eallag the subdivisions of the Cambrian Quartzite are well exposed in many S places , but the higher Cambrian rocks , namely , Fucoid Beds , erpulite

G D O . rit and urness Limestone , are ften obscured th e Beginning at north end , we find in the area about Loch L a aidh th e - g that a good deal of quartzite is drift covered , but the base

- line is clearly traceable , and in several places west and north west of this loch the characteristic conglomerate— which forms the lowest ’ — rem a nie part of the quartzite is clearly exposed . It is a deposit , composed mainly O f pebbles derived from the underlying T orridon S andstone , and its junction with that formation is visible a little f to the south of the most easterly O the two small lochs there . The boundary between the False - bedded Quartzite and the P ipe R ock is t not always qui e clear , as some of the latter rock is occasionally false

- - n bedded . The trumpet pipe division (sub zo e iii . ) is well exposed

t - e L a aidh along the nor h western sid of Loch g , and loose blocks of the

- beds included in sub zone iv . occur nearly in place farther south . The dip of all these rocks is very steadily to the east - south - east at angles between 1 5 ° and

T h e ch aracte risti cs of the se fiv e s ub- zone s are d e scrib e d in th e M e moir on ” h - e land S c land M m uc u e t e N W H e . T h e G e ological S tr t r of orth st igh s of ot ,

372 3 73 . Geol ure . S . . pp , A rea rom L och L a a idh to S tra th na S hea lla 4 f g g . 7

The quartzose conglomerate at the base of the quartzite , several feet in thickness , may be seen on the north side of the small - L a aidh stream half a mile south west of Loch g , and again on the th e A llt h - I hine south side of next stream , na g , which comes from Loch i h h O f L aga d . In t is stream there is a good exposure the greater part A of th e quartzite . fault running along the gorge throws down about

. l 30 . A lt ft on the north side The next stream on the south , called ’ ’ C harnain B hain ff a Char, which comes from Loch a , a ords the most O f complete section the Cambrian rocks , as it exposes not only the d S G sub ivisions of the quartzite , but the Fucoid Beds and erpulite rit D S also , and a small portion of the urness Limestone . ome thin grey th e A shaly bands occur in section of the basal quartzite . scar south f 2 o f O 40 . the burn gives a measured thickness ft of Basal Quartzite ,

P R ock - and 1 00 ft . of ipe up to the trumpet zone (sub zone P - 3 0 robably the total thickness of the False bedded Quartzite is 0 ft . P R 2 50 . or more , and that of the ipe ock quite ft The brown , impure , or dolomitic limestone of th e Fucoid Beds and the blocky Serpulite G rit succeed in regular order , and above the latter appears some grey m li estone . The section on the south side of the burn is the following

G e l e n e e r y im sto , p rhaps S e rpulite G rit G e fl a a e l ce u F uc d B e d r y, ggy , r th r si i o s oi s

A bove th e limestone appears the thrust T orridon Sandstone else d h where describe . It must also be borne in mind that there are t rusts and disturbances in the Fucoid Beds and Serpulite G rit north of the stream . These latter divisions appear again in the next stream to C h orc uracb the south , on the north side of Creag , but no limestone A ll S C horcura h is visible except in t a Char . outhward from Creag c for some distance the quartzite is only occasionally exposed till we S R reach the trath Beg iver , where there is a good exposure of the

O f th e . middle portion the rock , at and below bridge To the south ward both divisions of the quartzite are clearly exposed for nearly four P R oe k re adin miles , the ipe s p g out over a dip slope extremely glaciated , while the Basal Quartzite generally forms a fine series of crags . Several small faults which mostly run in an east - north - east direction cross the outcrop of the quartzite . The most northerly of b ff these , which is the longest , exhi its for a long distance a fine cli fa h e e . on the south , whic is probably the upthrow side The one C h a orae h a in west of Loch Coire , with a downthrow to the north , appears to be nrue h the largest a nd shifts considerably the M oine thrust . The general dip O f the rocks both in direction and in L a aidh amount is much the same here as about Loch g . The Fucoid S G t A llt G Beds and erpulite ri crop out in the stream , leann C haorae h ain , and appear in places to the south , but the latter rock is soon overlapped by the M oine thr ust and does not appear at all n h l for a lo g distance north of S trath na S e al ag. The outliers of quartzite that are found on the three spurs of A n ll T e a ach a t r 300 0 ft. , a height of ove , and considerably to the west r r of the main outc op , prove that the Camb ian rocks once extended a r long way farthe r west than they do n o w. The most no therly of 1 — G M h e all M OT these outliers , which s also the smallest that on las contains only a small portion of the lower beds of the Basal Quartzite . 48 C a mbria n F orm a tion .

1 50 The outcrop is about yds . in length , and much of it is loose 5 6 . O f rock , but at the west end or ft of the pebbly base the in situ m f quartzite may be seen . The next outlier , a ile arther south , G M h eall on the hill called las Liath , is much more considerable . Though the base is almost everywhere obscured by tumbled rock , there is clear evidence that in this outlier there is not only the whole t bu t P R A of the Basal Quartzi e a small portion of the ipe ock also . t

the west end several feet of the pebbly base are visible , and the rock is exposed in places along the ridge eastwards to where the P ipe R ock

occurs . Viewed from the valley to the eastward , this outlier appears it to be a conical hill of quartzite , and as such has been sketched and

described , but it is only the end of a ridge . The numerous angular blocks of white quartzite which encumber the steep slopes far below the actual outcrop of the rock considerably increase the deceptive — appearance . The most southerly of the three outliers that which S — forms the top of ail Liath is much the largest , but it is principally r O f P R composed of the Basal Quartzite , only the lowe part the ipe ock appearing— probably no greater in amount that wh at appears on G las

M h e all Liath . A t a few places near the west end of the outlier and in numerous localities along the north - eastern side th ere are clear

- r outcrops of the False bedded Qua tzite , which is seen to have the same 1 5 ° dip ( to both in direction and amount, as the main mass of A ll t the same rock to the eastward . the hree outliers are alike in G this respect . w . .

FR R H N A S H E AL L AG T O KIN O C HE E F O R E S AR E A O M ST AT L W T. Throughout this tract the lower and upper divisions of the quartzites present their usual characters and retain their normal thickness . The former westward extension of the Cambrian strata is proved by an outlier of the basal quartzites on the crest O f R einn ’ hlaidh eimh 2750 . a C , at a height of ft and about a mile distant E from the main outcrop of the lower division . xcellent sections of ‘ the whole arenaceous series are laid bare on th e d ip slopes of Sgirrr M F h earch air Ban and M ullach Coire hic , where the beds are inclined E S E 1 6 ° A t to the at angles varying from to one locality , on S urr the crest of the ridge north of the top of g Ban , vertical worm

- casts were detected in one of the bands of False bedded Quartzite , this being the only recorded instance of the presence of organic life in

- the lower division of the quartzites in the North West Highlands . O n the southern declivity O f M ullach Coire M hic Fh e a re hair the outcrops of the quartzites are shifted more than a mile to the south h O n west by the F asag fault . the downthrow side of this fracture they appear on the S hore O f Lochan Fada and form a prominent G B iana sdail escarpment , on the east side of leann , which can be followed southwards to the Kinlochewe valley . Here again the outcrops of the arenaceous series are abruptly truncated by the Loch

M aree fault traversing that valley , and have been carried about two

- R h u oa miles to the north west beyond N . From that point they ’ M e all G hiubhais have been traced round the western face of a , the E f 1 5 ° beds having an E S . inclination at angles varying rom to Special interest attaches to the exposures of Fucoid Beds and G Serpulite rit, both being traceable , in the unthrust area , more or

C a m bria n F orm a tio 50 n .

The best section of the trilobite - bearing bands of the Fucoid Beds M occurs to the south of Loch aree, about a mile from the shore of that lake . The zone is laid bare in a small stream that issues from ’ Loch B ha nabh aig and flows do wn the northern slope of M eall a G hiubh a is ( 2282 a hill formed of an outlying mass of thrust id n T orr o S andstone . Though not far beneath the plane of the

Kinlochewe thrust, the beds are not deformed nor are the fossils i . A distorted The fossil ferous subdivisions as worked out by . M acconochie are given below in descending order

F I n t . . S ER PULI T E G R IT 7 B lue cl e and nd le ull all e c l . ay y sa y sha f of sm v rti a worm ca e ld n cc s on l e n O lenellus i as and sts, yi i g o a i a fragm ts of g g O lenellus L apworthi S ale e ll- e e e d brachiO Ods A crothele subsidua . h with w pr s rv p ( ) 5 D a fl a la ale a en Olenellus . rk ggy or p ty sh , with fr gm ts of at base 4 F e u n u ell d lo c nd c n c d l . rr gi o s y ow o miti ba , with o hoi a fracture 3 P l c n ne re m arns l e and . iso iti iro sto with of tri obit s e chin ode rms 2 H d e u n u d l c bn d the bottOm film c de d . ar f rr gi o s o omiti a , row with carapace s of O lenellus d le e d cla e le T h e e 1 . S n e c a . oft, j oi t , v , y y sha topmost s ams yi eld o cca sional c omple te spe cim e ns of Olenellus and fin e e xample s of O lenelloides ar ma tus ; th e lowe st two in che s are crowde d with disj ointe d and brok e n s e gm e n ts of O lenellus and ale e ed th e O lenellus . This b of sh is t rm lay e r The dolomitic Fucoid Beds are exposed in the stream farther down . The distribution of the Cambrian strata in the displaced masses between Strath na She allag and the Kinlochewe Forest is extremely D th e irregular . In the undonnell Forest and southward to Heights of Kinlochewe they appear as th in lenticles traceable for no great G B ruach ai distance . Beyond that locality , in the lower part of len g, S G folded and thrust quartzites , Fucoid Beds and erpulite rit, rise from underneath the mass of Lewisian G neiss overlying the - i . uco d Kinlochewe thrust plane The cleaved F Beds , visible in the A bh uinn B ruach ai channel and on the banks of g, contain the pisolitic ironstone and the soft shale beneath , from which carapaces Olenellus L a u’orthi H olithes of p and y have been obtained . A gain , among the materials carried westward by the Kinlochewe thrust there rs conclusive evidence of the double unconformability of T orrid n the basal quartzite on the o Sandstone and Lewisian G neiss . S r M R outh f om the head of Loch aree and the Kinlochewe iver , the Cambrian strata , repeated by numerous folds and thrusts , cover a ’ M hiu h i broad belt of ground to the east of call a G b a s .

N P . J . H . B . . , CHAPTER V I .

P O S - A M R A M O E M E N S T C B I N V T .

I N an the area between Loch Broom and Loch Nid , as already h t e . indicated , belt of complication is comparatively narrow Indeed , S th e E S in some localities , as , for instance , in trath Beg , astern chists overlap all underlying thrust materials and rest directly on the undisturbed Cambrian strata . The section of special interest in this northern portion occurs on the plateau east of D undonnell M S M - Lodge , where the oine chists and oine thrust plane , together with the underlying displaced materials , have all been thrown into M an anticlinal fold , while the Cambrian rocks beneath the Ben ore

- thrust plane have not been affected by that movement . the In the southern part of map , on either side of the Kinlochewe R valley , the belt of complication is several miles in width . emark able evidence is there O btained ( 1 ) of the reduplication of the strata over miles of ground by inverted folds and minor reversed faults in advance of the powerful lines of disruption ; ( 2) of the folding and faulting of the great thrust - planes ; and (3) of the formation of a large outlier of displaced materials overlying the Kinlochewe thrust ’ ° h on M eall G hiub ais . plane a , near Kinlochewe In the following e O f description , the Kinloch we thrust is regarded as the equivalent M A nt J ss . H the Ben ore thrust in y . .

R N A S H AL L AR E A FR O M LO C H B R O O M T O ST ATH E A G .

O n the west side O f Loch Broom the area occupied by thrust rocks stretches for nearly a mile along the S hore (Sheets 1 0 1 and

and the ground rises southwards so as to reach the level of 1 250 ft . S above the sea . It falls again gradually to the valley of trath Beg , 200 A where it is only ft . long this part of the belt of complication

there is only one place where the width is considerable , namely , in the

striking anticline just referred to east of D undonnell Lodge . South

of S trath Beg the thrust area is very limited in breadth . The f 1 500 t. ground , however rises to a height of , the highest point it

reaches in this drstrict. We shall begin the description of the line of complication at the e nd M north , where the oine thrust may be observed on the west side h B larnale voc . of Loch Broom , south of The displaced , flaggy , grey , quartzo - micaceous schists here overlie much altered T orridon Sand

- - stone , and the plane of separation dips to the east south east at an angle of The outcrop of the thrust - plane trends at first west

- w - h wards and then north est , till it attains a heig t of more than 1 00 0 ft . at a distance of nearly a mile and a half from the loch , where

it forms a good feature . It is clear that the plane has a gentle slope ° to the east - south - east O f about 1 0 and for a long way coincides with P o - a br a vem e ts 52 st C m i n M o n .

A - the slope of the ground . bout three quarters of a mile north from Loch L agaidh the line of thrust unmistakably crosses th e strike of

the schists , and here the direction of outcrop changes to the south

- south west . In this area west of Loch Broom there is only one other main

thrust , which is probably continuous with that which has brought G T orridon S westwards the Lewisian neiss with patches of andstone , P - S east of Corry oint , on the north east side of Loch Broom ( heet It appears for a considerable distance to keep along an even surface S G near the top of the erpulite rit, and it enters this sheet one mile - - L a aidh north north east of Loch g , along the eastern side of which

loch it pass es . Between these two main thrusts the ground west of G Loch Broom is occupied mainly by deformed Lewisian neiss , on which repose unconformably many patches of crushed T orridon S andstone , whose boundaries are often obscured by glacial drift . S B larnale voch ections of the sandstone may be noticed along the shore .

It is often crushed or shattered is generally of a reddish colour , but n is sometimes gree , and usually veined with many interlacing quartz t s rings . It varies much in coarseness of grain , and the bedding is often obscure . The largest mass of it is about a mile from the loch .

The grey hornblendic gneiss , mainly of an acid character , is also a good deal covered by drift in the lower ground . In it there are a I u good many large rreg lar masses of basic composition , some of which b be may possi ly deformed dykes , but probably most of them form O ne part of the Fundamental Complex . of the largest of these is mainly within the enclosed ground of B larnale voc h ; others may be - - L a aidh seen on the high ground north north east of Loch g . There is li ttle trace of any foliation to be O bserved in these basic masses or in h h t e acid gneiss wit which they are associated .

When we follow the thrust a rea southward , we find that the L a aidh gneiss ends not far to the south of Loch g , and for some distance beyond that lake T orridon Sandstone only is found in a band d 80 s . . about y wide The rock is much deformed in c haracter , and generally is much less coarse than the arkose division of unthrust T orridon S andstone which forms the high hills to the westwards . S oon the width of the complicated belt increases , and again we find in it Le wisian G neiss ; but this latter rock occurs only for a distance 2 M 0 0 . t of yds , and is adjacent to the oine thrus . Farther south for about half a mile the displaced T orridon Sandstone forms a strip 1 0 . S G . 7 yds in width , and apparently it overlies the erpulite rit But near the next stream there must be one or more minor thrusts to the S G ucoid westward , for we find the erpulite rit and part of the F Beds

repeated , and the dip of the latter zone much increased . This may A llt ’ be seen in the principal stream here called a Char , which flows ’ C harnain B hain S G from Loch a . The erpulite rit appears in this u b rn to the eastward , and above it , on the south side , a band of grey 20 limestone about ft . thick apparently . O ver the limestone is T orrido n S c u thrust the andstone , sections of whi h are fo nd in the t 20 0 . burn for a dis ance of yds higher up , followed by the crystalline,

fla M S lo - ggy oine chists dipping at a w angle to the north east . W e n e w e approach an area of remarkabl structure , for the displaced rocks have been bent or contorted in a wonderful manner , while the main mass of the Cambrian and Torridonian strata in the A a r L och B room to S tra th na Shea lla re f om g . 53

‘ t e u i undisturbed region to he west hav their sual nclination . The folded tract stretches in an east - north - east direction for more than a d A llt ’ mile , with a brea th of a quarter of a mile , and it lies between a C h orcurac h Char and Creag . The structure is that of a sharp anticline , the axis of which is in the direction of the length of the ff area , and the disturbance a ects not only the thrust rocks but extends eastward for many miles into the region of the M oine S . chists . The map shows E . S that the outcrop of the . S M oine thrust - plane takes a sharp bend eastward on the north side of the anticline , and returns 0 11 the south side to resume its usual - A direction . large part of a the complication is covered by drift and peat , but the rocks exposed give a clue to the general structure (Fig. In the western part of the central line of the anti c line there is an almost 0 continuous outcrop of the uc oid F Beds (Cc in Fig . 2) 6 50 for a distance of yds . They are everywhere vertical with a general strike to . ea - - W st north east , and though . N . necessarily repeated by the N sharp fold , they probably . represent the whole thick E of ness, as the width outcrop in some places is nearly 1 50 ft . They disappear under thick peat at the eastern end of the slight ridge which im os they form , and it is sible to say how much fartpher they may extend in that direction . Their western outcrop is also lost about

1 50 - yds . to the north east of the ordnance station 1 1 9 3 ( ft . ) on Creag Choren 3 rach . Here a small exposure of S erpulite G rit occurs on the south side of them , so that it seems probable from this and other C d 2 i indications that this rock ( , Fig . ) stretches in a vertical str p on

u id . either side of the ridge formed by the F c o Beds In one place , 20 0 about yds . from the eastern end , there is found , some way to

- ua rtzI te 0 3 ° the north west of the Fucoid ridge , an outcrop of q ( trr i s Fig . and it appears probable that there is a thr ust s p of th - 54 P ost C a m bria n M ooem ents.

n rock on both sides of the anticli e , though little can be seen on the south side for peat and drift . T orridon S E h It is quite certain , however , that thrust andstone ( ) O f l occurs on both sides the antic ine, for we find it in several places ; and it may fairly be inferred that there is a continuous strip of this M S rock all round the sharp curve , adjoining the oine chists , and a aidh connected with the band that has been traced from Loch L g .

From the position of this sandstone , with respect to the quartzite on O the north side of the anticline , it is evident that the lder rock is superimposed on the quartzite by a thrust , and the latter in like manner has been brought over the Serpulite G rit . That these rocks M S - and the oine chists also have moved westwards, on a thrust plane which is not arched like the others , is evident from the fact that the main masses of quartzite and T orridon Sandstone in the undisturbed area to the west S how no trace of the anticline which exists in the T rridon S thrust rocks (see Fig . The o andstone on the south side of the anticlinal fold is a light - coloured siliceous grit which is some a times conglomerate , but rendered so schistose as at first sight to be barely recognisable . It is much veined with quartz , like the same A s - material on the north side of the arch . we go south eastward the and rock is still more altered , and , having the same dip strike as the fl a M S fi ggy oine chists , it becomes exceedingly dif cult to determine ffi where the line separating them should be . This di culty does not occur on the north side of the area in question , for we find to the n T orridon S i north of the recog isable andstone , and at no great d stance from it, a laminated very siliceous grey rock , much contorted , in a - - hi ridge along an east and west strike , w ch is undoubtedly a portion of M S the oine eries . But on the south side , to the east of the ordnance C h orcurach station on Creag , there occur here and there bands of a M i coarse , gritty schist or crushed gneiss alternating with finer o ne T orridon like bands , and whether the whole of this material is altered Sandstone or that rockalternating with the M oine S chist it is impossible to determine . It should therefore be understood that the line here drawn on the map separating the sch istose T orridon Sandstone from M S S the oine eries is purely conventional . everal specimens from this district have been microscopically examined , but the rocks are so S much crushed that no definite opinion can be formed of them . ome are more probably crushed grits , while others more resemble crushed gneisses or pegmatites . To the south of the small burn immediately north of Creag C h orcura ch S G , the erpulite rit and the Fucoid Beds soon disappear , P R ock and the main thrust occurs just above the ipe , and probably C h orc u there are minor reversed faults in that zone . Under Creag rach is a thick m ass of flaggy siliceous mylonite apparently S hattered norm al fa ul ts . by , To the south of this crag the Fucoid Beds and S G erpulite rit are traceable for some hundreds of yards , and midway along this strip some schistose quartzite appears over the Serpulite G rit . Farther south the undisturbed P ipe R ock is immediately overlain by a thick mass of siliceous mylonite , which forms the lower parts of Creag M h Or and Creag Bheag to the east of D undonnell S . O fl a M House ver the mylonite comes the ggy oine chist , but the boundary between the two rocks is not well defined , and , in fact , they n appear to pass into each other . It seems probable that the mylo ite A ea r m tra th na Shea lla to Kin lochewe F orest 55 r f o S g . represents not only crushed and rolled - out members of the Cambrian S T orridon S l eries and of the andstone , but also crushed crystal ine D T orridon S r schists . eformed andstone perhaps enters more la g ely t into the composition of this mylonite , and there are indications tha a

- considerable portion may consist of rolled out Lewisian G neiss . S The belt of complication in trath Beg is much contracted , and it appears that the M oine thrust has here brought the mylonite and

M oine Schists over the undisturbed Cambrian strata . This line of disruption apparently continues just above the Serpulite G rit for a mile to the southward of the river up the east side of A llt G leann C h aora h ain A fl a e . large part of the ggy schistose rock forming the dha B uidh C a e . crags of is probably mylonite The rock is , for the S fl a most part , very iliceous and ggy , and some of it has much the appearance of a deformed grit . There is not much mica on the u surfaces of the planes adjacent to the line of thr st , but no good line can be drawn between these rocks which have comparatively little mica and the more micaceous schists to the eastward . O n the watershed wes t from Loch Coire C h aorae h ain a thin slice of deformed T orridon Sandstone again appears between the M oine

thrust to the east , and the Fucoid Beds in their normal position M - th e beneath the Ben ore thrust plane to west . It is traceable for 600 O ff n about yds . , till it is cut at the south end by a fault ru ning in l N E . S h al a E . S e an direction Farther south , towards trath na g, the M i oine thrust again overlaps all underlying d srupted rocks , and , for a E S long distance , the astern chists rest directly on the undisturbed

. G . Fucoid Beds W.

R E FR O M S T R H N A S H E AL L AG T O KIN O C HE E F R E S A A AT L W O T.

S S healla In the tract between trath na g and Loch an Nid , one point of special interest is the occurrence of the double unc onform a bility of the Cambrian quartzite on the T orridon Sandstone and Lewisian G neiss in the masses brought westward by the Ben M ore

thrust , to which reference will now be made . The two powerful displacements (Ben M ore and M oine) run close

to and nearly parallel with each other for about three miles , except S S E A ch ne i ie at a point about a mile and a half . from g , where the E S astern chists rest directly on the unthrust Cambrian strata . The positions of these lines of disruption are well defined in the burn sections and on the escarpment on the east side of A m h ainn Loch an M Nid . For a long distance the materials above the Ben ore thrust plane consist of a thin wedge of T orridon grit not much deformed

till the observer approaches Loch an Nid . In that direction , at w G various localities , the Le isian neiss rises from beneath the h A t Torridonian strata which rest unconformably upon t e gneiss . 2 t 0 . one point , about 7 yds south from a turf and stone dyke tha

crosses the valley , the junction between the two is clearly seen . M - S a lterella Beneath the Ben ore thrust plane , the dolomite there

rests in normal sequence above the S erpulite G rit and Fucoid Beds . A bove the plane , the disrupted gneiss is seen to consist of pink

granitoid rock with basic knots . The basal Torridonian conglomerate , th e A d probably marking the local base of pplecross ivision , is coarse ,

and contains pebbles varying from seven inches to a foot across . - 56 P ost C a m bria n M ovem ents.

T he largest are compose d of pink granitic and basic material like the

rocks of the underlying floor , the smaller ones , from half an inch to

an inch in diameter , consist of felsite , jasper , quartz , and altered

purple quartzite . It is worthy of note that these pebbles are not

deformed , nor is the matrix schistose , as is the ease with the same M - O conglomerate above the Ben ore thrust plane in the ykell valley , A ss nt y . The overlying grits and shales are not schistose ; they are z merely crushed and veined with quart . 3 A bout 0 0 yds . south from the locality just described and along

- the 1 250 ft. contour line a small patch of basal quartzite is seen to T i on orr d . rest unconformably on the grits Farther south , and almost m due east of the outlet of Loch an Nid , another unconfor able outlier of the quartzite reposes partly on th e T orridon Sandstone and partly

on the Le wisian G neiss . The relations of the strata at Loch an Nid and in th e mountainous

3 . ground to the west are shown in the section given in Fig . The

western part of this section , beyond the belt of complication , illustrates the uneven character of the land - surface on which the O n Torridonian sediments were laid down . the western slope of M M h e arch air r E h ullach Coire hic F these sandstones and g its ( ) , 2000 f t . which reach there a thickness of about , can be seen to have been accumulated around and above hills of Lewisian G neiss that rise 1 00 0 ft to a height of . , and are now gradually being uncovered in the A progress of denudation . bove this pile of sediment the Cambrian quartzites (Ca) rest unconformably on the eroded edges of th e T orridon S P R th e andstone , followed in order by the ipe ock (Cb) , S G Fucoid Beds (Cc) , erpulite rit (Cd) , and a few feet of the basal A t S un dolomite ( Ce) . this horizon in the Cambrian eries the

disturbed strata are abruptly truncated by the Kinlochewe thrust (T) , which has brought westwards a cake of Lewisian basic and acid B A gneisses traversed by epidiorite dykes ( G ) . These rocks ( ) rest on

- the inclined thrust plane , and form a serrated ridge on the eastern S i slope of the mountain . everal m nor thrusts or reversed faults, not

' ff th e c ourse O n shown in the figure , a ect of the dykes . the west side ‘ S i1 rr of the Loch an Nid valley , on the dip slope of g Ban , a small

patch of gneiss , which has been isolated by denudation from the M M F h e arc h air M e allan thrust mass on ullach Coire hic , is named L aoi h ucoid S G an g (the calf hillock) . The F Beds and erpulite rit n can be traced rou d this outlier , and the basal dolomite appears on e its western side , truncated in like manner by the Kinlochew

thrust (see Fig . E ast of Loch an Nid a normal sequence of undisturbed Cambrian is P R rocks traceable from the ipe ock to the basal dolomite , above S h a s which , as already indicated , the rest of the Cambrian eries

been displaced by the Kinlochewe thrust . The Lewisian rocks T orridon S which now supervene are overlain by the andstone (B) , A with the basal quartzite (Ca) resting unconformably on both . bove P R these displaced materials , thrust ipe ocks , Fucoid Beds , and a thin wedge of Lewisian G neiss are truncated by the M oine thrust which has driven westward the granulitic schists of the M oine S M eries ( ) . The belt of Lewisian G neiss between the Kinlochewe and M oine - t thrust planes , which stretches southwards from the eas ern slope of

58 P ost C a mbria n M ovem ents .

M ullach Coire M hic F he arch air to the Kinlochewe valley is not much O f deformed except near the great lines displacement . The basic dykes preserve their north - westerly trend and their clear intrusive n O n junctions with the g eiss . the surface of this plateau of dis rupte d Lewisian rocks small isolated patches of T orridon Sandstone occur, as shown on the map . Thus , about half a mile east of Lochan

Fada , the basal breccia is seen to rest unconformably on the old floor , followed by shales , but the strata are here highly contorted and

- . B e inn inverted Farther to the north east , on the western slope of M - e Bheag and close to the outcrop of the oine thrust plane , the doubl unconformability of the Cambrian quartzite on the T orridon Sand vi stone and Lewisian G neiss is again sible .

- The outcrop of the Kinlochewe thrust plane , which bounds the displaced Lewisian rocks to the west , is shifted for about a mile to the south - west by the F asagh fault to a point near the outlet s of Lochan Fada . It then pas es southwards along the escarpment ’ B in M hirinidh R west of e n a to the Kinlochewe iver . A t the Heights O f Kinlochewe evidence has been obtained of an M intermediate displacement in advance of the oine thrust , aecom anie d A p by marked deformation . triangular mass of highly sheared gneiss here displays a narrow infold of T orridon Sandstone D G and shales ( iabaig group) , traceable along the east side of leann

- na M uice for three quarters of a mile . These sediments have been rendered schistose , an alteration specially apparent in the grits . The deformed gneiss and T orridon Sandstone have been driven westwards G M along a plane that runs up leann na uice, and truncates the under lying Lewisian G neiss with its basic dykes . O ver a great part of the area between Loch an Nid and the Heights of Kinlochewe the exact position of the M oine thrust cannot be definitely determined, owing partly to the absence of sections in m lonise d the direction of the dip of the strata , and partly to the y rocks that so often accompany this great line of displacement . These m ylon ise d materials have resulted from the S hearing of gneiss ’ and green epidotic grits . They are well developed near Loch a M h e allain O dhair a , two and a h lf miles north of the Heights of On S r D . Kinlochewe , and also on the western slope of ubh But on - B e inn the south west declivity of Bheag , and particularly in the A bh uinn B rua ch ai valley of g, below the Heights of Kinlochewe , the

M . oine thrust is clearly traceable Indeed , in the latter area , where E S the ground is bare of drift , the astern chists above that plane of disruption pass transgressively across the displaced Lewisian G neiss and the T orridon Sandstone with a small patch of the basal quart zi te s. Beyond the Heights of Kinlochewe the structure of the country A becomes remarkably complicated . conspicuous example of this complexity may be seen on the rocky ridge on the north side of the

R . Kinlochewe iver (Fig where , owing to the inversion of the M displaced materials , the folding of the Kinlochewe or Ben ore

- thrust plane , and the subsequent denudation of the rocks overlying ff l that plane , the structure has been found most di icult to unrave . The western part of this section supplies another illustration O f the T orridon S uneven land surface on which the andstone reposes , the ridge of M call R iabhach being flanked by pre - Torridonian valleys on ra th na Shea lla to Kinlochewe F orest 59 A rea from St g . 6 0 - v en P ost C a mbria n M o e m ts.

G n B iana il ul either side . In lean sda the position of the Fasagh fa t (f) T orrid on S th e S is shown , whereby the andstone on east ide of the v alley is let down against the hornblende - schists of Lewisian age to A the west . long the eastern slope of this valley runs the un c on z formable junction between the Cambrian quart ites (Ca , Cb) and T orridon A can underlying Sandstone (E h) . normal sequence here be followed from the basal quartzites to the mem bers of the Olenellus zone (Cc , Cd) , and in places to the basal dolomite (Ce) . O n Craig R oy the succession is interrupted by the Kinlochewe M - (Ben ore and Kishorn) thrust plane (T) , above which appear the A Lewisian rocks ( ) with an infold of the Basal Quartzite ( Ca) , the A unconformable j unction between the two being well exposed . bout ’ ‘ half a mile to th e south of the top of B e inn a M hrrinidh the Lewisian rocks are covered unconformably by the T orridon Sandstone n (Ba) , with infolds of the Basal Quartzite (Ca) , arra ged in isoclinal

folds . The axial planes of these folds are inclined generally to the E S E h , and are truncated in places by minor t rusts heading in the

same direction . These red sandstones stretch eastwards from M e allan G h obh ar to the hills beyond A llt C hnaim he an (the burn of S the bones) , and cover more than a square mile of ground (see heet Al ong their northern m argin their unconformable boundary he line with the gneiss has been traced , and they are found to usually

inverted and to pass underneath th e older formation . The basal breccia

at the line of junction contains fragments of the underlying gneiss . The gorge in the lower part of A llt C h naim h e an has been cut

by the stream through the overlying cake of thrust Lewisian rocks , T orridon S i andstone , and Basal Quartzite , so as to reveal the p led

u . S G p Fucoid Beds , erpulite rit , and basal dolomite beneath the

- Kinlochewe thrust plane (T) . The exposure of these successive

layers of displaced materials is due not only to denudation , but partly also to the folding of the rocks above and below this line of

in . 4 . A displacement , as represented Fig still more striking example of this complicated structure occurs about half a mile to the east A llt C h naimh e an - of , where the thrust plane , together with the rocks

which it separates , has been sharply folded , and where the thin veneer of gneiss and red sandstone overlying the thrust - plane has

- been removed from th e crest of the arch . The dome shaped arrangement of the Cambrian strata beneath that plane is well seen on the hilltop and southern slope facing the road that leads to t P R Kinlochewe . The hird subdivision of the ipe ock is the lowest d Cambrian zone here represente . It is followed by the higher sub S G zones , the Fucoid Beds and erpulite rit , which are repeated by

reversed faults . Farther east, owing to a minor fold , a lobe of the displaced materials that lies above the Kinlochewe thrust - plane con A sists of gneiss with an infold of T orridon S andstone . lthough 4 represented as an outlier in Fig . , it is really connected with the O n A bh uinn B rua c h ai main mass . the slope towards g the bare plane

of the Kinlochewe thrust is exposed , and for part of the distance the G Lewisian neiss rests mainly on the Cambrian Limestone . Here , th e T orrid on S too , inverted junction of the andstone (Ba) with the A gneiss ( ) above the line of displacement is visible , while to the south of the outcrop of the thrust - plane the repetition O f the Fucoid

S G . Beds , erpulite rit and basal dolomite is clearly observable a ll to Kinlochewe F orest A re from S tra th na S hea ag . 6 1

In the channel of A bh uinn B rua chai g, about two miles up the valley from Kinlochewe , the same important line of disruption is laid d bare , where pink epi otic granitoid ” gneiss ( “ Logan R ock ‘ of Heddle) is superimposed on the dolomite G h rudaidh of the group , the upper S a lterella band being visible within

- a fe w yards of the thrust plane . ucoid Close by are the F Beds , which lenellus have yielded fragments of O . Farther down the stream the is gneiss , exposed in several places , associate d with a mass of crushed T orridon S andstone (Ba) in the triangular space between the A h h uinn B ruach aig and G len D och e rt A t y . one locality , as shown 4 in Fig . , the crushed sandstone is succeeded by the Basal Quartzite (Ca) beneath the M oine thrust plane R eference has already been made to the correc t iden tifica tion ' by P rofessor Bonney of the Lewisian G neiss and T orridon Sandstone in A bh uinn B ruach aig G len Logan and to the recog nition of th e reversed fault whereby the gneiss has been brought to the surface .

The horizontal section in Fig . 4 shows that the materials above and below the Kinlochewe thrust plane , together with that plane itself , have been thrown into a compound anticline and syncline , and that the folding was developed subsequent to the thrusting . A ttention has already been directed to the great fault that runs along Loch M aree and up the G D valley of len ocherty , whereby the undisturbed strata , the suc c e ssive - thrust planes , and the dis placed masses , have been shifted north - westwards on the south side of the dislocation . A long the South - west side of M Loch aree , in the undisturbed T orridon S G G andstone in len rudic , we find the prolongation of the F asa h g fault , which has been 6 2 P ost- C a m bri a n M ovem ents .

S hifted about three miles to the west of its position in the F asa h G th e n g len at the head of loch . O the eastern slope G G d 5 n of len ru ic (see Fig . ) undisturbed Cambrian strata , ra ging S G from the Basal Quartzites to the erpulite rit (Ca to Cd) , and in places to the basal dolomite (Ce) , dip in an easterly direction at angles varying from 1 0 ° to These unthrust strata are abruptly truncated by the Kinlochewe thrust , and are over a T orridon S B b lain by large mass of andstone (Ba , ) with inliers G A of Lewisian neiss ( ) , which together cover an area of a square ’ M all G hiubh ai mile and a half round e a s . This prominent hill 2882 M ( about two miles to the west of the head of Loch aree ,

- forms a conspicuous outlier of displaced materials . The thrust plane

on which these materials lie can be traced round the mountain , where it appears as a circular fault or line of discordance between the rock

- masses . It is worthy of note that on the south west side of the

hill , not far from the line of section (Fig . the basal quartzite is seen to rest unconformably on the T orridon Sandstone as an infold - T rri above the Kinlochewe thrust plane . While the o don Sandstone

t - res s on unthrust Cambrian strata on the north and north west , a P R slice of Basal Quartzite and ipe ock , which has been driven west an ward by intermediate minor thrust , comes beneath the thrust u S 4 plane on the so th and east , as hown in Fig . , and is recognisable from a distance owing to the white fringe which the strata form

beneath the darker overlying sandstone . In this outlier the D iabaig and A pplecross groups of the T orridon S andstone are both represented , the strata being arranged generally in the form of a syncline with a compound anticline towards the d west . The members of this formation are traverse by minor

thrusts, one of which has been traced round the hill . They rest on G 5 the Lewisian neiss , which , as shown in Fig . , appears in places

- between them and the thrust plane . The strata are here not much

- deformed , except near the thrust plane and the other minor displace

ments . Where the arkose has become slightly schistose , the dark

and grey shales have been cleaved , and along the actual lines of * flin - movement the strata have been transformed into ty crush rocks . A small patch of displaced T orridon Sandstone that lies to the east ’ of the main outlier on M e all a G hiubh ais rests partly on Basal

Quartzite and partly on Serpulite G rit . E astwards for a distance of two miles the Cambrian zones up to S G the erpulite rit are repeated by inverted folds and reversed faults , i E S E E their general nclination being towards . and . The under

‘ T orridon S lying andstone has shared in these plications , for, on the M C f wooded slopes facing Loch aree and in the li f above , the members

of that system , not much deformed , can be seen to rise from under

fl ex ure s ' neath the quartzite in great , and along the line of section

5 . (Fig . ) in sharp isoclinal folds A bout a mile up the valley from the head of Loch M aree the

“ ” T h e rocks forming th e sole of th e thr ust - plane at this lo cality have not een uc fe c ed th e e en I n one l ce cl e th e e e th e b m h af t by mov m t . p a , os to spot wh r F uc d B e d e elded th e fine e c e n O lenellus th e a al d l e oi s hav yi st sp im s of , b s o omit is l le d u e d n n c e O f th e u - lane th e ell - unded so itt ist rb , that withi two i h s thr st p w ro a n a nd and th e u e Sa lterella ulche lla c c a c e e th e ne gr i s of s t b s of p , whi h h ra t ris zo ,

are uncrush ed . rea rom tra th na Shea lla to Kinlochewe r A f S g F o est. 63

n mai outcrop of the Kinlochewe thrust appears , where the T orridon Sandstone ( B b) is superimposed on the Cambrian Quart

zi s . te The grits are schistose in places , the planes of schistosity b being inclined at higher angles than the planes of edding . This fl a se r structure becomes more conspicuous as the sandstones are followed up the Kinlochewe R iver beyond C rom asag ( Sheet M The position of the oine thrust is concealed by alluvium , but the green schists that overlie it are exposed in the river close to the S B N . P J H . Kinlochewe Hotel ( heet . . , . T E V I I C H AP R .

T H E E AS E R S S S T N CHI T .

T H E E S astern chists , as already indicated in the general geological 1 m l ni description of this region (p . comprise ( ) y o se d rocks ; ( 2) v - - granulitic quartzose schists and musco ite biotite gneiss or schist , representing the psammitic and pelitic types of the M oine S eries ; 3 and ( ) a limited development of micaceous and hornblendic rocks , resembling in some particulars types of Lewisian G neiss in the areas - R - to the west of the post Cambrian movements in oss shire . The feature of exceptional interest presented by the E astern S chists is the sequence of rock groups and their structural relations as worked out by the G eological Survey in the Fannich M ountains and in the tract immediately to the north . “ S P 1 89 M r G 7 . In the ummary of rogress for , unn described the area mapped by him between the valley of the Broom and the

F annich M . 38 watershed of the ountains He there advanced (p . ) M S an order of succession in the schists of the oine eries , the lowest subdivision occurring near the M oine thrust . He pointed out that

- the highest member of the series , consisting of muscovite biotite gneiss , was overlain by coarse acid gneisses of Lewisian type with basic lenticles and bands of diorite, exposed along the northern F a ni slopes of the western part of the n ch range . From the distribution of these rocks he inferred that they form the northern end of a great synclinal fold . F anni h 1 8 8 D r c 9 . From Lodge , in , Horne mapped part of the ground between Loch F annich and the watershed of the F annich be range , when identified the various rock groups previously “ M r S P G . described by . unn In the ummary of rogress of the 1 1 G eological S urvey for that year (pp . he showed that these groups could be traced , at high inclinations , from the watershed ann ich south to Loch F along the eastern limb of the fold , and that the subdivisions of the M oine S eries rise from underneath the R gneisses of Lewisian type along the western limb . egarding the super of M S position the acid gneisses of Lewisian type on the oine eries , he stated that two hypotheses may be advanced to explai n the relation ship : ( 1 ) that the structure may be analogous to that north of L oéh M - - aree , where the biotite gneisses and hornblende schists of M call R iabhach are superimposed on the sedimentary series of

2 - Letterewe ; and ( ) that the structure may be fan shaped , the rocks u of Lewisian facies , tho gh apparently the highest , being in reality the lowest, while the sequence of the other groups may be deceptive . From the uniform characters and persistence of the siliceous members of the M oine S eries throughout the folded area of F annich he suggested that their crystalline characters were probably developed

- before the post Cambrian movements . 64

T h e E a stern chists 66 S .

’ h aidh the M ea ll a C rasg R ock . The members of this group have apparently a thickness of from 1 200 to 1 50 0 ft . 3 - - ( ) Biotite schist , dark coloured , of a pelitic character , with occa S irrr M Or - sioual small garnets ( g Biotite schist) . It includes a strong

. band of quartzose granulitic schist. The group appears to be

2000 . altogether nearly ft in thickness , made up of

B iotite - S chist Q uartzose S chist B iotite - S chist

4 A - fl a ( ) thick group of light coloured , ggy , granulitic quartzose

- - mica schists , with occasional thin bands of dark coloured biotite schist . This group occupies the larger part of the area surveyed , and is apparently several thousand feet in thickness . It is the typical

M oine S chist . A in S before noticed , these rocks are disposed a synclinal form R about the watershed at the head of the valley of the iver Broom . G G roup , with rocks resembling Lewisian types , occupies a con side ra ble area between Sgirrr Breac and Sgurr nan Clach G eala . n The gneisses there dip at a high a gle , being often vertical , and strike

- - north west an d south east . It is difficult to determine the relation 1 between the members of this group and those of group , but the 4 1 . divisions from No . to No form a regular and apparently descending ’ series which successively crop out to the north of Loch a B h raoin

- with a southerly or south easterly dip . Traced westward , they M approach the oine thrust near Loch an Nid , where they turn 4 th e southward , and the upper part of division No . . abuts against line O f thrust . It is evident that in the area north of Loch an Nid there is no exact parallelism between the li ne of the M oine thrust and the strike of the foliation in the schists , for as we proceed in this direction towards Loch Broom lower and lower parts of this division S O m a successively crop out , that whatever y be the age of these schists they existed as such prior to the formation of the M oine thrust plane . — of G roup G r The rocks this group are typically developed at the head of A llt B re baig between Sgirrr Breac and Sgurr nan Clach - G eala , and the coarse grained grey acid gneiss has a decided north G west strike . enerally the gneiss is of a very acid type ; some parts of it which are granulitic might at first sight be considered to belong ’ ll C h ras aidh r to the M e a a g rock , if it were not for the p esence of basic A 751 0 n bands . grey granulitic rock ( ) with a marked linear foliatio , ll B r ai 1 50 0 which 1 s found m th e eastern branch of A t e b g yds . north S irrr east of g Breac , is composed of quartz , felspar and two micas r with S phene as an accesso y . Not far west of this place , in the burn l E r r r called A l t nan ilig ( the othe b anch) , is a well banded g ey and

- - - cream coloure d rock which is an epidote pyrox e ne granulite . I n i - r It contains epidote gra ns and crystals , pale green pyroxene , ho n r blende (scarce) , water clear felspar and quartz , forming an ir egular mosaic , with sphene as an accessory . A bout a quarter of a mile farther up the same stream occur O ne coarse grained massi ve rocks of a basic character . of the broad black bands (7508) is a granitoid aggregate of green or greenish brown hornblende and oligoclase , with some sphene . These basic A rea N orth o the F a nnich Wa tershed 6 f . 7

d a nd rocks appear to have the characters of intrusive ykes , bear the same relation to the acid gneiss as the epidiorite dykes d o to the Fundamental Complex in the area west of the post - Cambrian dis placements . They have been traced for about two miles in a north

- west a nd south east direction . Their total width is between 1 0 0 and

200 . yds , and in some places they appear to be wholly of basic

o f. s material , while in others thin strips acid gnei s divide them into

- well marked bands . A somewhat different type of basic rock also occurs in association with the acid gneiss . It is represented by lenticles of basic material ,

- and irregular lumps and thin bands of hornblende schist , which seem to bear the same relation to th e acid gneiss of the district as the earlier basic rock does to the acid types of the Lewisian G neiss in the west of S utherland and R oss .

The rocks of this area are much folded , a beautiful example of which on a large scale occurs in the crags to the south - west of Sgurr ’ G A llt o B h l i h . e a a c nan Clach eala In ascending the stream Lea a ,

- S W d S . three quarters of a mile from the hilltop , a ban of epidiorite 300 3 0 . . is encountered about yds in breadth , and , yds farther up , 0 bre ad 50 7 . . another band yds is met with , having a strip of gneiss ft th e wide in the middle of it . The foliation in gneiss in this locality m E E A N . s dips unifor ly and steeply towards . the broader band is followed northward for about half a mile to the great precipice of Creag huara in - S urr G th e in an F , on the south west slope of g nan Clach eala, cluded strip of gneiss disappears , and we find a single broad dyke of 1 about 0 0 yds . The smaller basic band widens out also to some extent as it is traced northward into the same crag , where the two are found to form two separate limbs of one isoclinal fold which curves round and spreads out over the crag in a dark basic mass . The foliation in the adjoining gneiss and the occasional foliation in the dyke itself exhibit the structure clearly. In one part of the crag 80 A t the breadth of the mass of epidiorite is quite 0 ft . the head of

- O f S urr Coire Breac , to the north west g Breac , the folding is so intense u 1 that the acid gneiss is felted with the garnetiferous gneiss of gro p , and both are traversed by numerous pegmatites . Various acid bands met with in th e garnetiferous gneiss around Loch Toll an L ochain and ’ A C h ailleach G on appear to be folded portions of group , as the two acid bands seen in A llt na G oibhre (the stream flowing northward i l from Loch Toll an L och a n) certain y are . The highest of these S th e forms a marked feature in its outcrop on either ide of burn , and it can be distinctly traced round as a coarsely crystalline rock to the ’ A C h aille ach west side of , where a thinner band of a similar character appears below it to the westward . The lowest of the two acid bands A llt G oibhre in na , which is of considerable width in the burn , seems O n to disappear when followed westw ards . the east side of the burn d it is probably connected with th e main mass of aci gneiss . ’ No basic igneous rocks were noticed in the acid bands under A C haille ach A llt G oibh re , but the two acid bands in na both contain dark basic hornblendic masses . In the uppermost band some of the basic masses are foliated , and in one excellent section the foliation of the acid gneiss cuts across that of the included basic rock nearly at — right angles a structure almost exactly similar to that so often seen in the Lewisian G neiss of the G ruinard district . 6 8 T he E a stern S chists .

— ‘ rou 1 M ll - G . e a t S rth e p The an rock has a peculiar character , and is M quite unlike the ordinary type of oine Schists . It is so full of large garnets that in some places a layer of them is spread over the ground ,

as the result of the decomposition of the rock , and once after a ’ v A llt G oibh re B h raoin hea y spate in na , which runs into Loch a from L och ain Loch Toll an , a bed of garnet sand was found in the delta of h ’ . O n t e o f B h raoin the stream north side Loch a this rock , stretching M e a ll D E E ini h S . R a c from ubh , a hill about half a mile of Creag , to

M t - Si a n ul - call an the , forms outlier , probably fa ted on the south east P B S . side ( late III . , ection , group To the south of this loch the rock stretches as a marked band high up on the hillside from the ’ — western shoulder of A C h aille ach round to A llt B rebaig the stream ‘ S S irrr — that rises on the north lope of g Breac crosses the valley , and ’ M C h ras aidh r forms the southern declivity of call a g , whence it st ikes southward with a high westerly dip over the top of Sgurr nan Clach G 3 58 1 ft. eala , , the second highest hill of the district . M eall t- Si The garnetiferous gneiss outlier of an the , which is three R ainich miles in length , extending westward to near Creag , lies in the centre of a small syncline . The rock is often massive in appearance , and is largely made up of S mall irregular bands of white or grey pegmatite , which for the most part are parallel to the foliation planes u of the rock . Irreg lar bosses and sills of a basic intrusive rock are often met with . For some distance on either side of th e fault that crosses A llt na D R Faine (a tributary of the undonnell iver) , about a mile and a - R ainich quarter north east of the top of Creag , the exact base of the garnetiferous gneiss is concealed by drift . But after passing over the O bscure ground to the south - west the line between this rock and the

- quartz schists is remarkably clear and straight , and the dip is steadily E E 1 ° S . 0 at angles of to Nearer the centre of the syncline , u however, the o tcrops of the rock are not so clear and the dip is irregular . Near the northern edge of this mass bands of a very acid schist ff or gneiss occur quite di erent in character from the rest of the rock .

The largest and most important of these , visible about a mile slightly ‘ tO M e all t - S rth e in south of west of the p of an , is almost certainly an 2 oi S . . fold the iliceous rock No , which apparently lies below G ood sections of the garnetiferous gneiss are fo und in the crags all along the northern boundary , but perhaps the finest continuous ’ exposure occurs in the crag on the south side of Loch a B h ra oin from A llt G oibh re near the burn called na , which issues from Loch Toll an l r bai L och ain A l t B e . , round to g eastward In the latter locality , near its upper boundary the rock is comparatively free from garnets , is more evenly foliated than usual , and contains abundance of white A mica wi th little biotite . good exposure of the garnetiferous gneiss A llt G oibhre appears in na , but to the westward the boundary between it and the siliceous flags is much obscured by drift for a long l d distance , only smal isolated outcrops occurring ; but on the west si e ’ of A C h a ille a ch the rock is again exposed at the surface . A llt G oibh re In na , above the uppermost of the two bands of acid n S M e all t- Si g eiss (group ) , the an the rock , or one very similar , crops out in great force . It occupies the whole of the valley , spreads over and the bounding ridges on either side , forms the upper parts of A ea h o th e Fa nnich Wa tersh ed r N e at f . 6 9

’ ‘ A C ha ille ach S rrrr and g Breac with the high ground between them , m n thus Occupying the watershed for a distance of two iles . O th ese hills , owing to the rarity of the small pegmatitic bands , the rock

- occasionally resembles a biotite schist. O nly brief references may here be made to the intru sive igneous rocks of these groups , as they have for the most part been described in the account of the strata in which they occur . Those found in the acid gneiss (group S ) are generally m assive epidiorites or hornblende schists ; the bosses and sills of basic material associated with the garnetiferous gneiss (group 1 ) are generally hornblendic in character ' an d full of garnets . These garnets have generally no crystalline a - form , being more or less rounded ggregates of garnet rock . In places they attain a large size ; masses which are as much as 3 to 4 n h ins . in diameter havi g been met wit . a d riartzo - The small pegm tites , compose of q felspathic material , which are generally extremely abundant in the garnetiferous gneiss , must be considered as segregations from the adjacent gneiss , but it is doubtful if some of the larger pegmatites are not intrusive in O n L och ain character . the east side of Toll an and elsewhere masses

- of coarse pink and white pegmatite have a dyke like form , and several of them which are many feet in width can be traced for a considerable distance . They generally run along the strike of the foliation , but some may be seen to penetrate both the garnetiferous muscovite - 1 P biotite gneiss (group , late and the acid gneiss of Lewisian type S P D ruim R éidh (group , late IL) . They are very conspicuous in to the - - L och ain n east north east of Loch Toll an , where they are mai ly composed of microcline felspar . ’ Grou 2 — M eall C h ras aidh h p , The a g rock is per aps rather more i M S s liceous than the typical oine chist and contains less mica . This band of fl aggy quartz - schist occupies the upper part of the valley of D R A llt the undonnell iver ( na Faine) , where it is crossed by a rather

- - large fault running north west with a downthrow to the south west .

- - - The beds there dip to the east south east and south east , but near R ainich Creag , at the head of the valley , they curve round and run across the ridge to the south , while the inclination changes to a ’ B h ra oin northerly direction along the north side of Loch a . Hence th e th e band forms a synclinal fold , in centre of which , and forming 1 P the highest ground , is the garnetiferous gneiss (No . , late Numerous sections of these fl aggy quartz - schists are exposed in the ’ B h ra oin O n small streams on the north side of Loch a . the north ‘ ° side of M e all an t- S rthe the rock appears with a southerly dip of 1 0 ° ’ 20 B h raoin to it sweeps round the shores of Loch a , and , eastward , ‘ forms a band varying from a quarter to three - quarters of a milc in width , parallel to the outcrop of the rocks above and below . There ’ in B h raoin is a good section of it the river east of Loch a , but the ’ M C h ras aidh bill best section is in the scars of call a g , and from this it strikes almost due south With a westerly dip of from 30 ° to There is a marked band of biotite - schist in the lower part of the ’ M l h a idh group under e al a C r sga . No intrusions of igneous material and very few pegmatites hav e been met with in these siliceous schists . G rou — hist — 3 . u e c p Sg rr M or B iotit S . This group generally forms a much broader belt than either of the two preceding , and , owing to fold

. ing and repetition by faults , it spreads over a much larger area In 0 T he E a stern c ists 7 S h .

’ addition to the broad band that accompanies the M e all a C hrasgaidh

- - rock , circling round it from the north west to east , this biotite schist G appears on each side of the Broom valley about arvan , and a remarkable outlier of it forms the hills of R einu E naiglair and M e all

D - oire Faid to the east of Braemore . This biotite schist in several places appears to be much more plicated than the quartz - schists that S border it on either ide , which may be due to the former having been

m ore l . of a softer character , so that it yielded much readi y to pressure ’ M hada idh Fine sections are exposed in the crags about Loch a ,

i 1 0 00 . particularly in the scar under Carn na Cr che , which is ft in ‘ f M 36 3 t . . S irrr OT 7 height , and almost vertical It forms the peak of g , , - 514 the highest hill in the S heet . The felspathic biotite schist (7 ) here is dark - coloured and contains very little quartz ; and the felspar

- is water clear and for the most part untwinned (near andesine) . The rock may be examined in Abh uinn C uileig to the east of the ’

B hraoin . foot of Loch a , where there is a fairly good section of it The zoisite - rock hereafter described occurs in th e schist here near A llt E a s b M the foot of an B ig, which drains the northern slope of call ’ C h ras aidh A bh uinn C uile i a g and flows into g. ’ - B h raoin In the streams to the north west of the head of Loch a ,

- a band of biotite schist probably represents this rock , or is a part of R ainich it . It has been traced over Creag , thence southwards and ’ eastwards round the synclinal fold to the head of Loch a B hraoin . ’ O n - A C h aille ach the watershed to the south west of , a band of biotite schist occurs , which may be the continuation of that just referred to . It has been traced northward into the streams that run into the ’ B h raoin head of Loch a from the south . The band of quartz - schist which is found in the Sgarr M OT ’ - h M h adaidh biotite schist is strongly developed to the sout of Loch a , i S irrr M OT under Carn na Cr che and g , and it may be followed at A bh uinn C uile i intervals westward to g, beyond which it is lost in the ’ O n peat moors . the other side of the fault running from Loch a B h raoin to G arvan in S trath Broom we find it north - east of Fain ‘ t - S I th e in C am M OT h about Loch an and Breac , the top of w ich is an

- outlier of biotite schist , and it can be followed to the Broom valley ,

- where it is , like the biotite schist above and below , much broken by O n G lack our faults . the east side of the valley it appears above ,

where several streams have cut gorges through it . This band is not ’ M e all C h ra s aidh very unlike the a g rock , but , in some places , appears

more massive . The part of the biotite - schist which comes below this zone of quartz - schist is generally not so free from siliceous intercalations as i r the ma n mass which lies above it , and towa ds the base appear - so alternations of quartz schist with biotite schist , that the boundary r O f in some cases i s rather conventional . It is the lower pa t the large biotite - schist mass that spreads out by plications over Creag D h ubh th e A bh uinn D m to south of ro a , and that forms the outlier

of B e inn E naiglair and M e all D oire Faid to the north of that stream . The same rock is traceable from Fain on the D undonnell R iver to the

Broom valley , and we find it again east of the Broom , rising from G lack our S and passing above Inverbroom Lodge to trone Nea , whence ’

c ut off A llt B hrai h e . it trends eastward , to be by the large a g fault d - This fault boun s the biotite schist group on the east , and the lower e a ic a e 1 A rea N orth of th F nn h W tersh d . 7

a re a part particularly here spreads over a considerable , where it may ’ be easily studied in A llt a B hraigh e and in the burns to the north ’ A llt B hrai h e a lnrost ward . The rock in this portion of a g is free - A from quartz , and is dark coloured , with abundant biotite . specimen 7500 of the rock ( ) from the side of the path in Braemore Wood , 8 0 - lack our 0 . G nearly yds south east of , contains biotite in fairly large flakes , felspar , almost entirely oligoclase , garnet and a little quartz . Irregular veins of a white pegmatite are rather common in places th e M e all D in this schist, and perhaps y are more numerous about oire O ne Faid than anywhere else . of these , from beside the footpath in ’ Braemore Wood near A llt a B h raigh e and three - quarters of S E la k our - S . G c a mile from , is a coarse grained aggregate of quartz ,

- oligoclase and biotite in biotite schist . Under the microscope the in oligoclase is very abundant and large individuals . It appears most probable that this and other pegmatites of a like arts kind are not intrusive but formed by segregation . In p of the district where there are frequent alternations O f biotite - schist with - quartz schist , pegmatites are met with in the former rock , while in

- the latter quartz veins seem to replace the pegmatites . In the biotite -schist in many places a peculiar rock largely composed of zoisite occurs , and deserves a somewhat extended notice .

It is found in thin bands from half an inch to two inches in thickness , ’ which are frequently met with on the north side of A llt a B h raigh e . The bands appear always to lie along the foliation planes of the O ne schist, and when the latter is folded the bands are folded also . of these bands occurs on the west side of the footpath in Braemore

- 80 0 . G la ck our Wood , nearly yds south east of , and a specimen of it D r was submitted to . Teall for microscopical examination , who has furnished the following description of it

de l - e nd c a n A e c a e ne d da ande d c . O n a n mo rat y o rs grai , rk , b ro k b o t i s ude e en e u n 8 in le n and n no 7 . r prisms of zoisit oft m as ri g or mm gth , showi g e nde nc a de fin e orie n i i ll c al a ne 2 are al t at on S a . t y to it . m ryst s of g r t ( mm ) so c n U nd th l c n l e and . e e c c e e a ne en e u e ommo r mi ros op , zoisit , g r t , sph , r ti , a ti o it , a anul c ua - al e 2 a c are e a le T h e e ccu in l n and gr iti q rtz bit ( ) mos i obs rv b . zoisit o rs o g

- e a e ula n dle a e d n d dual en ea u in 7 8 . som wh t irr g r spi sh p i ivi s, oft m s r g or mm by

1 2 in - uen e of, . th e d e l c in c n e c or mm broa st pa rt . The se are micro poiki iti o s q th e e e nce nu e u n c u n u G a ne ccu in d c pr s of m ro s i l sio s of q artz . r t o rs i iomorphi c al and al c n a n in th e a ne and e th e ryst s so o t i s inclusions . B oth g r t zoisit nclu n i sio s are more nu me rous in th e ce ntral than in th e m arginal parts . A ctinolite is pre sent in lon sle n de r prisms sphe ne as granule s crowd ed to e the r in e a u le in d e ta c e d a n and c al T h e at th e rocg a str ks ; r ti gr i s ryst s . m rix of is ” anul c a c ua and un w nne d el a e u a l l e . gr iti mos i of q rtz t i f sp r, pr s m b y a bit

’ A nother specimen (750 2) from the west side of A llt a B hraigh e above the wood showed the junction of the zoisite - rock with garnet

- biotite schists , the latter consisting of a granulitic mosaic of quartz 2 m m 1 and felspar to ) , flakes of biotite (average size about by 2 mm . ) and idiomorphic garnets ( 1 to 2 mm . ) A somewhat different specimen showing the junction of the two ’ 30 0 rocks was taken from the west side of A llt a B h raigh e yds .

D r. . above the wood . This is fully described by Teall below

“ B and l t ( 750 3 ) B an d e d gn e issose rock studd e d with sm all re d garn e ts . s i h . g i i e and da th e e l ua e th e la e c in a ne and . rk ; form r high y q rtzos , tt r ri h g r t b ot t E a n e o f zorsrte a re e e n x mi ed with th e microscop e som e la rge irre gular patch s s , , 2 h e E e i 7 T a st rn S ch sts.

a c e d th e ua in th e l e and T he da nd e d a el sso iat with q rtz ight r b s . rk ba imm i t y ad n n th e l nd 1 c e d a n e e en n le nde e d e 1n all j oi i g ight ba s s ompos of g r t , gr hor b , pi ot sm ain a nd c al e s h cne and ccu e d el uld be gr s ryst s, biotit , p . This b , if it o rr by its f, wo a garne t - e pidote a mph ibolite O th e r portion s of th e slid e a re form e d of garne t e e d e nd n le nd e a e n th e e e c acc r a . biotit s hists, with sso y pi ot hor b T k with oth r sp e cime ns it prove s that the re i s no sh a rp li ne betwe e n th e ga rne t -an1 ph ibolite s e T h e e f r e n l n ande d and and th biotite schists . two typ s o ock a r i timate y i te rb ” c e shade into e a h oth r .

Though the zoisite - amphibolite is most abundant in thin bands ’ A llt B h rai h e near a g and some other streams to the northward , it has ’ also been found to the east of Loch a B hraoin in the R iver C uile ig A llt E a s b near the foot of an B ig , and on the west side of the Broom M e adh onach valley to the north of Carn Breac , about half a mile

W . N . W . of Carn Breac Beag . In all cases it is associated with the

- same broad band of biotite schist . It has not been noticed in the M quartzose type of oine schist . Since the discovery of these zoisite - amphibolites and zoisite E S S 9 2 granulites in the astern chists of heet , similar bands have h been met with in t e M oine S eries in other parts of the Highlands . c They usually occur in the coarser peliti schists , which are believed r to be altered sediments of a somewhat calcareous characte . A long its eastern edge the mass of biotite schist (group 3) becomes involved in the north and - south series of plications r I n l subsequently desc ibed , so that its eastern boundary the out ier on B e inn E nai lair M e all D g and oire Faid is an inversion , as is also that ’

D h ubh M hadaidh A bh uin n D . from Creag to Loch a , south of roma u — G ro p 4 . The greater part of the rock comprised in this division ’ m ore M is or less quartzose , and somewhat similar to the call a i 2 C hrasga dh rock (group ) above described . Felspar appears to be S S generally present . ome portions are very iliceous and rather

massive , with little or no mica , and might be described as quartz

schist , but there is generally some biotite in the rock , and often both

black and white micas are present . The mica is most abundant

along the foliation planes , which causes the rock to split into flags , A varying much in thickness . long the road up the Broom valley, ’ A llt B hrai h e A llt h - I h ine 36 between a g and na g , as many as

distinct bands or beds may be counted in a thickness of 6 ft . of 1 1 th rock . In another place by the roadside close to the milestone , which is about three - quarters of a mile down the valley from 22 f Braemore Lodge , there are dif erent beds in a section 7 ft . in 4 height , giving an average of ins . to each . The amount of mica

varies greatly , so that while on the one side the rock graduates into

- quartz granulite , on the other , by becoming poor in quartz and rich

- in biotite , parts of the rock assume the character of a biotite schist . In many places there are extremely thin partings of the latter rock

- 0 11 separating the beds of quartz schist from each other . a weathered

- section the quartz schist beds project while the partings recede . l A These quartzose flags are a l granulites . grey flaggy specimen 751 3 - t ( ) from near Inverbroom bridge is a biotite granulite , bioti e

being the most abundant mica . When both micas are present in t 751 8 abou equal proportions , as in a specimen ( ) from the burn

” “ - T h e G e l G le ne l c al a nd S u ea S e M em . o ogy of g, Lo h sh , o th st part of ky , “ ” 5 2 T h e G e l B e n is e G ol urv . W v tc . M em . e S Geo S urv . . l. p ; o ogy of y , , J u G l l IX 4 10 r . r eo . S oc. vo . . 1 9 ua t o . . p . Q , p .

T he E ster chist a n S s .

C re a ain O f th e - M l g to the east loch , and passes north eastward to e a l D ubh , where all the rocks are much plicated . The number of fine sections in the quartzose type of this group is

so great that one can only notice the more important . The fine gorge

of Braemore , which is so striking an object from the coach road , and the one almost as good on the western branch of the river (or A bh uinn C uilei g) , where the rocks dip gently southward , exhibit O f - many hundreds feet of evenly bedded , fiaggy , siliceous rock . Below the large fall in the form e r ravine there is a marked long joint (or fault running close to the south side of the stream and parallel with

it . Near the principal bend in the stream farther down , the rock has been bared for a long distance above the road by the bursting of a ar dam at the Home Loch some ye s ago . The lower part of A llt na h - I hine g gives a good section , and so do the smaller streams to the P ff southward . erhaps the finest long section is a orded by the scars which range on the south side of th e R ive r Lael from opposite Inver broom eastward to B einn D earg for a distance of from four to five 1 000 ° . 1 0 miles with a height of ft . or more in places The dip of to 2 ° E th 0 S S . e in these rocks is directed towards near Broom valley , but gradually changes to south - west in the higher part of the Lael valley , where the angle of dip is also somewhat greater ; and even tually th e rocks become involved in a rapid series of north - and - south h plications at the head of the valley . Farther north t e lower parts ’ of the A rdcharnich Burn and of A llt R aon a C h roisg also afford good sections ; and most of the streams on the west of Loch Broom run in A llt ’ rocky channels , but none are so good as those mentioned . a C h airn D R , which falls into the undonnell iver , crosses the strike of a broad tract of these rocks and gives a good section . The gorge is traversed for a long distance by a fault which is accompanied by a 1 5 ° 20 ° good deal of brecciation . The general dip is here to to south E E are east or S . The finest exposures of rock south of the stream i n numerous crags . The D undonnell R iver cuts for a long distance across the strike f of the rocks and af ords a fair section , but the most striking part of the gorge which it forms is impassable . To the east of the river , where its course is nearly north and south , is a conspicuous crag called ’ ’ ’ D hubh ua rte r Creag Coill a Bhun , about a q of a mile west of Carn a B h i r in A ll E i in o a and Loch t g . In this scar many hundreds of feet of strong quartzose schist are exhibited . Thin bands of a darker - 1 colour , noticeable here and there , are beds of biotite schist from E 3 E S . to ft . in thickness . The beds have the usual dip about and in several places the rocks are crossed by crushes or faults r which cause gullies in the crag . These range in di ection from nearly - A s due east to north east . we pass up the stream , the beds seen in the crag one after another cross to the opposite side , forming a d series of pretty waterfalls, which are largest nearer the bri ge at the end of the gorge . Near the bridge also the dip of the rocks is higher , being in places from 50 ° to The contrast between the gently dipping flaggy rocks of th e

Braemore gorge , and the same rocks two miles to the eastward brought up in a rapid series of steep inverted folds , is very striking . A good view of the ground where these complica tions begin may be had from the pony - track in the forest about half a mile south of the A rea N orth of the F a nnich Wa tershed . 75

O n lodge . looking eastward to the rocky country north of the old ’ ’ A llt D oir M h uillin 3rd road and east of a ( stream east of lodge) , it may be seen that all the prominent features run in a north - and - south ff direction , which is quite di erent to what we find in the ground to m l the west . This is ainly due to the fact that a series of sharp fo ds or contortions which run nearly north - and - south begin in that area

and increase in number to the eastward . There appears to be comparatively little folding in the siliceous schists east of th e ° ° — 5 1 0 -L Home Loch . They dip eastward at low angles to and

the outcrops make small strike features , but we cannot advance far into th e biotite - schist towards the east without finding evidence of T h e considerable folding which increases in that direction . majority

of these plications are flattened overfolds , the result of which is to a give a series of practic lly flat beds , so that as we trace the southern boundary of the biotite - schist on M eall D oire Faid we find it runs - n nearly horizontally along the hillside in a south east directio . This c d ontinues till we reach its eastern e ge , where, owing to the high inclination of the inverted folds , the boundary runs almost due north f r o a long distance . G ood examples of the forms of folds may be seen in many places M e all D over the eastern part of oire Faid , especially to the east of O S - the rdnance tation , where the biotite schist contains a good many - A bhuinn D quartz veins and whitish pegmatites . In the roma , near the A ll L e aca ch ain foot of t , there is a very fine section of a similar series of folds in the S iliceous schists which apparently underlie the - P biotite schist . erhaps the most instructive section of all is that 1 50 : - 1 3th in a scar about yds . north east of the milestone from

- Ullapool, which shows how the gently dipping siliceous schists to the west become inverted and form a series of sharply - folded rocks to the east . The forest path which runs between B einn E naiglair and M call D oire Faid crosses the biotite - schist and affords an interesting series

- of sections . It passes close to good exposures of the evenly bedded ’ fl aggy quartz - schist in the upper part of A llt a C hum h ainn above the

Home Loch , where the burn runs in gorges . These beds have a low

- easterly dip . Beyond the biotite schist , about a quarter of a mile e C leire ach find - west from Loch F ith nan , we the siliceous rock or

- quartz schist brought up by a series of sharp inverted folds . In the cliff on the north side of the path there is a very fine clear section 200 l n some yds . in length , which shows the p icated junctio between

- the biotite and quartz schists . The structure of B einn E naiglair is similar to that of M eall D oire

- Faid , except that the northerly termination of the biotite schist outlier is mainly due to a general change in the direction of the dip A B e inn of the strata . bout half a mile west from the top of E naiglair a rather broad band of siliceous rock appears which seems 2 - - 50 . to run for yds . along the strike , or north and south It is

- probably an infold of the quartz schist before described , as occurring - S irrr M OT in the biotite schist under g . The lower portion of the biotite - schist is repeated north of B e inn E naiglair by a considerable

E . fault running E S which makes a marked feature . It is evident S - - that , to the north of this hill , the series of harp north and south folds is dying out . The dip in the underlying siliceous schists 76 Th e E a ster n S chists .

changes gradually from E S E round to south and then to south it west , exactly as does when we follow the beds up the Lael valley , and the occasional sharp north and south folds visible to the north of B e inn E na iglair do not follow the general strike and do not f seriously af ect the general dip . They appear here to be something r r superimposed on the general st uctu e exactly as in other localities .

R E na i la ir - To the east of einu g , however, the sharp north and south plications continue to a greater distance northward the farther east ’ A t D laid ill B h ri we go. the eastern end of iol a M b c we find the

- normal south west dip gradually changing to west , so that the strike

- - coincides with the direction of the sharp north and south folds , as I il r u l 2 6 2 . it does on the conical hill called o g ( 8 ft . ) to the south The ’ northerly strike appears in the valley of A llt Coir an Leth - Gboin to

- R D G . the south east and on einu earg . W. The axis of plication on B einn D earg is continued northwards M e all C e a raich e an E ididh G through nan p and nan Clach eala , along which the beds are suddenly T uck e d up into sharp asym o i metrical folds , one limb the fold being nearly horizontal , while the other may be vertical or even slightly overfolded . A nother zone of extreme plication crosses the summit of M call D E far N . N . . . ubh , three miles of Inverlael The overfolding is here more pronounced , and the limbs of the folds often appear to be lying horizontally and parallel to one another . The structure of the ground between these t wo lines is generally simple . The beds dip at uniformly gentle angles , in directions varying from east by south round to south by west . This appearance of regularity is , however , possibly deceptive , for even where the beds seem to be arranged in regular succession , the crests of flattened overfolds can sometimes be detected , and it is thus possible that only a small thickness of rock may be involved in the plications that cover a wide area .

Numerous thin veins of quartz and a few veins of pegmatite , both probably of segregative origin , have been found in these rocks . Allt L airi e D ouch ar R In the na g , near its junction with the y iver , and A llt G D uibh e in the latter stream below the foot of na reige , there

are veins of quartz with pyroxene , which occurs in strings or th e amorphous masses in quartz , and also in isolated idiomorphic A A ll L airi e 1 0 1 22 crystals . section of a specimen taken from t na g ( ) “ D r : A - is thus described by . Flett massive quartz rock with long

- crystals of dark green pyroxene (diopside) , idiomorphic in transverse section , slightly dichroic but with a high extinction angle . The felspar proves to be albite , with a little of the oligoclase molecule . W H L. . . In the north - east corner of the map bands of garnetiferous muscovite - biotite - schist are largely developed on the eastern spur of ’ S B h ra i h round D h e ir eana g and Loch a Chadha g, but elsewhere the type of rock is a granulitic quartzose schist of the M oine S eries with

- O v S B h rai h occasional bands of biotite schist . er eana g and the ’ northern slopes of G leann a Chadha D h e irg th e schists a re inclined S E 20 ° S G ’ d to the S . at angles of from to outh of leann a Cha ha D he ir T o m ain C oinic h — a g the dip becomes more easterly , and on hill — E N E E ididh G it E N E . about half a mile . of nan Clach eala is

O ver these districts the rocks seem to be arranged in isoclinal folds .

C . B . C . ’ A rea S outh o th e F a nnieh Wa tershed f . 77

R E S O H O F T H E F A N N I C H E HED A A UT WAT RS . In the description of this area we shall begin with those rocks G that resemble certain types of Lewisian neiss , and refer to the other

P L A T E ll .

A C HA N .

é S . E . C R E A G H A N A N C O I L E A C HA N

U B IE R IV E R .

" was

' i = h M hr - = s t s M e a ll a C h ra s a id h G ro u . 3 S r r bio t ite s c h ist s F la ( g p) g . 4 g "y

d e r u li e - r i i n . S p t g t . C e . L m e s t o e .

- K LT D . (7 0 0 7 s) 2 4 5 0 0 4 /l2 B AN S & C O .

u u u u w v a v u u u u u L U l L C bU l U L l U L U U U “ U l u i l t / 1 5 5 g , like the epidiorite dykes in the Lewisian G neiss in the west of R oss

shire . 7 6 The E a ster n S chists .

E . E changes gradually from S . . round to south and then to south it a west , exactly as does when we follow the beds up the L el valley , and the occasional sharp north - and - south folds visible to the north of R einu E na iglair do not follow the general strike and do not L ‘ - m L

U L u r u z u u m a ul V L Q L I I w e a ra

O ver these districts the rocks seem to be arranged in isoclinal folds .

C . B . C . ' A rea S outh o th e F a uu ich Wa tershed f . 77

R E S O T H O F T H E FAN N I C H E R S HE D A A U WAT .

In th e description of this area we shall begin with those rocks G that resemble certain types of Lewisian neiss , and refer to the other r r F ann rc h groups in orde on eithe side of the fold . rou A cid G neiss with L ewisia n T es — O u G p Qt. yp the eastern limb of the F annich fold the members of this group have been traced from S urr G R ua dh the watershed on g nan Clach eala to Torran , within F annich half a mile of Loch . The best section of them along this ’ A llt B h ealaic h belt is to be found at the head of Leao a , a stream that drains the southern slope of Sgurr nan Clach G eala and Joins F nni A bh uinn N id near the head of Loch a ch . It lays bare a m ore or less continuous section for over half a mile . The strike of the rocks there is N and th e foliation planes are generally inclined to the E - - . E . N . The prominent type consists of quartz biotite gneiss with

- - basic knots or lenticles of hornblende rock or hornblende schist . The gneiss is usually granulitic , especially near the margins of the belt . 6 The two basic bands already described (p . 7) that come together to th e S urr G west of g nan Clach eala appear near the head of this stream . ’ A A llt B h e alaich nother section is exposed in a tributary of Leao a , - d S urr E that rises one thir of a mile, west of the top of g nan ach . and neiss with Near the head of this burn pink grey granulitic g , basic lenticles appears , and between the stream and the margin of the belt of acid gneiss a band of epidiorite has been traced which merges in

- places into hornblende schist . O n the south west slope of Sgurr nan Clach G eala at the eastern

- boundary , the acid gneiss rests on the muscovite biotite gneiss (group 1 A P W S . W S . , ection , late both being inclined to the This westerly dip is continued in a long tongue of the acid group that runs ur E S r . southwards for a mile , east of g nan ach But along the main R uadh belt between that hill and Torran , the prevalent inclination of the foliation planes is towards the east or where the fiase r f character of the acid group , indicating much dif erential movement of

i - u l corrS cuo s . the constituents , is p y developed P assing now to the outcrops of the acid gneiss on the south - west F annich d re limb of the fol , we find that the members of this group appear a t the foot of a burn that enters Loch F a nnich about three quarters of a mile from Torran R uadh and about a mile from 25 the head of the loch . Here they are exposed for about 0 yds . in the stream with varying dips , but at the junction with the overlying - n i ro u 1 S P h r e ss . t e a e d muscovite biotite g (g p , ection B , late II ) y incline to the north east and plunge beneath the latter group . They consist of grey and pink granulitic acid gneiss with knots of hornblende rock 3 r m about ft . ac oss . This outcrop is traceable for about a ile , r 50 200 in the fo m of a narrow belt from to yds . broad , along the M 1 250 S o . . south west slope of ail h r , about the ft level Their upper boundary is clearly defined as they rise from underneath the over

- - lying cake of muscovite biotite gneiss , but their lower boundary is n concealed by drift . Here , we find again a band of epidiorite mergi g

' - h a s into hornblende schist , which been followed for about a third of a A . t mile one locality it cuts across the foliation of the acid gneiss , like the epidiorite dykes in the Lewisian G neiss in the west of R oss shire . 8 T h e E a stern S chists 7 .

' O drift e a t wing to the covering of , p and alluvium , no solid rock is visible at the Nest at the head of Loch Fannic h nor in the lower t A h inn par of b u Nid . Hence the boundary on the east side of the valley at the Nest is conjectural . But above the alluvial flat at th e Nest the pink acid gneiss reappears in the channel of the A bh uinn

Nid about a mile from the head of the loch . From this point the outcrop of the acid gneiss in th e western part of the F a nnich Forest O is noteworthy . wing to the gentle inclination of the rocks the members of the acid group there present a highly sinuous outcrop . They wind round th e head of the valley of A bh uinn Nid to the ridge ’ A C haillea ch south of , where they unite with the belt on the western slope of that mountain . Thence they extend southward along the crest of that ridge and sweep round both sides of A n Sgum a n to within half a mile of the Nest at the head of Loch F annich (see map B P A S A . and ections . and , late long this outcrop numerous stream sections show the lithological characters of the rocks . The evidence clearly indicates that the acid gneiss is underlain and overlain by the muscovite - biotite - gneiss (group O n the crest of the dividing ridge ( An Sgum a n) the overlying pelitic gneiss has been removed by denudation for nearly a mile , and the acid gneiss with its basic bands n F annich is laid bare in gentle u dulations . H re as elsewhere in the Forest the dominant type is a pink or egrey granulitic quartzose gneiss r - with a fer o magnesian constituent often much decomposed . Bands of hornblende - gneiss are associated with the acid gneiss on the crest A n S um an of g , round the smaller outlier of pelitic gneiss about a mile and a half north - wes t of the he ad of Loch F a nnich (S e e section B P late rou M uscovite - B iotite - G neiss— M ea ll a n t- Sith e R och — G p 1 . The pelitic gneiss of this group , as already indicated , both underlies A and overlies the acid gneiss with Lewisian types . ttention will first be directed to the outcrops benea th the acid gneiss on either F a nnich A n side of the fold . excellent exposure occurs on the great crag on the eastern face of Sgurr nan Clach G eala (P late and ex ur E S r . tends southwards to g nan ach In this escarpment, which lies fold th e on the eastern limb of the , , characteristic features of the rock are the abundance of garnets , the large plates of muscovite and biotite , and the presence in it of quartzo - felspathic material in knots and m strings . The peg atitic lenticles are arranged more or less parallel P with the foliation of the schists , as shown in late III . The type varies considerably along the strike . Thus , the garnets become less numerous , the muscovite is hardly represented in places , and biotite

- is the dominant constituent , while the lenticles of quartzo felspathic material disappear , and the rock then merges into a flaky biotite fl a t schist . Bands of ggy , siliceous , granuli ic gneiss are intercalated with the members of this group . In the great crag on the eastern face of Sgurr nan Clach G eala the pelitic schist is seen to pass beneath the acid gneiss , the general a t dip of the foliation planes being to the WS W . angles varying from ° ° d i 25 6 0 1 S A . P S d re c to (group , ection , late outhwar s in the tion of Loch F annich it forms a belt from a quarter to half a m ile ~ in width . The extreme breadth of the belt where the angle of inclina S urr tion is high is clearly due to folding . For example , on g nan E ach the pelitic gneiss appears on either side of the long tongue of

A rea S outh o the F a nnich Wa ters d f he . 79

acid gneiss , the former being traceable round the end of the tongue . A R ua dh fl a gain , east of Torran the ggy , siliceous , granulitic gneiss , ex irr the - - is posed a stream in midst of the muscovite biotite schist ,

. . . S S E i . m folded along axial planes running N N W and . . It is not of fla probable that this narrow belt ggy , siliceous gneiss may be an infold of another zone (group 2) (see Sheet S outh from Sgurr nan E ach the general dip of the pelitic schist is towards the that n S urr G is , in a directio opposite to that on g nan Clach eala . O n the western limb of the fold the underlying outcrop of pelitic ’ A C h aille ach gneiss has been traced from the western slope of , where this rock is exposed between the contour lines of 1 7 50 and ‘ 2 0 ft - A n S rrm n 00 . a , along the south western declivity of g to the C abuie R th e F annich mouth of the iver and head of Loch , thence up the valley of the Nest of F annich to the corrie at the head of A that valley . long this sinuous outcrop the pelitic gneiss passes 1 S underneath the acid gneiss with basic lenticles (group , ections B A h uinn A . . P b and , late In the valley of the Nid there appears to be a slight anticlinal roll of these two rock groups , for on referring to the map it will be seen that the dip swings round in accordance with the outcrop of the boundary line between them . It is note worthy that along the outcrop ou A n Sgum an and in the exposures near the mouth of the O abuie R iver the lenticles of quartzo - felspathic materials are hardly represented in the pelitic gneiss . In places they disappear altogether , and the rock becomes a flaky garnetiferous

- - muscovite biotite schist . The mass of muscovite - biotite - schist that overlies the acid gneiss with basic lenticles covers a large area to the south of the F a nnich A P ’ 1 S . A watershed (group , ection , late It extends from Chail ‘ leach and Sgurr Breac south - eastwards by Sail t i r to the shore of — Loch F annich a distance of four miles . It there occupies the centre A n of the apparent synclinal fold of the acid gneiss . excellent cross — ’ — section is exposed in the stream A llt Leao a B he alaich which A F a nni h joins bh uinn Nid half a mile above Loch c . Here the rock presents lithological characters similar to those already described ,

- except in one particular , that the quartzo felspathic lenticles are not so abundant as in the great escarpment on the east face of Sgurr nan 1 2 G . Clach eala . Thin pegmatites from to ft thick with small prisms O n - of tourmaline have been observed in this section . the south west ’ slope of Sgurr Breac and in the lower part of A llt Leao a B h e alaich the general dip of the foliation planes is towards the north - east at angles varying from 1 5 ° to But in Sail M hor and along the eastern margin of the overlying mass , they are highly inclined , folded , d and contorte . Two small outliers of the overlying mass of garnetiferous A n S um an B . P 1 S . gneiss (group , ection , late II ) occur on g , where they rest on the narrow denuded plateau of the acid and basic gneiss

(group g ) already described . Such evidence furnishes clear proof of the denudation of the rock groups in this recumbent fold in the i h A bh uinn western part of the F ann c Forest . For the Nid in the u 1 Nest of F an nich has cut thro gh the overlying mass of group , th e n u through the sheet of acid gneiss , down to underlyi g m scovite

- B P 1 S . biotite schist (group , ection , late

In the sequel (Chapter VIII . ) reference will be made to the occur 80 T he E a ster n S chists . rence of lenticular bands of garnetiferous hornblende - rock in the

- - muscovite biotite schist . O n the south side of the F annich watershed no trace of a con glomerate has been detected at the margin of the pelitic gneiss (group 1 ) along its line of junction with the acid gneiss (g roup H) . The marked linear foliation a n d striping of the acid gneiss at and near the boundary line between the two rock g‘ roups implies considerable f dif erential movement of the constituents . Hence it may be inferred that the original relation between these two groups has been effaced by this movement . Nevertheless there can be little doubt that the u nderlying and overlying masses of garnetiferous gneiss are portions of one and the same sheet . ’ G rou 2 M ea ll a C h ra s a idh iliceous chist — a n p . g S S s South of the F fl a ran ulitic nich watershed the members of this group consist of ggy , g , quartzose schists in marked con trast with the garnetiferous gneiss just described . The beds as a whole are highly siliceous , but in most of the bands some minute biotite is present and occasionally h . S muscovite The divisional planes are coated wit mica. ometimes

- h thin layers of mica schist alternate with t e siliceous flags . The n ormal phase of this group may be taken as a typical granulitic quartzose M oine Schist . annich The best exposure occurs on the eastern limb of the F fold , on the east slope of Sgurr nan Clach G eala (P late where they di WS W 40 ° p to the west and . at angles varying from to and 1 S A . P plunge underneath the pelitic gneiss (group , ection , late From that point southwards they can be traced as a narrow belt ’ A llt M r about a quarter of a mile broad to a Choire ho r , where they ve - - become vertical , and e ntually dip to the east and east north east 0 ° 2 S B P 7 . at about (see group , ection , late O n the western limb of the fold these fl aggy siliceous schists ’ A C haille ach and M e allan C h ua ich appear on the col between , where they rise from below the garnetiferous muscovite - biotite - gneiss (group 1 ) and dip to the east at an angle of The boundary line between these two groups is there well defined . They have been traced south eastwards along th e south slope of A n Sgum an to a point on the

C abuie R iver about a mile west from Loch F an nic h . rou S ur r M or B iotite - S chist — O n G p 3 . g the eastern limb of the fold this group has been traced from the watershed to the shore of Loch a nnic h - l F . Consisting mainly of biotite schist with occasional sma l garnets and thin intercalations of siliceous schist , the strata are ’ A llt M hoir S urr displayed on the col at the head of a Choire , on g idh - M or D ruim R é . , and on The prominent band of quartz schist in the midst of this group has been followed from the corrie on the east ’ S urr M or A llt side of g , across the watershed , to near the foot of a

- h B hi . A C oire g lthough the mica schists are highly puckered , the sections on the cliffs round the west side of SgurrgM or show that the rocks are generally inclined to the west , while about three miles to the south they are either vertical or highly inclined to the east or A th west . long e eastern margin of this belt on the watershed the

i - - - biot te schist is inclined to the east south east , thus indicating an S A P inversion of the strata (see ection . , late IL) .

- M r G The bands of zoisite schist , detected by . unn in this group , F annic h on the north side of the watershed , have been observed at P A E I V L T .

’ F G S O S S c nrsrs M e ll LA I LICE U ( a a C h ras aidh group M oin e S e rie s e ast ace of GY g ) , , f S urr nan C lac G e al F annich F g h a, orest .

A rea S outh o the F a nnich Wa tershed f . 8 1

S urr M or various localities , along the outcrop between g and Loch F anni h - 1 c . They occur in the biotite schist in seams from to 3 ins

thick , which , on weathered surfaces , show prisms of zoisite about

. S a quarter of an inch in length ometimes , where the schists ‘ - l are highly puckered , the zoisite rocks appear as small enticles . Specimens collected from this region were sliced and examined under

D r. the microscope by Teall , who furnished descriptions , two of which are given below

or F annich - e l e S rr M . e fine ne d anul e W st s op of Light gr y , grai gr it with con spi cuous prisms o zoisite abo ut i inch in le ngth on th e flat surface of h c e t e e c e n . U nd e th e c e a a a ne c l u le in n e c n sp im r mi ros op pp r g r t ( o o r ss thi s tio ) , e a nd u e c l e and en e as cce e U nd u e dl zoisit q artz , with biotit , h orit sph a ssori s . o bt y ’ all e d M r G unn c but u th e n lende u - - i to . s ro k , witho t hor b ; q artz garne t zoisite anul e in e - anul e gr it , or, short, zoisit gr it . 2 l S la th e b 8 05 S a e cal . a e ut d e and c n a n n la e ( ) m o ity imi r to bov , ark r , o t i i g rg

a ne . U n de th e c c e a re e en a n e e ua la cla e g r ts r mi ros op s g r t, zoisit , q rtz , p gio s ,

n le nde and e . O a ue a cle as in 820 4 T h e ne al are no t hor b biotit p q p rti s . mi r s un l d u e d T h e n le nde u u ll in a c a n l iform y istrib t . hor b is s a y sso i tio with th e fe spar and th e e th e u and a ne T h e c e le anded zoisit with q artz g r t . ro k is mor or ss b ne - e - l e gar t zoisit amphibo it .

- Three small outliers of biotite schist , which are correlated with F annich w this group, occur in the eastern part of the range , to hich 4 special reference will be made in the description of group . O n the western limb of the Fannich fold a narrow band of biotite ’ schist with small garnets appears on th e col to the west of A Chail M eallan C hua ich leach , and on the north portion of the hill named , ’ where it rises from underneath the M e all a C h rasga idh siliceous - - P la t 2 t S A . e schists (group ) wi h a dip to the east north east ( ection ,

S urr M or - This band has been correlated with the g biotite schist , but as it occurs here in a highly attenuated form it may represent part A h as only of that group . glance at the map will show that it been ‘ - A n S rrm an C abuie R mapped along the south west slope of g to the iver , d and a nni h where it is expose about a mile a quarter above Loch F c . It is probable that certain ill - de fine d bands of biotite - schist that have not been traced to the west of this outcrop on either side of the

C abuie R iver may also represent part of this group . This view is strengthened by the occurrence of seams of zoisite - amphibolite rock on inn n n R am h the plateau to the west of B e a . hi t e — G rou 4 F la Gra nulitic S c s s a nd G neiss s. O n p . ggy the west limb of the F annic h fold the members of this group occupy the ground between the M o ine thrust and the outcrop of the Sgurr M or biotite l h u i h A t M schist on M e al an C a c . certain localities near the oine ’ M h eallain O dha ir thrust , as , for instance , on the ridge east of Loch a ,

there is a development of green and streaky mylonites , the origin of S which is difficult to determine . ome of these rocks may be due to G the deformation of bands of Lewisian neiss , others to the crushing T orridon G m a of rit , and , in one instance the rock y not M S improbably be a member of the oine eries , the structure of which

- has been modified by the post Cambrian movements . It is worthy fine- - of note , however , that the grained , greenish grey schist that immediately overlies the M oine thrust - plane at th e south end of the M S Loch an Nid crag is a typical oine chist . It is composed of a granulitic aggregate of quartz and felspar , with scales of white mica “ ” and eyes of felspar , 6 E a stern chists 8 2 T he S .

The members of this group are displayed on B e inn Bheag and ’ A C h aille ach S A P A n G . rohan , west from ( ection , late IL) , where they consist of fine - grained granulitic quartzose schists with occasional - fla thin intercalations of mica schist . The ggy and fissile character e ' of the series is here w ll pronounced . Lithologically they indicate a low grade of metamorphism compared with their representatives on the eastern limb of the fold north of Loch F annich . The general ’ dip of the strata between B e inn Bheag and the west slope of A C h aille a ch is easterly , so that they plunge below the groups already F annich described which enter into the structure of the fold . But there are indications of overfolding and reduplication of the strata , and the steady ascending sequence may thus be deceptive . When these rocks reappear on the eastern limb of th e fold they fl a u present a higher grade of metamorphism . The ggy gran litic character is still persistent, but the rocks are more highly crystalline , A and biotite as a rule is more abundant . long their line of junction with the Sgurr M or biotite - schists on the F annich watershed there O n C rea ch an B is evidence of sharp plication and inversion . airi idh S urr M or M e all G g , the lofty ridge between g and orm , the quar tzose granulites (group 4 ) have been made to overlie the Sgurr Z M or biotite schists . The system of shaped folding characteristic ’ of this inversion is well seen on the clifi at the head of A llt a Choire B hi h g. T is inversion is more or less in the line of the axis of M G plication and overfolding already described by r. unn as running northwards through the Braemore Forrest along the eastern l pe s B inn E n i lair of M e all D oire Faid and e a g . A F a nnich C re ach an long the eastern part of the range , from R airigidh by A n C oileac h an to the mouth of Loch F a nnich the 4 members of group are arranged in an apparent synclinal fold , with the axis of which the crest of the range more or less coincides , in a

- - b - O n south east y south direction . both limbs of this fold the rocks dip at gentle angles of 1 2° to till in the eastern limit of the t chain they becom e ver ical or highly inclined to the west . The westerly dip of the flaggy quartz - biotite - schists and gneisses is well displayed in G arbh Choire M or about a mile to the north of the i h h F nn 4 . B . P a c S A . mout of Loch (group , ections and , late IL) A n interesting feature in the structure of the eastern part of the F a nnich range is the occurrence of three outliers of bioti te - schist : ( 1 ) on the south e nd of C re a cha n R airigidh ; 2) on A n C oile a c h an ; (3) on ‘ h a bo ut h alf th e annic h a ill a mile to north of the mouth of Loch F . They for m thin cakes composed of flaky and granulitic biotite - schist i - rest ng on the gently inclined quartzose granulites . The largest out f t lier , about hal a mile in diameter , occurs at the first locali y , where h t S S W t e schis s dip to the . at and contain a band rich in A - ou zoisite . nother zoisite bearing band has been found in the t h c F a nni h lier near the mout of Lo h c . In view of the lithological t o f charac ers the rocks in these outliers , they have been correlated S urr M or - A P 4 S . . with the g biotite schist (group , ection , late IL) No sills or bands of hornblende - schist have as ye t been detected in the thick g roup of siliceous schists or gneiss (group 4 ) in the t F a nnic h P t eastern par of the range . egmati es are of rare

A - occurrence . thin vein of microcline pegm atite was observed in the e te - on M G outli r of bioti schist the top of call orm , and another

84 T h e E a ste his s rn S c t .

O n referring to the map , it will be seen that two narrow bands of biotite - schist occur from a quarter to half a mile west of that on ’ B e inn D earg. They lie close to the stream named A llt a C h oin — I dhir a tributary of the G rudie R iver that issues from Loch F a nnich — a S urr M frr and m y also be repetitions of the g schist . In the more westerly of these two outcrops the zoisite - amphibolite - rock was

500 . found at a point about yds north from the foot of that stream . The quartzose gneiss on the east side of the broad band of biotite schist on B einn D earg and C am n a R eiste resembles that in the great corrie at the eastern end of the F a nnich range (G arbh Choire M or) in general characters , but is somewhat more massive , and in places n contains thin folia of pink felspar . It rises into the promi ent crag B eiste that forms the eastern shoulder of Carn na . P assing now to the ground lying between the C abuie R iver ’ ’ A bh uinn C h adh B huidh e S C hrom buill ( a ) and rath , we find the southern prolongation of the coarse , flaky , garnetiferous gneiss (group 1 of the F annich sequence) on the top and eastern slopes of R einu R 2 f A in F nni h am h 333 t . s a c n nan ( ) the region , it here co sists , in o its most typical form , f folia of muscovite and biotite , is full of dark n red garnets , and co tains lenticles of pegmatite from a quarter of an inch to an inch in thickness . But it presents considerable variations S fi ne r- in character . ome of its grained portions contain little or no

- pegmatite , and cannot be distinguished in hand specimens from - M S O ordinary bands of mica schist in the oine eries . thers display m - t the peg atite arranged in sub parallel len icles , while a third type presents muscovite developed almost to the exclusion of biotite . The pegmatites of this rock sometimes measure several feet in thickness . A fe w of the larger veins contain a beautiful rock made up of large 3 plates of muscovite up to ins . in diameter , set in a quartzose matrix , crowded with small stumpy prisms of black tourmaline . 5 Some of the tourmaline crystals attain a length of 4 or ins . Closely associated with the flaky gneiss is a granitoid gneiss made up of coarse white quartzo - felspathic layers with intensely contorted 10 B e inn nan micaceous folia . It is well seen on the eastern s pes of B it amh , where is folded up with the flaky gneiss on a general north

- d west and south east axis . Farther west several istinct outcrops of a o fine - similar r ck occur , some of which pass into a grained quartzose gneiss with thin folia and eyes of felspar resembling the acid F a nni h n gneiss (group g ) of the c ra ge . The basic portions of the

- granitoid gneiss usually appear as hornblende schist dykes , traceable t for short distances , and folded wi h the main mass of the rock . It is uncertain whether this granitoid gneiss with its basic bands of hornblende - schist represents the acid gneiss with Lewisian types of

a nnic h . . I P . the F sequence T . A t tention will now be directed to the area lying to the south o f Srath C h rom buill and to the south of the eastern part of Loch

F a nni h I m nr diate l M o - n c . e y above the ine thrust pla e at the mouth a of the Leckie Burn and ne r the Heights of Kinlochewe , we find a ni 0 0 50 0 bel t of green schist or m ylo se d rock from 3 to ft . in thick ness , which includes both pelitic and psammitic representatives of the M S A t h t M t oine eries . t is locali y the outcrop of the oine thrus has been shifted for three - quarters of a m ile to near the foot of G leann N E W u T ana a idh E . . W S g by an . and . fa lt . This zone is succeeded A rea S outh of S ra th C h rombuill a nd L och F a nnich 85

fl a fi ne - - l by ggy , grained quartz granu ites with white mica . The flags are separated by partings of micaceous material , chiefly white mica - E and chlorite , but occasional intercalations of mica schist occur . ast wards in the area traversed by A llt na D oire - giubha is and the small burn about half a mile to the east of that stream , the pelitic

- - mica schists are as abundant as the quartz granulites . Up to this point the schists are traversed only by veins of quartz , which are ranuli i d usually thin and g t se . Farther east there is a marked increase in the grade of meta morphism . The constituents of the granulites become larger , and biotite becomes more abundant both in th e pelitic and psammitic ’ A llt hlai inn— a S trath crom l . C be schists In a g stream south from ,

— - a cottage now in ruins fl aggy quartz granulites alternate with

- - I t biotite granulites and biotite schists in about equal proportions . th e is highly probable that the belt of these schists , exposed in lower S urr M or - u reaches of this stream , represent the g biotite schist (gro p 3 F a nnich of the sequence) . This pelitic zone is succeeded towards

fl a - the east by ggy quartz granulites , which may be the southern pro ’ longa tion of th e M e a ll a C hrasga idh quartz - schist (group 2) of the a n nich F succession . Next in order we find a prominent belt of muscovite - biotite - schist which is well displayed on Fionn B h e in n (30 60 ft. ) and stretches east M M wards to Loch na oine or. It presents the characteristic features ‘ M t - S i 1 F annic h of the call an the gneiss (group ) of the sequence ,

- with lenticles of quartzo felspathic material and abundant garnets , and is doub tless the southern continuation of that group . With this type are associated fl aggy mica - schists and minor intercalations of - n B h e inn le n ticu quartz granulite . O the eastern slopes of Fionn occur l - lar knots and bands of garnetiferous hornb ende rock , which probably represent folded and disrupted portions of sills or dykes of basic rock t in rusive in th e original sediments . The mass of pelitic gneiss round Fion n B he inn is followed east

- wards by a belt of quartz granulite , which may be a repetition of the ’ M e all a C h ra sgaidh quartz - schist (group with a second outcrop of

- - M h M or E the muscovite biotite schist east of Loch na ine . ast of the

th e . latter belt rocks are much concealed by peat and drift , The ex posure s reveal an alternation of quartz - granulites and bands of biotite 3 4 F annich schist , probably representing groups and of the

succe ssron . R egarding the tectonics of the area lying to the south of Srath C hrom buill F annich and Loch , it may be remarked that the schists east of the M oine thrust- plane appear to dip to the east - south - east or east at comparatively low angles ; but this is evidently due to flat f n u over oldi g , which can be observed in numero s sections on a small

d . scale , where the overfolds are only a few feet or yar s in amplitude

The mapping of a wider area , however , makes it clear that flat or lowly inclined overfolds of great amplitude also occur . For the garnetiferous muscovite - biotite - gneiss (group 1 of th e F annich sequence) has been traced from R einu D ronaig in Sheet 82 to the F anni h c M ountains in Sheet 92 . In the former region it occupies the crest of a recumbent anticlinal fold with a core of Lewisian G G neiss . It is the same band of pelitic gneiss which , in lenelg and A m rle A G . at ttadale , rests upon the Lewisian neiss gain , within a T h e E a tern i s s S ch st .

S 9 2 A ch nash e an from the south edge of heet , near , there is a small ex osure G d p of Lewisian neiss in the mi st of this band , while in the F annich M ountains the double outcrop of garnetiferous gneiss (group 1 h as i ) an intervening belt of acid gneiss with Lew sian types . It follows that the sil i ceous and micaceous schists that lie between the M oine thrust - plane and Fionn B heinn must occupy a broad synclinal

S . fold , which is a continuation northwards of the trathcarron syncline In Fionn B h e inn the pitch of the Fa nnic h fold has evidently carried a the acid gneiss below the existing level of denudation , lthough the F a nnich structure is doubtless repeated in the area south of Loch anni h F c . M o n M br The belt of siliceous granulite , which at Loch na i e separates the two broad mas s es of pelitic gneiss south of Loch ’ annic h M e a ll F , may represent a recumbent downfold of the a Chras ga idh quartz - schist (gro up The tops of M ea llan O dhar and Carn D a raic h south of Loch Fannic h are capped by al ternations of biotite

- th e A n - schist and quartz schist , while to east , on Cabar , the back fold or recumbent anticline in the eastern part of the Fannich range is still traceable .

0 4 0 0 0 8 0 0 0 f L' C T

N B A I? A E IIU/ N N B R UA C HA C Q

F I 6 —D a a a c S e c n n e a th e He K nl c G . e e . i gr mm ti tio from r ights of i o h w by F n n B h e inn and A n C a a th e e a e n e d e S e e 9 2 io b r to st r g of h t .

6 The accompanying diagrammatic section (Fig . ) expresses the probable nature of these folds . The thick continuous line represents the existing surface contour of the ground relatively to the sea- level on the scale of one inch to four miles . The interrupted line indicates the old floor of Lewisian G neiss u pon which the M oine S n chists rest , while the thin continuous line illustrates the divisio al plane between the Sgurr M or biotite - schist (group 3) and the gra nu — 4 F a nnic h litic quartzose mica schists (group ) of the sequence . These two gro ups have not been separated from each other by a line on the map in the areas to the south of Loch Fannic h and the west of Fionn

B he inn . B P . N . .

88 G a rnet- H ornblende R ocks a nd D kes o M ica - T ra , y f p .

grain and decidedly pink in colour . Traces of a red lamprophyre D ruim R uadh found in two places at the north end of , probably belong to a sill or dyke similar in character to those already referred to . D r . Flett reports that all the lamprophyres which have been microscopically examined from this sheet belong to the minette

- m vogesite series , and no representatives of the camptonite onchiquite S association are known to occur in it , though such are found in heet 82 h to the sout . O n th e west side of the M oine thrust several mica - trap dykes d have been recor ed . The most northerly example is seen cutting the Torridonian strata S urr o A n rather less than half a mile slightly east of south of g Fi na , W T e alla ch S W . 2 3 , in a deep , narrow nick striking It is only or A ft . thick and much decomposed . nother deep gorge just on the south side , is possibly also occupied by a similar dyke . It continues h ll na S e a a . O n westwards nearly to Loch g, about a mile distant the L ochain w east side of Loch Toll an , a conspicuous hollo , almost in the

E N . E line of the two gorges referred to , continues . . more than two miles , as far as the Cambrian quartzite , where it gives place to a - n c fault scar faci g north . No dyke has been noti ed along this fault , but the ground is in places very obscure . of n In a little burn about a mile south Car more , a small dyke of

- l f N W m o . . . n ica trap , with arge scales biotite , strikes in a N directio 2 G . . through the Lewisian neiss It is generally about ft thick , but l occasiona ly disappears entirely for a short space . The most southerly dyke of mica- trap makes a conspicuous hollow n d G rudie in the Torridonia strata on the east side of the Bri ge of ,

M . south of Loch aree It has been traced westwards for about a mile , f and shows in one place a thickness of 4 t. I n A m h ainn - the valley of Loch an Nid , and about two thirds of i a mile north from that loch , the unthrust Cambr an quartzites are — traversed by a dyke of mica trap with plates of biotite . It trends

and has been traced for about 1 0 0 yds .

c . c T . c B . N . P . J H . w . , . , . C H A P T E R I X .

M E Z R S SO O IC O CK .

R I S T A .

T H E Trias is represented in a very small area , probably less than

- 30 . acres in extent, at the extreme north western corner of the map It forms part of a strip of M esozoic rocks which have been let down between the harder Torridonian strata by two great faults , striking

E . N . N . , and have thus been protected from denudation r of The only exposu e is on and close to the shore , and consists white and mottled sandstones with reddish clays and shales and some

- bands of conglomerate , dipping south or south west , at angles between 6 ° 30 40 and The east end of the exposure shows about or ft . of mottled clay with bands of white sandstone . From the disposition of the strata in the adjoining one - inch maps it is clear that these ex posure s belong to th e highest beds of the formation : the lower beds are m ainly composed of conglomerates made up to a large exten t M of fragments of Cambrian Limestone , Cambrian Quartzite , and oine

S chist . The whole series is somewhat calcareous . Lumps of con cretionary limestone are not uncommon , and all the sandstones P ‘ ‘ . J weather with rough carious surfaces . rof ndd l considers that the total thickness of the formation in this district exceeds 1 000 ft but only a small part of this comes into the map being described . The numerous pieces of Cambrian Quartzite and Limestone in the conglomerate indicate that in the Triassic period these beds probably extended much farther west and made more extensive outcrops than in situ they do now . The nearest Cambrian rocks are now more than

a dozen miles distant , with the exception of a few small crushed fragments which have been dragged down into the large fault at B einn D C h ailleach m earg Bad , about three and a half iles south from

' the Triassic conglomerate . It is , however , to be noted that where N W - the base of the Trias is seen , a mile N . . . of the north west corner m of the map , it is resting unconfor ably , not on Cambrian beds , but on Torridonian strata belonging to the highest or A ultbea group i

“ ” “ P Judd T h e S e c nda R c S c lan d d P a e . T rof , o ry o ks of ot . Thir p r . h e ” S a a th e e e n C a and I land u rt J ou G l oc l a r. eo . S v o . tr t of W st r o st s s, Q . . , xxxiv. M c ll c and P r N l . 6 70 . ac u . c al e fe e d e e a a th e p o h of i o so r rr to th s str t , ” le of S c land l e i n e e n I v o . 9 9 and P la e form r his W st r s s ot , ii . p . , t xxxii . “ l in a e v ol . . and th e a e O n th e N e e R e d S and n e and on of iii , tt r his p p r w r sto e e G e l cal P e n e na n ea G u na d in R e ua rt . J ou som oth r o ogi h om r r i r , oss shir , Q r .

G S c v ol . 1 6 eol. o . . 7 , xiv p .

' cit 6 80 . 1 0p . p . I A picture of a n atural se ction in which th e unconform ability is ve ry l i d nc 1 s n P N c c t. . 1 e . 0 6 8 . isti t giv by rof i o . p . p 89 M e z ic R cks 90 so o o .

The Lias , it is believed , conformably succeeds the Trias just

- described , in a south east direction , and forms most of the hamlet of Sand In this one - inch map it probably occupies a somewha t larger it to the area than the Trias , but does not extend shore , and is there n fore ot well exposed . A bl ue argillaceous limestone has been dug out of the ground for

- 60 . use in an old limekiln about yds south west of the coast road , R and is supposed to be very near the base of the formation . ather more than ha lf a mile slightly west of south of the north - west corner i - 9 1 of the map , and thus a l ttle within the adjoining one inch map , k t 3 another lime iln is seen , and an old limes one quarry , showing

4 f - t . t or of ligh coloured sandy limestone . In another small tract lying between these two kilns , but nearer the latter than the former , u a bl e shelly limestone is said to be close to the surface . The only fossil determined from the Lias of Sand is G ryphaea

a rcua ta . t m , Lam , but the exact locali y from which the speci en was collec ted is not known . t The Liassic s rata continue , however , under drift for some miles - - N E we . south west , to the north east shore of Loch umerous blocks t A of Liassic limestone are found on his shore near ultbea , and they n it doubtless represent beds which occur i s u near at hand . From these blocks a number of fossils have been collected by the G e o S logical urvey, as the following list shows

L uc na 3 i p . M odiola sca l rum J S ow p . . h itla na J . S ow . P i a s nn p . P teria O x tom a ine iva lvis J ( y ) qu ( . e il i G ru l a sp. L im a P la iostom a ectinoi des J S ow ( g ) p ( . . hetta ngiensis Te rq P ecten S nc clonem a lia sinus N st ( y y ) y . O str s ea lia sica S t rickl .

P leur m st t n n o ya co a a (Y ou g a d B ird) . G a e d st ropo s .

P J The list of fossils collected by rof . udd in the same locality is given by him as follows

O Strea irre u laris M unst Gr hre a a rcua ta P inna H artm a nni g , yp , Lam . , Z L i s hl th s nd e n e . s m a uccincta S c o L ima i a ntea S ow a i t p , . p g g , fragm ts of “ E chinode rm ata fi G W. .

i 4 0 . c t . 70 . p . p

9 2 F a ul s t .

c ate d , it shifts the outcrops of the undisturbed Cambrian strata and overlying thrust masses for some distance to the west . u The fa lt running in a NN E . direction which bounds the Liassic S 1 000 and Triassic rocks at and has a downthrow to the west of ft . or more . It is visible on the shore , where it may be seen to hade westward at an angle of and a reef of brecciated T orridon Sand out stone runs to sea on the east side . To the southward for a long T orridon S distance the upthrown andstone forms a good feature .

This fault is later in date than the Lias , for the Liassic strata are t displaced by it . Farther wes ward on the coast are two faults parallel to this , which throw the Trias , and it is probable that all three belong to the same period . In its gene ral direction the First Coast fracture is like the Sand t I t faul , but its course is more irregular . has a very large downthrow t to the west , the higher Torridonian strata on that side abu ting against the lowest beds on the east side . Its position is clearly marked on the shore , where the two divisions of this formation dip towards each other . P art of its course southward is obscured by peat and drift , but about B e inn D C haille a ch earg Bad its position is clear, as a lenticular mass b of Cambrian rocks has een let down in the fault. These appear about 1 0 l u 7 . D yds south of the hill , and inc ude a wedge of rness Limestone , 3 9 ft . long and ins . thick in one place , and a much larger mass , 30 probably yds . in length , of a whitish and grey siliceous sandstone S or quartzite which is almost certainly a part of the erpulite G rit .

The throw of this fault must be several thousand feet, and it is - th evidently of post Cambrian age . For in addition to e evidence

C oi a ch . already given , it passes through g in its course northwards , and there throws down the Cambrian Quartzite against the local basement T rrid n a ars h o wev r - o o S . e e beds of the andstone It pp , , to be pre Triassic , S and therefore much older in date than the parallel and faults . The parallel fault at Second Coast has a downthrow to the east. A long the shore numerous faults appear both in the Lewisian G T orridon S neiss and in the andstone , and give rise to geos or little bays . There is often much crushed material , but probably little displacement of the rocks . These crushes generally trend between T rid n N . E . E h or o . N . E . N and . T ey are numerous in the area along the north side of Little Loch Broom , and many running in the same general direction give rise to features on the hillside to the south of the loch . Faults having a similar trend are also common in the gneiss region

- - between the two G ruinard R ivers . The north and south fault that passes along the Little G ruinard R iver has a downthrow to the east and is post - T orridon ; but the marked crushes or faults in the gneiss which coincide nearly with the course of the I nve ria nv ie R iver and ’ i with that of U isge Toll a M hada dh are more probably of older date . The m ost important of the Loch Broom dislocations is that which ’ th e A llt B h rai he for half a mile coincides with course of a g , the longest of the small streams on the east side of the valley between Inverlael and Braemore . It is a most important feature in the geology of the S urr M or - district , as it repeats the g biotite schist band and a large - direc part of the underlying rocks . It runs in a general north east

- 2000 . tion , and must have a downthrow to the north west of about ft ’ The mass of fault breccia in places in A llt a B hraigh e is several yards in - width , and the contrast between the biotite schist on the west or h m D istrict 9 3 L oc B roo .

downthrow side and the cliff of fl aggy quartz - schist on the east is very A llt G striking . This fault has been traced northwards as far as leann ’ M hadaidh a a , where there is lso much brecciation , but the displace m ent cannot be estimated , as rocks of a similar character appear on

- either side of the crush line . O n the west side of the valley of Loch Broom there are several important faults between A u chindre an a nd G arvan which have the ’ ll B h r i same general direction as that of A t a aghe . The set which is G w near to arvan forms a series of step faults , all thro ing down suc ’ iv l t h e A llt B h rai h e cess e . y to east , or opposite to the a g dislocation

The largest, which has a downthrow of several hundred feet , is well G exhibited in the arvan Burn , with the course of which it coincides

- for a long distance . The crush breccia appears in several places , and the throw is clearly ascertained by the displace nre n ts of the lower

- A uchindre an part of the biotite schist . Nearer to there is another set and — of parallel faults , and the rocks are much shattered disturbed the G general result being downthrows the reverse of those near arvan . O ne of the fractures coincides for some distance with the course of i h in u h indr n S A llt Cuil an D ro g n to the west of A c ea . ome of these ’ l B h raoin th e arge faults are probably prolonged as far as Loch a , across obscure peat - covered ground by Carn Breac Beag and Loch Badan na M oine , where there seems fair evidence for a large fault with a down

- throw to the north west . There must also be a large fault along the valley of the R iver h in dr an A uc e . Broom , north of , but it is nowhere exposed ’ t A llt C h um h ainn There is clearly a faul along a , the burn south of

Braemore House . The smashed rock may be observed from the

bridge where the main road crosses the stream , and the fault has prob a w h ably downthro on the nort side , as the hade is in that direction be . 50 0 and the rock overhangs There appears to a crush yds .

N . N . E higher up the road , crossing the deep gorge in a . direction at the sharp bend in the stream . It is visible in the south bank .

‘ There is another set of faults , with a general direction about east - M e all south east , of which there are a good many examples about D B e inn E nai la ir oire Faid and to the north of g , where the schists are B in much contorted . The longest and most important of those near e n E na i lair g clearly has a downthrow to the north , as it repeats a portion - A ll i of the Sgurr M or bio tite schist . of them give r se to marked M e all D features . The fault which passes north of oire Faid is prob ably continuous with that v isible in the gorge of the stream to the n - - A llt A rra chd orth west and with a crush line which passes up nan , in nai lair the burn west of B e n E g . The latter appears in Braemore W 200 ood , where above the footpath the stream runs for about yds . d in 3 4 s . a narrow gorge only to y wide , with perpendicular

- . n sides about 1 00 ft . high The crush breccia runs alo g the burn to

the bend at the waterfall , and occurs again in the stream higher up d and near the top of the woo . M uch shattered and crushed rock appears for a long distance up ’ A llt M huc arnaich G ha rbhrain , above Loch a , and the line of crush is prolonged in a south - east direction towards Stra thde rie in the S 9 3 th e heet ( ) to east , and it probably passes along the course of the h R G lascarnoc iver . A marked fault accompanied by much brecciation runs in the 94 F a ults .

’ e A llt C hairn f gorg of a , which orms the northern boundary of the D undonnell deer forest . It appears to shift the rocks on the north

w . side about 50 yds . to the west ard ’ A B hiorain decidedly reddened band to the south of Carn a , a hill 2 - about 4 miles west from Inverbroom , has a course nearly north and of south , and cuts distinctly across the strike the schist . It can be 200 traced for yds . , and in places contains lumps of a metallic ore

- probably iron ore .

9 6 P leistocene a nd R ecent D e osits p .

I C E - R R K S U R F C E S WO N O C A .

The accompanying map (Fig . 7) is intended to represent the direction of the ice movement during the successive phases of the - O n glaciation of the region , as indicated by the ice markings . refer ring to this map it will be seen that most of the recorded instances G T orridon S occur in the areas occupied by the Lewisian neiss , and u M stone and Cambrian Q artzite to the west of the oine thrust . The relatively smaller number east of that structural line is due partly to th e th e wider covering of glacial deposits , and partly to softer char M S acter of the oine chists . Nevertheless , the rounded form imprinted on the rock surfaces by the grinding action of ice is to be seen in the F annich M ountains and in the high ground in the north - east corner ma of the p. M any of the striae belong to the period of maximum glaciation when the ice moved independently of the minor physical features . Thus n S urr E F a nnich o g nan ach , one of the peaks of the range , at a f - 30 0 t . . 0 . height of about , the ice markings point W N W . In the t - t A n S um a n sou h west par of the same range , on the western part of g , 1 500 ft at an elevation of . , their trend is west , that is across the valley All R ab S of t Coire nam Fear i hach . imilar evidence is obtained on B e inn D - the south slope of earg in the north east part of the map, 200 0 about ft . level where the direction is westerly across the valley ,’ A llt M hu arnaich of c . A M gain , in the mountainous ground west of the oine thrust the striae show that the high plateaux were glaciated by ice moving gen e rall - n y in a W . N . W . or north west direction , of which the followi g O n G examples may be adduced. the plateau of thrust Lewisian neiss , R R M huinidh 223 1 north of the Kinlochewe iver , round einu a ( the movement was towards the and on the south -west B i n 1 50 - ft e n 7 . slope of Lair , above the level , the markings point in h the same direction . It is worthy of note t at the volume of ice which passed along the valley of Lochan Fada was thick enough to G arbhai - S override the plateau at Loch g north west of lioch , as indi c ate d a M M by the stri e . Beyond Loch aree , on the plateau round call ’ ’ ’ G h iu bh ais R C h e arcaill A C hhine ac h a and on einu a and Beag, - n numerous strra te d surfaces have been recorded between the 1 500 ft . a d

- f n - — 1 50 t . . 7 co tour levels , pointing in a west north westerly direction ’ M t m e B e in n C hais e in North from Loch aree , on the sou h p of a g

t 1 750 ft . a Beag , at an elevation of abou , the trend of the stri e is north G M h e all M or west , and on the northern declivity of las , which forms - A n T a lla h t e c . the nor h eastern spur of , the direction is more northerly In many cases the striae occurring at lower elevations than 1 50 0 f - t. , especially in the west and north west parts of the region under d descri ption , may have been produce either during the maximum ex tension o f the ice or during the stage of confluent glaciers . These have been expressed in the sketch map (Fig . 7) by feathered arrows . In the lower plateau extending from the Fionn Loch northwa rds to G R D R S the ruinard iver , and between the undonnell iver and trath

- Broom , the general trend of the ice markings varies from W . N . W . to W N . . N . The striae further show that during the period of confluent valley glaciers the Famnieh M ountains formed one of the main centres of

d ecent e sits 98 P leistocene a n R D po .

dispersion from which the ice radiated in all directions . It passed - F annich south east over the heights at the lower end of Loch , south across the ridge beyond that loch to S trath Bran (Sheet and north towards Loch Broom . The westerly moving mass was deflected by nuna ta ks - fi eld n the great that rose above the ice , amo g which may ’ A n T e allach B einn C hlaidh e im h S urr M be mentioned , , a , g Ban , ullach

M he archair S . Coire hic F , and lioch The evidence pointing to this O n deflection is worthy of note . referring to the sketch map (Fig . 7) it will be seen that along the hollow extending north wards from Loch D th e S tl ‘ lEB an Nid to undonnell House have a northerly trend , while from the south slope of M ullach Coire M hic Fh e a rchair down G leann t h na M uice to the Heights of Kinlochewe hey point towards the sout . The volume of ice that mo ved northwards rose to a high level on the ’ i A eastern declivity of Sgurr Ban and B e inn a C hla dh e imh . small part of it streamed over the col separating these peaks , a large portion S he alla f escaped down the valley of Loch na g, but a su ficient body w D was left to find its way north ards over the pass to undonnell . Here it was deflected north westwards towards Little Loch Broom by the l e e radiating from the north side of the F a nnich range and the - d high ground in the north east corner of the map . The ice eflected G M G B iana sdail southwards , escaped down leann na uice and leann M - to the Loch aree valley , and a part of it advanced north westwards by Lochan Fada . The striae also throw light on the direction of movement of the valley glaciers which radiated from many independent centres throughout the region . They show that when the confluent ice was waning , local glaciers supervened , of which some instances may be S M adduced . outh from Loch aree there are two important valleys , S L un ard G G rudie A namely , rath g and len . part from the moraines , the ice markings prove that they were occupied by glaciers that emanated from the great corries on the north slopes of B e inn E igh e t M A and B e inn D earg ( Sheet and moved nor h to Loch aree . nother instance occurs in the valley of Loch Toll an L oc hain on the eastern slope of A n T ealla ch ( P late where the striae produced by a local glacier point almost due east, that is , nearly at right angles to n the direction of movement during the stage of confluent ice . O e

- instance of cross hatches may be referred to , due to the ice moving in different directions at successive stages . They are to be seen on T orridon S D R - a boss of andstone in the undonnell iver , one third of - D d a n a mile north west of undonnell Lo ge , one set of stri e poi ting W . ° 1 5 N . and the other nearly due north .

D R Y A N D M R IN E B O U L E C LA O A S .

The glacial deposits range from compact bluish boulder - clay or till with striated stones to the loose sandy and gravelly material m which forms definite oraines and moraine drift . The former is generally found on smooth , flat , or gently sloping ground , while the latter is usually arranged in conical heaps or ridges . The boulder bills clay is often covered with peat , and is rarely met with on the h n or upland glens . It spreads over parts of t e lower plateaux a d occurs in the lower valleys .

B oulder la a nd M ora ines C y . 99 There is a species of material on some of the hilltops which may l - be designated p ateau frost debris . It either lies directly above the * parent rocks , or has been transported only for short distances . The materials are frequently arranged in parallel lines or terraces due to - w soil creep aided by the movement of sno . This feature is beauti fully illustrated in the accompanying photograph of part of the cres t of the F a nnich range ( P late f The dif erent varieties of drift merge into one another , and it has been found impracticable to separate the till and morainic drift t generally over the low grounds , especially as there are few sec ions in which the glacial deposits are exposed . Both deposits are ex of 2 pressed by one style ornamentation in Sheet 9 . The glacial drift on the western side of the Broom valley is

- largely boulder clay or till , which is specially prominent and of i A uchluna ch an great th ckness in the lower part of the Burn , nearly

opposite Inverbroom Lodge , and in the side valley north from u hi A c ndre a n farther up the strath . It contains boulders of grani toid - - gneiss , biotite gneiss , epidiorite and hornblende rock which have ’ w d m h B h raoin travelled north ar s fro the neig bourhood of Loch a . A uchindrean - In the case near , while the lower part of the pre glacial t valley is deeply buried in till , the s ream has cut for itself a narrow

- — and deep post -glacial ravine in the fl aggy quartz schists a fine example of the numerous impassable gorges with waterfalls in which R - so many of the streams run in this part of oss shire . O n th e the east side of Loch Broom , about a mile north from t head of the loch , there is a grea thickness of genuine till with t A A t glacia ed stones up the rdcharnich Burn . the bend in the m stream 500 yds . above the road leading to Ullapool a great ass of t n till with striated s ones appears on the orth bank . Half a mile higher up is another instance where the thickness of boulder - clay is 0 f th e 1 0 t. about , as shown on the north side of northern branch A t of the burn . narrow ridge of drif separates this tributary from

the main stream on the south , which now runs in a beautiful post in glacial ravine and forms a series of waterfalls about 200 ft . total A of height . Near rdcharnich , marked drift banks , apparently , till

- and allied to drumlins , run in a north west direction parallel to that

of the general glaciation . There is also a great thickness of boulder ’ A llt R C h rois - clay in the middle part of aon a g, south east of Leck

melm . In the highest part of the Broom valley much of the drift is

probably genuine till , and in one place there is a section of that d 25 . eposit about ft in thickness on the south bank of the river ,

about a mile up stream from Braemore Lodge .

In the streams east of Kildonan , on the east side of Little Loch - l Broom , there are several sections in blue boulder c ay with striated M n S stones , many of which are composed of oi e chist from the east of - ward , the direction carry indicated by the adjacent ice markings T - on the orridon Sandstone being north west . M uch of the drift in the Little G ruinard area in the north - west - S part of the map is probably boulder clay . everal exposures by the

path at Bad Bog, nearly six miles slightly west of south of Little

G . ruinard , show a deposit which may be regarded as sandy till “ S e e T h e G e l B e n W vis C a n C h uinn e a I n chbae and th e sur o ogy of y , r g, ” und n M urv . 19 12 1 59 c un Geol. S . r em . o i g o try, , , p , P leistocene a nd R ecent D e osits 1 0 0 p .

M - A orainic mounds occur not far to the south east . gain , on the

th e - east side of Fionn Loch , between three quarters of a mile and two

- miles north west of Carnmore , the upper slopes between that loch and the crags are of a smooth character compared with the morain ic E F raoch contour of the drift areas a little farther north and near ilean . In this smooth tract a number of shallow excavations at the side of the forest path disclose a stiff brown sandy clay which frequently

- shows an obscure lamination inclining south west , nearly with the O n - slope of the hill . the south west side of the Fionn Loch some of

the drift is of the same character . The burn about a mile and a quarter south - west of Carnmore old house shows such a deposit lying

under looser sandy and gravelly material . O n the north - east side of Loch M aree a stiff brown stony clay is N E seen in a small burn a quarter of a mile N . . . of Letterewe . In another stream about a mile and a quarter north from Letterewe an equally stiff stony clay is exposed beneath a less firmly compacted P deposit . art of the adjoining ground has a smooth , even surface , r though a burn section th ough it shows 3 0 ft . of drift which is of a loose gravelly character at the top . O n u M the so th west side of Loch aree , about a mile and a r R hu quarte slightly west of south of Noa pier, a stream discloses - M n S tough grey boulder clay with many fragments of oi e chist , which

- occurs in place about a mile to the south east . R eference has already been made to the rare occurrence of

- d . boul er clay in the mountainous regions It has , however, been F nni h observed at considerable elevations in the a c range . Thus on the north side of Loch Famnieh various pits have been opened at the side of the road between F annich Lodge and the foot of the loch close

- f S 800 t . by the . contour level ome of these excavations display stiff boulder - clay with striated stones composed of s iliceous - M oine O Schists resembling those in the eastern part of the chain . thers reveal loose moraine matter , which is here sprinkled irregularly A over the surface , there being no morainic contour . gain , between 1 1 5 f 500 0 t. ft . and 7 , the burns draining Coire Beag south of Crea A chan R airigidh cut through stiff stony clay overlain by moraines . still more remarkable instance occurs on the north side of the chain ’ S urr M or M h adaidh beyond g near the outlet of Loch a , which is

- f 1 83 1 . ft . above sea level Here there is a section of stif till about 20 ft . thick , with striated stones , while in the corrie to the west of the loch there is the usual morainic contour . From the evidence n ow adduced it is clear that throughout the region under description various sections are to be found of stiff

- nd boulder clay with striated stones , i istinguishable in most cases

- from the usual ground moraine of an ice sheet . This deposit may have been formed either during the maxim um extension of the ice or d uring the period of confluent glaciers . The distribution of the moraines shows that they must have been deposited partly during the period of confluent glaciers and partly during the later stage of valley glaciers . They occur through

- - S out the drift covered areas down to the sea level . ometimes they are situated on dividing ridges , sometimes they are spread irregularly over the lower plateaux , but their typical development is to be found in the larger upland valleys .

P le stocene a nd R ecent D e osits 1 0 2 i p .

’ east towards M a c us M ath air (2293 rising gradually to higher n ground in that direction . O e of them is a mile in length . Its k trend varies , but its general stri e is slightly north of west . In the - A n T e a llach valley draining the north west side of , just below

‘ R uadh - - Lochan , there is an example of a horse shoe shaped terminal

- moraine , and about half a mile north west of that lochan another

moraine crosses the main valley . In the middle corrie on the east the G M h e all M or side of mountain , south of las , a beautifully curved terminal moraine extends across the valley at a height of about a re 1 400 ft . The of the curve is nearly half a mile in length in a

t - - nor h and south line , and inside the curve are many small mounds ,

while the outside is free from drift. In the corrie immediately to L och ain the south , in which is situated Loch Toll an , there is a lateral moraine more than a mile long and a terminal moraine also (P late P roceeding southwards to the high ground between Loch na S he alla M g and Loch aree , we find some striking instances of n moraines indicati g stages in the recession of the valley glaciers , of O n B e inn which a few examples may be adduced . the north side of D earg M hor a series of concentric ridges occur near the foot of the stream that drains Loch Toll an L och ain and flows into L och na ‘ S h e allag. The lowest is semicircular and measures nearly half a

mile in diameter . In the large corrie on the east side of the

mountain still finer examples are to be found . Three successive

terminal moraines , laid down by the corrie glacier , form conspicuous

. features in the landscape The lowest one , which forms a huge, m se icircular rampart , stretches for about half a mile across the 1 00 1 30 . valley. It measures about or ft in height on its outer side ,

- and at the lowest point the base is slightly below the 600 ft . contour

line . G M - The glacier that descended leann na uice , south east of Loch S h e a lla t na g , was one of the largest of the valley sys em between S h e a lla M Loch na g and Loch aree . Fed by numerous small tributary ice - streams emanating from the high corries on either side of that S Sh e alla valley , it carried downwards towards trath na g a large quantity of material derived from the crags and escarpments of G T orridon S Lewisian neiss and andstone , which is now distributed

in the form of irregular mounds and terraced moraines . In the 1 6 sequel (p . 0 ) it will be shown that this glacier interrupted for a time the drainage of S trath na S he a llag and gave rise to fl uv io

glacial terraces . D u ionn B e inn C hais e in Between bh Loch and F Loch , south of a g M or , the two arms of a large semicircular moraine come down to the

- 560 . water level about ft above sea level . The concave side faces A - th e eastwards . few hundred yards north east of highest part of

the northern arm , a terrace , composed of sand and gravel and strewn

with boulders , can be followed eastwards for half a mile . It rises

gently in this direction until it reaches a height of more than 4 0 0 ft . D above the surface of the ubh Loch . It seems probable that it was formed by water flowing along the northern side of the same glacier th e which deposited semicircular moraine . S M e all In the valley draining the eastern slope of lioch , between E S urr T uill B hain - ach and g an , a typical horseshoe shaped moraine

e st cene nd R ecent D e osits P l i o a p .

this type have been detected in S trath Broom till we reach Inverlael . Between that house and A rdcharnich near Leckmelm they are fairly _

A 1 50 . numerous . group of them is to be found yds north of

co 1 08 . . Inverlael Lodge , the largest ntaining about cubic ft of rock Several have been noted in the little bay north of R udha A rd an

T uirc th e A . , and also close to the bridge over stream at rdcharnich 0 11 4 . The largest at the latter locality is 5 ft . long by ft . broad the S 92 west side of Loch Broom and near the northern margin of heet , 53 two boulders of this type have been detected about 0 yds . west of

R ' ‘ fi J zf L

M A UG E N G N E I IN P L A C E 0 L D R E D S A N D S T O N E I N P LA C E . S S . -

° B O U L D E R S O F A U G E N G N E I S B O ULD ER S O F O L D R ED S AN D ST O N E . S . 0

F I G 8 — M a a C en al and e R - e n d u n . , p of p rts of tr W st oss shir , showi g istrib tio ulde o f A u e n G ne and O ld R e d S n of bo rs g iss a dstone .

D un R ui h R uadh B la rna le vo h north of an g near c . O ne of them

3 . 2 . measures ft . in in length The most northerly instance occurs

- 50 0 . D un L a aidh S 1 0 1 on the shore about yds north west of g in heet , within two miles of Ullapool .

In connection with the evidence just described , it is worthy of note that a boulder of O ld R e d S andstone h as been recorded close to

Inverlael Lodge (see Fig . which must also have been transported S trathvaich has from , as no rock of this type been found in place in 2 Sheet 9 . r bution o E rra tic B locks 1 D ist i f . 0 5

A ttention will now be directed to the occurrence of erratic blocks at high elevations along the range of mountains stretching from A n T ealla ch S t th e M to lioch , in the region situa ed to west of the oine thrust . O n S - A n T e allach ail Liath , which forms the south eastern spur of (3483 blocks of M oine Schist and thrust T orridon Sandstone have - f 3 000 t. been found close to the contour level , where they rest upon a small outlier of undisturbed Cambrian Quartzite . In the belt of displaced rocks between Loch Broom and Loch an Nid the thrust 1 50 0 T orridon S . andstone does not exceed ft in height , hence the 1 50 0 erratics of this material must have ascended about ft . to the E S ridge of Sail Liath . Blocks of the astern chists from the interior of the region are fairly numerous all round A n T e allach but not over M r G the top . From this evidence the late . unn inferred that the highest part of the mountain had never been overridden by the

- inland ice . He suggested that it might have had a small ice cap nuna ta k of its own , or that it formed a above the surrounding m er de la ce g . S urr 31 94 Farther south , on g Ban ( blocks of thrust Lewisian E - G 40 . S E 30 f neiss occur about yds of the cairn and above the 00 t. contour line , where they rest on undisturbed Cambrian Quartzite .

O n B e inn T a rsuinn ( 2750 ft . ) have been recorded erratics of M oine S G chist , Lewisian neiss , Cambrian Quartzite and Fucoid Beds resting n S 321 7 on T orridon Sandstone . O lioch ( boulders of M oine S G - P R chist, thrust Lewisian neiss , hornblende schist and ipe ock have been found not far from the cairn on the hilltop with T orridon

Sandstone beneath . The blocks of thrust gneiss indicate a minimum

1 000 . uplift of ft within a horizontal distance of two and a half miles , P R while the boulders of ipe ock point to a still greater ascent , from any probable parent source along the path of the ice , as indicated by S urr T uill B hain the striae . Similar evidence is obtained on g an (30 58 3000 S M at a height of about ft . outh from Loch aree on M e a ll ’ hiu h 2 2 M G b ais 88 . a ( ft ) numerous blocks of quartzite , siliceous oine S - - i m chist, and garnetiferous muscovite biotite gneiss l ke the ass on

- B h einn 2500 ft. c Fionn , have been noted between the ontour level S B e inn E o and the top of the hill . cattered over an in , in some places within a few feet of the hilltop ( 280 1 there are pieces of M oine S - in situ chist, hornblende schist, and Cambrian Quartzite . The rock T orridon is Sandstone . The facts now adduced regarding the distribution of erratic blocks enable us to furnish an estimate of the thickness of the ice - sheet M S S which transported blocks of oine chist to the top of lioch . The ’ deepest sounding of Loch M aree between that mountain and M e all a h h i G iub a S 6 ft . s 3 7 335 . , ascertained by the Lake urvey , is , that is ft - S below sea level . If to this amount we add the height of lioch above the O rdnance D atum line (3 21 7 it follows that the thickn ess of the ice , which crossed this part of the area under description , may

3500 ft . have been upwards of , which is greater than the height of A n T ll e a a ch . Throughout the area of Lewisian G neiss in the western part of the map numerous boulders of Cambrian Quartzite and T orridon Sand stone are to be found , which have been carried westwards and north westwards by the ice during successive stages of the glaciation of the 1 06 P l i ocene a nd R ecent D e osits e st p .

- m region . The north westerly move ent can be proved independently by the transport of blocks derived from some member of the Lewisian G neiss itself . Thus from a small outcrop of serpentine and peridotite

. E . . E . E r ml N of ilean Fraoeh in the F onn Loch , a well defined train of boulders can be traced for a distance of four and a half miles 111 a r north westerly di ection (see Fig .

A - to S gain , in the north west corner of the map the south of and many large boulders of Lewisian G neiss are scattered over the area T orridon S of andstone , which have been carried from the Lewisian

- tract to the south east . S ome of the erratic blocks are of very large size . For example , a block of biotite -schist in the corrie south - east of Sgurr M or Fa nnich F huar M hOir f and 3 50 yds . north of Loch an Thuill measures rom 1 0 1 2 A to yds . in length . nother of the same material is to be found on the boundary between the Braemore and Inverlael deer ll i ’ D io a d M bill W . B h ric . . forests , on the hill named a , two miles N W of B inn D i 1 0 e . s earg It about yds . long , and a cairn has been erected A A n on the top of it . gain , in the great corrie on the east side of T e alla c h L oc hain , a short distance east of Loch Toll an , a boulder of T orrid n 5400 o Sandstone contains cubic ft . of rock .

F I - I S D A N D G V LU V O GLAC AL AN S R A ELS . R eference has already been made to the interruption of the drainage of S trath na Sh e allag by the glacier that descended G leann M fl uvio - na uice . High terraces of glacial material extend up that t strath for a dis ance of two miles , from a point about a mile above

h h all off - Loc na S e ag. The terraces end abruptly down stream as if they had been deposited against a barrier that had been removed . O n the north side of the strath , a moraine , containing boulders of G G M Lewisian neiss that must have emanated from leann na uice , is be found on the slope of the hill , which can traced down the valley for some distance . It crosses the alluvial flat , being there breached B e inn D by the main stream , ascends the declivity of earg , and G M u t eventually passes into leann na ice . This ridge eviden ly G M represents the terminal moraine of the leann na uice glacier, S which , at its lower end , spread out like a fan when trath na Sh e a lla S h e nav all g, for some distance above , was free from ice . The th e area occupied by terraces was probably a temporary lake , perhaps held back by the ice , in which the alluvial detritus from the upper fl uv io part of the valley was arrested . The terraces cut out of this glacial material represent stages in the erosion of the valley by the main stream . The area on the inner side of the terminal moraine O t S he nava ll u pposi e now forms an all vial flat , and may represent a - u sil ted p lake impounded by the moraine . A t B e inn A iridh bout a mile and a quarter eas of Charr , two

t 1 0 30 . smoo h ridges , from to yds wide at the base , extend in a line

- south eastward from a small lochan for a quarter of a mile . They

- appear to be composed of well rounded gravel and sand , and may ,

perhaps , be classed as

T h e high -le vel te rrace s n e ar I nve rbroo m and on th e n orth -ea st side of Loch M a e e a bl had a d fe e n n th e R a e d B e ac e se e 10 9 r prob y if r t origi from is h s ( pp . ,

1 0 8 P leistocene a nd R ecent D e s po its.

d n ot the eastern floor of Lochan Fa a is faulted down to the west . It is worthy of note that the deepest part of the basin , and the deepest i 248 ft . S B e nn T arsuinn sounding ( ) lie between lioch and , where the erosion by the ice during the maximum glaciation would probably be greatest .

The Fionn Loch lies wholly within the area of Lewisian G neiss .

n 1 00 . It contai s several irregular basins , two of them exceeding ft in depth , and the contour lines in most places are extremely sinuous . T he 144 maximum depth of the lake ( ft . ) was recorded in two - th e places , one near the south eastern end , and second in the central part of the loch , opposite the mouth of the stream that issues from nn h h ubh Lochan B e a ac . The eastern arm of the lake east of A ird D

- is impounded by drift , which probably fills up a pre glacial channel . WS W The present outlet is about a mile and a half to the . of this G R locality , and here the Little ruinard iver leaves the loch by a series of rapids and waterfalls . The Fionn Loch is one of the few

Scottish lakes which fork downwards . L och M a ree is a composite rock - basin lying partly alOng the G len D ocherty shatter belt or fault and partly in Lewisian G neiss and l T orridon Sandstone outside of this ine of disturbance . Brief allusion will here be made to the portion of the lake that falls within Sheet 2 9 . This fault runs along the floor of the loch from the mouth of R E S ubhainn the Kinlochewe iver to a point opposite ilean , where d it leaves the lake for a short istance , and a little further on skirts l i the base of the slope behind A rd a r. The soundings of the Lake S urvey show that a well - marked U - shaped basin extends from the head of the loch to a point midway between E ilean S ubh ainn and

- . 367 ft . the north east shore The greatest depth , , occurs where the 2 1 valley is most constricted between Slioch ( 3 7 ft . ) on the north and ’ i 2 2 M e all G hiubh a s 88 . a ( ft ) on the south , and where the erosive action of the ice would naturally be most powerful . Between the m i ra air . . S o s small bay one mile W N W . from and a point on the shore O C e ach ff pposite pp y , the e ect of a fault in weakening the strata is

- shown by the widening of the basin and the loop of the 250 ft . contour line in that portion of the lake . To the south and south

of 200 . west the islands there is an independent basin , exceeding ft M in depth , evidently resting in Torridonian strata . Loch aree - but apparently extended farther up the valley in post glacial time , it has been silted up by the streams that converge near Kinlochewe . E This part of the lake was probably comparatively shallow , as ilean C raoibh e na , near the head of the existing loch , is a moraine more or less levelled by the action of the waves . ’ B h a oi f L och a r n 3 t . , with a maximum depth of 7 , is surrounded by morainic drift , and has been partly determined by a line of fracture . L och G a rbh a i t S t g, to the nor h of lioch , is over a mile in leng h , and evidently a rock - basin from the appearance of Lewisian G neiss at its i A m h a nn F uirne is. exit , where it is drained by the na The soundings th e t prove the existence of two basins separated by a ridge , eas ern

9 3 50 . one reaching a depth of ft and the western , ft close to its

outlet . This lake lies mainly along the junction of the Lewisian G T orridon S neiss and andstone , the older rocks forming the greater t part of the north shore , and the red sandstone the larger por ion of

the south margin . F res wa ter L ochs a nd R a ised B ea ches 1 0 h . 9

’ L och a B hrisidh 2 - ft 000 . S urr , near the contour line between g Ban ’ B e inn C hlaidhe im h t - and a , is a ypical example of a small rock basin T rri excavated by ice action at a great elevation . It rests in o don S andstone , the floor being beautifully glaciated at the outlet of the A M or lake . nother example of this type is Fuar Loch , which occurs ’ - f A 1 750 t. M hai hdean above the level to the north of g , where it rests in Lewisian G neiss . L och D rom a is impounded by moraines and alluvium , and is partly of - artificial . It is situated on the main watershed the North West

- Highlands . It has already been shown that in this case the ice shed during the maximum glaciation must have lain several miles to the east of the present watershed , as proved by the distribution of - Strath vai h S boulders of augen gneiss from c . uch watersheds have almost invariably had the gradient on each side much lessened , while

- many have been hollowed into rock basins . A mong the small lochs on the plateau of Lewisian G neiss which

- are bare of drift and may be regarded as true rock basins , the following may be mentioned

n u ri m B e c le E le n d L c a D a a S E . G u a and o h bh r , two mi s of Litt r i r , two n el l c an d le th - a e a e u e a one . m ss o h s, thir of a mi to so th st of this A n ele l c e e - u e of l e E lean an E c B an in am ss o h thr q art rs a mi S S W . of i i h h n c th e F io n Lo h . ’ A na e le l c a ua e a le n - e c an B hra h ad u m ss o h q rt r of mi orth w st of Lo h a g , so th

o f B e inn D e arg M hor . l l n l d n L och in C na ach ee le S le S e e a c a nc u a S W. v r o h s, i i g p , thr mi s of Litt G u na d r i r .

R - eference may here be made to the rock basin , excavated by ice P action , in Little Loch Broom , which has been described by rofessor i elf h James G e ik e . It extends beyond the limits of t e present map - S 1 0 1 into the one inch heet . He notes that , at the mouth of the A rdross R loch , the rock actually comes to the surface at ock , north of Stattic P east oint , and that between this islet and the shores the h - Y e maximum dept s are ten and twenty six fathoms . t the soundings - fif - half way up the loch show a depth of ty seven fathoms . E B H . r . c . G N . P J . w G c . . , . , . , . , . .

R IS E D E HE A B AC S .

The highest beaches of sand and gravel , distinguished in the map

by the sign of three inverted crows , are not necessarily of quite the ff same height in di erent districts . It is believed , however, that in 1 00 ft O each the highest parts are not far from . above rdnance D atum . It should be stated also that there is room for doubt whether

some of these platforms are of marine origin . Those on the open G coast by ruinard and Leckmelm may , perhaps , be accepted as

but the high terraces near Inverbroom , four or five miles ff t farther towards the interior , may have a di eren origin , because in S districts a little farther south , as , for instance, in trath Carron , it is

“ ” T h e G e a I ce A e 1 89 4 . 232 cl se . r t g , , p , q e U lla 0 0 1 in on e - l nch m a 10 1 e e f L e ckmelm is only thre e mile s abov , p , wh r e ed th e high e st raised beach is un usually well dev op . 1 1 0 P leistocene a nd R ecent D e osits p . clear that the upper parts of some of the sea - lochs were occupied by

- 1 0 f . ice at the time of the 0 t beach . T h e - M high terraces on the north east side of Loch aree , both those marked with the sign of two inverted crows and one nearly 1 0 1 2 1 0 0 or ft . higher, are not far from the level of ft . If these are marine , it is surprising to find them extending so far into the u mo ntains , and our doubts are increased by the absence of any r - P corresponding ter aces on the south west side of the loch . ossibly these terraces may in reality have been deposited in some sheet of water which was held up between an ice fron t on the south - west side

- and t he mountains on the north east . M ost of the terraces indicated by the sign of two inverted crows

- 50 ft. have their highest parts near the contour , with the exception A M t . of those in Loch aree , as already s ated good many are seen C oast L ittle G D along the shore near First , ruinard , Kildonan , undonnell D Inn and Leckmelm . A good section in the terrace near undonnell h Inn shows gra vel at the top wit sand and gravel below . The inner margin of t he lowest raised beach is believed to be E generally a t a height of about 20 ft . xamples of this beach are well seen in Loch Broom and Little Loch Broo m . T he tracts between low and high tide marks are of considerable h R G I nv e rianv ie D extent at the mout s of the ivers ruinard , , undonnell m and Broo , which is due to the deposition of alluvial material carried G t . do wn by the streams . Near Li tle ruinard the beach mostly but - consists of sand , a small portion at the south west end is composed of gravel and shingle . The northern portion of the beach at the foot of S trath Beg is partly composed of gravel .

F R E S HWATE R ALLU VIA . M ost of the streams have a steep gradient and considerable carrying power , and , consequently , the terraces formed along their h m sides are c iefly co posed of coarse material , often gravel or even

- boulder beds . The older and higher terraces are perhaps best seen near the foot of S trath Beg . The total breadth of the terraces is generally greatest in the lower parts of the valleys , just above the sea A or some large freshwater loch . great part of the flat land at the heads of the lochs has evidently been acquired from the water space

, it is being continually added to year by year during recent times , and A by the material brought down by the streams . good number of small lochs which once existed have now been entirely filled in this way : as an example of an old loch site we may mention th e small

- M A t S m iorasa ir . allu vial flat at , north east of Loch aree the head of Loch M aree the flat land is about half a mile wide and extends A t S about two miles up the glen . the foot of trath Beg it is less than half a mile wide but about three miles long . Near the foot of the

R iver Broom the total breadth , including some terraces which may be marine , is generally less than half a mile , and the length is about four miles . When streams descend from steep mountain sides on to much t flat er areas , they often deposit great accumulations of gravel and ” G n o boulders in the form of steep deltas or cones . ood co es f this

1 1 2 P leistocene a nd R ecent D e osi s p t .

n Besides the above , various patches of blown sand occur far inla d , and have evidently been formed from sands deposited in fresh water a T or from disintegr ted orridon Sandstone . These patches are not A n first- shown on the published map . example of the mentioned - h ll type occurs at the south east end of Loch na S e a ag. Those of the second type are especially common in high exposed positions , such as the top of S lioch and the high plateau between A n T eallach and ’ M a h ir c us M at a . In the latter locality the sand forms dunes

- . G B . N . P . comparable to those on the sea shore w . TE CHAP R XII .

E O O M G E O O G Y C N IC L .

N - O R E IR O .

I T is widely known that iron smelting was formerly carried on at o M various sites on the shores of L ch aree and the vicinity . From * M r J D h . . t e . account given by H ixon , it is clear that a number of prehistoric bloomeries existed in the district , as well as more modern Sir G furnaces . The latter were started by eorge Hay early in the seventeenth century, and were carried on for at least sixty years . Sir G eorge Hay is claimed as the pioneer of the modern iron S industry of cotland, and his furnaces must have been constructed on much more scientific principles than the prehistoric works , for

60 . c while the slag from the latter yields over p . of iron , that from the former yields only 20 or There is also evidence that some of

the ores used in the later furnaces were calcined before being smelted . O ne of the historic furnaces was situated at Furnace (whence the - M T alla dale name) , on the north east side of Loch aree , another at , on “ - R e d the south west side , and a third , the most recent , called The S - - R E we middy (one inch map on the north east side of the iver , nearly a mile from its mouth . The presence of the remains and slag heaps of these old furnaces have naturally led people to think that iron - ores of considerable value must exist in the district, but this does not appear to be the case . The only local ores that are known consist of comparatively - A small pans of bog iron ore . good representative of these pans formerly existed at South E rradale (one - inch map where a field

- wall has been constructed of blocks of iron ore obtained from it . S 1 3 . . M r ome of the blocks are ft long and ft . thick . Ivison M acadam made an analysis of two samples of this S outh E rradale ore with the following results

l ual to

F e i c O xrd e . rr M efgllic I on r .

Sample a 49 6 1

M r M . Ivison acadam adds that the ore was thus equal to many of the red iron - ores and superior to many black - band orea i The pans of hog iron - ore do not appear at present to be either M r D numerous or large . In the map given by . ixon at the end of

” — E d n u 1 8 G a l c 2 . 86 96 . . 7 ir o h , pp i b rgh , “ M r I d N e o n th e A nc en I n I ndu S c land . v n M aca a f W . iso m , ot s i t ro stry of ot ,

P c. 1 ro S oc. A ti ot D ce e 886 n S c . e . q. , mb r ,

O . cit I p . s 14 E conomics 1 .

n - 92 his volume none are indicated withi the limits of one inch map .

But it may be assumed that they were formerly more numerous , and that the best were all used up by the old bloomeries and furnaces . The presence of these local pans may have been one of the induce th e ments which led to the first establishment of the works , but extensive woods which formerly clothed most of the hillsides were probably a greater attraction , as , from these , fuel and charcoal could be readily prepared for smelting purposes . It is certain that ores not for found anywhere in the district were , in later times , imported , pieces of such ores can still be found lying on the ground near the sites of some of the old furnaces . The only pieces of ore found by M r M . Ivison acadam near the site of the Fasagh works consisted of ho - a g iron ore , but near the later works at Furnace red h ematite and

- carboniferous clay ironstone nodules were also used .

- The rusty scars largely composed of graphitic mica schist , which extend along th e north - east side of Loch M aree from Furnace to F a sa h g , are sometimes locally claimed as the source of the ore which was used in the furnaces , and definite spots in these scars have been pointed out as the scenes of former quarrying O perations . But the spots may be more reasonably interpreted as the site of small rock d slips . These rusty rocks owe their colour to the oxi ation of finely disseminated iron pyrites , and it does not seem at all likely that they - M r M can ever have been used as iron ores . . Ivison acadam estimated that the amount of iron in these rocks , calculated as the metal , 3 8 c varied from a little over to p. . The few seams , already referred to in Chapter III . , which contain magnetite , occasionally yield a considerable proportion of iron , but they are all too thin to be useful u l at sources of s pp y . F asa h There is no historical account of the g furnace , but the level of Lochan Fada appears to have been slightly raised by a dam at n was the time this fur ace in operation , and water was conveyed in a conduit from this loch to the works , presumably for the purpose of

- turning water wheels to work sledge hammers , etc .

LIM ESTO N E .

The Cambrian limestone which crops out at the south - east end

of Lochan Fada has been quarried , and was probably used as a flux i n the smelting operations of the adjacent F asagh furnace . In addition to the above limestone the Lewisian limestone of

M r. Letterewe has also been quarried , under the direction of Banks ,

one of the former proprietors of the Letterewe estate , long after the

adjoining iron works at Furnace ceased operations . Whether this limestone was also quarried while the iron works were productive is

. r not known The quarry opened by M . Banks was on the west side

200 - F lai o s. of the burn about yds . north west of the ruined house of

It was of considerable size , and was connected with the loch by o f 20 means a tramway . The limestone now exposed is about ft .

thick, but is a good deal mixed with impurities in the form of biotite

and broken lumps of actinolite .

S la c w e a in e ne al e e a e a un imi r s hists , ith p rh ps g r a som what r t r mo t of a ne e a re un d al in one -in c m a 9 1 S e e T h e G e ogo ical S uc u e o f m g tit , fo so h p . g tr t r ” th e N - We H land M em Ge l u 22 . v 8 . o . S r . 1 90 . orth st igh s, , 7, p

1 s 1 6 E conomic .

h - carbonate of copper . The vein occurs in ornblende schist, and is at h e . t least a foot thick It cannot be traced beyond burn , but the fault

appears to continue a considerable distance in both directions . The Lewisian rocks in the burn about three - quarters of a mile N N E . . . of Letterewe House are considerably crushed , and are traversed by a vertical vein of calcite running along the bum in a 50 north east direction . The vein can be followed about yds . , and a contains a small quantity of galena s well as iron pyrites . O n M M the north east side of Loch aree , opposite Isle aree , an excavation or short day level has been made into the hornblende h 1 20 3 . t 8 r 0 e . schist , pe haps or ft above level of the loch The hole “ ” “ U am h O ir usually called an , which means the cave of gold A n inspection of the cave showed that it had been excavated for

W S W . 7 or 8 yds . along veins of calcite which have a general direction and southerly inclination : no metalliferous ore was noticed excepting a little iron pyrites . Very near the cave various other crushes and calcite veins are observed inclining gently east in the same schist . The faul t that crosses A llt na Faine (a tributary of the D undon R - nell iver) , about a mile and a quarter north east of the top of Creag R aini h u c . , is accompanied by minor crushes The joints of the q artz r m schist t aversed by these lines of move ent are , in places , coated with some green mineral , probably a carbonate of copper . The amount of graphite l n the graphitic schists 1s probably much i too small to be of economic value . No specimen of the ron pyrites - h as associated with it in this one inch map been analysed , but it is known that the pyrites and pyrrhotite associated with somewhat similar schists in the district of Kintail (one - inch map often — contain a trace of gold too little to repay working . M Or - ionn The pegmatites of Carn , on the north east side of the F

Loch , which are described in Chapter III . , contain plates of clear white S mica of considerable size . ome exceptional examples of these plates 1 9 0 . attain a length of or ins , and a good many may be as much 3 4 as or ins . These pegmatites , however, are in a hard , sound n co dition , and so is the gneiss in which they occur , so that the mica fi M plates would probably be dif cult to extract . oreover, the locality is far removed from any good road , and the minute folds which f sometimes af ect the plates would impair their value .

P LANTATIO N S . A d lmost the whole of the land is in a wil , uncultivated condition , and merely used as deer forests for sporting purposes . It is for the M most part very bare and treeless , but the islands of Loch aree and

- some of the slopes adjoining the loch , particularly on the south west S P inus s luestris side , are still clothed with the cottish fir ( y ) , the self sown descendants of older more extensive forests . Within historical times the natural forest growth was much more extensive , and it seems clear that it was partially destroyed in order to provide fuel for the old iron furnaces .

“ ” I n th e N e w S a cal A cc un S c land E d n u and nd n t tisti o t of ot , i b rgh Lo o , 9 3 a d th e e c n e 1 845 . a ade e one u h , p , it is s i that x vatio was m by som who tho ght h d c e re d l e e a dis ov a si v r v in . 1 1 P la nta tions. 7

O nly in one portion of the map, on the Braemore estate at the

- of . head Loch Broom , has planting on a large scale been attempted A s is well known , this experiment has met with a considerable h measure of success , and it seems , t erefore, probable that a similar system of planting might be carried out with advantage in many other sh eltered positions which are now almost treeless . The proximity of th e sea would facilitate the transport of timber to more populous centres . The basis of the following particulars about the l Braemore p antations has been kindly supplied , through Lady Fowler , M r S by . W . inclair , forester , Braemore The late Sir John Fowler acquired Braemore estate in the year 1 865 l , and in that and the two fol owing years he planted close on 1 - 0 0 850 . . trees , at altitudes varying from to ft above sea level P revious to 1 865 the timber trees growing on the property consisted

- almost entirely of self sown alder and birch , and other indigenous trees common in the Highlands of Scotland . The following measure ments of trees , typical of their kind , will , it is believed , convey a fair idea of the rate of growth between the period of planting and the 1 year 908 . The measurement of height is from the ground to the : 5 apex of the stem the circumference is taken at a height of ft . or upwards from the ground .

C O N IFE R O S R E E U T S .

e c e s . H e h . R E M A R KS S p i ig t .

P c a s G ll i e excel a rows we . S om e are of gre ate r he ight P seudotsuga D ougla sii e e in cl e a n wh r os form tio . O n e of a e e lle d this v ri ty, f e ce n l was de ca n in r t y , yi g P icea Sitchensis (M enziesii) 72 ce ntre its circumfe re nce

was 9 ft . G ell rows w . F e w of this varie ty ; what are a e a e al , pp r h thy . Th e re we re a c onside rable numbe r of this class planted and foun d un P inus a ustria ca suitable most h ave b e en r e move d ; what re main s e en a u e d nu pr s ts r gg , e al a e a h thy pp rance . A bies ectina ta le n d dl p rows sp i y he re . A bies nobilis G e e ll rows v ry w . O nly a fe w o f this kind ; A bies lasioca rpa th e m e asu re m e nts given are th e la e of rg st . M ore of an ornam e n tal ch ar A bies P insapo ac e an c e c l t r th omm r ia . G rows e xcelle n tly at low T huj a giga ntea e l e n va tio s . A ll th e cypre ss vari e ti e s C ha m re cypa ris L a wsonia na e e ll e e thriv w h r . Throughout th e plantations thousan ds of larch a re L a ri e e n 2 ft e at europea s 0 . high r than this the se m ea sure m e n ts are an a e a e e c en of v r g sp im . 1 18 E conomics.

D HAR D WO O TR E E S .

S e c e s . H e h t . R E M R p i ig A KS .

A cer P seu do- la ta s p nu G rows ve ry fast . A cer la ta noides ll p G rows we . E sculus H i ocasta num well pp G rows . N aturally grown he re a nd A lnus lutinosa e e d ea e a a e n g th r is s pp r t, d ue a c fun to p rasiti i . be plant e d birch r uce s more timbe r t an th e B etu la a lb l n e d n u l c a (p a t ) at ra bir h . This is owing to a more regula r und form ation ove r th e gro . C a stanea uesca G rows we ll . F a us s lva tica ll g y G rows we . G rows ve ry fast in close F ra xinus ea celsi or a n form tio . P o ulus C a na de nsis e p ( ) Fast grow r . T i i euro ee l a ( p a ) G rows well . This spe cim en is th e b e st Quercus peduncula ta of a numb e r plante d th e e e a sam y r . U lm us m ont na 4 ll ( a ) 0 G rows we .

th e M In area west of the oine thrust the peat mosses , though

very abundant , are not individually very extensive . Those mosses

which are nearest the hamlets and scattered houses are cut for fuel,

even though they are but thin a nd small in extent . The land under cultivation is m ainly con fined to the immediate th e neighbourhood of the hamlets , or to small gardens and potato ’ S plots near isolated foresters houses . The favourite ituations for

such plots are the alluvial terraces , which , being composed of light

th e h . sandy or gravelly soil , can best stand usually eavy rainfall The

climate , though wet , is in the lower positions usually very mild in O n winter , the district being so near the west coast . the other hand , the prevalent wet or cloudy weather in summer leads to a deficiency of summer heat and of ripening power .

R IN F A ALL. The following table giving the rainfall in inches for the seven 1 90 1— th e - years 7 for three places on one inch map being described , and for Kinlochewe , which is in the adjoining map to the south , has A S M r. S been kindly compiled by ndrew Watt , ecretary of the cottish M eteorological Society

’ B rae m ore H ouse Loch a B h raoin Loch D rom a Ki nloch e we '

in h e h t . 50 ft . in h e h . 850 1t . in h e h . h ei h t Y (750 ft . ig ) (7 ig t) ( ig t) ( g

A P P E N D I X .

B B L I IO G RAPH Y .

LIS T O F WO R KS R E FE R R ING T O T H E G E O LO G Y O F T H E A R E A D E D M * INCLU IN THIS E M O IR .

1 8 1 M “ 9 . CC LLO CH J . A D sc th e s s ds S c d A U , e ription of We tern I lan of otlan , ” c ud T h e sl M an . 3 V . s . d . 6 5 89 in l ing I e of vol Lon . ol . ii pp , “ 1 0 4. G l R s on th e S d s ds and th e enera emark an stone I lan , on ” S d s th e s l s ii . an tone of We tern Coa t, vol . iii . p . xxx “ 1834 . S W A and R . M R l I C . . CH I S O . O n th e O ld s EDG K , , I U N Cong omerate , ” and S c d D s on h e d other e on ary epo its t North Coasts of S cotlan .

P roc. G e l. oc l o S . vo . . . 77 . , i p 1 83 S W 5 . A d an R . M IC . . R CH IS O O n th e S uc u and EDG K, , I U N . tr t re R elations of th e D e posits c ontained between th e P rimary R oc ks and th e O l c S s in th e T ra ns. G eol. o iti erie North of S cotland .

S oc. e r. 2 l S vo . . 1 2 5 . , , iii p . “ 1 840 . M CC LLO CH J . A G l c l M a l u s d S c d . P A U , eo ogi a p of ot an bli he by d th e or er of Lords of th e Treasury . “ 1 845 . T h e N e w S s c A cc S c l d th e M s th e tati ti al ount of ot an , by ini ters of R s P c s s vol. s R ss and e pe tive ari he , xiv. Invernes , o Cromarty, 9 3 . p . ’ ’ 1 85 O - 2 . S HA R D . n h e d t u c M acculloch s M a S c l . PE, Q artz ro k of p of ot an

ua rt. Jour l G eo S oc . 2 . 1 0 Q . . , vol viii . p . . “ 1 8 - 58 . M R H IS O I R R T he u l s C S . c s U N , I . Q artz ro ks , Cry ta line Lime tone,

and M c c u S c s th e h - H l d S c la d i a eo s hi ts of Nort Western igh an s of ot n , d be S lu A e u th e R c l prove to of Lower i rian g , thro gh e ent Fossi D c s r P c n h ss s M . . o t e is overie of C W. ea h , with a Note Fo il by J ” B r . S . R e . it. A ss c 1 5 2 . . 8 . o 8 7 . W alter p for , p “ O l l M a l IC L J . c G S c d . N , eo ogi a p of ot an “ ICO L J . O n th e N R e d S d and s G e o N , ewer an stone, on ome other ” - P uart. c c G re inord R ss S . logi al henomena, near Lo h , in o hire Q

J our. G eol oc 1 6 . . S . . . . 7 , vol xiv p “ 1858 . M R CH IS O I R R h c R c s in th e S . O n t e S uc U N , . I ession of o k H ds th e O d G u S Northern ighlan , from l est neiss , thro gh trata of and o S u a A e to th e O ld R e d S d Cambrian L wer il ri n g , an stone l ” c t our . e l o ol 0 1 us ua r J G o S c . . . . 5 . . . v in ive Q . , xiv p M R I lu H I R 3 rd e d . C SO N S R . S U , . I i ria. “ M uR H rs N S I R R n th e u h ld R c s in o o . O S cc s o t e O , I . es i n of er o k th e orth e rnm ost u e s S c l d w O N Co nti of ot an , ith some bservations th e O and l d d D u s s s on rkney S het an Islan s . " rne s Lime tone Fossil

d . . d . alto eol. oc. sc J. S n rt r S ua . Jou . G e ribe by W ] Q , vol xv 3 53 . “ 1 1511 R l R e d S d and 860 . 0 J . O n th e s th e G s N , e ation of neis an stone,

- B rit. Assoc u h H l d . R e . Q artzite in t e North West igh an s p , A d M 1 85 1 9 . 1 9 . ber een eeting, , p

M D a . l h as n c le d r . This ist be e ompi by . T it 1 20 B blio ra h i g p y . 1 2 1

“ R I . a nd I R R CH S I R A . G I M I O S . I S . s S h U N , , " ] E K E Fir t ketc of a w l M l N e G eologica ap of S cot and . "S ca le 1 5 miles to an inch ]

- ICO L J . O n th e S uc u th e es H ds and N , tr t re of North W tern ighlan , th e R s th e G ss R e d S ds an d u elation of nei , an tone , Q artzite of ” - S u d and R ss . ua rt. Jour eol G . oc Q . S . . x . therlan o shire , vol vii 85 p . . “ 1 1 M R I R d S I R A . G n h 86 . CHI S R an I I O S . . O t e A U N , L , " ] E K E ltered R ocks th e sl d S c d and th e - of Western I an s of otlan , North Western and ” l u rt ur e l. o Jo . o S c . v l H ds. a . G o . 1 1 Central igh an Q , xvi . p . 7 . “ G I I S I R A . T h e S c S c d d n c E K E , " ] enery of otlan viewe in Con e tion ” 1 i 865 . 2n e d 1 8 ts P c G d . 8 r 7 3 d e d . 1 90 1 with hysi al eology , . “ M R I R R s s th CH IS O S . . O e S c u th e U N, I b ervation on tru t re of - T ds r ns E din . eol s H . a . G . oc S . . 1 8 North We t ighlan , vol ii. p .

. 1 an e l M a 1 8 0 . 3 4. d G o . 7 . g , , vol vii p “ l M a c d . G I I S I R A . G c S E K E, " ] eologi a p of otlan "Topography by A K J s c 1 l s an i c 0 d . an . . . S e E d W . ohn ton al mi e to n h . ] in

Lond . ” c d c S d . J J . . T h e S R c d P . UDD , W e on ary o ks of otlan Thir aper “ T h t th e s s and s d e S . ua rt. r tra a of We tern Coa t I lan s Q Jou . a d 6 l. oc. . ui 0 . G eo S . G . , vol xxxiv "r n r Bay] , p 7 “ n h e c and O l HIC S H . O t M R c s th e K , etamorphi ver ying o k in ” u ua rt . J r d c M . u eol l G . oc. v o . . S Neighbo rhoo of Lo h aree Q o ,

. 8 1 1 . xxxiv. p h e s s H U D L E S T O N . H . O n t c th e G s , W Controver y re pe ting neis ” h e - s hl d P roc e l A sso R c s t H . G o . . c . . o k of North We t ig an s , vol vi 4 p . 7 . “ 1 880 . O Y . G P c e s th e V c n th e U B NNE , T etrologi al Not on i i ity of pper ”

r 9 . P M t Jou . 3 c . u . r. G eol. S oc . . . art of Lo h aree Q a , vol xxxvi p “ ” h e P re - r - S l G . T R ss . eo O N . R c s G . B N EY , T Camb ian o k of o hire 2 l 3 29 M a . D e c vo . . . . g , . , vii p

- 1 880 HICKS H . O n th e P re R c s s and R ss . , Cambrian o k of We t Central o ”

l M . N r. 1 3 w se D . 0 155 S . G eo . a e c d . . hire g , e a e ii . , vol vii pp , , 2 222 26 3 . , 6 , 7 “ LL T h e T rrid n ds l th e O r 1 882 . A W Y . o o S R C A A , C an tone in e ation to h r l t. Jou e n c s e H r . d ov icia R t ds ua . G o o k of Northern ighlan . Q 1 4 1 . S oc. . x . . , vol xxviii p “ HIC H O n th e M c and R c s P s 1 883 . S . O K , etamorphi verlying o k in art of R oss and Inverness S hire s ; with Notes on th e M icroscopic ”

u th e R c P B . ua rt. S truc t re of some of o ks by rof. T. G . onney Q

l . 1 4 J u e l. c. v 1 o r. G o S o o . . . , xxxix p “ h R s th e 1 L L . T h e A e t e w c c 883 . W G CA A AY , C g of Ne er neissi o k of

Northern Highlands ; with N otes on th e Lithology by T . G . ” 5 t J ur eol. oc 5 u 3 . . a r . o . G S . . . . Bonney Q , vol xxxix p “ ” 1 85 A n e A dd d 8 . 1 O . s th e P 885 . . G B NNEY, T niv rsary res of resi ent ,

l S c. . 50 ua rt Jour. G eo . o . . Q . , vol xli p . “ - - R c d D IX O N H . a c R s J . G s , irlo h in North We t o s shire, its e or s , T d s and u l H s h G u d ra itions, Inhabitant , Nat ra i tory, wit a i e to ” a n M E d G airloch d Loch aree. in .

1 88 M C W o th e A c du S c d . 7 . . . A ADAM , I N tes on n ient Iron In stry of otlan

A nti . ot v ol; . 89 . P roc S oc. S c . . . q , xxi p H I N XMA N H J . O R . G . . O H . P C N . H N L 1 888 . . EA , B , E, W UNN , C T C UG , L h e R c r th e G e o H LL . t M . R an d . CADE eport on e ent Wo k of u in h e - s H l d S c l d s d logical S rvey t North We t igh an s of ot an , ba e ” l . G eol. oc . v o . M u rt. J our S ld s and . a on th e Fie Note aps Q ,

l 3 8 . x iv. p . 7 1 22 A endix pp .

“ . . P c 888 LL J J . H R ce 1 . TEA , British etrography ; with spe ial eferen to ”

d . th e us R c s . IOgneo o k Lon

G I I S IE A . A nnua l R e ort o th e D irector Ge nera l o the 1 9 2 . 8 E K E , " ] p f f h “ G eolo ica l S urve t e 1 89 1 . 384 . D sc g y for year , p " i overy of

O lenellus. “ I I S I R A . D sc e th e O l us Z th e . G 1892 E K E , " ] i ov ry of enell one in North s e B rit A ssoc di f M H d . R . e s . 1 8 1 . 9 . 633 W t ighlan p . , Car f eeting, , p “ Z H and J . O R T h e O us th e P C . H . h 1 89 2 . EA , B N NE lenell one in Nort

ds d . rt. ur. G eo S co ua Jo l. l. s S oc . v o . We t Highlan of tlan Q , xlviii

227 . p . “ h I - - . nd J . O R T CH N a H . e c S 3 P . e th e 1 89 . EA , B , NE heet in North West h M A ss c . H ds d t e m u G c B rit. o R e . ighlan uring axi m la iation . p ,

E d u M 1 892 . 720 inb r Dgh eeting, , p “ I I h e G I c e A e and its R h A u J . T t e 4 . G 189 E K E, reat g elation to ntiq ity of 2 d 3 2 . rd e . . M an . 3 p “A dd s th e l Z the CH . P . th e O us 1 8 94. EA , B N ition to Fauna of lene l one of ” - h s d . u r 1 6 1 . a t J r . . 6 H . ou . e l c G o S o . . North We t ig lan s Q . , vol p ” sc P - d P E N C K A . G aus ord s S c . 189 7 . , eomorphologi he robleme N We t hottlan ur E r Z tschr t d er G esellscha t dkund e z B B d x . ei if f f u erlin. an x xii i 46 19 1 . A s c n T he eo ra l l . . . 1 G hica Journa pp b tra t g p , vol xi

1 63 . ( 1 898) p .

G I I S I R A . A nnua l R e ort o the G eolo ica l S urve 1 897 . E K E, p f g y for the

1 876 . 1 7 1 8 . year , pp “ H R c D sc u s and its O R J . D d 1 898 . NE , The e ent i overy in n onnell Fore t, ” - h e G th e T ra ns . bearing on t eology of North West Highlands . S oc a nd F ield lub I rn ss ci . . . . 15 1 nve e S C . . , vol iv p d “ an P R . u M R R S IR J . LL c S 8 . 1 8 9 U AY , L U A Bathymetri al rvey of l L c s d e oc . s S c d . R o G o r . S th e Fre hwater o h of ot an . Lon y . g

3 a . s 7 G d s 40 . c s th e . Lo h of Broom Ba in, p ruinar B in , p “ ” 89 8 G O O CHI L J . G . D s d in . T ra ns . E din. 1 . D D , e ert Con itions Britain

. 22 . G eol. S oc . . . 0 , vol vii p “ M C I . T h e s s P s in S d R c s as I n 1 898 . A K E, W Fel par re ent e imentary o k ” di cators O f th e Conditions of Contemporaneous Climate. T ra ns .

c . . 44 . l. S o . . 3 E d in. eo G , vol vii p

C I s s and . T ra ns . I nverness S ci . S oc . a nd 9 0 2 . M . 1 A K E, W Fel par Climate

F ield C lub . . . 19 7 . , vol v p “ H R c A d c s I n S c s G P es d l 2 R J. . 90 . O 1 NE, e ent van e otti h eology "r i entia

R e . B rit. A ssoc . G s M 1 90 1 A dd ss S c . re to e tion C p , la gow eeting, , 5 p . 6 1 . “ and P LL R . m c u th e I R J. . S 9 4 . M R R A S 1 0 U Y , , L U A Bathy etri al rvey of ” s c d . P T h e L o c th e E we Freshwater L o ch of S otlan art VI . hs of ”

J our. . x . . 5 46 . . G eo r. Basin g , vol xiv p “ h c S u th e s L c S I R J . 1 90 5 . M R R U AY , Bat ymetri al rvey of Fre hwater o hs “ ” P V T h e c th e . l d . s of S cot an . art II Lo hs of Conon Ba in i u . 42 . c F a nn ch eo r. Jo r. . . G g , vol xxvi p "Lo h ] T d . . H R . . L H an G . O C J . HO 9 P . . 1 0 . 7 EA , B N NE , W UNN , C C UG L W T h e G c S uc u th e o - s H I N X M A N . eologi al tr t re of N rth We t ”

l r . M em . G eo . S u v Highlands of S cotland . “ I I l c M a S c l d d c d c e A . G 1 9 10 . G S I R E K E , eo ogi al p of ot an , re u e hi fly from ” th e O rdnanc e and G eological Surveys .

4: I ndex 12 .

’ in 2 D ioll id a M hill B h ri B inn T arsu n . a c 6 10 . e , , 7 , 6 M e u 9 5 1 55 58 D e 24 B en . . or Thr st, , , , iorit , - 2 1 D n 25 . 1 13 . e e I XO N J H . B . iotit g iss , , , ,

- - le nde c 3 6 . n 1 1 n B c a R e 5 1 . hor b s hist, o h ry , iv r, , - c 19 6 0 5 8 D r im R i 6 6 9 7 7 7 79 u é dh 69 80 . s hist, , , , , , , , , , R uadh 88 , . l voc h 5 1 5 2 10 4 D u c 25 10 2 B larna e . 6 , , , bh Lo h , , , . 1 1 14 2 2 G 1 1 n e 8 . NN . B O 6 . C a EY , T . , , , , of r mor , - l —1 3 D n R dh 10 4 c a 9 8 0 . un a R ui h ua B ulde . o r y , g ,

B ae e 5 1 0 7 1 72 73 75 9 2 93 D und nne ll 5 0 5 1 5 4 9 8 . r mor , , , , , , , , , o , , , , I nn 1 10 , .

B d e G ud c 88 R e 4 5 6 8 69 74 9 6 10 9 . ri g of r i iv r, , , , , , , B R e 4 5 109 D un L a aidh 10 4 room , iv r . g , .

- B ruach ai 9 1 . D e 9 15 1 8 19 2 1 24 25 26 29 g, yk s , , , , , , , , , ld n ne 1 1 5 B u . i i g sto ,

e e n 26 . gr ,

A B E 8 . C U I , 7 T C H I T 4 1 5 1 R e 79 80 8 1 84 . E S R N S S S 2 5 9 0 iv r, , , , A E , , , , , , , — 2 2 2 4 M ne G ne e . adh a B e a 5 2 7 . 6 88 . S ee C g, , , ( oi iss s )

idh 5 . B u e 55 . ucce n in 6 66 , s ssio , , E id id n l la C a a M or 9 1 . h an C ac G ea 76 . m s , h , — E l F an 4 6 6 3 . ea n raoch 2 4 2 5 1 0 6 a . C mbri , i , , , 1 n i F uc d B ed 0 . a C ra bh e 1 6 o 0 8 . oi s, , , e 4 4 60 S u h n 1 ne 9 6 7 b ain 9 1 0 8 . Lim sto , , , , . , , ua e see al P e R c E d e 4 1 Q rtzit ( so ip o k pi osit , . 2 E d e 4 1 42 2 9 10 46 47 53 60 6 63 89 . 3 7 . , , , , , , , , , pi ot , , , E d e - - nul fr n s 5 4 99 . e e 73 C a o 6 7 . , , , , pi ot biotit gra it , ’ B hior in 3 4 4 E d e - e ne - a n l a n a 7 9 . u e 66 a 7 . C r , , , pi ot pyrox gr it , n L och ain 25 E d le S 1 1 a u 3 . , . rra a , o th , — B eac B e a 72 9 3 . E a c B l c 3 5 103 10 6 . r g, , rr ti o ks, , B e c M Or 70 r a , .

B eac M eadh onach 72 . F A N N I C H M O UNT I NS 3 10 64 9 5 96 r , A , , , , , , D ich ara 8 . , 6 M r 1 1 F asa h 2 1 4 o 6 . 6 1 , g , , . C a n e 1 6 1 8 20 23 24 25 28 32 F ul F asa h 14 3 9 44 4 8 6 1 r mor , , , , , , , , , a t, g , , , , , , 9 1 is 4 F C a 3 2 C a n na B e te 83 8 . 9 9 r , , irst o st, , . na C ic e 0 c M e e 1 4 44 1 3 9 48 9 1 . 7 . 6 r h , Lo h ar , , , , , , n a m B uailtean 2 5 F ul 6 39 4 7 89 9 1—9 4 10 8 , . a ts, , , , , , . l c re - d n 3 6 . n a 1 8 C e . h orit s hist, p Torri o i , F l 4 C l a e d n an e 12 40 . e e 3 56 im t of Torri o i tim s, , sit s, , . i F nn B h e inn 1 1 5 1 C o ach 9 2 . 8 86 8 1 1 7 . g , io , , , , ,

C e B e a 100 . c l 6 1 5 25 9 6 1 0 0 10 1 oir g, Lo h , , , , , , , , R a ac 83 i bh h , . ” C nan R e 4 F ndla e C a le R c 0 3 . o , iv r, . i t r st o k , F n l e e 9 . C a 39 4 1 92 1 C a 0 9 1 1 1 . o g om r t , irst o st , , , , , h 28 0 3 3 38 10 8 F J C o ac 3 . L TT 88 S . pp y , , , , , E , , ” F l n - u C e 1 1 6 . c c 1 8 2 1 opp r, i ty r sh ro ks , , . P n 2 F olais 1 C 5 . 6 1 1 8 20 34 5 1 7 3 13 . orry oi t, , , , , , , , R F C a o 60 . a n e l ca l 8 r ig y , orm tio s , g o ogi , . R a iri i h 8 2 1 F O W R d 00 . C reach an L S I R JO HN 1 15 1 1 7 . g , , E , , , F F h ua r in 6 . t d e C e a an a 7 99 . r g , ros bris , F ua M r 4 2 B ea 5 4 . c o h g, r Lo h , .

C h orcurach 47 53 5 4 . F uc d B e d 8 9 10 48 49 52 , , , oi s , , , , , , , — bh 2 D h u 0 . , 7 , 7 ’ ’ C l a B un 74 . F u nace 16 1 7 18 2 7 30 3 2 33 1 13 oi h , r , , , , , , , , ,

- C e mh e all B ea 1 9 24 26 . 1 14 . r ag g, , , M e adh o n ch 19 a , . —M h0r 5 4 G L N 1 1 6 . , . A E A ,

na S oinne 19 . G a C e M or 82 84 g , rbh hoir , , .

~ h ornbl n ~ R ainich 6 68 69 70 . G arne t e rock s , , , , de , 87 . C rom asa 3 G n e 4 6 . 3 7 6 8 69 7 1 78 8 . g, ar ts , , , , , , G a an 70 93 rv , , . D I B I G R O O R R I O I 4 1 G I KI J 1 9 S 0 . A A G UP (T D N AN) , , E E , AME , S I R A 12 34 4 . , , , 3 . I ndex . 1 5

- G lac al E n 6 9 6 . nd u ace re d n n 3 12 i rosio , , La s rf , p Torri o ia , , , l a n 5 —1 5 G ac 9 0 . i tio , G lackour 0 1 e c e B u n 4 7 . 8 . , 7 , L ki r , m G lascarnoch R e 5 . e c e l 10 99 10 4 10 9 1 10 , iv r , L k m , , , , , . G la M e all a 4 8 L ed own 9 1 . s h Li th , . g , M or 10 2 e e e e 2 . 3 3 6 . , L tt r w , , ’ G leann C ad a D h e ir l e n e 1 2 76 . 6 5 3 4 a h h g, im sto , , , . B ian asdail 48 4 9 60 9 1 9 8 ncl ne 1 7 20 24 26 , , , , , . sy i , , , , . na M u ce 5 58 98 10 1 10 2 e an G n e 1 3 6 8 9 10 1 2 i , , , , , L wisi iss, , , , , , , , 1 4

ana idh 5 84 1 1 1 e a o f M ne . u lane T , , , st oi Thr st p , ul c a 3 4 16 17 18 30 6 4 6 5 66 77 78 83 84 85 8 6 . T a , , , , , , , , , , , , , , , e l e 23 Lh rzo it , . e ne 3 5 a c c 10 l l 1 2 90 1 1 5 Lim sto , . Li ssi ro ks, , , , , . len e n e 1 G B ruach ai 1 1 2 7 50 . 9 5 34 3 5 3 6 45 46 4 g, , , Lim sto , , , , , , , , 7, D 8 9 90 c e 6 1 9 1 . . o h rty, , , G d c ua e 1 14 u 6 1 62 9 1 9 8 . 1 15 . r i , , , , q rri s, , n 14 ne l n a . 19 . Lagg , Li ar fo iatio , an 1 1 6 1 e a u e 1 1 Log , , . Lit r t r , . G len l le G u na d 22 2 e 85 . 3 28 39 4 1 1 1 1 g, Litt r i r , , , , , , .

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