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Tous les sutres sxemplsirss origineux sent filmis an commencant par la premiere pege qui comporte une empreinte d'impreasion ou d'illustration at an terminant par la damiire page qui comporte une telle empreinte. Un dee symboles suivants spparaltra sur Is damiire imege de cheque microfiche, selon Is ces: le symbols — »> signifis "A SUIVflE". Is symbols ▼ signifis "FIN ". Les cartes, planches, tableaux, etc.. peuvent Atre filmic A das taux de riduction diffirents. Lorsque le document est trop grand pour itra reproduit en un soul clichi. il est filmi A psrtir de Tangle supirieur gauche, de gauche A droite. et de haut an baa. an pranant le nombre d'imeges nAcsssaira. Lea diagrammas suivsnts illustrent la mAthode. 1 2 3 1 2 3 4 5 6 .' '( McGILL UNIVERSITY PAPERS FROM THK DKPARTMKNT or Geology, No. 13. — Geology of Rigaud Mountain. Canada. OSMOND EDGAR LeROY. [Reprintcil from the Bulletin of the Geolocicsl Society of Amctiia, Vol. xii, pp. 377-394. P'*- 33 34) Montreal, 1902. ■"mmm 1^. 1i J BULLETIN OF THE UEOLOGICAL SOCIETY OF AMERICA Vu. 12, '^ 377-394, n> 33-34 t.KDi.lH.V (l|- IMl.All) MiM Nl\|\, ( \.\\|)\ u^MiiNK i;i.(, \|< I i; i;ii\ |{i>( .h>ii:u rriU.lsllKli ilY IIIK -i>(||;iV SKnKMHKK. I KM '*.?""■ BULLETIN OF THE QCOLOOICAL SOCIETY OF AMERICA VOL 1?, PP. Sr7-3»*, Pt». JJ.J4 SfPTtMMM 4, IMI GEOLOCJY OF KUiAUf) MOUNTAIN, CANADA BY 08MOMI KnoAK I.K KOY ♦ (Read Itffore Ike Society Ihiemher J/l, lln)0) 0»NTKNT» IiitiiMliirtk»i „' ~, , o< < To|K>Kra|i|U-iii|i> Kyeiiiu> ,a.. Quartz-aycnite |>or|>liyry ' ^^ Quartx (mrphyry ' " .^^ Aplitif (like ] '^.^ L4iiireiitiHii li(>riil>IfiiiU'-Kmnil<- Kiieiiw ;{„|, Ani|tliil>oli(<> " IWrttioii of KikhikI td hy V. l>. Adamii. I'lY— Hull. Gut. Soc. An., Vol. I», I9UU (377) :!7s o. K. r.K Rov— nKni.ooY or kkiai'd moistais, cASAnA R.,UK...n..nt. Bel.H.il, M.mUrvill... M-ui.t Koval, an.l RipiU'l T','" ''''.'" of |{r...ne,lvinKH.mtlM.f Shertor.l.an.l mount J.,lin.-.on..ouiliof Hdoeil. lire on unothiT line, but fvidenlly I.eloiiK to ll.f -anu- »«TieM. Sir W ill...in LoKim ha.« .leHcril.e.1 them ns I.einK of post-SiluriiUi a(ie, and from the lield rehitioUH of th.w« rec.i.tlv exaniine-l smh has I.een lound to \^ the cane, with the ex.-eption of Ui«nu.l, wh..He a>?e i>* douhtU.l. owiiiK to the fact that the tontacl In-tween the Paleozoic and iKneouw rocks ifl wholly .oncealed hv drift. In the atmence, then, of any direct jmmf su.h ,i- a .ontaet would afford, it w.w thought l.y the writer that imw8iI:1 y the petroKraphical character of the rm-ks wouUi «how Hipiud to he closely relate.! to the other hill... Willi this eml in view, a detailed examina- tion of Rixaud mountain was made, and the following piiRe^ conUin the resultH of the field an.l laboratory work, together with the concaisiona arrived at. ToKXlHArHV Rigaud, owing to the general levelness of the immediate surrounding country, occupie8 a more jiroininen' position than iU height would other- wi.-ie warrant. In shape the mountain i.s rou;;hly ohlong, and has an area of al><)ut 15 square miles. The topographic features closely resemble those of the neighboring I jiurentian— rounded ridges and kiiolw of rock, partly bare, partly wcK.ded, w ith drift-tloored valleys of varying width between. The marginal area and some parts of the interior are well foresteted ritlg. -i, and longer axes of which have an east-aiul-west trend. The cen- tral part is rather plateau-like in character, and is made up of suhor- dinate elevations of the roche moutonnee type, which exhibit in many instances stoss and lee s1o|H!s. On the line benveen Saint George and Siiinte Marthe the plateau terminates in an abrupt slope to the south, and on this line the highest iK)int of the mountain is situated, there attaining a height of T'M) feet above sealevel. From this slope south- ward the area is but little higher than the immediate surrounding country. The eastern part is marked by one ridge, which is continuous throughout the width of the mountain, and runs in a northeast direction. The valleys between the plateau and principal ridges are comparatively broad, shallow depressions, well drained by intermittent creeks into the rivers ^ la GraLsse and Raciiuette. They are floored with gravel, sand, and sandy loam, which in recent cuts show a very even stratification. The most prominent ridge is the one fronting on the Ottawa river, the western part of which is shown in figure 1, plate 3-3. Its average eleva- tion is about 'v>() feet, but attains at its jieak a height of 704 feet above •UlL. OtOl. toe. AW. vol t? two, n M KlKtM I. — I!l«»ll' M"i »T«n, »«-tr«» I'lllT "f INI »..lii»i«< Hn«u Kl.il I i. — Mir...l-H.rtiH.»4PH "» lil.iU !■ H.ill>Bl lL»IiH<> t^ltf riark .■..ii«lilil.'lil i» iMirnl.l.lia.- iiil.Ti{r..»ii «ilh r.l.l»|..ii in :i uri«|ilil. nialili.r /...lial iilt.T.ili.iii"f li..riil.l.n.lf »l— "•••■n. ilr.liliiiry li|{lil »1 RH}*UO w.•XI>tT*l^4 4Nn HORNBLENDE-SYENITE TXnXXIKAPIIY ;{7'.» sealevel The »Io|m) t« the north U quite ruxnwl. and many sumll preii- ,»ice« from 15 to 40 feet high have heen developwl. due to the ea«e with which the rtKjk jointH. The particular interest alta.t.ed to thw Hlo|)e, however, i« due to the occurrence of two lar^-e boulder de,KM,it*,^ One of these fills a depr««Jon just east of the peak, an.l tinge*l hy Uh^I tradi- tion 'M popularly known as the Devils garden. It is .-.n irregular oval in form, with tli'e longer axi.. running southwest, and occupies an area of alH.ut .50 acres. Higher parU of the mounUin incUmc it on all sides 53 »»««■« G3 •*«-»« ■•-.-I Kl«l«« i.-Hlip of Sxjaitd MounlaiH, OrlHO<*i. except the northern, which is lower, especially in the northeast wlrere Z deposit terminates in a rath.r abrupt fall of about 2() feet. he boulder, are subangular or well rounde.1, from 5 U, 20 inches in diunieter and are arranged in a series of parallel ridges which run in a •>'r««t"';' »^ right angles to the longer axis. These ridges when well marked have convex cresto. thus giving to the garden an undulat^ing ■'I'l';^«['''!^« ;^;^" viewe yards apart. In some part* of the area the ridges are very uulistuut, and 380 O...KKOV-CKO..OO.O,K..COMO..T.S,C..XO. , , ,.^U.,e to .tate t.e exact "-^.^J^^^^^^^^ it neiKM-oTIoa of -25. ''j'^^f-^^.r ^^^^^ and highest ridge is west; the difference u, level »>«t««^' ^^„,,,,,. Practically all about 12.5 feet, the former be.ng ^ j^ ;' /j^ ,,,, i„,n,e.liate vicinity, the boulders are the debns of ^"^.^-^X ^n ^ ,-entian erratics. The not n,orethan 1 per cent U -g 1 "■l^l^^l^^. ,^„^, i„ o.e northeast ,mrt, spaces between the '7>''«- '^^"^ Vx Il^tions have been made, one where the deposit is deepest. stNen ^ .^,^^^^ ^^^^.,„„^ of which wu. continue.l to the dep h ^ ^^'^ _ u is probable, bed rock or any a.eun.ulat.on ol o.l n « »^; , .^. f,,t, ,^ part of however, that the deepest parU do no^ - " ^.^ ,,,,„,„ u.e trick- the country south i^'^-"•-'. ""';^, 1':,? 'h 1^ on the occasion of one ,i„« of the water be,n« '>'f "^ > , ^foo Vole- visit running water w.is noted in the - " "^ ; 4,,^ second de- Separated by but a short distance "^ '"; ';;°;,i., k, fi,u i„ the posit, which, connnencing just ^^^^tlt^- T^e ridges are at Triangular area between the l-j'*^ / . f j^j; ,„a ,Ughtly rounded first irregular and are conip.«e7;»'-^;;:\,U? a^ltristics are the same as ;;r :l:^:r nSle":it;. U. exception that this deposit is ^'tx:::::^L bonders . u. i-iM^tu" r :;;^ ti t,.t they came from tj' -""— rril Som U.e cliffs below the composing the second deposit were «"^; , ^ j.^t,, aeposits were peak. With reference to the ""«»";^ ;" .^''"Ji Ueial submergence, Lmed by the action of the waves ;'""' « '^ ^° ^j^^ ,,„,, „,,, the ex- and that, owing to a -'"'1--^';;^ f ^'^ ., y the finer detritus was ,o.ed position the •»-;^-; ^f ' i^; ," ' Jnd terraces which now wa.shed out and .leposite. mi the gravel ^^^^^^ ^,^^ fiank the mountai.i in t»H« vicinity I that were ^ .^ nevilsgarden woidd have t ec^ o^ made to the above Lnt parts of the --'"*-''• I'^^^.f,;':' coupes of thLe glacial rirr U=;r ':Strl:^:e t.. ... a., the other to TOPOORATHY 381 . f -.u-r from the nieUini? i«-c wouUl .h« ««.t of the pe.k. The torrenU of *»»«''J;?'" , ^^, ,„„ent^. Win,; X"y or who^y round the ^^-^^^^^^^^^^^^Cm th.- finer n..-.riul diffident force and volume, wmjld u.rry aw ^^^ ^^^^ . ^^^^^^.^^ ^^,,, and de,.>«it it farther south, ^^l^'' j^" , luk-r ..laiuH w««M to .on.e i„,lhe.uh.eq«ent«ubn,er. n e.u^^^^^ ^^^^J^^^^ ^^^^^^ extent have been worked o.er y^ ^^^ ^^^^^^,j ^^, ,,„.,,,.t. lln. !ucce«.ive parallel rulK** »' ^^-^ J^i,,lc" and nu.re fuUy account, for r„a. origin ^n.« to be ^^^ --'^'^^C^neri.tic of ..ot»> dc,,...^ than „ecu»iaritie8 of de,.o«.t,on *huh are - ^^^^^^^ fthe whole work were »-"'f .^; J^ .J ^.^ention. i. a fi.Kure .,nns Another l^int of interest, »" \''»f > ,^.^,f ^ ,„i,e ea.t ..f tl>c »)evd* ,hll"« «" ^»>« -f "" "S-e d ^1 it- hc.,ht and it. be.n« Irden U i* 500 ^^^ **'"''^ .It a,M.ear .i»at the water .u,.,dy ^ ;S::;ted by .ea-onal variaUon« - ^^^^^^,, u.e nei,.d>oru.. is derive.1 from «.me higher lana, I Laurentian country. GkSEKAU GcX)LO«iV The greater part of Ri«aud -;;;;::;; J^^rrt:^;;::^;^^^ :l;:;Su;^-"^ which vary *- -^; ;X;ti;;;a;:iry nun..... Tl ock joinU into rough -^jXrt v - cuttin, the .yenite are cnn- aong the eastern margin. ^!,';^;\\^^^^^^^^^^^ .„o« in all part« of the area. "' J "^ J,,, ,,, u. a hundred feet u. length follow irregular course., from a lew »^^ structure i. .levelope.!. eN »- A ong the northwestern .nargm -' '" ".^ ^^^j ,, ,Ue Baveno gra.>ite on denUy quite similar in character ^^f^'^^ f^.„, u.e nu-.t .ninnte u, SU^-re. The cavH^s^-f^ :,:;::: They either conunw^ to those having a diameter "^ - [ ^^,, f„„„er occurring a. Ha x. f Imed crystals of feldqnvr and ,uarU '> .,f ^,,,. feldspar. 1 b.n S -crystals ^>^r:T^::^^^^^^ '^ ^'^ ''^^''' ^^"'r' r'^': ;rructuresee.nstoindicatethat «h 1 t e .^^ ^., ^,,,,,,.1 the forma- ■ he then existing pressure >f'« ;;;:„.„,, .u younger rock, ot h.. tn of these cavities, wh.ch ^'"^U Mountain n.iniug dUr.ct. Mon- H.S such as the granite of tl « C asU. ■ ,,,.,,. ..ccupies a mugldy t a! descrihe^l by NVeer>. "-r ^c;:;e^.n;:;:^^-'^- - ^^ ^^^^ ^^ '""'^^- which consist* ctueny :{.s2 (I. v.. I.K iSOY- liKOLOUY UK KltiAl 1> MOl STAIN. ( ANAOA To the m.uth. in the apex of the triangle, the groundnuts changes ».«- ,.,„ninK' a ate iH.undarv line between the two rocks follows the deepest part of the irregular valley which separates them. A small .like of ap- lite .uts the svenite in the west. It is 2* inches wi.le an.l was traced for (i2 fe.-t in a n.>rtheii.sl .lirection. This was the only .like noted in the whole area. , , , r • - i A small exposure of I'alc.zoic rock occurs in the be.l of river a la (iraisse, about a .,uarter .)f a mile north o<- the mountain. The be.ls are transitional ones between the l'.)tsdam and t'alciferous forniation.s ; they represent a thickness of about 40 feet, and dip south at an angle .)f 4 .legrees. This exposure .)f stratified r.)cks is the .)nly .)ne in the vicinity, and as they are not in contact with the igiu>.)us rocks nothing definite can be .leduced from them as to the age .)f the hitter. In the ,-ioutheast of the sheet and .separated from Uigau.l mountain by the vallev .)f the Uacquette river there is an exposure of Laurentiau r.ickn, consisting .)f an area of gneiss overlain in part by an amphib..lite. This outcrop .)f nietainoiphic rocks is due, according to Logan,* to an anti- clinal axis, .vhich divides longitudinally the great tr.>ugh of Paleozoic rocks lying between the Ottawa and Saint Lawrence rivers. M.mt Cal- vaire, li pr.)minent outlier of the [-aurentian. lies to the northeast of Kigaud, on the opposite side of Ottawa river. The rocks on the sl.jpes facing Higaud are gneisses and aniphii)olites, much like the above, and it is probable that these older rocks on both sides of the river are closely related. The drift which surr.iunds Kigaud ni.)untain and separates it from the Pal.'.izoic an.l [>aurentian rocks has un.lerg.me a certain amount of a.ss.)rting by water, the iiDuntain being flanked by a broad zone of gravel an.l san.l, which gradually pass int.) the san.ly clays and clays of the plain. Erratics are m.>re common on the iDrthern margin than else- where, an.l onsist chiefly of angular boul.lers of P.)tsdain sandstone. Fragments .)f Laurentiau rock, together with those .if I'liper t:ambrian age, are found generally th.>ugh sparingly over the wliole area. In mapping, therefore, the ontact between the igneous r.icks an.l the drift wits taken as the limiting line, except in such parts where it was • .iiM)logU'«l Survey of Canula. report of progr»»», 1«.'.1-'.V2, p. K. |.ETK<>OI?.\rHY .,„rtl.ern l.onJer fa^on. tia corn ..„„Urt ».otwet!ii tho l^:lH->u^< ,„....tcorrect. -ok.. O. e opi « > ^ j^^^^. ^ ,,,. ,^. ..^ ,.,.„« t.rtl.er ..nth than the present '-""'; J ;'';f^^,,, ,.u,er n«-k.. Kr..n. • t>.en, Ki,aua nunuUam - -'^ ton! the I.uuentian nn-U. hy a „.,rthwe«t to southeaHt It m ''^P"'* *■ , j,^ •„, ^i,uh fron. :• to ,„„., of arift-covere,! I'aleozo.c strata '*^^^" ; j^. ^..„„,, Uetween la n.iU.. In the southeast "" *''>7; ^^^ ' £ Touih an.l west that Petroobai-hy llOBXBLKSnEsrBXITE The syenite in hand specimens is ^^Zt^^^^^^^ pose.loffeiasparand.u,rn.enae.U a u lam . .^ ^^^^^ ^^^. ;,uartz. When Iresh, the ^f^V-^^--^ ^ J ^,,,,,,,. U the rock, is a:..rk ,ray .n color, ••.^.' ' «/ '^'^ ,,,,v stainea along the «.eathers to a rea or gray.sh whu. anl '■;^^ ;,,,,,„.,, i, ,aack a.ul ...eavage planes l.y hyaratea "- e^^, ^ t characteristic ' -ava.e. brilliant, showing m l'-";^- ^\\';' ^^ „.,t ,tt,,,tea it heyo: U^».t Orainarily the weathering 1'^ '^^ f"; ^:;,,,,,es. Unaer the n scope ,eposition of V^nonUe alon^Uhe ea ^ 'U ^^^^^ .^ ^^^ the rock presents the ty|''.f \ > «;" uk, W'th accessory plagi.n-lase, ,«sentiallyof mioroperthaeana 1.0 «^^^ ^^,,,, ,.,,„ augite, ixotite, ,«art.. ^^^;J'^Z^ orthoclase ana The «.icroperth,t« consists "[. " "[^^^^^^^^i The orth.H-hi.se is .put- plagiocRse. the for.ner R^«f ^^^^^^^^^^^^^ which is prohablv alhite. urhia fron. kftolinizatu,n,wlnle the plaguK^e ^^^ ^.^^^ ^^ lusually clear ana finely '^''''''l:"^^ ^ i^- inaivia«alsare ,oc:.sion;iaeve%>pmentofU.epenclnet« n „ ^^^^^^^^^^^^^ twinnea accoraing t« t e ^';- ^ jj^^^^ ;;; VaitlerJ;uly oriente• "■-'' '■■;:' ""i; '"" "',,,. ,ei,.,.m...t of »». ..t u,. rry:*tiil faces, iiieiem.v i ,.:ir:illel to '' {->--• ^-^I'^on^ the cleavage plane, instanees it is seen alter,.., to ;' ^'l f ,^ '/y ' /^e greater part of the or,.o.,allyfro,.ahei..ter.,.r,,aat.^ .^^^^^^^^ ,„i„,ral f..llows the onhnary law ( rj -I" ^^J U is rarely i.lionu,rpluc, •,. ,e.,erally inter.rown -^1. augUe a.ul In e^ l^^ .orly aevelo,>ed, „,,.,rri,.gin pris.natie seet.ons - t^^ «1 "^^^ ' Ji^^u^i.,,.,,, i,.roun.le.,„.;„<» the feldspar, m many ,,„,.,, ,Wv,l,.|. ........ "I^"™ •„ I,,,, 33..1u.«. till, .truclure; the ;:;:;;;::r,i. i' r„"r,t. ,.i»»» » -sr,'«r r .,"rr. fe : nite an.l .e.erine occurs with the colorless const.tuent . Cle! when present^ ahnost invariahly occupj^ the^enterol^ . D». „.,,.,.li..e.ye»i.geble. .t,7enlinous material with granular structure, low douhle refraction, and ag>.'rtgale polarization. Biutite is subordinate in amount to the augilc ; it is brown and dtrongly pleochroic in deep brown and pale yellow tones with u greenish tinge. With a few exceptions it seems to have been one of the fir!Uomorphic forms are common both in prismatic and basjil sections. In some in- stances the biotite shows that strong allotriomorphism toward the feld- spai, which ha»l)een previously not««I in the hornblende {»ee plate :M, figure 1). Though generally quite fresh, a few individuals have par- tially altered the chlorite along the cleavage planes, while others have been partially or wholly bleachetl to muscovite with a faint greenish • tinge and higher double refraction. Quart* is present in but small amount and fills angular sj^ces be- tween the feldspar individuals. Fluid and opa(iue inclusions are very numerous in some grains. The following accessory minerals exhibit but slight variations U) their usual mode of occurrence: Apatite in very small amount is present in idiomorphic, prismatic, and basal sections, rounded grains and needles being rare. Colorless zircon occurs in square basal sections, stout prisms with pyramidal terminations, and in large and smi^l grains, the latter being sometimes arrange*! in radiate clusters. Basal sections show the uniaxial and positive character of the mineral as well as the cleavage parallel to x> P, which is distinct When the zircon is included m the hornblende or biotite it is always surrounder.K H\n\ I> MorVTAIN. lANAnA i„ HM.all lon^itu.liiuil plates ■.rmnK-.l ulonK the cleuvn^e plan.--. A f«v in^r!.'- pvrit.. of ■•..l.io outlin.., with an ulteraliou Ix.r.l.T ..f l.enmt.te. ..„ah>i...ftl>.. fr..slM.>l ro..k pnKural.l.- wa. ma.le.U.e result, o. ,,,ii,,.,nM.la.H..!nUl..-l..ft.han.l..ol«mn,an.l.fortl.e.akeof..om,umHo,,. ,„ I tl.r riaii.Mi M-.-iiiU-* i« jtiven in the riKlit. sn t, M,o. MnO.. »'nO. Xiu. I. 11. 62.62 fiO.83 I5.6fl l«t.Hr> 2.07 — 4.7.'? 7.01 .10 — 2.«0 4.43 l.tll I'.iil :!.H7 2.44 .i.a". 6 57 .61 1.29 »l».76 101.0:1 2.6S 2.7;; SjKM'ilic gravity 1 lloriiblcii.le sveiiite, Kinaii.l (analyml by O. K. l-e Koy). 11. ll,.rntiU'ii.U- -vfiiiti-, I'huifii \{lv in ha'n.lx «n.l patches in the ^n.iin.lMm^H. Il..un.«e.l trrnin. »l olear vitVeiHix -luartx are very xuhonlitrnte in aiuount t.. the fel.l*|mr Tlie Broun(Jma!« weath.rx to a light l.r..«..i^h cray. un.l the .•xi«h..h1 r.K!k often i renentx an iinKuhirly pitte.l iipix-anuK-e. .hie t.. the ea^v removal of the feliNpar in.livi.Uml- Mier.««.ol.i.-allv. the rock i. eonM....e.l of I'.n.l. .te.l le .iMmr '»"•' .,„art^ phen.^-rvitH. with a few ^-rainn of pla^i.^-la^.. Motile horn-len.e. an.l /.inon in a fine ^raine,! .,u..rtr fel.l.par jrroun.ln.a.-.. K-U. th.- fel.l- .par an.l the .,»«'»» '«'«'"' i" ^"""''••'' i''*""""-!'''*"- "'"' '"'f'"' '"":;'• with erenulate honlen* an.l eml.ayn.entK lUl.-l with ^mun.hna.^. I b- feUlspar iH apparent! v h...n..Rene.,nH,an.l present, a .n..ttle.l apiH.aran.e. ,„.e l. kaoHni.ation. It in evi.lenlly. fron. t^.e >;-' r":,":: Hw 'o Iv" ..la.e or anorthorlase. Twinning i. rare an.l hy the t arUha. law -n > , J-Uhan irregular ..ontaet plane, whieh i. -f V '' '''> -'';J';;;;;; "i strain «hmlows are oo«un..n. an.l many in.l.v..luals hay.- h-en hr ,k. n I^ -ah where thev are elo.ely erow.le.l ...,.ther. A large nn.nher. ,^ eT.ocr;.t.s were carefully fr-a fron. Ih- ha.e, .n.l a me,.hanual . . r - i!;: „,a:ie by nv-an. of ThouletV ..UUi..n. Th. ...h.. ma ..^ U-^ 'M a M.eeifie Kravitv of 2M^, which w.n.hl nulu-ale. a. tU analyHM ha^., :T^1 f.hi;p.r. A ..w .nail ronnde.] •'''•-« l"'^- ':;:;; ^ ,.la.'i..cla.e, which is prol.aV.ly alhito.an.l son.e Mna 1 «nun. ..t part.al.v .Iteml hornl.len.le and hi.rtite, are in.lu.le.1 in the f.l.Upar The . m»rt. .n^cur. very .paringly in lar.e phen.Kryst.. an.l tre.,.u h..Uh:inclu.ion..l,..th Hui.lan.l ..>li.l, the latt.r >:-;';P-[- .^ " Kl.mlow^ cnvcke.1, an.l hn.ken in.livi.lual. appear u. every .1..1. . .i"-'; Inte^ie^^f the feWUpar. are no a.n,>.t .Ine t.> the .train exerU-d .l«r.n« the final »olidificati..n .)f the magma. ..i.arac- TheeflecUof resorption an.l secondary r-.'wH«- «»'"»' '"/''V , .. ter ot. tare in iJth the fel.l.par an.l .,..-t. are -"- -^ j;;:^ the latter In Loth nuneral. the ,r..wtl. i. .,u.te regular taking th fo r r..ate rather than ---'- ;-;- ~^^^^^^^^^ and in optical -"t"-ty w.th t. - " ^ ^^;, „..^^.,,,i,; ,,,„,,,,. is sometimes seiKirate.1 hy a .lark line "' " J- res..rpti..n whi.h This structure sln.ws that, u. ad.htmn t.. the usaal ■^^' ^ t I 1- »t.;^ ..loMw tli»>re was a furtlier ^ !■ ■ 'gt m comuv. sr;r„s?:nHr:.;r.:;' :.L . -ue ,„,,„, -- ;;;:r in composition with the original. V igure 2, plate .U, is typ. ,,e of 1 ..uartz PJ-o^y^^^;;^;;;;; Z S ^^ enah,e.l t.. exan.- .:^^;::':f":;;:;::p";=-^^ , .1 , „.k ilu- s,.,M.n.liirv growth of Uu- quartz i» much M..ntun.. In tl"^ r-k '" ."i .."..t a .M.ro.ml xone than .I.hjh thai »- """7 ;T,r'' ; V 1 ^-ription of the IHl.y '" ;'", "r::' ..i:'' :^-v :.,; hi... .. ..« ....i Me.aicai, m for... """'•■ .1 n I . I A. this .tr..,t..™ i.> tl... U.«n«.> |H.r,.hyry ,al»'M.i.«'thtliat "Mi"' • ,,revioii-lv .Im-rihwl hv ." "'^ ••" "- •^"r:;: :::::: 1.^!:.: .:;:u... o.i«i.. «.ain. .,,ar.«-.th a '''."■"V'''"''^ 1 . , .,.1h. 1- a...l l.row.. hiotite. the two latter of zir....... ,,lu.M.K-..-.-. »■'-'',,;,, .,,,..iu.. an.l lhno,.ite. The ';^:^.i;t I::; • -1 ^■'•':''-* "'"^ ^^ ^ i^'*'-'-^' "-' .rV-.lv ir.-.....l:.rly i....-rl....k..l. Tho,.Kh very tine .n |rran,. ;;,;,;; Sh ,..v..r. ll..- l-lls,.:.r ,..e.-..t. ;he .an.e appearance a. do the pj If r.nl,li.J.... Vi.uipally io th.- h.^e, which n.ega«;op.cally ' , ',,. ..ut ■.ln.,wt l>t .ck i.. -olor. a.,.l weather, to a hrowninh pray. M : ; : Sv:;.. M,1 t...- .,..-.. .how the f ^t. .. re^or... , . „ ,,„l h.-e-has h,.c„ .,o .Ul.s...,u..,.t growth, the honler. of the ... .;..,. ,,..i„. ,,uW ....oo,h. The «roun.l.nas. .. .in extre.ne j h.,e 1 ,„.r,.lM.p..- ...osai.. with a tlow str..ct«re. -'■«f'f' '^^ s, 1. of. ..a,...ti.e «ra....h-.. whi.h ••..in.-i.h. i.. .l.rect.o,, w.th the tlow. K. Tthi. struct.... Ci is evi.h...t that this type ,«ay he re^arda .vs trans.- ,io.,.l hctwcc. the .,uart/-sve..ite porphyry and a quarts trachyte. Hi\RT7. ronvurnr ■n,.. .,,,.rt/, |. .rphvrv is sepanite.1 fron, the ahove hy a hroa.l hand of tra..siti ... ro.k which "shows a gradual h.crease in the nun.her of quartz rn....rvsts. a.,d a corrcspo.uli.,« decrease i.. the ca.e <.f the felospar. „ ,,,,„i sp..ci...c..s the quartz-porphyry is a li^'ht gray fels.t.c rock wc.aheri...'to apaU> re,l. a..d is thickly studded with roun.le.1 pheno- 'r'st- of clear vitreous ,p.artz. Under the n.icroscope the s.une con- stitucts arc p.cscnt that were fou..d in the .,uartz-syenUe porphyry, with the cxceptio,. that the quart/, is in very lar^^e an.ount wr>.le he iVl.lHpar is represc.ted hv o.dy a few phenoc^yst. in each slide. At the ,,„„I,., of the ,,uart., porphyry n.ul the hornhlende syenite the former los,.s its .•hara.tcristic stn.ct..re. an.l occurs as a granular mosaic of q.-artz •u.d feldspar, the latter hei..;: present larj,'ely in the form of Carlsha.! twins. This co.itact facics is a little coarser in gnviii than would be expected. . l-r... .„>..r,.n I «„.■„„.. .r^-k- -f ,h.. Fox H.-t V.>ll..y. Wi.pon.in, .«.", p. «... VKTKtXiRAI'HV :lH',» Analy«.- of bc.th vari«ti«. of the ,K>rphy ry «ave th. foUowing re-u>U I 11. >ll. s,o, ■•■ T,«»,.. Al.lH. F^O. Fe<) . MnO. CaO.. M«<>.. N»,0. K,«>.. I!,0. I. 14. l« ;(,*• J. 47 .12 .«> «H .•S.:f.' 4.»4 .72 10\,n . gr., .tt:l 77W ll.OH S.'.ll :t.44 111. M •.•■.' .wl I.i.'JV! I.IH 111 Tr. i.;!2 H.4(t .■..7tl »V'. IkO Sr«» S«), n Kl »n««<'•» *«-v-';'>;,,,;j:,,% ..„.iy...t «.y 111. tlimrlr,-»yenitP p..r|.tiyry, B..,ir,.a« m..-im»in H N. StokpK). „; the grounaman... the r.su t V''»'' ' ^ f" ^^ J^.^u. ^ Tho rather hi,h Wtwe^n the feia.par... ^»;«^7;;; ; ^^ t^^^^U in the «ro„n...na.. the -K-rcentaKf of lime an.l niam.e.m. iri.lTlr nIKE ,,e aiUe cnttin. the .yenite ^ ^^^ ^ j ^S 11;:;::;:'^ when fre«h \. ^rav in coh.r and we. Uur. .> a . .^^^^^^^^^^ ^^^^^^^^^^ _ _^_^ , .^ aminea micro.eo,,ioany. .t i-s «"en "^ ; , ^^.,,, ,, ,,„., .,uart/.. „„ae «,. of ""'f""":''--'''' ' /'"XjloW >M.atite. ana hrow.> hiotite. Thefeia.pari. -^'^if jf, ,",,::! 1 .n.all .»e<-ks of hn.wni.h viauals; it is very turhul an.l ... u ,^,,„.i,tea with it are U„.,nite along the ceava^e ana .UapU^^ ^^^^^^^^ ^^^j. .^^._, .p,,.. ^t:S:;::i,:woSi:t^-^"-a ....... The..art. :',!Mt c. i:. I.K UUV— (iKOMKJY OV KUiAlI) MOIXTAIN, fA.N.M.A is suLonliimte in amount to the feWspar, and frequently holds inclu- sions of the latter mineral in ii poikilitic manner. /,.! fRKMIA .V lloUSHLESIlE-UliA MTK UXF.ISS Tin- mttiuuori.liif rocks shown in the southeast corner of the map are, as l.cf..re stated, a hornhlende-ranitc gneiss and amphil.olite. Tho«iieiss is a li^'ht colored rock of medium jirain, with a rude folia- tion of th." essential constituents. Microscopically, it is composed of Mllotrioniorphic jrrains of feldspar, hornl.lende. and .piartz. with acces- sory apatite, iron ore, an.l hrowu sphene. The iron ore is nenerally surroundcl hy the sphene and is prohably ilmenite. The feldspar is crvptoperthite. consisting of an extremely fine parallel intergrowth of ..rlholanes. It is twinned in broad lamel- he according to the alhite law, and gives along the twinning plane an extinction angle of ',\^.^ degrees, which indicates labradorite. This wjis checked by a mechanical separation, which shows that it ha.s a specific gravity of 2.(i!t. The ln.rn.blende. which is in large am unt, is brownish green, plcochroic, and has an extinction angle of 'J) degrees. Reddish brown, stronuly )deochroic biotite is in smaller amount than the horn- bleniie, but crystallized before it. I'rismatic .sections are lengthened in the direction of the a axis and exhibit skeleton structure. The garnet is fresh, pale pink in color, and perfectly isotropic. It is much traversed by cracks and occurs in large, irregular individuals, either partly or w holly surrounding some of the hornblende and magnetite grains. RkLATION Ob- RUJAID TO THK OTHKK Id.NKOlIS HiLLS IN THK VlCLNITY The examination of Rigaud has shown that holii in petrographic character and chemical composition the rocks are (juite difl'crent from tho.se composing the other hills on the same line. Two of these hills KKLATIONSHIP To OTHER HlUA •»! ,„agn.a channel con-ulem .ly, ^^ »=;:;' /"^^^'^^ On tl,e other h.n-l. oon- ,iacring the fact thai Uisaua s *''""3 ^^„^,li,e •„. ll.e l-=iurent.un to ascertain if it wouUl »''^^«.*"> «;;';; „f ,„ area of hornhlenae Accorain,ly a brief '•-"-';';"', 7,, "trentiar, in the town.hi,. o. ,ve«ite which occurs on the '^^ ^^. ,.,il,, „„nhwe.t of K,ga«a. Greuville, Chatham, a.ul \N e.U« orth. al.oui GHKNV,U.K AHK. OK SVKN.TK A«n I'oKrHVHV • „n are', of »'• *'\»«'^ ""^'■^' ""'* ''"' The Grenville syenite occupies an area ' ,^;^,, rooks on described by Sir ^Vill-m 1^.-.^ -^^^,,,,,,^„,,,,, ,, u.e U,,- Sr-^^'Sirris;::! . -..stern .art by a.naU pear-shaped mass of porphyry. I'KTROGKAPHY „ORSBl.F.yDKsyF.SITR .e«ascopieaiiy,tbesyenite;.arsa^e.semb.^^^^^^^ ,,„t contaiL a larger proportion of ■ '*;\.^.^^,.„,i,,Uy, it is com- vlil tinally the rook passes into '^ ^ ' ' ^ ,, ,„,i^,, Urown biotite osedof febl«P-anah..rnblenae ..til- - ^^J ^^ ^^^.^^ .„ ,i, ,,U luartz, apatite, zircon, and iron ore. h |^^ ,^^,,i,,, ,,.„h bem, parts of the area from an v.nstrmted one .,„,, and occurs :! kaolinized. The «nstr.at.d fe d • » ^^^^ ^^^^ „,...perth.te in thick lath-shaped and '"•*'«"';^;; ^^'^rthoolase and a finely twinned consist* of a parallel '"terKrowtli of the or „^,,,.,,,,,,, and from .la^ioclase. The latter ^^^^J^^r. as Carlsbad twins and is It. association .solder. J, "^^^^^ ^j^.J.ie in a graphic manner. The the feldspar, are idiomorphic. Ihe 1"^' ' j „.e,. The strong u:J':^;y»"»»--'i';'«;:^j^;;:;:';:r:i;^^ ^ ^"^ TITT^iuin li«Vl Report, p. 4*>. VJ ;?!>'2 O. K. I.K UOY— GEOUKIV OK ntr.AlD MOtrXTAIX, CANADA wl.i.h oii..^e the Ivtter forms the interior /...ne. Both minerals alter to a Vflliiw serpent. lions material. " The -luiirtz oeenrs in roun.le.l an.l angular grains, tilling n interst.ees between th.- fei.lsi.ar in-lividuals. Flui.l inclusions are numerous, an.l strain sha- lishe.l in tiie Geol.)gy .)f Canada, 18t5.'5 I{ep'>''. ''"'• ii|'l>«'"^ '" '■'"'' ''""«'■ column below. I. 11. SiO, '^-^ «'••»» AM), '-'-^ '^•'«' F.M), - :'•«" Ke«) ^"0 '■•»" MnO — •'■-' CiO i« •"» Mk<> — •** Nh,0 S™ ■'■'■^- K.,(> :'■«« ^-^^ IM) ■"" J^ It'.t.OS 101.11 .SptH-iti.' gravity 2.6! '■i.'Xi I. Quartz-syenite imrptiyry, (irenville (analyst unknown). II. Qimrtz-Byenite porphyry, Higaud (analyzeU by O. E. Le Koy). VKTUOt.ltArllY "I- ..i;i II. IV. •^ii'-'^'' :\'x\ VK.TUOt.ltAl I" '■■ Tho««h tho conM..rHou of i'-;';;;>^;;;:j:;^ :.,„,,„, u. . ..n.,o.ituvn. thele.. .how« that 0,o tw-. - W - -^^^^^^^^^.^ ,,„ . u.t.aonb^ , prove. =-f-*; :;;:;', t... .-i-M- -^ ^'"- ^-""''-^'^^ From the vatio of the .Uk.in evidently a soclv-orlhodase. UK.vno^ovT„KU..M..AM.«^>-vn.u:A... 1 rihvrvhas^liowii k:'.:s^::-»:---^ - ;"■; te .1 « "" the ir.^au.l ,ua,.. .,„„ ,,, , narrow h.n.l KM • * ^ „ J p.,,cioic-Moi>.ScALt ll neetea in such a -- -^ ^^ J,,, ..^ ,, Thi. -.uM^- • ...our- ,„ne.. with a known "^^ '^ ' ,, ,,,a ,ith other masses ot ^^^^^ Sm^,nverS.ntUwre.p^.W;;;^^^^^^,,^^^ "^^CZZtk^ systen.. ana ^ -^ J ^ .H^.^U-aiy aeveio,. ^^ tt^^^Turn;:- the em,..-, t.. ,... ... r^^^ ^ .^^ _^ . ,■ ,,f Vll' ot itxneiiU:- nee, lis ''i~' 3'.U i>. K. I.K KOY— OKOI.fMiY OF KHi.M 1> MolNTMN, <'.\N.\I>.V Rwiu.l is cinpoHea niiiinlv of H normal lu.rnl.lMule syenite pieree.l in the nortlnvst l-y itn area of porphyry, wl.i.l. .lifferentiates from a HXinrtt Mvenite varifty to a typical (piartz porphyry. Tin- other hills, ho far as known, consist of an alkali ric' venite. associated with a ha-ic ro.k of the same petro-raphical j.rov.i.ce, such as therulite or ess.'xite. hoth of which arc totally (linVrent from the Uiganil rocks. In the township of (irenville a mass of hornhlentle syenite o! pre- t;amhrian age cnts the F.aurentian an.l is iUelf pierce