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M.U.. !..>,., „ ,^rAlM I.L.D.. K.K.S. <;i':*>i.o(:\ A.\i» iM:n!0(;i!Ai"iiv MoINT DAMASK A i'K( )\- 1 N( ■]•: , .!■' , J , i.-.m -J li A, Ykii iiMuntiiiii, C^ui'bt'c, tugftlicr with a iniij> ta illu'<- tiviti' till' -aiiic. 1 liau; iiiiiiciar t" lir, Sir, ^■.llll i.lnilii lit >i'i\aiil. (;. A. VdlNi. On \UA, .I.-mv., 1!I05. 1(;_„_11 CONTENTS Ti.|«>Krn|.l>v S*Hli!in'Ut.ii-y riick.^. . . . Stnieturt- nf Mjiini*, . . Fii'ld ffffcts of M>'taHior|ihHiij PitrnK'^l'liy. Akerite KitM-xitv . Y;ini:i*ku»- Ihk.- l!.i»toim. Crtiiiptonite .... Syenite-aplite. . Ni|)liilit< ■Syenite . . YainaMkit«- . MetaiiiiU'phomHl apdiiii'-iitary n>ok!i Oriifiii iif Mijimtain lllt. Yi»iiiii»ka luoiintiiiii is iitu.it. d in th.- proviiKf of Viflo'c. al.out thill V Miil.> ii.'aily -iiif ''"^t froiu th.- city ..< M-mtival. It ri«-i al.rui.tly from th.- «un-..iiii.hn« (.lain, in th.- t.nviishii. of Sh.-Uorl. just .-Hst of th»- St. llym-inth.! luul St. (JuiilHiiim- hriim-h ..f (h.- Ciiiiii.liaii PaciH.' Ilailwayiiii'l iH-tw.t-n tin- viliai,'.'s of AI>lx)t»forla ti.m h..-. h.ii^' 1h-cii ■•.■.■o;;iii/;.-. A.lanis ( ') has proiK.,H.Hl t.. call them tli«^ Monti'iv;:iaii Mills, .l.-iiviiiK llu- nam- from Mount l«..yal, tin- Ust kii..wn in U-r ..f t!u';;r.mp, an.l at whose foot lies th.- city of Mont real. As {...int.-.! out l»y Sir William I^.^an, (») six ..f those m..un t.iins. in.lii.linu Y.im.iska, li." in a ii.arly strai;iht line .-astwar-l from Moiuit Uoyal, uii.l this, th.- most west.-ily, is aUmt fifty miles from ShelVonl, the most east.-rly- Th.- two remaiiiiii- m.-mU-rs ,.f tlu- i;r..ii|. li,. i„ a ,i, II. I liii.>, sli-.'htly to th.- -mitli of th.- first. The l.n-.'.t ..(■ the .Muut.'iv-iiin Hill- is I'.r mi.-, ulios- i-m-ius .-..iv hi. an iiiv.i nf thiity wiuare mil.'- iin.l .-i tn.isinmin iiltitml.- of 1, 1 1'" f.ft alsiv.' th.- s,.H. "( ■■) Yaiii.i^ka c..i.'i> iihout liv.-aii.l a half s.|imre mile-, h;is uii ii;n.-ou- ...iv ..t llir.'c -^|ii.ir(- mil.-s an.l is l,.»tiO f.-ef l,i«li. Til.' -iii..ll.-t Mt th.' _'!■.. u|.. Mniint .I..I111- ha- :iii area .>f i^'neous inrk- ..t I.',- thiiii hull' :i -niai.' mil.- an.l it- .iltilu.l.' 1- S7."> f.-et. (') All th.'-.' tii..,ii,t.iii,-. a. -t.it. .1 l.y I'l- A.lains aiv .-haiateii/cl hy i ,,t' i:;ii.'.iii- P'.'k- li.iviiiL.' a rclal isi-ly lii-li ronti'iit ..f ,-|i|,f vari.'li.- "I' th.' fii.'k- .u-' ilkali- xit.'-. Ill 'iiiifin. th.' ni"Uiitiiiiis „,,r t.i I imriisions of th.- natiii.' -t l,i.v..lilh-., tin.' iic.k- an.' halilv al-n Ii.'IIIl; .■.iiii|i alkalis an. svenite.i. II .t i:;ii.' ahiniiii.i. ih.'lini- -vcnit.'s .111. 1 ■intrusions of the .t ~ti»-ks." ( ■') iM ,Ioiir. of (J.'.il., V..1. \i, p. -W. (^) (iwil.iKy "f 0111.1(1.1. IHtW. ).. '■'■ (") .-luminary Rei«irt ('.«.!. Surv. .'.in., l'.".!, p. ISO. (M Jour, of ChoL, vol. XI, p. i").''. (•) .lour. ..f (:.'..l.. v.,1. \i. p. ■2:>i. i 8 II ciEol.or.K \i, srnM:v ok ( av.iiv Tu|'iM,l; W\\\ Ml Mill .\ I S Wl \-KA Mmint Yaiiiaskii i-, ncaiiy i-inular in i.utliiir, but iiioip clipsclv apiniixiiiiatt's an flli|ise, whusc tiaiisvi-isi' axis runs alxiut twclvi' clegn-es east ot' nortli ami nieasuivs l'.."< miles, wliilo the i'i>njui,'at(> axis i> 1.MJ niilfs li.ni.'. Tin' area nt' tlit- muiintaiti i> slii.'litlv less thin live and three i|uarti'r si|uare miles. The shape <>i the hill .s suniewliat |ieiiiliar. Two |.aiallel riilires rise abruptly to lieii^hts of lietween l.OiKt au.i l.l'Od feet almve the surrouiidini,' country, and the hiuhest point of the mountain. l.l'OO feet almve the plain or 1.47l» feet above the sea. is found on one of the small peaks of the northern riiL'--. Thes,. two ridtres, runnins; about northu.st and --.unhe.i-t. form the >teep tioitln-rn and southern faces, and are eonniMted liy a somewhat lower and m inarreij. however, by one isolated peak on the eastern side, about tnidway betuein tin- luo main ridires. Approaehini; from the <'ast or west, the imjiression is of a \oleanic mountain, whose crater's rim, still staniliiiL'on the northern and southern faces, has ln-en broken down on the I'asternand western sides. ri;i:\ mi - I'Km iiii tiun.s;. Dr. 1. .Sterry Hunt ( ' ) has di s(iii,.d in detail certain roek speiiinens from Yamaska and «i\en several analyses of theiifeldspathic constitu- ents. He sui)posed the m .in part of the mountain i.i brtninied of a mica- ceous syenite, but stateil that the rock of the southeastern [lart was entirely ditVeretit, iH'ini.' compos,.il hugely of hornblende and plai,'ioclase feldspar with considerable ilmenite and mau'netii- imn. Dr. Ells I-) lias biielly ijescribed tin' syc-nitic type as exposed in une locality and has called it a nepheline svenite. i;i:m:i;.\i, (;i;iii.i)i,\ The dilliciilt |iroblenis involved in um-avellinj; the i.'eoloi,'v of that part of the proxiiice of QueU-e lyin:; east of the Lauientian hills ha\e enitaiicd the attention of various meniU'rs of the Canadian Geolojiical Survey, at intervals, ever since its inception. The geolojiy ,i{ this re'don a.s it is now understoiKi, i-, ijiven in the later rejiort.s of Dr. R;1Is. (■') The MontereLrinn hills form a xery strikini; fi'ature of the landscape, their well w-otwied slojies risin.^' abru|itly from the broiid. marlv level, cultivateil |.lain of the St. I.Mwnniv. vallr-y. This |,.ve| muntrv (M tienl. Slir\ (.'.III. lS.\s. t'\ CimI. .Siiri. C.in. VmI 7, ism. i.,.i. .1. i.. 71;. C) ii.-.,|. .'Siir>,. fan.. >■■!, l-J. |..e' .1: v 1 :f. I ss; ,s |,,,|, f^ . ^,,\ - ^)^,^^ pa- 1 .1 . >KilNT \AM' 9 II is iiiMTi'ii Ia .1 niaiilic- oi if unikeil r];\\ .iini ^ilIl(l iliitt. > il'toii ut i,'ri'iit thickni'ss. aiiW iiwiiii; it^ jiri'M'nt |"i-,iti..n t^i tin- s.m. uhicli ilocjiied thf area at tlio iId.m; ot tlir Lihuial inTiuil. The plain lia-., in t!n' pMninri> of ( alxiut seventy miles. It i^ liniinileil by twn cunveiLtini,' line>cit' elevateil country, tlu l.auientian liii;iilnnii^ nn the nortiiuest and the mountain^ anil hill- lit fl]f nciitiiern e\trii--icin nt th. .\|']ia[arliian n[ilitt on the southeast. The wholr lit till- river \alii-v. «itli the i-\ie[.t inn I't' niuinr intni-ivi' Ijodies, is iiiuierlain liv I'alaen/iiic tnrniati'in-. 'I'he geoloj^ieal structure of tliis area is eharactcri/eil iiy a ;,'reat fault, the St. Lawrenee and Chani|ilaiii fault. «liieh eriis»;e- the Jnteriiational Hnumiary through tile valley of Lake Chani|ilain and i un- llieine in a northeasterly direction. It crosses the .St.Lawrenii- ri\er just aUive (.i>ue!«x', strikes across the Inland of Orleans and jiasses thence along the lower valley of the river. The strata on the northwest side of this lault lie hori zontallyor ,vith verv ^'entle dip-, while on the simthea-t side they occur in -tiep, I'tien imatiiineil fnlil-. ciiuiplicitiil liv faultini:. The Mat -trata nn the "c-t nf the fault range from Lower Devonian downv^ard intn the i'lit-dain sand-tone at the ha-e of the C'auihrn- Siliirian. • In the east, the -trata range from the eipiivalent in age of the 'I'lvntiin and Black Hivcr linie-tones, of Caml)ro Silurian a:;e, down into the Cpjier Ca::il)rian. The formation- on the eastern -ide ditl'er in the character of thi ir -■■dinirnt - and in their fauna from those on the West ; they lia\e liccn ^neii Imal n.imt- and together compi'i-e the (Jneb'c (,'riinp. m |.l;■lI.|||.^■ M|- Ai;i:\ -i i;i;mimiim. Mm nt ^ \m.\sIv \ A- ilhi-lrated on the ;.'eiilo;.'ii-al ni.ip of the di-trict in "Inch the Monterei.'ian hills aie situated. Vamaska umuntain lii- almut a mile and a half we>t of the .St. Lawrence and Chaniplain fault, and so is surround(>d by memlH'rs of the folded and faulted (ifuebee Group. A probable line of faulting, running jiarallel with thealxne main fault, is shown as iias-ini; tliiough Uie centre of the mountain and forming the line of contact lictueen two memlH>rs of the l,tuebec (donp. The older of the-e lies on the east of the fault and is know n a- the Silleri/ formation, the vounger, on the west, i- the F'lriih'iin division. The outcrops of Sillerv rocks east of .Mount Yamaska occur in a band-like area rniniing aljout southwest and northeast, whose iiorth- westerlv luinndarv passing thi'ouLrh the untain, forms » nearly straight line. This c.rea is the southerly extension of a band of Sillery rocks reaching far to the noith. Thirty llxe miles uorllieasi lium Y.inia-k.i till- band i- a mile wide: in a -outherlv direction frnin this 10 II <;eolo(,kai. srK\KV '>y < \\\ia point it IMpiiilv "Icli'M^t'i il lllM\illlllIPl l>lr:liltll nt ■.I'Vl'Iltrrll inilf", tlifii gradually rniitnu-t- fi.i a wiilili ..t iiirir mile- mIi.'Ii M|,|u.-it.' Yaiw- aska and, c'.iitinuiiiu Ijci wr"ii .'i-ht an. I litt' m inili- tartlicr south. end- in a numli'i- ..t ton-n.' lik.' |ii"|rrtii.n-. Tiif Silk'iy consi ts almost ('xc-lu--ivi'ly of r.'cl and yi-t^rn -latt's \wili ImmIs of i,'i('i'ni-li ^ifv saiiiistoni' ami u''"it. Tin" rock outcrop- aio usujdlv limited in extent anr. KIN, "tlie nx-ks of this area ajijiear to liave been tln.iun into a serie- of folds, and |.roha!ily -ome of tlie -yncline- are over- turned " ( ) The Sillerv ha- been a—iirned to the I'l'i.c! Canibriaii. I'he beds of the formation are iionf..— ilifemus and it- a^e lias been detei'iiiiiieM on stratii,'rai>hical and litholo^ica! urounds as -hou ii in other areas, especially in the vicinity of Point Le\is. Strata of the Kanriaui t'. iriiiation -urroiiiid the alio\e de-cribed area of Sillerv locks, except « here the Sillerv is coiitiinied a- a narrow bind to tlie northeast. The rocks of this series lon-i-t mainly ..t black limestones and slate-. The slates are sometimes gritty ami, in certain area.s, are pebbly. i)n -traiigraphicid ground- the pebblv slates ai-e thought to Iu'lollg to the upper pejrtion of the l"ai nliaiii tei-iiiation. The scattereil nature of the outcrop- prcvi^nts the working cait, in detail, the -e.iuence of the Vieds, liiit it would appi'ar th.it the Farii- ham -ti-ata, al-o. have l)een ;.'reat!y folded. This formation i- fo— iliferou- ami fos-ils have been found witliin a ifw miles of .Mount Yamaska, -bowing the strata to be of Lower Trenton age. At several localities between the line of the St. Lawrence and- Chainplain fault and the band of Kandiam strata forming the western border of the Sillery area, oee\ir fo— il- of Chazy aspect, thus sbouin,' the presence of beds of C'ambio-.silurian age older than the l-"ariihaiii. Arranged in desc«niling order, the following foi in.ition- .iie present, except th.'ise in pareii'hesis. which do not oi eiu' in the immediate neiiihbourhocHl of the mountain. (.'ambro-Silurian (Lorraine or Mud-. in liiver.) I I'tie.-i.; 'Trenton and ISIack River.) i'arnham or Lower Trenton. t'hazy. iC'alciferous. ) i Potsdam.) I'pper Cambrian Sillery. (•; (;..,!. Snr., f'-m., \i.l. 7, Is'll. |ar' .1 . p. .'):.'. MorST VAMA^K\ 11 II In :i .livtiioi in xv Inch rXj".Miii- .iiv .,'|,,im'.'.l -o wi.l.'ly ms in the CUM. it thl';HV,l liri.lcl .li-CU^-inll. thl- IKltUP' aii.l I'n-lti.in nf Im.'- .if rnntan nm-t ..tten he, l.'ir}.'--ly, mattcix ,,t' ii.f.'icii.v. In the L"'..ln-i cal iv]..,,! (l.-ciiliin;; thi-^ area the cnntact U•t^^.■.■n tli." Sillci v. (I'l.l.pr Canihiian). aii.l the .un.am.hn- Farnhain tianiat i-u. (I.iav.t •rrmtnul, is tli.inuh! t.. Ii" .if tli.i iiiituiv ,.f an unri.nl.inhal.l.' .'liai. al.-n- th.- en-t.Ttl l..a.lrr ..f tl,,. SilhTV ai va \v liil.' al..ni.' thr u.i-tcni Mile it I- sujipii-.l tn '"■ il'ii- ti. faultin-.l ) The position of tins siippos.'d fault, ,,n nhi.l, Yaniaska i- sitiiat-i.l, is known within naiTow limits at a ninnhri-..f hK-alities. At a i.i.int thn-.. nul.i< ti. tliLMii.ithnf Varnaska. aii.l at a mt,,u.1 point alxmt the same .listanre t.. ih.- -oiith. . \]...-ui-os .,f the t»o t'orniatioiis occin- within short disiama's ..f oiii' ani.liiri-. |'„uv.a.n thii-. ,^v., p..ints. .-nc rp! on tlie ni.iunlain or at the fu.it ..f it. tli.Te iuv n.. ni.'k .Mitcrop^ (.. in.li.'ate the p..Mtion of the fault. .\ straii.'ht line ,oinin- the .ihovelwn ,leie,niin.il pi.ini-> w.ail.l pass thi.iUuh about the centre ..f Yainaska aii.l on the n^ap ..f the iHstriel, ^uch a line has l.een drawn to mark the prohahU- poMti..n of ih.. line .if c. intact. riir, --KlilMI'.NTAIIV lini'KS nl MnlNT ^' A M \>K \. Th,, i..n...iis rocks, .f M..unt Vania-ka ar.' Mn i..nn.|e,l !,v .i /..n.' of. Miainlv, .netatn..rpl' 1 -"a,.,. Th.. li, f ctita... h.-t^.'en the ,.^n...u^ -e an.l tli.' M.hrnentai v .-.illar is \erv irr.i:.:nlar Imt approM- mal.i- an .illip-.. wl„,.,. tian.-ver...,,xis runs northwct an.l s,,„theast ,,, parallel « ,th tli.. t u,. niani, ..uter riiL'es of the m.mntain. Dnthe n,„ii, an.l ^...uh ta.a.. tlu' In.,. .,f cnta.'l .-l.-.-lv f. .11. ■» > tlu' sununit ..f themain n.k'olmt ...I il a^t.ni.i u.-t m,1..s it passes al.ai- cU.se t., the f..ot ..f tlie ^lop,.s, Th. M.,lnn.n1aiy .olUr i< ihu^ ui.h-t ..n the Miuth an.l north ta,.e> an.l iva.hes i!- ni.ixi.niiin uMth .,n the latter ta..'. ^^h■ !■■■. f.ir a -l-il .li-tan..'. it i- l.alf .a mil., hr.ia.l. Within a ,a,luis ,,t -cNeial mil. ^ fr.iiN tli.i to.,t . .f th.' mountain, th.'re aiv n.. exposures. ,.x,.ept ..n the u, .stern m.1,. ^^h.■^■ th.'r.. ,.:■.• a f.-w ^rnXU-vvd r..ik .. uteri. p~. ■rh..M.li.nen.arvro.'ks,.f the ,-. .liar are of I lir.v t vp.-. -laf.. liorn- tclsi.r mi.r..hiehlv m.lam..rph..M-il forms ..f slate, an.l san.l-t. .lie. .\t ,,„c,.xp..Mne the r....k i^a ^lat i-L.tuerat.' with pel.l.l.-^ ..f ^an.l ., , with this on.. ,.x,-epti.ai all of the r...k, helonu W .me ..r oth.^r of the above t! : -e this^.s. The una!tere.Ulates ..f ill.' mountain, « h.'rev.ir tli.-y ..ivur, are alwavs .lark „i ciloiir, usually l.lek. an.l lun ,^ a w.^ll .i,.v ..li.pe.i -laiy .lartine svhi.h 111 m..-t .a^.s. at least, appe.u - L. f..ll..w til.' .. al Ix'ildinH planev, whuh are s.mietnnes iiu licat...l liv tm.i liiii's .it mm -m (1). Uwl. Surv. Can., vol. 7, IsDt. I't .'. 1-2 11 (.l>il.ni.l|-.\|, >i m |.;v tjl ( vs \i, \ liuht (-..Idurf.! :;rairi^. Thr ,l,it.^ ,uv -ojnrtiiii.-^ Iii:,'lily cnnt,,i ir.l. I'ltli.T en a l.ii;.'!' M'iilc. iiiiliiatr.l l,y rapi.l cliaiiije^ in llic -ti'ikc ami ilij.. ..r una much lin.T -,al.- and iIhmi -Imwu !.y ininutr i,li<-jitii)M>. The uiialt.M-f.l slat.-- a|.[.-ar cviy^ hriv i,, ^n,,!,. inl.. .., I.. !«• intcrlHMMc.l witli lu.rntVls, th.- luttor lu'iiii,' umlouhtly a iia'raiii..i|ih.i„.,l t,.! f the former. Th.' slati's an- iii..st i'.)!!!!!!!!!! al.ui;; the ui'st.-iii t'.K.I .it the ini)iintaiii.--|..'<'ially..ii th.- ii..i ihu.-tciii sl.ipe ; (■xpiisure:4are als.. t'.iuiul on tin- fastciii side aii.l at iut.'rials ..nth.' iicirthiTii an.l s.intheni sIi.i.ms The f.Mit .)t' thi' in..utitaiti a(ipni\iiiiat.-lv marks th.' ..iit.'r limit ..f tii.- /..n.' '.t i,i.tairi.|ilii~iii \iithiii «lii.h .'xpn-uivs ..f iinah.-io.l slate ari' lar-.-. Ihc hciiitVK \ari.'s -lijlitiy |„ ;,|,|,,..,raM.e ; iisuaily it i- ..t a .lark .•.'l-cy .■..I..in- with a -iiuhtly \iliv,.us lii~tr": -.,iii,.li |h I..iiri> ilark.a- an. I th.' r..ik lli.n ap|..'ar-. .Ln-.-i. All \ ariatl.,iis, tr.irn th.' .•.iin|.arativ.'ly s,,ti sl,,f,. t,, th.' MTy hai'.i h..iiit.ls l.i .'akin- » itii an irr.'-ulai ..r .•..M.'h..i.Jal fra.'tur.', ar.' i.rcs.'iit. N.'at tli.' In f .'..n- ta.'t v\itli th,' ii.'ii.'.iiis I'.M'ks, ,Miall tVUKpars iic-ur in th.' h..iiif.'ls an.l s..ni.'tini.'~ th.' r...k jiasM'-. int.. a more hiifhly alt.r.'.l tniii; .'..nji...-.'.! mainly ..t' lar^v an.l -mall t.'|.l-.|,ar in.livi.juals. Th.' ..li-inal li.'.l.liinr plane is still in.ii.'at.'.l ;,. many . \|-.isiii'..s ,,t th.- h..inf.'ls hv lin,- lines of liL'hl .'..liHiied grains slmwiny false hclilin- ..n a niiniit.' s. ai.' as in til.' .'ase of till' unaltereil slates. Hi.riifels i- ilii'!ii..st al.ini.lanl ..t' tlie rocks i.f s,',lim,.ni;iiy i.iiMi,, t.mn.l ..n tli.' in..initain an.l .h.-iiis eM'rywher.', l.iit ni..r,' .'si^niallv ..t, th.' n..ilh,'in an.l s,,u;hrni faces. ■| h.' saii.lsinii.'s ar.' Usually lin.' t.. in.'.liuui ma inc. I r... ks ,■, ,ini.,,seAMA^K.\ 1.1 II (-). l.i'i'ii t'lt Mt vl.itr .iiiil liiirnt'.-K « ith ,c nuruln'r "t ri.miiaratiM-ly thirk t"'ilv ot Siiiiil-.ti.u.-. {'■'>). l.."iiMi flit ut' >liiti> iiihl liMint'i 1< witli iM-ra-iiiiii.il li('r|> lit' -^aiiil' •^tmit'. (4). l,."ii"i tVri nt ^lati' anil imrtit'i'U "itli i.roasiniial lir. i- ot' -ami- stone. (5). 1,000 fcfi iif slalr. li -iiiti U aii'l -iriiUt. .lev ((■)). L',000 tVet lit ~lali' "itli iiiraMimal lieil- nt •.aniUti.n.'. -riti i'n i;i; m i iii: ^KhlMK^■^\l;^■ >ii;.\i a. Tlir -tiiki' lit' till' -triita. a< i'\|io-.iil mi tlir iiiiniiitain. \ .ii !•- niii- >iilnalil\ ami ..tti ii ia|iiillv tVnin |.iiinl ti ]iiint. liiH in niMirial, lie-- a few ilcL'irr- tu till ra-t ■ it n.ntli. 'I'lii' ilip \aiii-- «iilil\, -iiniiitinu- ttiirty 111- fill ty ilciii-i'i's within a lii^tain t" imr humlivii yai-ii-. 'Hi.' strata i-> ufti'ii vcitical, but iiioiv fiein-rally i-. iinliin'il at ratliia- lii.'h aiii.'li''^ ami tlicn aKvav~ tn the cast. The striki' a-nl ilip du Mnt a|>]irai- to liavc lif. 11 ai.iniTialily alfr'tiii liy tin- iuMn-mis intrusion. i'\..'|it iniiiu'diately aloiii; tin- eiinla.t. uIhii-. --i.iiirt iim--, tlicrn appeals tn h>' a temieiiry for the strike to rnnfiiiin tn tin ilinrtinn nt the line of rnn- taet. Till' rapid vai-iatimis in the stiikr and di[i .uv smnitiiiies -n-n to ln' Miir tn minor tli-xuivs. At otlnr pniiit- thr ■■\|iii-.iii ■■■- are iint^iiili C'tentlv eontiimoii- tn pin\i \\hitliii tlin laiiatinn- aiv diir In tnldiii.; Ill- to faultini; hut, a- .a rulr. tin y appr.ir tn lir due tn Inr.d t'nliU. A /nne of Uri'cri.-itinii. aliniit t \> i • liiindivd ya'd- ill « idt''. i'\tend< t'rnlll llir t'nii' lit till' lilnlinlaill tip tn thi' line nt i-nlltarT ,lt alinllt thi' eeiilie nt till' -until taie. Wit in 11 tins /niie. thr lii'ii-, niainl\ partially altered -lates ,ind lini-ntrU. .iiv limkiii intn laiL'e and -mall Murks which ha\e shifti'd tlirii positions ri'lalivrlv I' niir :innther and are soiiietiiiies faulted nii a minute seale. Thi- aiiule <>i dip of the strata on the western side of tiie lireeeiated /nnc is ii-iiall\ hrlweeii t'nrty an I ninety decrees, wliile on the eastern -ide it is seldom a'.nn r thirty (le;.'rees. This jrein'ral decrease in the .iiiliIc of di]i i- e-piri.illy noticeable tou an Is the -iiiiiniit nf lim rid- i the ca-t sidi t the zone, where tin- l.id- lie in a linri/niilal pii-itinii. The cnndil inn nt alValrs seen in the litv. ri.ited /niie and t he strata mi either side may 1k> explained as beiiii; due tn fnldin^ ■ r faiilliti^. If it l>e tlioULdit 'II li.ne miu'iiiated fmiii faultim^. I hen t lie fault runs liarallel with the -trike nf tin- -iiat.i and the bed- nt' the .a-terii siile il.lNe iieen reial Im'Iv U pi III el i. 1- -ilil" II il\ i in 11 in"e| ,01:;ie ni ,,,[., The Zone of brecciatiiiii ma V also be thouj/ht to mark the sharp fold- ing and fracturing of the strata alon^' the axis of an overturned anti- 14 II OEOLOCilCM. -rK\l:\ (IF I AVAUA tlillr. Tllc -UlPl"iNitiiill nt ,1 toi'l I- tUllll.T -U].l...|t.. \i\ till' ;i|.|-ui'llt ri'jx'titiiiii lit' tlic stnitii ciii I'itlin -i.l.- i.t the lirccciiitt'il zoiic ii,i ^Imwn in the iji'iuTiil sci'tidii ulrrailv i^i^'ii, tli>' zdin- ot" l)ri*ci'iiitii>ii lyiii;.' l)ft»i-i-M ili\ i^i'iiiN ( :i) ,iMil I I ). Fiis>.iK ji|i]icai' til !«■ iiliM'iit t'luin tlir vtuk- lit' till' ni(i\iiit.'iin .iinl thi'Ti-t'iii'i' till' ciin-clatinii of tin strata niii-l prnrml mi litliulnLjiral ami structural LiinuniU. A^ .ilnaily vlalnl, tin; L:«'i>Iiii:iral iiia|i of tin' ill- trirt siiiiw-. Mnuiit ^■al^as^;a a- Ihiiil' ^ituati-il nii tin' Inn' ut lulilai!, .suiijiiimmHv a fault, IwIwim-m two tuliliil ti iriiMt n m^, tin- Silli-ry, ir|,|ii-i Cainliriaii I .III till- ra-l, ami the laiiiliain il.nuir 'rniitun. ( aiiilirn Silurian) nil llir \M-t. 'I'lir diarai tn i.t'tln' -trata ..f t hi-. I wn fur- niiitiims is quite ili-iiin-i, tiir SiUriy liriiii.' r ) -il iliirlly nt' li-ii ami ;;ri'fii slates with iiumernu^ liciU nt -amUlniif. uliil.- llir l'"ariiiiaiM t'orniatiiiii i> fiiriinvl nf dark slatr-. : liiMi-sti ^ ainl -aml-toiies ur.- iml ki'iiu n to 11,- ].i,'~i-iit. The lilark slates nt' tile western llaiik of tlie MKiuntaiii a]>]iear, Imth (111 lithiilin,'ical ami structural i.'iiMiiiils, tn hclui!:: tn the Fanihain tnriii atiiin ('» ami the |.resincc lit a pcMily -late at i-iic iiuti|ii|i |if..haMv indicates the presence lit' ihc upper iiietulicrs it' the t'ni inatiMii, At (iiie expdsure, se\eral thin hill- nt -aiiil-tmie are iiiter-tratilieil with tin- slate- and, piinj; eastward, across the strike, the -lati-. aluays dippinu tiiwariis the east, ajipear tn pa-s i-nnt'nriiiahly intn lui-asiires in which sand-t'iiies are \crv alMiinlaiit. Sime -atiil-tnlics are not klinwii tn occur in the Farnhaiii t'ni mat imi il apjiear- tint tile limit of tie- I'arn iiani must he snniewlicic tn tin- west of tiie lieavy sandstmie heil-. t In litlinlnj;ical ;,'rnuiiil-aiiil timii the cnn-iileiatinn nt' tiic structure nt tile di-trict it seems necessary tn .issunie that the strata cnniposini; tiie eastern two thirds nf the sedimentary collar helmiL' tn the Silieiy fnrmatinn. ( i Ihe -and-tniie lied- nf thi< pnrtinii nt' tin- mnuntaiti lire similar to those sn eliaraeteristic nf tlie Silli-ry t'nrinatinii tn tin- east tii0U}.'li he red slates whidi u-ually .iccnNipany the -.iiid-tnin - •ire not seen. The absence of tliese slates may he lunre ajipaieiit than real, since the interlK>dded slates of tlie sandstniie area arc now mainly elian;;e(i tn hnrnfcK. Assuming tiiat the alin\e cnrrelation of the strata i-cmreet. the /one nf brecciiition alnadv de-crihed. even if it h" due In .-i t'ault. (-,-uinot mark the contact of the Silleiy ami I'ai idi.nti I'miiitii imi- -im-e it lie~ within tile Sillery area, sandstone iieiU being eipially ahundaiit nii either side nf the /one. At no other point on the mountain is there .anv iiiflication of a fault su(-h a- wmild liiijc.' the twn fmiiiatinn- ilito contact, but, on the other hand, the ;irala of the i«o lormallons |i) UhiI. Snrv. Can., vn!. T, WH. |iart .1, p. ?•. (■■■) (ieol. Surv. Can., vul. 7. 1S|14. |..iTt .1. |.. .VJ. 'm\ vol' Ml MiilNl \.\MANKA ID II „|.l„-ai ,-..iit..niiiil.i.' to nil,, iiliuilier. It i> cTtiin, tliat tl..' f..niiatini,s !„.t«.MTi tlir l'- aloni,' the oavtcrn I>opIci- of tic Sij- ley .uca, m «liicU tlic strike ami ,lil. of tlic two formation, arc nearly jmralU'l. While the /one of lawciation may mark the i^i--.!,'.- thron-li tlie SiUerv of the fault uhich. cKcNNh,-,e. ha. he, ,i .u|to-.l t., torn, the ..ontact l.et"e,.„ the tuo tormalion.. Vet the facts seem to in.lcMte that in-!ea.l it leia.srnis theaxisof an overturned anticline within ,1„. Silleiy fonualion .ucl that this fohl passes into a syncline in the (';,ml.io.Siluiian strata on tlie uest of the mountain. rii;l.|i K!'! i:i -IS ciF MKTAM'iiaill-sM '11 uter houn.larvof the/oneof tamorphi-m MiiTounilim; the i-neous core uf .Mount Yaumska ,8 appioMinalely marke.i hy the toot ,",f the mountain. Within this limit the shu.-,. which on-nially Ion,,- ,.,1 ,1, .,,,,,,.,. ,,,,it of the stiat.i. usually ha\e hi-en more or less com ,,letelv'altere.l t . homfeN. t ,„ the cast aid west shies of the moun- tain, where the sclimentai- collar is naironcst aid the ::cneral strike of the strato is al-proxinrntely (.arallel to the lin- .,f coiita.t ot the i.rneous core, m-arlv unalterci slates sometime- u. ;,lmost m .on- tact with the i-ne,ms rocks aid the y.mv of tiie metamori.hism seldom ai.pcars to he wider than one hundred yards, i 'n the north and south faces, where the -eneral -trike is almost at rmht aii-les to the line of i-ontact, unaller.Mi slates usu.-illy occur only aU,n-, or ^,■vv near the ,■,„„ ,,i, liie I intam, at distances \aryin^' hetweeii luo and six hun- ,lre.l Viirds from the line of contact. The heddin- planes, as is so often the case, appear to have been the direction of least resistance to the steam and other nietaim.ri.hizin^ a-ents ac.'ompanving the igneous intrusion, with the lesult, that where the strike is at riiiht an^le- to the line of contact, as alon- the north- ern and .southern faces, these a;,'ents worked most enerixetically and the slates are verv eenerallv .altered to hard, resistant l.ornfels. Where the line of contact wa- more nearly paraUel to tlu' .strike, as alon- the eastern and western sides, the penetration of the heils was more ditiicult and the metamorphism more limited in extent. Ihe slates, altered to tou-h hoinfels aK.iiL' the north and south faces, acted as a shield .and prevented the wastinu away, by erosion, of the ijineous I ... -.- :.]... «1... l^uc .>lt*irt>-l >i till' fa. t ilim it is i-i>iii|K>>i>i| .if a iri.iif itMistant variety of iiineims rock. NuTK. Tlie ciiliiur" of the fectitin r D on .ici'iim|innvin;,' ina|' n' prrscntiii;: csvxiti', Hulixarii'ty I. hIi.,u1i1 Ij.' culoino'l. in^fpi.l, t.i \r pr<'5»'iit fssexite, varii-ty tl. i'KTK<";i; \Pir> . Illi; iiVE.ils i:ii(KN. Thf i;.'iii'ims cure iif Mount Y.ini.iska h s jin uri-ii of tlut'p and oiif fftith si|iiaiv miles and it* outline, thmiali very irreirulur, apiiriixiniatt's an fllipse. Tlie ilitfertMit varietifs .if the iynp.lll^ rocks funii a scries riin..'ing from ii syenite of th.. nkerite tyfw to a v.Ty lia-ic rock ,i!liepfiire or after complete ditloreiiti iti.ii «ill !„■ .liseusse.l later. Init, frnm evidence furnished in the li.ld an.l from the iiiicru seiipie exaniinatimi of th.' Picks, it is certain that 'he maL'iiia underwent con.siderahle iMin.anent during ..r aftei- •he pei lu.l ..t dillei'entiation. This miivement. whi.h helps to explain t he irrei,'iilar cnitlini's ..t the areas of the ditlerent types, i^ «ell -.huwn in many localities bv liand- ing and tlii« slructiiies. Till' h.Mindaries uf tlu' varimis area>, as -.hnvvn un the accompanvini: map. aie >..meuliat arhitrarily drawn. This is due mure to the lack .if exp.isure than to the difticulty uf a-ssiirning the rock of aiiv one locality t.i .me .ir other of the three main divisions, for. in most cases, the two extriiiM- types ajipear to pass rather ahrujitly into phiuse.s of the iiit.Tuiediate \ariety. The ahrupl tian.sition ..f .hlleient tvpes ..f r[ai.'net Cove, Arkansas. There the symmctrirally aiiaii^.^.l r.icks, apparently without inierniccjiate types, or, ur in -.■vi-]i .li-tmct /ones ■.-iry.rirr it! i-hara.-ter from jaeui>iraiipitcal the centre toanaii.i ->. uiie .if till' pulaskite ty)ie at the periphery. Local causes have, in i. riain parts .if the essexite area of Nariiaska. srt uj. suili struct iiri'^ as iian.!- ^"^"^ MOCNT Y\M->K\ 17 II iiiK whorcbv s|i(Miiiiens tioiii si, me lovalitir^ omsiikTcd liy tlii'iiisolvcs would !«• urh an instuncf, neither ri>ik, but a i-iiiu- biiiatiuii of till' tud, is tln)ii;.'lit tn repii'sciit tin' trui' naturi' of tin- iiH-k iif lilt' liitality anil it is with siu-h an iiiKlrislaniliii;; that the area has bot-n ma|ipi'ii. Tlip aUcrit" tyi"' imtui- m- a ii:iirM>v lumil aloii;; the w.'stcrii h.ii Icr mill in a small di'taclicd aiv.i .m ilir «i-stei'ri sjdi. ,,f tiie ijinwiug core. Till' yama^kite f,- its trachytie structure and. at some exposures elose to the contact, the ijrain is niueh finer. It is probable, thou;;!) not cer- tain, that thc-c chanj,'es are endomorphic in ori;;i!i, since they occur only hIicic the essexiti- is in contact with the sedimentary strata. The area^ of these, presumably, contact varieties of the essexite, are indicated on the map. The yamaskite does not occur aloiii.' tin n- tact and shows none of tin results of endomorphism. AKi I.TIK. The .iki'iite is of medium to coarse itrain. Iiolociv-Mllinc nia^-iM- in sti'ucliiic .111.1 "f a lif.'ht !,'rey or i.'i'i'eiiisli-i^rev colour u . atheriiiv' to a liL'hti'r, Usually slijihtly yellowish tiiii."'. Plaixioclasc a-,. I alkali ti'ld- -pal- fireatly predominate over the dark colounii cousiitu.nts wiiicli, ty[iically. consist of biotite with small amounts of pvioxene and soine- tiiiK's a little hornblende. The relative proportions of the ditierent Iti— ii-J !■< II OKOLOcilCAL .'•I H^K^ i.K CKWIIV .,,11-tituriit- lui.l III.' -i/f '•{ i.'iain vary frum imiiil i.. pnint, ot't.-n witli in th.' liiiiii- .>t' .1 ItAuA ^yi'i-'uwu . Tlii" folimivil con^titiii'iits. :it tiini"<, ,,.,i,| |,, t,.i 111 in Ii.iimI- Iimv iiil; tin' inti'i-spaces (nvr fi-i'iii tlimi tlun in til.' ,iv.Ta-f r.Hk. In u-inTal, tin- t.-lilspars .K.'iir in lai-i' irtv-iilailv uiTilliKi'|,vnl h- apix'anmi'i' to tlto nu-k, wlnii- llir Lini;. nai r,.w fai'.'s, parall.'l »itli n'l'l), an" usually ili-l iti.tly >tnat.-.l. I'lir i-:,lli.'i ;ilMiii.l,inl l.i.itit. t iiiiiH in thin llaki-^ wliusr clcava;;!' t'aii-. iir.'u'iilar -t millnir aii'l ..flrn mntaininL' ^iiiall fi-LUpars (..•ikilitiially. ..I'l.ii iiiiM~uii'~ I"" t'l l"i " in iliaiiiil. I, tlii.ui;li tin' ni;i|i'iily ■iif sinalU'i-. Th.' I'Vinxcnr anii ill'- [[■.nilil.'ii'i.'. "Km piwi-nt, l'.'Ii.'i.iI1\ at-.' in nnu-li snialliT, l."-s nntic.:iMi' iii'liM'In.iU an.l, »illi "ii<' "i '"" ,.\c.'|ptii.n~. .iiv ^>■^v iiiu.h l.--^^ aliiiii.l:inl tlun llu' lii.itit.'. >'\('.'|.i alui^ til.. l„ii,lfr ..t til.' main ak.'iit.' aiva. uli.'iv tli.' liornlil.'nil.' ratlin rai>iilly takr~ lli" placr of tli,' liiotit,' ami l..'c.jin.'> coai mt of -rani Imt >.till ri'taiii'" it- irr.'-ularontlim--. Tli.' innva-o in amount of li..inlili-ii.lr is u-uallv a ii].aiiir(l hy a iliTiva-c in 111.' ainoiiiit of f.-LI-par . tli.' plaLlioila-.' U'.Miiir^ i ■.■ lia-ir an' t'ol- lowiii;; niiii.'i-als : ].lii^'i.H-las,. ir\.\-, ■i, alkali f.'l.l-i.ar. .luai!/. lii..til.', pvi'..x.'nf', lioniUl.'ii.li'. ii-..ii ..r.'. [.yrit.-, tilaniti', apatitv. zn.'.ai an. I .small am.'unl- "f -.■•■oii.iary min.'ials. 'I'll.- M-rv ali.in.laiit |ilaL'i".la-.- f.'l.l-J'ar. f..niiiiiL.' al.oiit ..ii.'iialf . .f i-a.li M'cli.'ii. ."■'■m- in in.li\ i.lual- \aiyinL' -'i.'atly m -i/.', ii'.t only t'loiii i-...k I .k Imt in tli.' -am.' -.■.li.m. Tli.- lar-.'r f.^Npar- aiv. i- i,,nU ai' i.li..m.iri.lii<' than th.- -iii,ill.-i ami iiMially i>o--.--s l.illL.'. lath-lik.' f.inii-, wliili- tin- -luall.f .m.-. th..u:.'li liaMir.; tli.- --am.' t.'n.l.'iii-v t.. a-Mim.' lath-hk.' ..iitlm.-, ..ft.ii a|i|i.Mi toi...l liy ih.'ii nuiiihi'is to a-.ium.' iii.'iv ..f 1«'- iii.i:ular -lia|..>, Th.' laiL'.'r plaLim ila-i". ai'O not sharply s,.parati'.l fr.'m Hi.' -iiiall.i on.'-, -im'.' all ..it.'r nii'.liat.' -', ar'tcr |.lai;i.M l;i,c. iln. nnMt iiliuii /..iial intrri;r.,« ih «iili |.lri;;ii>- ila^r, ijinli- li' i|Ui-ri!ly an iinli\ pliial "t alk.ili t'.-M~[i,ii- aii^l •'■^ <« ii tliat lli.-v t'niin i.n.- sfctmii. r.aiipu^i'il in ■ iiic i>ait •<( |il:ii.'iai-, uini lia\iiii; tlieie Hu. |iaits rniiiii'i-liHJ liv an ana .it |.rrlliitic nii'ii'ii.'1'm I li. A ^niall ahiniint cil' .jiiart/ nrciii--- in -ni t' tl tiipti-. in ^mall ii ir^'iilar ;,'i'aiii>, tln' la>t to t'.'ini. 'I'Im' l.ic.titi' i^ Ipioun in (■..]., Ill-, \,i\- ^In.n^lv |>1 Iiii.ir, c li::lit Vfiiiiwi^li I1I..WI1, n .|i-,.|, lin.vMi. 'I'll.- tlak.'- aiv .ptt.n \.-iv la:.':."'! anil have t'iiriii'' u^iiallv a-->.M-iatt'ii uitli thr pyiuM-iii- ami li. .|-nli|.'nil>>, ami tVi-i|iiriil ly lias a [".ikilitic •-triirturi' iliir to inclii^ioii^ of |.lai;iiH'hi>r trliUpar. I'yroM'n'', tlioii^li aluay. |.ifsi-iit. i^ ^iliioni llic iiionI aliuiHlani coloiiri'il i-on^litui'iit. 'I'lii- I'l-isinatii- clravai,'!' i-- ratliiT ui'll il-\f] o[Miic trmls lo form in |iii^nioii|,. It lia~ a paK' i,'ircn colour uitli scarcciv anv pl.-ocliroi-m 'I'lic rxtinction ani,'lc, measuit'd in a section wliicli iliil not ^'ive ,iiiv '■ptical liLiiirf in con\cri.'cnt liiilii, was :ls . Tliis low extinction ani;le tou'etlier uith the pale i;reen coloiii- imiiiates tleit the pyroxene is a ilioji-iile ,inil poor in iron. Ilornlilemie is, in tin- normal akente, the least aliunil.int of tJie I ojoiired constitui'iits anil fn-ipientlv appears to ln' ah-.ent. The niineral fornw iiae;,'iilar imln uliials very often iiiter:;ro\vn or associated "itli the liiotii''- In two sections a u'rceii \,. ietv oi'curs. ipiite strongly pleoi'hioic, from dark irra^^ irreeii to H^ht ;,'ieeii. In some of tlie sections, apparently from more liable \ .irieties of the aki'iite. ih.' hornlilende isliniwti in colour, \eiy pleochroic, f -dark ip-ddish hro"ii II = dark brown, a - li^'ht yellowisii-hrown, absorption, f ;• b ^fl- I In'- hornblende clo.~ely reseiiibk-s the hornblende of the essexite and yamaskite, w liich has an extinction an^le of alxait It and appeal^ to be a b.i-.altic hornlilende. The ininerai, al times, is charucd in sj.iots "ith dii-tdike particles so that it Ix'comes tiearlv "paqne. Sonietiine.s, these title iiiclilsions take the form of ndnute rods lyin;; parallel with fine aiiotlier, or, as in basal sections, I'l-ossini,' one -mother in tiiree directions. in one section ot a liornhlemlic yariety, in.iny ot tin; brown hoi'iiblende indiyidiials, either alxiut their margins oi' sometimes towards the interior, haye ihani;ed to an ai;ij;rei;ate uf j,'rains re.senib l(i — ii-li.t 20 II i.EOLCMiUAL BUnvKY OF c WM'V li„« iron or^. with ..,l,er.'.ain,,....tV.,ly .•..l.„nl...s,u,.l al ,,.,ui,-..ntly r.-mnwnt^ <.f tin- h..inl>UMi.l.-. -ft.... appoiirint: nm-m-li. |,.,.„nr.-i.. usimllv, i...tv.-ry anuM.l.int in tl.- no.„.al ak.-rit.- It «emTallv -K.i.r. in iVrt'^ular uminn ii.clu.l.Ml in or aKs.H,at..,l w.th tl- c.,lo,,r.-.i Lisilioat.-.. At ti.u.-s it n,.,H..ns y,.,>nK.;r than tl.o r.v-x-ne an.l th.' i.lH«i.H-las.- may !»• i.li..nic.rvl«if t.mar.ls it. rsuallv a few Muall u'rainn of ,.yiMt.. an vr.s.Mt ,,,,.1 il.- v-n to Ik. ..riuiarv l.ut. in on.' s.rtion, «l,..|e it is ra.l.-. al.un.lant, n.mh ot .1 is ,...omlarv. «inc.. it .K^-urs U-t..:u tlu- f.MM-.s i„ irf..,ular .ran,.. with all tix- «,.,«.ar«m-s of haMM. l- m .1. ,.oMt...l Uy ,..n ,.!„.,..« solution-. V Muall a.no.Mt of vUovv. slightly ,.l,.KiMo„ M,,nn- i- V-vsmt, usually in im-jiiilar grains, in on.- scrtion in.'loswm -„,„■ ot tho u<.u ore. \,.atit.. is always present an.l s..M..'tin..'s ,s ,,uit.' alnin-lant It f..;„'ssn>all. 8tou, ,.r>sn,s ,..Tfe.-tly colourl.-ss. l.ut .Hrasinnallv hol.l.ng z..nally a.iaii:;.'.l .lu-t in.-lusi.nis. \ few minute /.ircons sometimes .Kvur. .n.lHMl.le.I in the .■..loui.-.l .-onstitm-nts and .•„.• -...■.!„„ hel.l a c.n.l.arativ.ly lar;.'- .n.ln.-lual of the mineral. Small a unts „f eahit.'. ka..lin a.,.1 otl„- „1„ V nii.ior.U are j.resent in many of ili.' thin -pctioiis. The verv al.un.lant lath lik- in.livi.iuals of i.lau'io.luM. .haia.l. , >/.■ the thin seeti.-ns: the oth.T .■..nstitm-nts, espeeially the ,o]„ur.-.l hisilicat^s. u,mv in l.-^.s r.-^'ular an.l usually sn.all.T to,,,,-. ,,|.|...Mnn^' t., lie h<.tvv.-n. ..r to Ik- ,«..n.'tra,..l hy, th,- i.la.i.K-la^- t.l.l-,.,.. . Ih.- l„r'er,,la:.'i...-lases mv.u t., hav f..n,..-l h,.f,.r... ..r at tl„. -a n„H' „s^he nvn.x.'n.-. l.ut th.' lHii.»l ..f .■i-ystalli/.ati..n ..t thr lMm""' overhms U.at ..f the ,,y>ovne an.l the later, small.-. n,.hM.l..aU ot plaui.K-lase a,. voun..T .!,:,.. ,,yr..xem- l.u, ..Uler than .!,.• horn . l.n.l.- ni.l l.i.-tite. Th.- n.i.a is son.etimes int.-r-rown with th.- hornhl.-n.le t,ut „„.re,-.,nMn.,Mlva,.,.,-ars t., hav.- fo,„,...l lat.r. Tl„- >,-..n ore ,s .„.m.,-allv ..M.-r than the f.-l.ls,,ar an.l pyroxene th..u^h ,t. .•■no.l ..t ",-v.stalliV.ation has soe.eti.n.-s overla,,,,.-! that ..f th.- ,.yr..N. n.-. \\ .th ,heexeeptionof.,uart/, th th...las,. ai,i..^ars t.. hav.- l«-.-n th.- la-t mineral to fo, in a.,.1. .-..n-.-iU'iitly, lia- irr.-i:ul.,r ,-ntlm.-s. I„ ,1„. :„-,-,„„„anvn,- tahl.- i- uix.n ai, ,;„„lyM. ..f a m.-.hu,,, u'niui.-l ,■,„. f,l„.ak.-ritefn-.-fr..mh..nihlen.l.-. Th,> ai„l tl..- -...■.-■.■.nni.' anal- ysis w,.,-,- „,a.l. m ,lui.li.-ate an.l th- analyti,-al n,.-th...ls n-,-..,Mmen.l.-.l l.y Hillehran-l w.r,- us.-.l. Analyses of ake.ite fr..n. N.,rw..^Man l.,.-al.ties Mol N 1 > AM \^h\ 21 n liiivi- U-i'ii ii'lilel fur (•oiiiiMirison and tli<-y iliow the very cliwe clu-iiii- oiil rettttioiiH existing l>etwt>t>ii litem ruckw. Ill Si<», . AI.O. K-, I » , JVC) Mk'>- fail X», <» K, 1) CO,. TH),. P, <>, V, S., Mnd Hu < ) HO 1 (i:, (I 'Ji (1 111 1)7 u 37 :.7 7'< W 01 Ml-.Vi 17 "■<> \>< -M 17 W) •J '.pj :t '."• 'i '.*> a '"4 :» 74 3 3* 1 ri> I '.« I '*7 ■t m; 3 W) 3 117 5 (IN » :4 4 «i* :t r.i B 20 4'4<> 1 i3 W I 008 "ntu \ is: !l!l 23 11)11 iili liK- "ix (I). Ak''iitr, .Muiiiit YMiii;i-k.i. (;. A. Y.itiiii.'. aiuilyst. ill), .\kfritf, W.C. \W'r^i:i'v. Kiiiptiv -I'^trin.- ili~ Kri>ti.iiiiiii;vlii.-trs II. !•. .•i.'l, IX'.t.', V. .S'liiiirl.l;, aiiuly-f lllh .\k.|ll., 11, <>. I.:. II-. NU. Mil-. NatuiM.I. .\.\\'. \. W, 1^-1, r, .l.inna^iii, aii.ilv^t. I'lMin lln' al' .\.- aiiaU^i- ■j.\\i-\i ih t.iM.- I. tlir a-ial il- |...,ili.,ri i.t' ihr I'" k li.i^ l>.-.-ii r.ilrulat.'.l t.i 1)1' a-. t'"ll"»-. ; (Quartz OrthiK'la«e. Albite Anorthit*' . Bintite Uio|iHide Tit»iiiferoin iiiagnftitf. Apatite Pyrite Calcite It' tlif aMTagi' jilailiix'la-'f fi'liispar l>i' a-suiiii-4 t" In- a ba.sic ulign- ( la-.' »itli llif ratio. Ah: .\ii:: •-'; 1, tlicii the aiiinuiii i.t i-liigioclaat' t'elil- .s|«i. invM'iit u.iiiM 1m' l.i.Tti aii'i ..t alkali t'i-kl-|.ar. --J «."i . I''i.iiii till- .uialv-i-^ iiivi'ii it i- I'Milnu that, in cliiMnical compo- .-iti..!!. thr rn , t'niiii Yaiua-ka l»-k.n^^ |,i tlif aki'iitc type of syenite H- il.'linril liv I'.iuir^,.,- I I I. 'I'lii^ i,„k. .1- fnini'l at ^■alila-k(l, is also 7 i»2 liflS 12 '.17 U Xi 86 t> IM) 11 -Ji 1 -S) (I). Die Minrralien der Sypnitliegmatitfrange. W. C. Br.i(tg*f. Zeit. tur Kryst. und Min.. v(.k Hi, issd, |,. 4.1. ai .. 11 i.KOLO'.KAI. StR\rY nK CANAIlA liicalitifs. Until air ^viMiitic- in ii)i]M'iiriiiH'c .iiid ri.iii]i..v,.,| cif alkali liiiiW'i'al<)j.'ii'ally \i rv -iiniiar t^ lliat nci-iii'int; at thi' typical Nni\i --i.iri fcl(isj)iir, pliwiiH-la^i- It'll ispai- ..ttni with an mitfr zone ositioii ot' this rock in the new system ot' cla^si- fiiation pi-oposid liy Messrs. Cross, lii(lini,'s, Pirssdii ami ^\'asllilll,'ton, the norm has Wn ealiuUited am' the roek assumes the followinj; |iosi- tion : — Class IT, ilosalane. Orili'P ■*!, lieniianare. Kail;.'. 1', inon/.onase. Sulii iiiu' t. akerose. r.ssr.xiTK. Thr 111 •-iriiilioii I'l the area niapj^ed as essexitc is atti'iioed with eoii- sidcrahle (litliculty. The I'neks ..f ditlerent exposures vary widely in mineral eompositi .n, in texture and in eheinieal composition, since they include the forms iiitenneiliate lietwcen tikerite aii-\ a'iety 1. Suh-variety 1". Siih-variety •'!. (/>'; M'tliiim to aHti'"" I/rained, tntc/iytlc. The areas of the-e varieties and suh-\aiirties have Ihcii indiiatid on the aceompanyinir i.'eolor;iral map. (Aj t'liiiry til /tiiK yraitiiii, i/rannhir /mr/'/ii/riii': The hub-varieties included here, with the exception of the tliiid, prolxihly represent endoniorphic pha.ses of the essexite ; they form a Zone of varying width along the line of contact, tM.j.i v\iiir.- iiie akerite ik-chis on the west<'rii and eastern Ixirders. Ml a- NT VAMA>KA •23 I. Sub I'llii'ti/ I. Tin- siili-\:ui.iv .K-ciii-s iil<.iig t!i.' ui-triii lialf nt' tli.' suutlieni («.uiiiliirv, au'l as a /oiif .■xteiuliiitr aLam tli'' ii.atli.rM ami cavlriii iiiaruin nt tin' >"V<- U-twffii ttie main ai.a ..t' thr ak'Tit.' "U thr «.-' anil the Miiall .Aii.iMin- ..t tlir -aw n.ck mi the ra-tnii linr ,,t ,(in- tart. riir m-\ t!i.- -al. \arirty aiv in. •ilium t.> c-mirs.' -iviini'il. li..l.'. mainly, small talmlar tVMsiiar- inv^'ularly arrani;.-il. wliirli, wh.-n ti.-li, ..t'ton haM' a i.'l..-sv ai.i..'aian.-i'. With in.iva-in- .■i.ai- m- • .'t urain. tli.' (lark cnstitufnts may Ijec.in.- v.a-y al.un.lant in.l ih.- r...-k thus ;.a.-s intuyamaskit.'..!-, inst<^a.l, th.' t. 1.1-i.ai- may i. m.' ..miimnllv talai lar, the h.irnlpk'n.l. .■nrrini.' altt.^'.^tli.-r int.i-titially an.l th.' r...k raj.i.lly Kradiuj; into th.' tiarhytic t'..rm ..f vaii.ay i I!). S.,i,„-tim.-, a tl,,w s'li'iR'ture is niipaivnt. th.' I'li-niati.' in.livi.iuaK ..f ImrnUionde lyin^' lianillel with onf anoth.M- ; in |.la.'.v ihi- tl..w ~t nut uiv passes into'a ban.lrd one in which the alteiiiate l.an.K aiv ri.lier aii-l [...orer in th.'.-..loui.'.l l.isilicates A (..a phyiitic strurtuiv has ..f ten devel- oped, with lar^'er indiviihial- ..f li..riilil.'nd.'. sometimes of pyn.xene or hiotite, Ivin;; in a im', pres.-nt, Th.' -mund ..f these p,,rphyritie r.n'ks mav hoionie very tin.' irraine.l an.l the roek thus pass int., Mib-xari.'ty :'.. ' th.'r .aM's, lar-.'. irn-ular. p,.ikilili.- indi- M.luals of horni.l.'iide, w Imse eleava-e t'a.a's fr...|U.aitly iu.M-.inv an inch or ni.MV across their l..nL:est diameter, lie in a ni.'.lium ;;iain.'.l un.un.l. I'n.ler th.- miv!u!e tli' '.-r /ones are s.imetinies composed of acid olig.«-lase and occasi.inally ..f .irthoclas,.. i >1 I'll ^;S ..-■ip.'ir cjcciir> in Xiiryiiii; ;iiiii>unt~, ^nii'-iiuic^ iii'.irlv I'cuiiil liii:; till' |ibi^'ii«.-|,i~i' umi at ntlicr tiiiu"- unlv ~|i,iiiM','lv prc^riit. It lia^ t'"rini'.l ill laii,'.' ,iii.l -Mi.ill irTi'L;iil:ii- iii.ii\ i.liiaK. the la-t, va\f iifi'hi' lili'. t.i I iy~tallizi'. Ill ^Miiif >.','ti,.iis t'' ..itli.irlav.' i^ \.TV roarer ailM \i"h\< ali till' ntlii'i- c.Jii^titii.iit-., .■\(c|.i til,. ii.|i|i.litr. |ioikilitir,-,llv. Tlir imiis iciiial- a IV usually iint » iiiU'', i, ^oinrt iiiio ~li..w |>i'rtliitic illtl'^- ul■"\M li- ami, at ntlirr tilllrv, aplirai tllnl, ln.M\W',ll rn.-,ii| lliiiil^. In 'iiu' iii-tanri' ii \\a> ii.i^^il,!,'. ,.ii a ^iMii.rii |Mrallrl tn Milii) tw iiii'a>urc till- cxtiiii'tiijii aiiuli', n . n. "iiirli «a^ t.uiii.l lo 1„. !_'■', iiwiicatiiii; alkali t'clilspai', licli in ~M.la. Till- aiiiMunt ■'t n''|ili<'lit,' vaiir- tVcHii ^.'.liMii tn ^rrtion ami >.,iiir- time.s it is absent. Tlu' iiiiiiiaal ncfuis in foi-iiiK'ss inilividuals tlio la^t • ' c-i-ystiilli/',', ^onictinii'- -n ' s.iini'tiini'^ lari."' anil then, like the orthoelase, (leeuiiiiiL' in i^i'MiihI !ik, area* hcihliim the i 'tlh r e. .nstitn- ents. except the alkali teliKjiar. |i.pikiliti.ali\-. The amount ni pyiMXeiie ehaii-''^ fi ->eti,.n-. \v here it i~ the ehi.^f' eiihmreil een^tituent, tn i.tlna- where ii i- aliment. The mineial. usually, i- in rather ^inall, iMumieil grains, pai'tly nr whnllv -in reuniieij hy lionihlenile. When ineie abiinilant. the indiviiiiiaN ti.' MUently have lunf ■ le-- |ieite(t ]ai-iiialie iMitlinev : tliev are .it'teii 1 w inneil anil show very ili-timt elea\ai;e-.. 'I'lie |i\ro\.ne i-. in iiiu'ix. a titanit'eroiis \ari"ty, ii-ually deriileilly ]i! -hroie tnun a pale Mnuky pink or th'sh eolmir to edoui l,>s^ or t'aintly uiveii. The eolour Is niueli more pronouiieeil in -nme sli.i,>s than in others anil, oeeasioii ally, is seen to vaiy irrei.'ularly tVoin v|iot to -p.it in tlu' -aiiie erv-tal, apparently unaeeompanie.l hy any ehaii^i. in tl \tinrtion an^le. In othei' in-tanee- till' pyroxe-iii' inili\ iilii.il- are .|i-tiiietly zonal, tlu' ilif t'eieiit /one- inilieati>(l hy the atran^eiiient of' the minut.- ilii-t like inelu-ion, •oiiimiinly present in the minia-.i'. The horillilelHle i- the lleep le.l.lish liloun, !ia-..llli<- I H Ull 1 lien, I, ■ ,|es- ,ril)e,l as .le, iin ini; in tin- iiioi,' ha-i,- t'oi in- ot thi' akei'il,-. Th.il thi' hnriilili'nile i- ot the ha-allie typ,'. am' i. it ot' tlw liarkevikite serii-s, i- apparent w:, n any attempt is ma.ie to work out the niineraliii,'ie)il composition ot' tli,' to, k from it- ehemieal eoiiipo-it ion. t'oi the uiin.'ral must l>> lii'.'h in ii,ith lini,' an, I iii:e_'n,'-ia. u hile the harke\ ikiti,- horn hleiules api'ear t" he too low in mai/ne-ia ami loo lii^'h in iron ami alkalis. TIm- iiiiii'Titl is usually very ahiiiulant. the imin i,luaU ai,- e,iiiiiiionly irreifiilir of outline .■imi freipientlv ocur surr'Uimlimr or interuniwn with the jiyroxeiie, thoiiL'h. in s,im,. -ei'tions, laii;er, more prismatie f,,rms, oeeur. Ueeasionully, a \erv -mall amount of a u'reen hot iihl'-n,i. with a ilitFereilt extinction aiiu'h' i- ine-ent, iiit,'i x'rown "ith th- Irjoivn variety, ul- tlie latter may ha\- a narrow, \aL:ii,iv (letinetl Ixiriier of it. m^^ W^^ VOl-NG MOL'.VT YAM.NSKA -•' H lildlitc i< |.ii''-iii' in :iU tlir ^^'I'tintis, usually in iMtluT -.mall aini'init-. It is vn-v jili-iirln nil', hrnwii in cdlDur anil coniinnnly lias fwi'nii"! in rat liiT small, irr.'-nlar tlakrs a-sm-iatiMl uitli oi intri'^'i. a\ n uith rlif liornl.l.'ii.l.-. \ i>-\\ small, invu'nlai' in'ii\ i'iuals ..t .ili\ iin' .n.- i.i"-.'rit in s,.,. Apatiti- i- u^iiillv alinnilan'. soni.lnnrs so nuirli sn as Ik i,'i\ca IHiikilitic apiicarancM' tn tin' hni-nl)l'-n'li\ "itli wlii.-li it i- titiii'iiI- ; orcasi.milly it Imli, zonaily ananL;''i du;-' -liki' inilii~ion^. i(in oil' is <'oiiinionly aluimiaiit. n.cun inu rlmtly ,i~ l.iiLTf ami sni.il! iL-cgnlar, (K-ca.sioii.illy i.iiMinia |iliir, ■,;i,iin- a"o.iat."l \sirh tin- lioiri lilfndraml hiotilr. FiiMnirntly by rcl!rctfly I'li-s.-nt. .is-.. ,(iati.'il "itli. or in.'luilnl i.y, till' iion on-. Titanito is ralliiT .■ilinndant, o.cuirinu' m pair yrl|o«, .li-tin.tly ].loo( hf.>i.' inili^i'iiial-, ori.;i^iun,illy idi.imorphir, hut nioi v oftrn \ .•^y irlv•_'lllal■ ot ..ut liin\ it is usually not as-oci.-ii...! with thi> ii'oii oiv. Small amounts ot' s.Tonilaiy iiiirLi-i'als, -uc-li a- caliit.'. sriictt.', aiiii, \vhfn nrjiliilito is inrsont, proljalily \Uo niinut.' ipKintities of zeolitfs, or(.\n' in tho thin ^i-ction~. As in tilt' akoiiti", the ("Tiods of ci-ystallization of tlic dirti'i-ent nnnrrals a].|M'ar to ha-.c oMalappc-d one aiiothef. The iion oi fteii siHMUs to haxe comMtrnri-d to form li.'foi>> any of the otii.'i' eonstilueiit-. exeept pel haps ap.atiti'. to h.a\e conlinuod to srpaiate out aft>-r thf phiLrioelase lii'_'an to eiy^tallize aiLil is usually \efy ahundantly included l>v the' hornblende. The pyi'o.xene is eomin.mly ohi, i- th.an t!ie plau'io- elase feldspar l)Ut their perioils of crystallization li.i\e often overlappoil. The outlines of the p\-ro\ene individtiaK are \eiy irri';;ul:ir, eousistin^ of small bays, a- if the mineral had sutVeivd from absorption. ,ind the oc<-uiTeiiee of the brown hornblende as a b.,idei- to the pyioxene. tillinu the irreiiidarities, is \c\-x ihararterist ir. The liiotite is partly eont.ni ],,,,.in, ou- with, paitlv vounu"'i' 'ban. the h..rnb.l.-nde with which it is so eommoiilv assoi'iated ; both of these niinerals seem _\ oun^'ei' than the pla;;ioelase, eonspieuouslv so in the ease of the hiotite. Ilii'oitho- elase and the ne])lu'lit.' always liaxe been the List to loini and, where tiiev occur in tiie i,iri.'e uround iii.c area-, ii i- no, i. i-.on.. ;i..iT tlicii inilusions consist far mor.' al)und.intlv of the coloured constituents (.EoL, Ff , O , FeO.. MgO CaO X.i. () K '!> < ■ i I Ti ( 1 l' "^• Vf s, Mnd >(. (I 4:t HI 4:t )»'. I'.i (i3 ir :« 4 If, 7 MK ."f * .'»") 5 40 :. •.>« 1 27 il 4il 11 at 4 lit :. I'j 1 M - "7 ;! so 1 -ji M :'.■> 1 «2 '.ttfSl •K) im; I. Kssrxitc, Mount Yiiiiiii^kii. . IT-', -M. Dittricli. analyst. An analv-i-- "f a sju'cinR'n <•{ tlii> tyjic cuntaiulii^i (•(in^ulci-aliK' alkali-fi'lri>|.ai' and nfiilielitf with hornldcmli' as the jiri'ilnMiinaMt i-o]ii\n'c aCLnnipanyiii'.,' t.ilili' with an^thiT analysis iMi' i.i chtain i!i" iiiirjiial rcaiii>osi- tinn of till' iniU fiMiii th.- I hcniical analysis. Tlic nuiiilifr nf |i,.>,iljl,' coMiiiinaticin^ Un- tiir li.i^.iltic liuriiMriidi' and thr tif.-iiiifiTou- |iyi'i\rn(' is too 1,'i-fat tuall'i" aiiv diliniti- -■ilul inn cit tip' |iriilili'iii. Tin' n-la tivf amounts of tho diHVrciit runstituonts |a'i'sriit in a -^cition fioin tin- -]ifciiiii'n aiiaivsi'd. a- diti-iinini'd liy tin- system of dianiftial iiii.isui'f mint- |.rn]iiisrd liv l{.'~iwal. i- LriM'ti iiitiif tcllnwiiiL; taWlc. (Imp :!(MI iiundrtMl avcraut' dianu'tcrs wci'c measured tint, siiiie ;ill I In- in<'asure- ments wi-rc made in I'Ue seetion and since the relative [.I'liportioiis of the ditVerent i nn^iit neiil s .ire ^.i \,u'i;d>li'. the amounts ^dviMi [H'obaljly oiilv repievenl .i| ijii i iMiii.ct 1' ■II- li> the truth, yet they wmild i;ive very rea-niiahle \ a hies t'"i thi , .■iiipe-iti.iii ..t' the .hlTi leiit e.,ii-t it ueiit -. I*lagit)L'liu*f feldi^l'Hr . . ^il '» Alkali-feldspar li"j 'i Ne|ilK-litt .."•■> Hornbl.iKi. 2« Pynixfiit t " Biotitc ... 1 " Titanite. '• ■' Iron ore. - . ■* ** Apatite ^ ■> Pyrite. .10 Secondary niineruK ..20 100 MmLNT vam \ska ■11 II (lii'iiiiially i-oiisidiTol, this rnck i^ M\ pssexiU', lh"\iL-li it !•- )iii;liiT ill iiiiiiiiiiiii ami lower in ^ilii'ii than in tlii' iiKire ty|iii-iil (HTniriMii'i-s. Till/ iilmiiilant t'ciiUpais am(ilii."-t \\\ni\\ |ii.,L'i"<-las(> pri'doiiiiiiati's, dis- tiii^'ui-ihes the rot'k mincndnL'irally t'mm tlir tlwialitc.-. tii wliidi it shiiws i-inisidfi-alilc i-cscirililaiice in ciiiiiiiiMi i'.'in|iM^itinii. Tlic 111. nil .'t' tin- rc«'l< has \n;en tahiilatnl and the valurs nliiaiii.'d ;,'i\i' the I'iik thi' fdlliiwiiiL; jiMsiti'm in tlir new systriiMit classilic-u- tiiin:- - ('lass 11., dcisahmo. ( ii-der C, iiiirt;aiv. Itunt; •!, sftlfiiiase. Suhran;' 1, ^jilt'iimso. Sill, riiri'ti/ .'. Tliis siih-varietv ocrurs in a iiarmw liaiid aloni; the- ra^ti.-iii halt' of the soutlici-n iMinler andal- previou- ilivi-ion. Tin- pink ,.vroxene is the chief coloured constituent and the am. ami .•:' hiotite is sometime- liir!.'i'r than that of the liorn- hlende. The f.-ldspars are very ahiui.lant an.i thealk«li f. 1.1-) ,ir no lon:.'er occurs in lar^e intliviouals h..l.lin^ the other eon-titiients poikilitically, but in smaller ones sometimes rudely prismatic. The alkal! fcldspat^ frtijuently show f^erthitic int<'r-;-ne.vt!: . .-.••.■A iilo oecir zonallv surrnundini.' and interirrown with the plaudiH'la-.'. " My 28 R OEOLOOlfAI. slliVKV Kf lANAflA Siihrarii'lij •{. The ri)ok of tliU (li\isiiin i -ijin in tliiri' |cK-iilitie«, .i!! of ulii.li ;iiv in tlu' ni'is{hlMmrliiMKl ot' I'xiioNuiiN ot' vaiiiji>.kite. TIh'v lii' !> ■t\vr,i.. ami connect, tlu' four isolittcil iircas of yaiiiaakiti- in the .soiitli»i-^tii ii i-oriicr ; tln'V form a -iiiiiill arfM at tliL" cml ^if tl»' iiortliwi'stcrii cxteii siou of the main area of yamaskiti' ; tln' thinl loi-alitv i^ near tin- eastern iitii' of contact, jii-t to tln' \m>s» of tin' -mall an-a ..f aki'iitc. This sul) variety is ilark of col.iur, almost black, and is formeii of a very fitie uraiin'd. hiack ami wMtr sjicckleil i;roiinil, in which lie pheno- crysts of il.iik hoi'nlijrn'li' and |'\io\cne UetwiH'U .'5""" ami 7""" lo'i^, m'casionally accompanied liy inv'^'ular llak.-s of ijrow n hiotite. I'niier the microscoiic, this varietv is >irn to !«■ ciiniiioseii of the followini; constituents; i.lai,'iiH'lase and alkali feldsiiar, iiephelite liornlilende, ]>yro.\ene. liiotite. afiatil.-. iron on-, |ivriti', titanite and small amounts of secondary minerals. The •■■mstituents apiiear' to hi' the same as those occuirini; In the |iri-\ iou-lv ilcscrihrd \arii'ti''s of e--i\ite. 'I'hi' dark pluiiociy-t- of thi- v.cii.'ty are -.-.■ii t., !„■ cliii'ilv of titani- ferous |iyroxene suiroimd-'d l>y liiown lioi nlii.-n.l.-. All variation- exist U'tween the nearly licrfeetly prismatic indi\iduals of pyroxene with scarcely any hordei' of hornhlende thriuii.'li others in which the Inmndarie- of the pyro\,iir aivfiill of linv liav-, uliirh lia\f K.-rn lilli'd with hornldendi', thus roiindiie^ iHil tlio irrri;iilaii!ii- of ihr mineral. to (ithei- cases wiiere only \cry ine-ular. ronoded like uiain- of pyroxene are left, somotimi-s ii'pri'scnted liy a small. i-oundi-d ki'rnei. entirely enclosed hy hornblemlo. These, toircthri' with lari;e, usuallv very irre.irular indi\ idual- of lnow n homlileiid.-, « liicli contain tinv latli- of piaeioidasi' anllo\vi'ie iiiiiierals : plaeioclasc and .ilkali-fclilsiiars, liornlilende. pvroxenc, liiotife. olivine, iron ore. pvrite. .ipatite. tit.inite. and small I'laiiioclas,. feldsp.ir IS verv ahund.int, fre.iueiit ly toriiiiiiu' one half of the thin srctions. It oi-.uisin w.ll twiiiiied. lath-like individuals 30 II l.l.iil.ui.lc.vl, M |(\ KV .IF lANAriA wliiili v.ry ..ttcii li;i\.' a p.ii .ill.-l ailMii^'MiuMil .iwi u^Uiiliv ap|..Mi i|nit.- ili lilii'- tMvvai'U till' r..|,iiir-.i| (■..n^tilucnt-, 'I'h.sr t.-MspaM an' iiLPi'.' I>asir than in tlii' [ii'i'v i"iis vaiictir>, (■iiiiiiii'.pilv li.liirii.' tu lia^ir liiln-adiiriti". sniiu'tiii!.'^ I., aiii.rtliifc ami, " iiilf /onal struct un"< i>c(iii-. tlit-y uri" ncitluT as j.i.iniin.'iit ii"! a^ r.uiimipii a^ in tlir ■.flirr cla^-'s |i lii,,«ii Lasaltic liMiiiliIni,!,. al- n-a.ly ilcMaiiH'd. It is ;.'i'ii. -rally fxrci'ili'il In animint li\ tin' i.\ luxt'in" with wliii.-h it is Usimlly assiH-iaffil. In si'vptiil slid.'^ a -niall amount of :.'r-.. II liMinl,|,.|ir|.' i- o|.Tirally iiil.-ii.'io\\ n with tli, laoun \aiiflv. 'I'lh' |iyii.\rri.- i- of til.- [link or i|.',h lol.an-.'il. titaiiiiini Wcaini:^ tv)ii- ali.-iil\ il.-riil)ii| aii.i soiiH'tini.'s i- tlir cliii-f 'oloni.''! ron-titiifiit. It toiiii-. ioiiihI.-.I to inri.'ular grains tr.Uiii. - «liiili the fi'ldspar is i'lioinoj jiliic. Kioiitr is |.ii->iit ill all till- -.•.tions. ii-ualU a— oriati'.i uitli tin' lioinlilriiiir and s liiii.-. -in-|ias-in^' it in am. aim. < l|i\ iiic or.ins in a fi'U lound.'d iiidi\ idiiaK in si-\rral slidi's. lion .„;■ j- oft,n \,iy alaindant and a|i|ii'ar- lo liav. fori 1 in laiu"' and small, iiri'u'ular in dividiials jati-r tliai> tin' ]iro\.'iii' and feldspar. I'vritr is usually ].iv .sciil in a irw small 1,'rain- as-orirtrd with tlio iron .ar. Apatitr is som.tiinis aliiindaiit in small and laiLio. |.oif,Tt|v idiomor|ihii' individ- ual- u hii-li an- ii-ually cl.-ar .ind i-ol.iurli— luit at timrs arc dusr.-d and thti! api»-ariili-o<-hi-oi(-. A small amount of liirlit v.-llou titanitc o, curs in a fi-u si-i-ti.iiis. Thi'-c rock- aro ili;ir.i,t.-ri/>-d Ijy tin- |i|i-d'iuiiiiaiii-i- of pla^iocla-c t'l-ld-par in lath sliap.-d indivi-lual-. \aiyiii;.' -ii-.-allv in mI/i- within tlio s.iiiii- -i-i-tion and usually lyiim with th>-ii loii:.'i-v a\i-s appro.\imati'lv l-aialli-l. Tin- i oloiiivd con-t it unit-, tliii-lly pink pvro.\i-ii<-. on-nr in a:.'(,'rt-i;ati-s l)i-tui-i>n thr fi-ldspais or. as in those transition fK\ V AM \>Krn: 31 II Id ; :i liiri,'!' ifritral .u.-ii i'\li'ii'lniu' niMi-lv t.. thr ^•Hllll.•l■Il \\w nf ivm- liiit. a --iMalhT I'Uf lyiiiL; iicir th>- I'u^t.'ir] licii.l.'f, a ijr'.up of >i'ii;iriHi'i| iiica-- ill III'' •v.Mitliw^ti'i 11 .oriiri, .iinl a -iiiall, li.'ta. Iir.l uiie situatfd iirar llii mart in tlir imi tliui-.liTn pari nt' llii' i;;ni-ous curf. 'I'li'Tr ail' t"o \ ai iri ii'"i lit' tlii-. iiii'k -liailiiiL,' int.) oiic iiiiDtliiT iiinl iiilii I 111- (■■^^.■\itl■. At oiii' fxtrciiii'. t!ir yi"U is lilark and iniiipnNi-il alnii>'-t cntiirlv "t laiui' aii'l small it i-.u'iii^n iii'lii idiiaU nt |i_vi"\.ciii- ami liiirnl)|i'iiilc uitli imirli iliiimitr aii'l ■.cari.'ly any t'fliis|iar. Tliis varit'tv is iisiialh m-i \ > nai^., tin- lari,'i' |iyin\i'n('- t'ii"Hifiilly iiirasiii- iii;.' lialt ati inch m ninif. 'l'lu'Sli;,'lit iiinuunt ot t'l^lilspar |ii-csi>nt mc'ui - in v.TV small. iin'^,'uliira^'i;n':,'al('s lyiiiL; inT.'aiMl tlnT.'. Willi in.iias ins,' amounts uf tVldspar, llif rock passrs int.. tlu' s.m.iihI vaii.-ly iii whicli till' (lark ri.nstitu.'iits usually ."-.■uf in much smalli'i- indiv i.liials a\fi-aL.'ini,' ■")""" in Ifii^thand llic fcldsj.ai-s l>.'c.iun' distim-lly iiiioiinjiplii.-, laluilar an.l i.t'lt'ii ai i-anu'i'd paiall.'l «itli oii.' another. ( )ei;asi.inally th.'s.' tabular t'.'I.Upars ai'.' M'ly laiLic m.'asuiiii',' liV'-"' to 15""' a.T.iss thf clfasai,'.. t'a.c p.iiallel L. (Oliij. riiil.'i- ill.. mi.-iMsi'.ipc, th>' ro.'k is s.^.'n t.. h.- conipos,'.! ,,f the f.illow ini.' iniiii'i-als ; -iivi'o.M'iii', liornhli'ii.l.'. hi. .tit.', j.lauioclasi- feldspar, ir.m '.m.'. The h.iriihleiiile is ihi' il.'.p ri'd.li-.h hrou n. h.i-.altii' liornblelldf lUreadv d.seribeil. It ...'I'urs ie..istly as-...iat.'.l with the liyroxene. formiiii; a Ix.r.'er aroiiml the latt.'r mineral. A few small llakes.'f hi. .tit.' ai.' sometimes present. The plai;i.ielas,' felilsjiar .leeui's, in s.nii.' plae.'s \.'ry spnriin;ly in siuiil!. iiT'i'irnlar inili\ i.lii.'ils. l)ut. wheri' if is re abun.iant. it forms lai'u.', lath like evstals pi'iu'tra*' .is the horiihl.'ii.l.'. It is well twinn.'.l aci'ordinf,' to the alhit.' la«. .piite ofti'ii aee.iinpani.'d by earlsl)a.i twinninji and .seldom shows any /..:;ial structure. Measurements of 32 II i;KOLO(iRAL srKVKY liK ( ANMH fJie i'\tir. ail' I'n.sscil liy tliirc ■-n'e liiiure in convergent hi;ht. 'I'liese masses some- tinii-s have distinct rrystii fac-^'s propctint.' into the hornlilende. I n one section, a small aiiioiiii' of titanit" is pn s.Mit. In siveral s.ctioiis, a shapi'Icss, iireeii mineral oeciiis het«i-.ii the ^.'rains of ilnien-te. This min.-ral is isotropic and a]ipar.iitlv is a spin, |, piohahlv pleoiiaste. These riK-ks are characterized by the ixreat abumlame of pvni\ene, horidilenile and ilmeiiite. The pyroxene occurs in rounded to prismatic' form- foianiiiu' a).'i.'rei:at.'- and xeiy often paitlv or uholjv surroiirid'd by in-oun hornlilende. 'I'he basaltii hornlilende contains much of ;.,i iron ore which at tines is seen to have formed later than the pvro.xone and sonietiniis i^ penetrated hv tin- plajiioclase feldspar. When feld spar is at all ahundanr it i- idi -phic and penetrates the hornlilende surioundim.' the pyroxeie-. liut s,.ldoi ni''s in contact with the l.ittrr mineral. The oecui i-enei', in a few instances, of apatite in .sha|)eles.s masses, whicli apjiear younger than tin' feldspar but older than the hornliii'iide. is r.atlier tioi.ihle. [n the accoin| anyiiiL; table are ;ii\en two analyses of this ro.k tv]ie. (No. i ; eonUuns scaiceis any feldspar wihietiie otiier, ^Xo. I), iias .1 considerable amount. Analyses from other |i«-alities are addid for Comparison. Tlie a-ialysis .if tlies.' iM.ks -hous the nne\p,-,ted ivsiilt, MOUNT \ \M\nK A .iU Fl tli.it the v.iiii'ty «liii-li cDiitaiiis i'(.ei-.i(I.T.ililr jilii;;iiii'liiM' is Iihht in lilica than the other whii-h contttiiiM sfan-ely any f<>l<|M)iiir. Al, O, »>.»', KeO... MgU . C»«).., N», O . K,0 . oo,..., TiO, Kk 8, . . MnO . . H, O . . . . a. •X i 1 an !i7 .■W 3J» as 38 X l\X 7 a'. (1 iri H (i;t !» I : I 10 72 .-. M.imi Vamaak.i, lit' ll iii,.|:,|s. .IS i|,l,.|iiiitii'' uul.s 111! lliml, it, ;i ~iiii;li -irtiiiii t'liiiii larl, .if tin- s|i,.|.ii,„.||s is J»iveil ill till' t"llii\v ini: talid's. Tliisr aiiinuMls sriM. a^ an in.lhal ion • if till- i|'i. lilt il Irs lit 1 111. Inilli.l'.lU jui^riil I, lit. sin. -r ..|||v nn,. ,.',ri..n uus lAannni'il ami I In' ii'l.it i\ r i mi. uinls i.i lir (jitli-iinl runsl il iirnt s ai-i' so \arialili', tliry .iri' pinli.il. v nut arriiiatc. Nn. 1 iiirii's|.iiiiiU i.. till' rhi'inii'iil aiialysi.s (No. I) .uni Nd. l' to aiialy.sis (,Ni>. 4). I,v I!. IS, aii.ilv-i'il. AiMrllal" . rvnixi'iic . ll'.iriilil,.M,I.. Iron ore . . .■\|iatiti'. . . I'yit" Seoiiidary I III' r. "•!; n.aini' [iliril til lucks "alliiMl Id the lu'lilifliiie U'iii-liig .scrits am 1 2 L* l."i 11 :,7 II l.'l 1 L1I ll L'l L' n; 7 1 II a 5 1! 1 100 00 100 txi as ap rutin;: (1) M.iBnt-titc On-, IHstrictnof .Ti>x<>ne witli iw«'f)«inint;ili', yi-t thry an' ill'y niinrmlii);iciil oncx, tin' imU tmrn Ytimnskii ciiiitiiinitiii iiliumlant imrTilili'inIi' and, soim'titni's, at iiiiii'li as 15 of iinortliitc, twu ininorals, aiiparmlly, alwi'iit t'rimi the typi- ral jacuiiii'iinKit*- iind fn)m the almost idrnticnl iiH'k from Miinm-I ( nvi'. Arkansas. The jaru|iiran);it<' also contains ncplu'lito, n iiiinrnil II'. t tiiiiiid in thi'riM'k of Yamuska. It is foil that llii-sc chcniiral and miiii'raliiui appliration of a ih'w iiaiii' to thf riH-k of this locality and arcordin^'ly tlwy aii' called yaniaskiti The iioiiiw of the t»-o ..iieciiiieiiM seliM'ted for aii.ilysis Imvi' U i-n i ;il cnlatisl Jiiid tlir two riK-ks as.snme the followinj; jxisitions in the new classifi.'atioii, No. 1 i-orroijMmdiiiu' to the feldsp.ir poor v.uiety. No ■_' to tlie feldspar liearim; variety : - Clii.-s I \'. ciofeiiiaiie. Order L', sc otare. Section I K.m- ' Sriiioii J, Viunaskase Sulii.iii;,' J, vaniaskosc Cla.sH I \', ilot'eiiiaiie. ftrdir .'!, s\crii,'arc-. S'ctinii 1 1, iHi'iteniare. li.iii.; I. JKTiji'Mase. S'CllOl. '. Suhraii;; '■'• DIKES 'I'll.' dilie rock, of ^'aiii.isk;! iniiipri'-r Ik.vI. mil r, i;iiiiiitoiii|,.. ^yriiil<' aplite, nephelite .syeriili' and a \;iiiety closely sillied to y;uii,i>kite. Thev are limitisl to a coiH|iaiiitiM Iv narrow zone tollnuliiL: the line of coiil.u I and .vliiidiii- l.ul a short di--lanir on .■illur si.li- i.f il, 'I'Ik' relative ai,'es ot I li.' dilVrivnl \arii'liis rvci II oil. .mil tuo fi'i ! in width, cut I h.' si.iiimcnl.iry strata, and al s.m-i.iI otli.T [...ints .ni.ill .likivl s ..cciir; al noollna- Im-alitios are dikes t'oun.l within lie' ~idinientai \ .-..liar. Al lull. me |Miint urie ihev l'..iind iMittili;; the akei-ite and in no instann. ilid tli. y (M-enr Willi the arras of vaniaskite. On the other hand, near I lie. on tart, ill.' essi'xitc is .itleli eiil 1 iv i Ii kelcf -, ^niiicl i ni. s a f. ■ w in. -Ill's in width liut iisiiallv m'IV iihuIi smallir. l;ii,-;inMIK. ScM-ral iianiiw iliki'- "t In.sii.nii .■ iiii tin- sclinicniary str.-it.i elosi' to til.' innlait on the u.-l.in sid.' . t tin- iii..iintaiii. 'I'hi' n.i k is loiii posed of a .lull, u'li'i'liisli uii'v, lim iirained L,'roiinii in whiili lie i.cias MOUNI' YAMAMKA ;J.') M loii.il |>liriiiu I'v^u •>( il.iik III I liMi rilili'inli' mill ^iiiiill tiiliiilar iiiiliw iliinlx of iiiucli iilti'ii'hiiiII grain's of pyi'ili-. I'tnli r tlic iiiirii>Hci>|M', till- i(»'l( is wen to lit' H'l'v iIl iiiiiiiily of M't'oiiilary iiiiii<*ml>MH.TurrinK in tliifKriiiiicil it^ ;'ii'){at("< wliicli -till |iif«Tvc tin- oulliiii's of tlii- oni»liiul ronstiluriitt Witli llir cMi'iiliiiii of till' iKciisioiial sli'iiit'i- jiiisiim of lirowii iiorii Ml lull . ilji' link .i{i|>i.ii~ til h.iM- Ih-cii iiliiioNt (Mitirrly i'iiiii|MMf|.ius, uimI, jiiilj;iti^' from the iiir;;c ninoiirit of sL'<-oiirolial)lc llial i>la!,'io|iiirs lie in irn ^iiliii- uijiiiis. I'lnlir till' iiiicrosco|n', tln' riK'k is -iccn IoIh ni|H>si'il of tlir follow ill;; miiirrals ;- iilii^iiK-lusc fcl(ls|iar, liornldcniU', titanitr, iron on- an;i"iin- vtlis or have a mottled aspect. A small amount of plai;ioelase-fclds])ar is |ireseiit. NepheliU' is rather ahundant in idioniuriihii' piisui.s of considerable size, oftt'li with small individuals of associated caiicriiiite. Small polvjjonal i;raiiis if an isotropic mineral, [imlialily sodalilc, also occur. Hornblende is the <'liief coloured l)isilirate, it forms small idiomorphie prisms ll-")""" or more in li'ii;;th and is of a Ljreen or j'ellnwish i;recn colour. 'I'he variations in colour are often zonal, the liiaiu'iii il parts distinctly L;rceu while tlie centre U yellowish ur sometinieM disl im-tly brown. 'I'ilaiiite and inm ore ,iic .■ilmiidaiil . iIh' titaiiili- I'm iiiiiiL' Imtli i AMASKA 37 H 'I'liry iifc usually I a iniinl ,ir. •Hiding: 'i' ' !»■ all)ltr lau ot'ti'U -■irc(iiii]iaiiii'>l liy fiirlslxiil luinriiiiij. A iiiiiiilnr' nf ilclcriniiiatiims of tlic cxtitictiiiii iiiij;li' of the I'jirKlMil t u Ills -.hnu ilpii i hr iVj.lsjiar is a l)asic lalM-aili)riU>. /nlial stl'lUI Uirr, air si iliirl iliu's \rl v |il i >liiinrlll, at iitllcl- limt's (ilment. The luitiiial iicca-iiiiiallv linlds ^ih^lII inilu^iiiiis nt' tlii' otlii-r I'oii stitui'iu^. 'I'lir Imriiliiriiilr is very aliuinla.-it, •-tniiiL.'ly |il ■Iirnic, frniii .lark lii-owii 111 a lijj;lit yt-lliiwisli l)ni\vii. Tin' individuals aif usually irrc- i;ular of outline and avcrai,'!' o-J'""' jn lcii;.'tli. Tlicv arc often ]Ktie- Irati'd or uioilifH'd l>y the |r!ai,'ioclas(' and nmlain luniirrous inrlusion^< ■ •t iion or>\ 'I'lir [lyroxciir orciirs in -mall rouiiiicd yrain-, a .rra^^'inj; -mi "" in dianii'trr. Tliry UMiallv Ih' in -mall ai,';;rt'gates with i"on ore ocun'n^ inlcrsiiiiaily, or are suuounded wholly or partly Uy iiornliiende. The mineral u)>]>ears to bo a titaiiiferoui variety, nearly colourless, but liavitig a pal<' suioky tinge. Iron ore i- \ . I'v aluindant in small grains alxiut the -'\/i' of those of pyroxene. The rehuive |ii i|iorl ions of the dillerenl eon.stitui'lits, as determi; • d by Uosiuals Mulliod. is ;,'i\(n in the f'lllowitif; tJible under the headniL,' of (1), while the relative amount of the const itueuts of the feldspar- U'aring variety of yamaskite are given under (2). IMagitK-l.v-f. Inin or** . . l'vr(>\»'iio . If.irnlilrn.lr Apatite (1). (2). •.f. fl 16 Is 1 n; 7 I'll I l.f 4 34 '.1 •^l 2 13 2 4 100 luo Till' i^eiirial resriiiMaiirr ill iiiiiii I aloi;ii'a| c-om|posit ion indicates that I his \ariely of i hr dikf locks is closely niaied in rheniiral eo,,, posit ion to vaniaskitr >i . ,Mi;r \M(:lM'll(i,-i;L> SKDIMKNTAliY 1' )CK.S. As It was I'ot |io,sih!i lo follow oul in detai' the rlianges due to melanmi phi-Ill in thr scdiuicnlary rocks, only a brief description will lie alti'inplcd of a nuiiilicr of thin sections of the dilTcrent vaiieties. The iiiiallcrcfj or less altered slat<'s are \ery line grained and are full of black grains varyiiiir in si/e f i-oni OOl' mm. down to exceedingly minute partiel.'s, too minute to be resoUi'd even with hiL.'h powers. 38 H liKcll.Oi.ICAL .SL'U\KV OK CANMiA 'I'liis .lust likr m.illir, wliil.- ii is in •jniciiil r\('iily Ji-I iiliiih-il, aKii (KTurs iiii rr aiiiind.-iiitlv in !),-uiii!il;r areas wliirh j'!"l'iilil_v imliealc (hi' (.liu'iiial lirdilini; cif tin- rnrk. 'I'lir l.'|"ihi.I is ruluiuli's-, ami. lirtur.Tl rriissril MlrnN, is sci'n tn !),■ lillr.l Ultll nHTi'itr llaki s ■ 't a liri^lillv |iiiliiri/.ini; iniiicral. inubalily niusc.pMti'. Snnircf llicslati-s ai'i' i\iilfntlv fiMiiii'il of nearly puic ilay 'H )ii;,t.iial iisulliMu' fr-noi tlie alteratinn wt' ilav, uhile, in iitli.r eases, they nm-t ha%e heen f.ii-meil lit' tine inateiial eeiilaininL' inueh telilspalliie iiiattei. Aee.aih ili}^ as the -lates uei-e c |i(jseil mole ..|- Ks-. emniiiel, ly ui elay or ue'', rthat iiiiLjIit lie tei-ineil, tine ai k.ise-. thi'tina! levult- . .f nieiaiu'ir- lihisiM were ijtiite ilistinct In till' ease .it' th.' |iin'.'f .lay rJi'ks in.r'easinu ni(>taniiii|iliiMii eaiis.'.l the tin.- .hist lik.' |iai-tieles to collect within small in.li\ i.hiaK ut' e.ir- derite. ami tiny lUike.s of yellow hiotite Ix'canie ahunilaiit. With inci-easing inelamoiijlii.sin, these rocks bocunie a veiy fine-gruiiieil afi^irej^ate uf flakes nf yellow bii ite, rmiiiiieil iiiflividiials of cord. 'rite having a yellnw pleoehroisni, small feldsii.iis, grains .it' ijiiai-tz ami the whole ehai'_'.'. I with .'l.-ai- tiee.lles ot sillinianite an. I -m.ili |aisins .if andahisite, iisuallv sh.iwini; a [.ink m i-..l |ile.iilnoism in s]i..ts within eaeh inilividnal. The m.if.- iiiiinne slates, \vhen most liiu'ldy m.tam.n j'li.i-. d. eliaie^.'.l to eoarsejiraiiieil rocks cuntainini; in.livi.kials ..f oitlmelase .) mm. t.i 10 nun. in length, accouipanie. I hy LTains of (ilai^iiiclase feldspar, aliundant hrown hi.itite, i|Uart/, n.-.'dl.-- of sillimanite an. I irrains of corderite. (iltli;|N id Mor.NI AIX mi Kf.liKNTl VI'HiN. It hits heen stale.l alreaily I hat M..uiit ^■a;llaska i- ..ni.'f a -.■lies. if eiu'ht hilK |i!..l..ihlv ennn.'i'te.l in .ai-in ami .'.111111..-, .| ..f nlat.'.l types .if r.i.ks. Se\i'ii iiiit i.f .'iLrht .!. Hiirv. Can.. HK.I1. p. 187. (31. '. .aia.tlali live, uf Sluuci. Viil. VIII, l^. ;il'f. MdL'NT VAMASKA 39 R c.lili'in iHiii'il 111 -liiiu lliiit il is ,1 luciiilil h, uliili- AchiMis slatrs lli;it, "tliciv is cvidciicc in tli(> cxistnici ,,i' .1 1. ii;;ii kalilr drpii.^it i,t' l>iriri;i- < iin^lDincniti' in scM'i'nl plnccs ufouiul tln' iiHuiiil.iin lli.il il iliil di'Si'liiji M-. a \ I lien nil and liial I in' iiialciiaK n instil ill iiii; I In' ili'in ■■-it in (jiir-'t Inn \MTi' cjiTli'd imiii il. I'l'tii till' |iii'sint time tlii'i'f cjiM's tint ajipcar to liavo Ihm'II jinv stali'iiii'iit I i.iH'i'i iiin^ till' iiiiu'iii and stnirturo iit' .Mount, ^'anlaska iitlii'i than il i> |iiiilialilv I'unnrrlcd in a lii'iinal wav with the Tiniain- ilii; nii'iidii'i''< lit t he Lrriin|i. Ihiee hvi«ithi'--e-- a-- tn it^ iiiiiiin a]i|ieal' jMissilile ; il may M'|i|event eithi'i' a )iaitly deniidiil larenlith nr tlie Ujiward exteiisinn nt' a lial hnlilh d masses nt llie stiata \ arviiii; in si/e trnm a tew teet in dianietei dnw 11 tn a few inches. These s('|iaraleil liiei'i's a|iiiari'nl ly nerur niily ,il the |ieriiih''ry, and their \aiiiiiis stages (it |irese|-vatiiin trnm anirular traiinients, olnselv resenililin;,' the liiirn fc'Isnf the sedimeni ly enllar. tnsmall patehes n( lii;;lilv inelainiiriihnsed malerial. .eeiii In indieale that the prnoess was nne whieh lasted till late in the arti\e hislnry 'tii the intnisi\e limlv. 'I'his prneess nt enlaruemeiil helps tn e.xiilain the mimilelv irreu'ular niillines nf the iiiiieniis eiiie. fnr its aetinlis wn'iild 1h' lai'i,'ely Linserned bv piirelv Incal cniiditinns \aryiii!4 fi'mn place tn |ilaco. Such a prneess 1 if eiilar;;eine'it wmdil lie i|inte ciiiisist4'nl with cither nf the li\pnlheses, 'hat the i','ncniis IkmIv rcprcscntiil the upward eNlcnsinn nf hatlinlitli which irradnallv enlari;ed its iHuindaries in a Vertical direelinii, nr that the mass had snlidilicd in a cniiihiit. .Manv of the pheiinmeiia luescntcd ijy .Mouiil Yainaska init;ht U' cx|ilaineil eiHially well on cither siipjinsitinn. lint the general .struct me of the mmiii tain, its smallncss nf si/e, its clli|ilical nutlinc, the narrnw /nne of cnn- 40 II c-.Kcn.nclC ■ I. •^L'KVKY OK CANADA taol Tii<'taill(ii'|i)ii'-iri ;iii(l tin' i.'ciii-r.il rliarMctiT-^ ;itii| |hi>i|i I llii- olhrr tiirnilx'i--. nf \\\r M' iMt.'ii-.'i.ili hills, all |"iiMt to tin' i>ri;,'iTi of tlic iiiiiiintaiii a- a ^Unk "i iicili which may have apficurcil at tlir sdifaoi- a-i a Mili-aiiM as in tln' rase of Mmint Hiiyal or, jHTliajis. led to -oiiii' liiana, laii;i'T' iriass, since iciiiom'cI 1>v erosion. I It in IV sio,. . Al» •• Ke.O, Ke O. . MgO.. Cb O. . . Na,0.. K,0... CO,... TiO,.. r, <>. VeH,. . MiiO. I'.a (I, II, 11. 57 75 « ill ^•■!I7 »•. 2) 17 50 l!l la s tw !l 0.1 2 1t2 4 ii; S !« III ••■4 2 (•4 .fi 55 7it!l (1 .'.K 1 711 5 -Jii 111 S2 7 7.'« 3 Mi 9 4'.l 1.5 IX 14 '.•7 5 (IS 4 4« 1 V.I 1 (1.-) o r,\ 1 51 74 • 1 43 •> ST. •1 :>i 1 1.^ 1 r..-? ,f xn 4 iif. 7 12 1 ••r. 1132 In 1 III 7 ••37 a-a (•■.■.7 II I'm 99 23 I 99 HI '.wn '.19 ; A cciinparison of tlio finir analyses maile, (jilari'il toi,'i'tlicr in tlio i\r- i-oinpanvini; titl)l(>), shows a vitv ri'i,'ulai' c liaiiuo in the • |ifci]iiirlicin.s of Ihc clilVcrc'iit c'lcaifiits prc'sc^nt. < ••! the whcih- a dcri-ci^c in silica is aci'oin- (laiiii'il liy : ili'cri'asc in alumina, s,,cla .■mil jiMa^h, ancl liy an incro.aso in tVn-i... I'cin, fcrnc iron, iiiai,'ni'si.i, linic nul tiliniuin. This serial \arialicin !- -o iciciiiiineiit. in s|iitc> cl' (■■•it.iin ir:'.'i;;il;irities, a^ in the c a~e ct' tli.' iluihina, ihat il li.iesncil ,1 |i|.c>.ir jiossilile lev ese.ijie t he rmi ehisiun ihal, the iL.'nec.iis roeUs ot ^'anl;l-ka ve|uv^iiil the results of some |iri)ee.ss hv whieli ililVereiilaticiii has taken |'l,iee in a luiily of unit niajxnia. Miner.iliiuieallv the 1 k^ ;:re sueh as mi;.'ht he e\| ted in a closely ciiiinec-tecl series. The plagiix-lase *''lcis]iais, e\(c'|.t in I he yamaskite. present \ei\ p]ci[nini>nt zonal ^-t luet iire-, tl liter /one freipieiilly U'iiii,' of alkali feldspar and the latter always a|ipeai^ to he rich in sikIii. The most aeici roek i-ontflins hiotite ;is its chief eoloured 1 stitupnt and the same mica is present in ,all of the. other types. With ilierc'.asini,' hasieitv a :;i-er-n hornhlend ■cm- «ith tln^ mici. in tin more hasii' forms ooi^uis the lia-altic liornMendc^ with interLrrow ths of the c_rreen \aripty ; in still imoi^c> hasic form- t itanifirons pyrcixeiie appears cxewMlinfj the hornbltiide (1) Akeritp. .Meiint \';iiiia.ska. (2) Kssc-xiti-. Mciunt VaniiLska. (3) Yttinimkitf (felcixpar iKKirl, Meunt Y.iiiinska. (4) Yttniaakit<'(Md«I«ir rich), Mcciait Yftnia»k». VOIM' VAMASKA 4t II Fill tlici' I'viili'iiri- thai llic ililVt'ifiit ty|ies all ri'incsiMit proihiits nt' nw iiMi,'iii.i is tuiiii-lifd liy n short, nearly coiitiiiuoiis i'x|>.isiirc on the summit ot' till- l>iilal('ii hill iMLurrilii,' at alxmt theniiililli'ut' thceasti'in liiH' lit' foiitiict. At this liii'.ality the i;^iii'()iis rocks artM'X|iosi(i along :i low ridge running aiiproxiinately mirth and south. At the north- ern end, the rosures end at this point hut, within twenty yards are others of hiotite-syenite, U'longing to the area of akeriti' shown on the map as present at this locality. At other points in the immeiliate vicinity, the akerite is found to pass gradually into a liornhlende syenite and, from this, into a more hornhlendic typi' thus fmnishiii^ all the n-mainim; links hetween akerite and yama-kite. Since the igneous rocks of tin- mountain are thus seen, chemically, miiieralotrically and in the held, to icr.-ule into one another, it seems clear that they are .ill ililh'reiitiatioii products of one hodv of iMML;ma. This deduction, evidently, is inile|icndent of tli.- ipiestion as to whether the rocks owe their pri'seiit jiositions t'l one or more intru- sions. Considering the state of atVairs ohtainiiii; at the exposure on the easti-rn Ijorder, it does not seem possible that precisely similar or clo,sely related typi's of rock^, situated elsewhere within .so suiall an area as the ignecius c(ae of the mountain, could lielong to separate perioils of intrusion. This conclusion is streii.;thi>ne(l by the apparent lack of exposures showing rocks of dillcrriit tvpes cutting one another. ll lias ,iliva.|\' lieeiL -.;,|ted lint the roi'ks of a large are.-i cif tlie il,ni'nus cdl'e pli'^elil lliiw .iliil b.mded st rilel lll'es. 'I'lie ilil-eellori c it ilow \arii's rapidly from place ti place as tliouj;li irrc^'ular n.ovemeiits had taken place. Sometimes the bands form nearly lioriz(tions, thoy an- soniotiiiifN slightly bent or broken. If niovi-inpnts, sucli as those imliciitfil liy thf baniliMi iintl How structures, tiM.k iihui- at so late a sta^o in till' history of the still tliiid r(M'k iiiattM-iiil, it is cviilent that, no iiiatlt-r how rc^uliir in thi'ir arran'.-ciiii'tit tlii' •lilVcri'nt i.roducts of diHtTcntia tion wens tlH'y coiilil liaidly iftaiii tliiir ori'.'inal i«isiti.'iis after tlii-sc niovcmcnts. That tlii'iv was somi' ri';,'iilai anaiiu'i'inent of the difTereiit ilillercii tiation products is In-lievcd from the distribution of the ditVerent tvpes; the basie forms towards the eenMe, the aeid about the maricin. The yauiask'te never oecurs in contact with the sodiinentary l)eds, but is alwavs surrounded by essexite and the acid akerite occurs oldy at the ]>eriphery of the mass. The general outlines of the larger area of vainaskite is suggestive of a once t'entral bisly which, through irre^'ular movement', a.ssume' that llie mass,., compos- ing till' iirneous core of Yamaska may have been partly or wholly dif fcrentiatci! hetoiv re.uhin^r tlirii ),ivMnt pcj-ition .md that the con centric structure which woulii !«-• exiiecteil to result tiom aiHereutialion (I) lirilj^jter, Ziit. Kryst., vol., xvi, IH'.M), p. ■).'>. (-.) Wfei! aiKl rirsson. Hull. Nn. W.t. \\ .S. Cis.l. .Siirv.-y. isttr,. i„.. Kll ;.n 1 1 In \'.\) \V:i-hiiLH''ai. Hull. Csil. Soc. .-Xiiiit.. vol. ii. p. 'Ml. MOUNT VAMASKA 43 n may liav,. l)o<-n prt-sriit. but vas partly ohliterattnl hy irie^'ular uu.vr- ii.cnt. vvl,i.-li may have N-on tli.- direct n-sult of tlio upwaiii inotio,,. It iIh alMiM. rcisiminK !«• well found.'d. it would appt-ar tliat dif- t.MVMliaiioii cou d not liav(, l„-,ii c(,i„pl,i,. «||,.„ i|„. later niov.-nieiit«, indi,at«i l.y tlic tlou .mil l«i,i.icd ^tni, tuns, srl in. For, if 't liad U-eri eon.pl,^,.,), ii u,..,|,| 1„. ,.xp ...t.-d ihut llic lai-.'r, s.paral,. aiva of yalna^kit^■ occuiriiii,' near the mNtcrn hjrdrr would k", as in tlir niuiii urea, MUToun.lcd by a wide zone of css-xiti- instead of passing, ,is it dw's, rapidly into akerite. Furtlier, since these movements, as already stated, must have taken plaee about the time .if erystillization ,,t' the nm-nia, that is, after it had entere Iiacture.1 materiid The few large dikes of bostonit.- and canipionile seem to represent a later stage vOim dilleivnti.ii ion had still tuitli.r progri'as(.