IMAGE EVALUATION TEST TARGET (MT-S) V. // :/. 1.0 irrllM III 1.25 1^ til e 1^ ^ l^^ 12.0 21 2.2 U IIIIII.6 V] «^ /i 'a c^. " <.1*. 9: cW 0% ■^y 'T- '/ /A Photographic Sciences Corporation ^ %s iV V \\ 23 WEST MAIN STREET WEBSTER, NY. 14580 (716) 873-4503 ^9> V ^ ^^"^^ <^ t #^ ^> %^^^ "anii Lake. Kaeh side of tliis trianjiU' is approximately 2."»() miles, and, allowin<>- for sinuosities in the houiidary, its area cannot be less than 30,000 square miles. Lx])lorations in this extensiv<> resiiou have not y^t put us in possession of the minute information desirable. In ISO,", Dr. ]fobert JJell made certain ex])lorations -wliich are described in his report to the Ceoloaical Survey of Canada in Ks7,'), and at a latiT date also he was euiployed for several years in this ilistrict. The results of liis in vest i,i>at ions may be found in the Jieport of the Geological Survey of Canada for lS.sO-2. .Mr. K. ]>, IJorron like- Avise made several jom-neys, particularly in ISSl and ]SS2, and re- ported on his explorations to the Ontario (iovernment.' li\ IMm; Mr. Alexander Niven was commissioned to lay down the bi'undary line between ^Xipissing and Algoma, which he extended for one hun- dred and twenty miles; he. was accom])anied by :Mr. E. Ihirwash, whose report r n the geology of the region traversed a])pears in the Iie])ort of the llureau of Mines of Ontario for 1 ^!Mi. This boundary line Avas continued to the ;Moose lliver in 1S1»S, and a base limi carried westward from the 120th iiost in IMIii. Lhe writer accom- panied the two latter ex]ieditions as geologist, and his reports ajipcar in the Reports of the Lurcau of ^Alines for these years. With the exception of the above mentioned reports, there is very little available litei-ature bearinii' on the* region in question. The southern and majra]ihieal natnre, sueh as J.o^an's oriuinal llnronian, Lawson's Keewatin and ( 'ouohouehiiig series, the Ani- niikie and Xepifi'on formations, the i>ray\vacke and associated roeks of the Sndlmry reji'ion and the various schists, altered erni)tiv(s and crushed li'ranites characteristic of wide areas in northern On- tario. In the reii'ion under discussion the Iluronian is representcfl hy a great variety of schists, presumahly of clastic oriain, and hy others of altered eruptive nature, clusely associated with both acid an former rock just south of the heiii'ht of land near the Montreal Ivivor, and Mr. Ijurwash also refers to it. It is in regard to the various schists that the great difficulty of determinatiou arises. To establish n fixed uomeuclature for these is almost impossible, as their varieties of colour, structure and texture are practically iniiumeralile. Jn a dislanco of twenty feet no less than seven distinct varieties were counted on one occasion. On the other hand, to pass by these rocks with a mere description is altogether unsatisfactory, as megascopic descrijitions by different observers might leave considerable doubt as to the identity of similar cxjiosures. For exam])le, the sanu' rock is describiMl as " dark (luartzite," " dark gray siliceous schist," " quartzose schist," f tc. To the trained scientist these terms, while not ])etrograi)liically synonymous, are sufficiently suggestive to recall the rock in ques- tion. In imblications, however, intended for the guidance of pros- pectors, this method causes great uncei'tainty. For economic i)ur- poses, it would suifice to establish the fact that, for a particular region, a certain varietv of rock was ore-bearing, leaving the ques- tion of its origin to more scientific ol)servers; luit there are too many gradations to render such a classification of any real value. It is only on the basis of origin that a satisfactory arrangement can bo effected. The petrogTaphical peculiarities of the rocks encountered will first be described, with little or no reference to geographical posi- tion, and afterwards the great Iluronian areas will be outlined and the location of particular species indicated. m. nil tlic roclin, l)Ut sueli a primary division is uselos in tlie present instance, where dviiamic' metaniori)liisni has ohliteratiMl the dividinii' line and in- duced resemblances -which forci' vork- of ditl'ereiit origin into the same grou)) on account of sinularity of structure. Xi'Vertheless it is to oriu'in that we nm>t look in deeidinu' the more nunutc divisions. AVe have therid'ore: — T. Tnaltered eruptive^. ]]. Much metamorphosed eruptives and elastics, p;encrally schistose in structure, which may be endiraced in the term srliisl. Aniono,' unaltei'eil eruptives are included all those rocks of primary ip-noous origin, in which tlu- oriiiinal -tructuro and mineral constituents are unaltered or but slightly att'ected. They may i>e grouped and will be considered in the foUowin*;- order: — (1) Acid or potash-felds)iar rocks: Clraiiilc, siioiilc, tiuii'ifc sye- )iile, qwiriz porijlii/ri/. {'2) Basic or plagioclase rock: Diorile, dinhnsc, oUviiie dinh^isr, ijahbro, basalt, (Uin/ydaloidal Ifiji. /ii/rcri'iiih'. unovliinsih'. Cininllc. — This rock, in an unaltereil condition, plays but a subordinate jiart in the geoloiiy of the district, as far as the \\\\- roinaii is concerned. "When present in this formation it is p'uer- ally in the form of narrow dykes, conforming: to the strike of the schists; the district described as the "second area" is mor(> remark- able for these rocks. ^Iusc(.>\ire, horidilende and biotite jiranitcH have ])een observed; in all eases they are typical and reipiirc^ no further notice, l.ariio masses of pranite, in some cases probal)ly eruptive, in others representina" the non-laminated portion of the Laurentian matrix, are common in manv parts of the reii'ions of that ajie. According' to the theory of Dr. Law-on ' the ^raidtic portion of the matrix wonld be distant from, and the ji'neissoid portion near to the iriu'oinan contact. On this assumption much of the i>ranite observed must be eruptive, for a loss of lamination on approaching- the contact is apparent in manv places. Some of these masses are ' Ueimrl on the Geoloinj of the Uatiiij Lake Region. (Report Geol. Sur\'. Cun., 1H87, im«e 112.) 6 mapped ns oniptivo cvanito bv T>r. Ilcll. It i> not within tlio icopo of tliis ])iip(M' to discuss tlic jHtiut. {Vov localities sec pages l'l', -J'-j, iir>, ■2(\, 27. :)(». :;i, ;!;; and :54.) Si/('nlh\ — This viK'k also i> not widespread, typical examples Ix'inii' very few. One mass occurs about Hfteen miles up the I'dack Itiver and shows altered honddende and feldspar, the cliaractcr of the latter beini>' somewhat hard tui deternnne in the specimen obtained; ])ut as the jicneral ficdd appearance is decidedly syonitic, j^nil the niicroscoix' reveals scarcely any trace of striation in the f(dds]iar, it is concluded that the rock is syeinte. altliouah it ]iro- bably contains some idat-ioclase. In addition to this exi)osur<- and some narrow bands associated with the s(diists, all the syeiute is, like the li'raiute, blended witii liiieiss and syenite a'ueiss and must be classed as LaiU'entian. (For localities see pat^cs -J'.) and :!(i.) Aiif/Hc siimHc — Th(' mass of eruptive which crns-e.- tho Abitibi Kiver, forming' the Lobstick and other rapids as well as the Great Canyon, is represented at its upper or southern margin by a rock of this nature, which continues with some variations for two or three miles. It is intersected by snuill dykes of tine black dia- base, Avliich present some beautiful exami)les of miniature faulting' and branchinji'. At the Lobstick Poi'tage it is somewhat schistose in places and much altered, showinc,- numerous red iiarnets, a little quartz, considerable oi-thoclase and some i)hi,uioclase with briiilit green aui>ite. At the Oil Can Portaue and above it, a section shows fairly lariie crystals of autiite in a somewhat tln(>r and mosaic- like mass of orthoclase Avith a little (luartz and phijiio(dase. The aupite is. in many places, almost entirely altered to fibrous horn- Ideude, fiakes of brown mica, i>-arnet and maji'uetite. This rock presents a gravish-black, somewhat speckle;e in arnet-i, a little •e with hriiiht [t section shows r and niosaic- g'ioclase. The ) fibvons lun'n- te. This rocdc nce with evid- 's more altered ee ])ace 'V-].) a good state of ion it is very ited, it cannot ■ the schists, ct anhetlra of ' and sonorous size of several )ni this coarse variety all gradations are seen down to that composed of individ- uals (it luieruscdpic si/.e. The tiuer examples oii fresji fraetm'o still shuw the ery>talliue structure, but the nmttled appearance i-i (■iitirejy lost, ])artly (aviug ti. the tiiieness of texture, but pcrlians nidi'e in (•iinseipieuee of diseojoi'iirion of the feldspar. Thi« ivp- is common ;in: in some instances the intrn-ive mass lia^ lifted the country schists to the suniinit of the hill, while the diorite a])))ears on the Ihmks. By far the ninst general manner of oeeur- renee is in bands of varying thickness, <'onfornKdile with the -trike and dip of the s(diists, whiidi is avnerallv at a high angle. Tliesa thin hands are invariahly iine-graineil and almost black in colour. 31any of them towards their borders have entirely lo^t the cry-tal- line structure and are honiogi'neous to the naki'd eye; the micro- scope, however, reveals some traces of crystallization in ill-forine.l hornblende and magnetite crystals, due, of course, to the more rapid cooling of the exterior of rue mass. An imjiortatit con-idera- tion now confronts us. \vv these interbedded diorites contempor- aneous with the schi>ts, are they sul.secpient eru])ti()ns, or are tho schists themscdves derived from the diorites^ it is in-obable that all these cas(>s occnr. The diorites can rims be divided into thre(> classes, (T) massive eru])rives, (2) contemporane(His diorites, (:;) diorites passing into diorite schists. (!) The class of massive eruptives can be recognized by a distinct crystalline structure nearly always increasing in fineness towards the borders and on. holh sides. All the irregular ma^sc:^ that form hills, the large dykes crossing the country r(xd-:, and nianv of the interlaminated sheets slmw this peculiarity. As far as the last variety is concerned, the bilateral symmetry of the mass can 1 o accounted for on no other assumption than that of snl)se(pieut in- jection. The accessory evidence of a sheet of diorite breaking acro.-s from one plane of stratification to another has not been observed heVe, although it is wcdl known to occur. (2) Confem])oraneons diorites a.re generally less crystalline, more easily weathered and more inclined to show irregularities of colour and structure. If these rocks were oriainallv overflows 8 tlicv iim-t liiivc ciiiiiulidiifod n.~ (liiil)a»('?, l)Oi'ii\i>o diorito is jroner- all.v (•(iii^idcnMl iis cssciitiallv phitoiiif. On the as.sniii]itiiiii that tin* (•rijiiiial iiiaiiiiia \va> covered liv (dii-tic 'Materials wliiidi eveiit>ially lieciiiiie iiietaiiin ^a\(' convincini:' evidenco of their contein))oraneous luitnre, and it -eenis advis;dile to inidiide in this cla^-s most of the narrow hands, ])erha|)s all in whi(di no hilateral arranuenient can he detected. (.'!) Jiocks of the thiril (dass. /•/',:., diorites pas.^iiiii' into diorit(! schists, consist of ordinary diorite towards the centre of th(> layer hecomiiii:' more and nioi-e ^(dnstose outwards, find tinally t'adin.ir away into other schists without any distinct line of dt'niarcation. This tyi^e of rock is doul)tles> the result of intense nietamurphism, ami, while easily rccogni/ed, affords very little information as to oriuin. While they seem to ho l)est i)lacetl in n (dass l)y thomselvos, th;'V are more jirohahlv dei'ived from tlie second than from the fir-t aTouj) on account of the difforence in composition towards tlio l)or(h'rs. Tlie outer parts show much more (piartx than llio inner. This co\dd hardly result from metamorphisni alone; there- fore it is concluiled that tliey were more or less mixed with aciil cdastics, \vliicli would point to a more contemporaneous origin. Any of these diorites mav jjresent varieties, hut more especi- ally those of the first class. While typical diorito consists of horn- hlende and ]daiiio(dase, the former initrodient may bo replaced wholly or in part by black l)iotite, fiiving a rock known as mica diorite, or quartz may occiir, fonniuii' (pnirtz diorite. ]iotli these varieties are found in the rejiion, as well as quartz mica diorite (tonalite). The latter genorallv has a pink feldspar and nuicli resembles cranite; a section to ascertain tlie nature of tlie feldspar is the only sure means f»f determination. The passage oi dioi-ite into diorite schist and the so-called " greonscliists " is a suVqect of much eontrovei'sy. The meta- morphisni is accompanied by various ])henomona of alteration, as changes in texture, softening, change of colour, alteration of horn- blende to actinolite or chlorite, or even to hematite, magnetite, etc., alteration of feldspar to epidoto and saussurite and in many places to calcite. These various changes have produced rocks which arc 9 iDi'ito IS ffoncr- iptiuii that till- licli c'vciitually pcct tn liiid ;l f^. Tliiri coM- A .^utHcioiit ^ CXiilcilCO (if -' t(i iiicliido ill fit ii<» liilatcral lii" into (.li(>rit(; (' of tlio layer Hnally tadinii' ■ r- and a more detailed dcM-ription will lie i-iveu later. (I'lir } loealiii,.- see ].ajies i';!, i',"), J7, l'>. ;;(i, ;;i, ;;j, ;;:; .,,,,1 ;m.) PkiIhisi'. — This rock is hv no mean^ a-> e(jmmon as diurito and il-< examples -eem to liejoni: to ditVei'eiit periods nt' injection. 'J hose of -imilar auc to the diorites and schists are ii'eiierally much altered; while a second >eries, of api»arentlv later aii'c, hetter retains the oriiiinal nature. llock< of the hitter type occur in narrow dyke^ cro-^iiii:- rhe countiy mek in all directions; they are particularlv iioficeal.le in the eruptive i-euion of the .\hitil>i Canyon. These helts aiv uniformly ver\- line-iiraineeriphei'y, which weathei-s smooth while tin centre has a nioi'e punctate.! api)earance. (See pa,uc< -J-J, -j:',, lil. ijC. and :;."..) Oliriiic (litilinal diahase -i uctnre with n, ■ dies of apatite and irrejiular patches of olivine. \.nich is nunh altered to mn j;;r: ite. Chihhro. — ""["he niost characteristic examjilis df p'althro occur on the northern jiart of the Ahitihi Canyon, and even there it can scarcely he considereil typical. The he-t eNpo^urc^s ar,. seen at the deepest part of the i>ori>e, where the clift'< .m- 100 feet liii;h ami of a dark massive apjicarance. Cnder the nucrosco]ie the auiiite is seen in distinct cry>tals hut little (lec(»mpoe ",",.) BoKolf, (i)iiiff/(kih)i(Jal fnip, pi/nirenllr and anoHlinsilr are of such rare occurrence that suliicient reference to them will he found in the notes of distrihntion. (See pages -j:] and :!:"'..) 'I he whole serie- of Iluronian rocks not inchided under the unaltered eruptives it i^ proiioseil to j>ronp together as schi>;ts, although tluy may not always ]n'es(.iit a schistose structure. Tiu> nse of this term is at the hest very uncertain, as is seen hv the interpretation placed ui)on it hy Professors Irving, Chamherlin aiul Van ITise. "Almost any non-fossil if orous rock presenting in sonic sort 10 a stratiform structure, and more compact ami indurated than i? usual Avith post-avchacau strata, lias Ix-en six.keu of as a crystalline schist. I'he near approach of cc-rtain foliated fragniental deriva- tives to tyi>ical crvstalline schists— indeed their oi-adation into un- distinjinishable, if not identical, forms, and the passaii'e of massive evn])tives into schistose phases — would render very dilhcnlt a shari)ly limited consideration of the typical crystalline schists.'' ' In this hroad sense our roi-iou is for the most part made up m])letely solidified by the sanu' aa-encv on the other, then; mu^t therefore be rocks whose original form must always remain uncertain." " Tn this connection see also Irvinsi-, Chamberlin and Van Ilisc, •'Tlie greenschists have buon derived by the modiilcation of original oruptives and present a degradatlonal development which may bo hioked upon as ottering a contrast to the constructive developmenr of the crystallines built up from clastic originals." ■'• It will therefore be evident that any attempt to classify tlusi' rocks must prove in some manner unsatisfactory; various author- will adoi)t diiVerent methods, and some overlapping and unccr- taintv will always exist. The above mentioned authorities classify the Lake Superior schists thus: — I. Eruptive derived (metamoriiliic) crystalline schists. IT. Tutf deriviMl crystalline sdasts, which were develojii 1 from igneo-fragmental mat(>rial. III. Clastic derived crystalline sidiists, which were develop. ] from fragniental rocks by secondarv growths of the constitue: t crvstalline fragments. 'Coiiiiit's Geolofiique Internatioiuil, KtUilci sitr les Schisten Cristdltins. L^ dres, 1S8S, pa-^e i)'2. - U. S. Geological Survey, V.ulU-tin G3, 18fl0, pajje IS;?. ■'CoiiKit's Geolotsique International, WiK^f*- siir Zfs Schiates CrishiUin». Lo fires, 1888, page 103. 1 tccl than i? u?;ual ■rvstalline st'lii?t, iginental doriva- adation into uii- ssaii'o of massive very diliioult a lino scliisis."' ^ part nuide up <>( r.ain SiTonps, (1) 38C whose orip,in ishine tive development : to (dassify tlusi' ; various author- iping and uncer- uthorities classit'v 10 schist^, were develojn 1 h were develo]ied ■ the constituoi.t ften CrintciUina. L ten CristaUins. Li (incriiui clienucul, organic and clastic agencies joined. Professor Dr. AlLuTt lleim, after showing the difricnlty of classification and sniiimari/.iiiii' tlie various etfects of dynamic motamorphism, savs, " I)i(> rx'^clialTenheit dor krystallinischen Scliiefi'r in den Al]ieii ist vicdfacdi dnndi den (ieliirg-stannnii>prozo-s verlindert worden. rrsi)riing!iclies nnd mochanis(di spiiter (owor- denes siiid sidir oft nocdi uar nicht von t'iiiander /u iiiiterschei- deii." - Dr. Andrew Law>'in cla>siti(>s the Keewatiu series of the Lake f the "Woods thus: — of the Woods thus: — I. Basic N'olcanic asic N'olcanic: Altered diahaso and galihro, massiv(^ and schistose with associated amidiiliolites or and hnvnlilende schists. II. Acid Volcanic: AUered (piartz porphvrie^, felsite sehi.-ts, -ericire -chist<, l>ii]'))hvroids, etc. III. Volcanic Clastic — pyrocdastic: Asji Ix'ds. many graywackes, tuft's, and agglumoratc-, hoih liasic and acid. IV. Detrital — epiclastic • Conglomerates, tpnu'tzitos, clav slates, micaceous slates: soft, gray, glossy hvdromica schists; with chlorite schist^, mica schists, and certain tine-grained gray gneisses, or ratlier feldspathic mica schists. iii.vti -v 111.-1.7, (lIUl HlliUM luie-jii ratlier feldspathic mica schists. A . (iai)l)ro, ser])ontine and granite.'' \r.,,,,. ,.4! tl.„ . .1.:, .^^ .J} '_ Alany ot the sclii.sts of our region are quite comparalde ti. LawsoiTs series, lint many of Lis mendiers are alnmst or eutirelv lacking, notahly the conglomerates, agglomerates, serpentine-, and g'ra\ wackes. It is not propo.sod here to deal with theoretical coiisidevatioiis as to the origin of the various represonta lives. Smdi ])oints can onlv 1)0 det ermined hy a detailed study of a more restricted area '/'"■''• P- lOJ- •-' Tl,i,l, p. 20. ■ C'on^res G.-'oioyiqne Internatioiml, Ktmh's .vir Ic.o S,-hi,t.:^ Cn.it„!lhi< Lon rtree, IMSw, ,nif:iii, to c'm])hiy tliat eviihiice onlv when the roek scfUis to l-e anaU^ii'ons to some described In- oood authorities. From this point of view the following' tabk' will iiive an outline of the method adopted: — I. S(diists of eruptive orii>'in: (a) The ''green_schists '' and diorite schists. (b) Altered ]iorpliyries anvc: (o) (Juartzose schists. (h) Sericite and chlorite schists. I. Schists of Eruptivk Origix. (a) The " f/rcen.^chisla '' and diorite S(diist.s. — As indicated in the descriinion of diorites, that type of rf)ck ]»asses nradually into diorite schist. retainin,<>' its mineral structure and merely bec'omin.u' schistose by dynamic etl'ects. These diorite schists are quite char- acteristic annized, if not in the field, at least by the examination of a thin section. The "stdiists" are doubtless eruptives which have been subjected to more intense metamorphism and while jicnerally occurrino- i„ narrow bands are sometinu's massive and of considerable extent. They do n,,r commonly invsent a schistose structure in the hand speciuKMi, and verv rarely can such a struc- ture be made out under the microsc(jpe. In the'tield tlH> weathered surface is a shade of dirty nroen; it .uenerallv shows a somewhat punctated a])])earance and fre(|uently exhibits >mall whitish specks. (These must not be confused with the lari-'er and more ani-ular blotches seen on manv altered porjihyrites). The freshlv broken surface is rather uneven, greenish to black in colour, and shows a 13 tlior to dopoi'ibe '(ivdiiisi' t(i their atrendin,!i' their .'k sei'ins to l-e ''mill thi?i point of the method 1 part to both Ls indicatrd in .uradually into rely beeoniinu,- ire quite ehar- istributed and e examination uptives which !im and whih' na>sive and of nt a sehisto.-e sncli a struo- tlH> weathered '^ a somewliat ^•hitish ^^peckg. more an^nhir reshly ])roken , and shows a pomewliat silky surface, which under the liand ^lass is seen to be distinctly ratUal in structure. Microscopic sections are decidedly unsatisfactory, showiiiii' generally but an indistinct dirty mixture of kaolinized and saussurized feldspar, a very little ipiartz and liyht ^reen liorul.lende and chlorite, with accessory pyite, hematite, magnetite, ,earnet. mica, etc. Some of these rocks very much resemble the darker varieties of quartzose schists to lie subsequently described. In the field they may be distinguished from th(> latter rock by beini-- more easily abraded l)y the hammer, and l>y the fact that they do not show the same tendency to break into rhomboidal blocks. This rock is one of the most frecpunt occurrence and ])rol.ably constitutes the bulk of the first or iireater Jluroidan area, the limits of which will be indicated in the second i)art of this paiu'r. The Avhole question of the nietamorpliism l)y which theso rot-ks were produced would fill volumes. As here cxemiililicd rluy are aualo- ,U-ous to the so-called " iireen Jhiroiiiau schists," and probably identical with the series described by Professor Williams in tlie "Greenstone schist area of Michii>an," where he says: "There seem to be only three different ways of explaininij,' the facts as th(>y are idainlv and al)uiulantly manifested in each of the several poiiit> examined on the ^lenominee Kiver, Wi' may supi)ose, as did Foster aiul Whitney, Whittlesey and Crcdner. that the schistose pditions of the rooks exposed at these several ])oint8 are more or less perfectly metamorphosed sedimentary material, Avhile the more massive ]iortions represent intercalated beds of eruptive oriiiin. AVe may ima.iiine on the other hand, as did Romiiiiier and P.rooks, that all of these rocks, includin- the most schistose and the most massive iihases. are ))rnbab|y altei('(l sedi- mentaries, supposing with Koniiniicr that the more ma-sive kinds are mercdy the same sedimentary material fus<>d by the iiitensitv of the metaniorphosinii' action so as to lose all trace ,,f the original stratification, or admittin-:- with IJrooks the iiossibility. thouo-h i;reat imj.rebability, that some of the more massive phases, like the pabln-o of Sturiicoii Falls, are of eruptive oriain. Finallv. we may imaiiine that all phases seen at these several places reiu-esent material of eruptive orii-in wliost^ stratiform structure is due to sccnndnrv rlynamic nconoios. (Trvin^.)" ' ' U. S. Geological Survey, liulletin 63, 1890, page 0(!. 14 m Here Professor "Williams nn(lou1)te(lly includes other schists than the variety now under dii^eussion, but from the description3 this particular rock must form a larae part of his series. The theor\' that the massive diorites are intensely altered sedi- ments is utterly untenable for this region; for pi'oof of this the reader is referred to the remarks already made regarding the more massive diorites, to the bilateral aiTangemeiit of many of the bands, to the fact that in many instances they abut with a sharp line of distinction against entirely dissimilar rocks, and further that an enormous number of similar belts of diorite traverse the neigh- bouring Laurentian gneiss, notably on Jlay Creek, Misanabie Lake, Little ]\Iisanabie Lake and Kiver and the Laurentian area around the Pishkanogama and ^lakozenda or Trout Kivers. Granted then that the massive variety is eru])tive, the freciuent and beautiful gradation into rocks of this type so constantly seen is suflftcient proof that they liad a innmary erui)tive origin. (For localities see pages 22, 28, 25, U), CI, 32 and 33.) In this connection mention must be made of the altered dia- bases. Ivocks of undoubted diabase origin are rare, but the possi- bilitv nnist be admitted that nuiny of our greenschists are of that nature. The ])roof of this in manv individual cases can never be obtained. IIowcA-er, greenschist, showing 710 trace of pyroxene but exhibiting undoubtedly the structure of diabase has been met with, notably on Kamiskotaia Lake. This rock is grayish green in colour, not extremely hard, and only by the microscope is its dia- base origin revealed; the feldspar is almost entirely altered and the augite changed to almost colourless hornblende and chlorite, but the ophitic structure is well ])reserved. (h) Altered purphj/ries and porph/rites. — As already men- tioned, unaltered rocks of this type are absent, but a large series of altered representatives are met with. Schistose quartz porphyries present almost invariably a light gray or white surface and Verv frequently the quartz individuals stand out on the exposed surface by the weathering away of the more decom])osable, constituents. Concerning the origin of these rocks Professor Williams says: "They contain small porphyritic crystals of feldspar and quartz, and a considerable amount of sericite or hydromica. . . . . Piocks of this general type have a M-ide distribution and have ar- rested the particular attention of petrographical investigators. In i >s other schists lie dcscriptiong Tories. ily altered scdi- x>f of this the rc'ii'iU'diun' thi' ii iiiauy of the t with a sharp tid further that erse tlie neigh- lisanabie Lake, 111 area around Granted then and beautiful Ml is suittcient ir localities see he altered dia- but the i)os.si- sts are of that 1 can never be of pyroxene has been met ayi^h green in 'oj)e is its dia- Itered and the . chlorite, but already men- large series of I'tz porphyries face antl x'ory cjjosed surface I constituents, niliams says: r and quartz, \ and have ar- stigators. In 15 some cases they have been conclusively proved to be the product of the metaniorphism of fragnicnral rocks— either tutis or true m'.H- '"'''^^^— ^'''i'^' "I other cases they have resulted from tlie action of great (lynauiic forces upon massive rocks of a correspondiui;- cou- iMi-mation, //■., quartz i.^rphyrics. Wlien it is possible to trace M-ith certainty the origin of these rock< to stratified deposits tbev aiv usually designated as por,)hyroi(ls, while iu case their mother rock can be shown to have boen quartz porphyry they are usually caHcd schistose pori)]ivries. ]u their extreme development these two ty].es are often i)etrographicall\- indistinguishable, and thev in'esent an instructive instance of tlie in'oduction of identical results by the action of the same physical forces tij.on matter of the same average composition, thougli widelv ditlVrent in orii-.in and >tru(- ture.'' ' It is extremely probable that numy of the rocks of this gen- eral appearance should, in accor.hince with the above view, be called porphyroids and as such be ineluded in the elastic division. ]t is probable, however, that an eru])tiv(. .u-igin. as true (pnirr.-i porjthyry, is the proi)er exiilanation of the i)res(>nce of most of them. In many cases, by the loss of the porjdiyritic individuals, they pass into felsite schists, a section of which iu some instanceo much resembles the ground mass or matrix of the altered porphvry. These rocks are associated with the diorites an.I greenschists as well as with the quartzose series; it may ])e that in the former case they are of eruptive origin and in the latt(>r belong to the porphvi'oiil type. A typical section from: near the .Montreal liiver shows a fine-grained ground nuiss mostlv of quartz bu. rendered somewhat dirtv an, lutich altered but retaining their augtdar outline, together with somewhat smaller qmirtz individuals which, in nearlv all cases, show a rounded outline. (For localities see pages 2r), 2(i and \^?^^ Jilany of the so-called speckled i.nd mottled schists as well as some more massive varieties are altered porphyrites. They nay, in general, be described as gray, green and inu-plish rocks n-it\ blotches of white matter of an angular form. Tluy are not as connnon in this region as in the TTuronian around Lake 'Minnie- takie to the westward, but exposures ar(> found at the first falls on ' U. S. Geological Survey, Hitlletin 6i, 1890, page ll'J. 16 the Fredorick ITmise, River, on tlio line of portapes between liratapinii River and Porenpine Lake, and in some few otlier locali- ties. A section shows a fine-iirained matrix, largely oi feldspar and secondary (piartz with hrii-ht ureen chlorite, hrown mica, etc Implanted in this are liu'iie mnch altered plaiiioclase crystals. Another pecnliar schist which proliahly bcdoiios here is seen on the same line of portapes mentioned above. Tt is bhu'kish preen in colonr, of a prononnced schistose character and exces-ively altei- ed. A section shows plapioclase individnals snrronnded by an exceedinply fine oronnd mass, in which the secondary minei'als, larpely mapnetite and chlorite, arc arranped in a distinctly spheroidal manner. (See pape 25.) In addition to these we find a series of very fine-prained schists of whitish or liphtly tinted pray and red colonr, readily w(>atherini;' and presentinp a soft and pray-white snrface. They seem to contain little or no ferro-mapnesian mineral and nnder the niici'oscopo show fine feldspar individnals and qnartz Avhich is larpely allotrio- morphic. This matrix is traversed liv fine dark lines, probably re])resentinp the remains of mica ur hornblende, and is dotted by relatively porjihyritic crystals of ])lapioclase. This rock passes iriio coarser exami)les (still very fine however), in which the crystals of plapioclase can jnst be made ont with th naked eye on fre.-li surfaces. The coarser of these rocks is nndoubtedly a sheared por- ])liyrite, and as it i)asses im]K'rce]itibly into the finer variety wc are qnite justified in assnminp the same origin for the latter. These schists are \ery common and have been loosely described as " whirt weatherinp schists," " >uft fine-prained schists " and i^ossibly a-i "fine-grained ash rocks." (For localities see pages 2r» and lil.) (r) CnisJicd i/raiiifrs (dkJ fi'lsilcs. — liocks which may with safety be i)laced in this grou)) are exceedingly Avide-sjiread aril present many stages of alteration. They are generally pink or light gray in colonr with ill defined dark specks, iiiid occur intercalate! with various schists, particularly near the head of Lake ^Litagani- ing. Fader the microscope the only well defined mineral is quart/:, and sometimes ortluwdaso, but the latter mineral is generally mudi altered and presents a muddv appearanc(>. The quartz unifonnlv shows undulatorv extinction and fre(iuentlv occurs in narrow band- of a sonunvhat coarser texture traversinii' the ground ma^s of tli(> rock. The mica or hornblende, as the case mav be, is alwavs mudi 17 rtac'os botwoon o\v other loenli- (>l_v (if feld-^ipui- :()\vn mica, etc. crystals. <>'s liei'i' is seen 1 lilai'lvisli a,T(H'u xccs-ively altei- roumlcd by an idary minerals, in a distinctly 0-e.rained schists dily weathering seem to contain the mici'oscopu hivaelv alhitrio- lines, probably nd is dotted by rock passes into 1 the crystals of 'd eye on fre.-li Y a sheared pnr- iner variety \vc le latter. These 'ribed as " white and ]"»ossibly as 25 and 31.)' diich may with \vide-si)read ainl lly pink or liii'ht 'cur intercalate] Lake ^[atagain- lineral is qnart>:. aenerally mui'li nartz nnifonnly in narrow band- md ma-s of tli(> , is alwavs mncli chan^'ed and drawn ont into indefinite patches in one direction so that it appears as oldontr or oval spots with the lonji' diajjonals parallel. In these spots the microscope reveals actinolite threads, ehlni'ite, majiiietite, hematite, pyrite, etc. (For localities see pages 20, 27, .'i2 and .".3.) {(I) lloniliU'iidc ciul hiodte viica scltists, — The first of the-c rucks is a dark pray rir sireen nKittled or honiogeneons rock accord- ing to the dimensions of the constituents. It is com])Osed of horn- blende and (piartz and frecpicntly shows little or no schistose strnc- tnre. Hiotite mica schist is somewhat lighter in colonr, with sliades of brown, never c,Teen, its schistositv is more prononneed, and it is mnch mon^ snljject to weatherinp;. I'oth rocks are more associated with the Laurentian than with the Ilnronian, and by the addition of feldspar freqnently pass into g-nciss. ^lore or less aniindar fi'aiinients r)f these rocks arc often seen indx'ilded in the trnoiss, and they probablv at one time played an important role. In this connection Ch. Lory, in " Les Schists Cristallins des Alpes Occidentales," says — "Les micas schistes s(> cluu'gent de folds jtath et passent a des jzneiss, avec lesqnels ils alternent .... I)n reste. la separation entre les denx parties de la scrie des schistes cristallins est loin d'etre absolue: de vrais micas schistes, avec des conches de calcaires cijiolins, et meme de vrais gneiss, se rencontrent jnstjiie dans le gronpe snperienr; ils alternent sonvent, li diverses leprises, avec les schistes chloritenx on amphiboliqnes .... Ainsi dans la serie des pierres vertes, connne dans cello des vrais nucas schistes et gneiss, les diverses strnctnres schistense, gneiss- icpie on granitoidc alternent entre elles, en concordance, sans qn'il y ait lieu de snpposer que le passage de Tune a 1" autre soit lie a rintervention de roches eniptivcs." * It will be observed that it is considered better to include here only typical examples of these rocks, and that many of the dark gray and green schists, containing, no doubt, hornblende and (luartz, are classified under the quartzose schists. There are two reasons for this; first, because the amount of hornblende or mica is so small compared' with the quartz and is generally so altered and indistinct that the megascopic appearance does not suggest a liorn blende schist; second, because the associations of these rocks ' Congres Geologiqne International, Les Schistes Cristallins. Londres, 1888 page 21. 2 18 point more to a clastic than to an ipnoons origin. It cannot bo Jenicd however that a sharp line is ditiieult to draw, and that the two classes pass one into the other. II. Schists of FuAr.MEXTAi. Origin. ((/) Pi/roclaslic sclih(. are practically svnonynions, altliongli a distinction is oencrally drawn, the fornier' tcriu being applied to examples showing round or angular fragments imbedded in a matrix, and the latter to fine- grained gray rocks. The first type is but sparingly develoiied in this region, the best examples being seen' at the head of the south arm of Lake :^ratagami. As here seen the rock is green in colour and very fine- grained; it presents a distinct How structure around the included fragments, which vary from a foot in diameter to very small dimen- sions, and consist for the most part of light gray granite. The rock is therefore a conglomerate and perhaps graywacke conglomerate. Mr. Burwash reports conglomerate near Little ITawk Lake.^ The term "fine-grained ash rock" has been excessively em- ployed to designate strata of a doubtful nature, but in many cases the expression is used without sufficient consideration. "When the rock can be conclusively proved to have arisen from fine vol- canic ejectamenta the term is as good as any other, but proof is not always available. This is possibly the origin of some of the rocks of our region, but it is preferable to class as quartzose schists and to ascribe to a doubtful or variable origin rocks which, by sonn' obserA-ers, midit be considered as ash derivatives. (See pages 21 an.l 22.) (7;) QuarfzUcs.— In order to distinguish these rocks from those which have been called quartzose schists we must restrict tli.^ tenn to rocks in which no ferro-magncsian or micaceous ingredient occurs, and in Avhicli feldspar plays but a small part. The colour varies from white to lic'ht aToen or pink. By deepcniuir of colon r owing to increase in accessory minerals the rock passes into quartzo^' schist. Two varieties occur: — (1) Compact: a bard rock, almost pure silica in grains and broken crystals; (2) Saccharine: a loose friable variety resembling loaf sugar. tyi")ically pure white, bur passing into brown and black exami)les by the occuiTcnce of hema- tite and magnetite which are frequentlv seen in beautiful littb' crystals. (See pages 24, 25, 20, 28 and 31.) iReiiort of tlie Bureau of Mines, Ontario, 18'J6, page 17S. .•fj^: t cannot be ind that the so tcrni> are rally drawn, is: round or ttcr to fiue- ; roc;ion, tlio irni of Lake lid very fine- tlie included small dimen- 0. The rock onji'lomerate. Lake/ ?e?sively em- 1 many case^^ ion. When rom fine vol- t proof is not f the rocks o{ ;chists and to ich, by sonii' ; pages 21 aii'l rocks from st restrict th>^ )US ingredient The colonv liuii" of cnlnnr into quartzoM' rock, almosr irine: a loofo •o white, hnr ence of hema- cautiful littli' 19 (r) Clmi slalos and micaceous clay slates occur hut sparingly and will !)(> noted later; thev are, in some cases, clifficult to dis- tinguish from true schists. (See page 20.) IIT. Schists ok Doubtful or Yariarle Origin. (n) Qiuirizose schists. — This group includes a great number of rocks of varied appearance, with gradations of colour from al- most white 1m dark r in colour, reddish or jireenish, frequent- Iv exhibitina' rapid chani-es in colour but alwavs showing a decided- lv quartz-like appearance on fresh fracture. This variety is seen t,, perfection at the third portage on the route between :Nrataganii River and Kamiskotaia Lake. Examples from this region give from (50 to TS per cent, of silica. The third type is dark gray in colour, sometimes containing ^v> more than 05 per cent, of silica, and is more readily weathereil: it very frequently contains pvrite and it is the variety in whicli hornblende, mica and other ferro-magnesian constituents may b.' identified. This rock is more closely related to the diorites, whicli it somewhat resembles in rowj^i megascopic characters, although its constitution is entirely different. (h) Seririte and clihr'dp sr/( /,s/.s.— The sericite schi-ts may bo distinguished from any of the preceding rocks by a greater tendencv to cleave; in fact thev may be described as extremelv fissile. Fresh fractured surfaces have a silvery appearance and sometimes aiv' greasy to the touch. Thev are much more subject to sub-acrinl decay; a talus of broken fragments almost always occurs at the foot of a cliff of this rock. It weathers rapidly and the surface is frequently rusty and spotted. Tender the microscope the schisto-o structure is most pronounced. (See pages 22, 23, 25, 20, 28, 29, 30. 31 and 32.) 21 iniglit be ex ^scribod. 11(1 vi'i-y wido lul fi'cqiiouTly s (if stvatifioa- zite. A frc'sli lirc^cMits small inch liko tin Iron lioiiiou," 1. fine-gTaiiu'd •ulitc . . . veddisb, HOtni- \\v ink'roseopc •tz poriibyrics. vod, and the thin soction." ct scq.). n\A\, froquont- i'inp; a dccided- riety is seen tn pen Matajranii jiion fiive from ; contair.inc; nn ily woatherod: riety in wbioh tnents may bi' diorites, wbioli 3ters, altboiisi'li scbi^ts may bf i-eater tendency .' fissile. Fresh sometimes aro it to sub-aerial 1 occurs at tbo 1 the surface is ie the scliisto-o 20, 28, 29, 80, 11 The types of rock wliidi form tlie llnri^nian in this reoion baviiiii' been briefly described, it remains now to outline ibe di-^- tribution and to point out some local peculiarities in the various scliists and otlier rocks enconnt(M'e(l. There niav be said to be six distinct Huronian areas in the basin of the "Nfoose Puver; two of these are of considerable extent and the others smaller. Iht^ first and greatest belt stretches in a north-west direction from Lake Alntibi to beyond the ^lisanabie Tiiver. Tt mijiht well be d(^sip;- nated the Abitibi-^risanaliie area, but for brevity's sake will be hereafter referred to as the first area. The southern Iwundary of this belt crosses the heip;ht of land near ^ruskepopima Lak(\ continues north and bending- eastward acr(jss ]\Iinniesina()ua Lake just touches the south l)ay of Lake ]\Iatafianii. Thence it extends a little east of north and cro.ssc3 the ;Xipissing-Algonia line near the IM'.tli ])ost, to which it con- tinues ajiproximately parallel up to about the 115th mile (Bur- wash), Avhen it bends ofi' ^:harply to the w(>st and crosses the ^Nlata- gami Kiver at the Wawiatan Fortage after sendiiio- out a spur Avhich crosses Lake Keuogamissee as a narrow band. From the p(^rtaii-e it holds north and west to bevond the Pishkanogama Iliver. There it bends northward and crosses the Trout River in a uin-th- west direction which it holds to beyond the ]\Iisanabie Kiver. Tlie latter river is crossed by two belts which probably both belong to this great area, and are so figured by Dr. Bell. The northern boundary is not so well known. It has been determined on the Abitibi, Frederick House, ^Matagami and ^lisanabie Uivers and is shown on the map as a continuous line joinuig these points. In the description of the rocks of this region they will first be noted as they occur on the Xii)issing-Algoma boundary, and afterwards on the various rivers and canoe-routes. The Xipissing-Algoma boundary crosses the height of land and enters our region at the TOth mile north of Proudfoot's line near Little Hawk Lake. At tliis point, Mr. Burwash thus describes the series, " Ileddish ihick-bedded rocks cross the line and occupy the east shore of the lake .... They are succeeded on the north In a greenish gray conglomerate, and this is in turn followed by gray ash rocks, which in places give way to what appears to be an amygdaloid, the light coloured amygdules of which weather out 22 at tlio .snrfiioo." ' Ash rook? appear hi follow tlipsp outprop*? to tlio nortli, iiiifl iit the ^'-Wd iiiilr a small area of roddish cnislu'd liTanito is met which Is succctMlcd bv a liivonish coimlniufnitL'. At the; S4th Jiiilc IJurwash ivports a " si'ricitc dnliiiiiitc schist," and at the S5th " sehistost' rocks stained with iron." At the >t>th unlc dccnrs a ■weathered diabase \vith cubes (if in'rite-. while to the eastward h" eneniintered the reddish tiiick-l)eildi'd rocks met with on Little IJawk Lake. Followini:' these nccur wt'athered diabase, jLiray ash rocks and chlorite schi-t with i)yrire. At the l»7th mile the line enters a i;ranite area ami cdiitimies in it to the 104th mile. This is. no dniilit, the corner i>f the Laurentian area which exteiuU a mile and a halt' east of the lino. Cirayish sandstone occurs at the con- tact, and exposures of dioritic schist, reddish slaty r<>ck and chloritic .schists continue to the 111th mile, where the line aiiain enter-; the Laurentian, finally leaving it at the llHth nnle, and enterim:' grayish slaty rocks. The rock from here northward is much obscured by the drift, and it is advisable to continue our secti(jn northward by f(»lli)wine- the water-course of Xiuht Hawk and Fredericdc House Lakes and Frederick House Kiver. Exposures on the south bay of Xiirht Hawk Lake, and on Starvation C'r^ek. which enters it, are not numerous and consist larti'ely of altered diorites or lirccnschists. After the main body of the lake is enter- ed the following' series is found on the west shore: — Massive green diurite, altered dioritic schists and quartzosc schists with pyrite, crushed granite (on an island oft' the mouth of the liedstone liiver ). coarse hornblende and mica diorites (one and a half miles nortli of Eedstono), fine-grained hornblende schist and a rather hard sericite schist (X. 30° E.j. Xorth of Porcupine Eiver is- a tiue-graint'd massive diorite and typical chlorotoid schist. X'o exposures occur on the river connecting Xight ILiwk and Frederick House Lakes, nor arc any seen on the latter lake except towards the north and on the easterlv side, where is presented a series of dark gray schists with streaks of pyrite exhibiting a bandi'd spheroidal weathering and showing nuclei of a jasper-like variety surrounded by the darker schist. I'his rock has a decidedly volcani • appearance and is followed by a fine-grained porphyrite strikin;:; S. E. and dipping 30° from the vertical. ' Report of the Bureau of Mines, Ontario, 189G, page 17S<. •2'i utorops tn tlio nislifd liTiinitc' At tll(! S-itll id at the Sotli mile occniv a {' eastward li- ith (.11 Little )ase, jurav a^li mile the line h mile. This L'XtemU a mil-' IS at the ei)ii- c and chhiritie aiii enters the and enteriiiti' vartl is nnieh le our seeti(jn it Hawk and Exposures on ■vat ion C'lvck. elv of altered ' lake is entei- Massive ureca ■ with pyrit( , dstone liiver), miles north of r hard sericito a tine-grained fht Hawk ami er hike except is presented a iting a banded crdike variety dedly volcani • lyrite striking At the first falls, one and a lialf miles holow the lake, oceurs a ridge of mneh altered jxiridiyrite weathering (Hit in white spots. At the foot of the fall is a line-grained gray qnartzose scdiist aoconi- panie(l hv alteretl dioritie mcks, showing under the iiiicrDseoiie feld>liar ery of Porcnpine Lake occnrs an ontcrop of a wft rock resembling soapstone, with crystals of magnetite and veinlets of chrysotile. Un- der the mi('rosco|)e the rock ajijiears to be nuide np of indistinct fibres of this substance mixed with qnartz. It is evidently a mncli altered example of the basic ernptive series. On the south side of the lake occnrs altered diabase and gray qnartzose schist Avith asbestifonn partings and veinlets of quartz. On the creek entering; from the south-west were found gray to white fine porphyrite schists, weathering quite white with streaks of quartz and pyrite. On the 25 r, at the " Two pyrite is seen, and omhract'S nnot be given le " Two Por- imtrv between a eauoe voute d to Frederick )ine River and itvetch of thi-- 3a ni on wbicli rom the bead il brino- ixs tr however tlu' cjray slatedikc ike X. 60° E., •evionsly meii- Tbe next out- sericite scbist ■ up is a rock as previou>ly iliea and very altered diaba>o scbist. Rocks 'ni^ine Lake, a nioutb of tlic the north ?itlt> ck resenddini;- irvsotile. Un- ) of indistinct lently a much he sonth side se schist "witli srcek enterinc diyrite schists, mte. On the passace overland sonthward fronr this lake an interestirpc series of Tocks is encountered as follows:— Soft mottled sericite schists yer>- ninch altered, nnder the microscope showing; irregidar and strained qnartz individuals, some feldspar in-esnmably orthoclaso, light in- distinct sericite and considerable calcite; soft schists weatheHng ^virh ferrnainous stains, associated with bands of qnartzite; mter- landnatiMl bands c'l qnartz and qnartzite. striking east and west, and go filled in places with hematite scales and crystals of magnetite as to become quite blacK. At one and a half miles from the lake were ^een diorite schists followed bv soft and hard exami)h'S of the sericltic scries. Another exploration line i^assina S. E. fronr about the middle of the south shore shows the fo'.lowing:— Ridge of granite, east and west, flanked by soft calcareous sericite schist; hard grav quartzoso schists; sericite schi>t; streaked quartz rock with pyrite (10 chains); sericite schist; 20 chains of granite; soft docomposul schists weathering out in brown spots. On the first portage westward t'r(im r()rcui)ine Lake occur gray qnartzose schists and greenschists. On the second portage are seen «oft, rusty s|)otted schists with sericite showi!tg on the cleavage ]danes. A fresh fracture across the planes shows very fine quartz. This is followed by diorite which is in turn succeeded by hard qnartzose schists, and at the eastern end a rock very ^^iiuilar to that at the west, all striking about ]^. 75° E. and dipping vertically. AitvY cr.pssing a small lake and a short portage, togeth(r about a mile, the route ent(>rs a lake about a mile and a half h>ng in a north-easterlv direction. On t\\o east side of this lake ar(> seen massive green diorite and diorite schist (pvritous). and on the westerlv side line urav quartz(.se schists l)o>siblv alterconisli ro;'k showing the stinicture of a crushed pnrjdiyriti' under the microscope. This is followed by greenish Iluroniaii scliists with one inch to two foot inclusions of gray granite, evidently conglomerate. Somewliat farther north on the west side, sheared granite and some bands of diorite form high precipitous shores. About a mile farther north on the east side, gray and greei; spotted micaceous and sericitic schists mixed with bands of granite and felsite are seen. These strike W. 10° S. and followed by mica and hornblende schists passing into gneiss. Dr. IjcII describes the rock on the east side of the southern lagoon as " greenish gray quartzite, holding transparent grains." ^ A ]iortage from near Fort i\Iatagami extends eastward to Lako Shattagami where the Iluronian is again encountered and is thus described by Dr. Dell:—" On the west side of the narrow cove which forms both its inlet and its outlet, beds of greenish gray clay slate .n' shale, which are full of pyrite, are found, standing vertically, ami striking S. 70° AV. About a mile up the south-west side, a soft green- ish gray rock occurs, which has a dioritic appearance, but is evidentlv of a magnesian character. It is rudely stratified, and beds, whic'h are on edge, run cast and west." Following the Grassy Jiiver eastward we finally aiTive at Little ILiwk Lake. The rofks on the route, according to Dr. Bell. are '' gi-ayish quartzite (sometimes of a conglomerate nature) and gTeenish diorite." On Little ILawk Lake lie describes a cliff of 200 feet of "grayish red fine-grained quartzite in thick beds, inti ossibly porphy- 'xtremely coin- le hike, i.e., iw istward, anil is )n the east side ifi'h bhiffs of a ;hed pnridivrilc ■nish Ilnroniaii gray iiranitc. 1 the west side, igh precipitoii'* gray and greci: inds of granite followed ];}■ . ijell descrlbts " greenish gray stward to Lake ed and is thtis •ow cove which ay clay slate ^r vertically, and le, a soft greeii- nit is evidently id beds, Avhich lally aiTive at ig to Dr. Bell. :e nature) aiul 3 u oliflF of 201) k beds, intiT- o holdinjj red grains.'' Tliis is doubtless the thick-bedded red rock of Eurwash already mentioned in this paper. '* On the north side of Little Hawk Lake greenish gray clay slate is seen at two points. At tlic outlet tliere is a massive light-green felsitic vijlcanic ash, marked with specks of liiihter and darker colours than thu matrix." J'"roia this exposure it is about forty miles northward through Mataganii and Kenogainissee Lakes until the Iluronian is again encountered. Here it consists of a narrow spur projecting west- ward from the main mass to the east. Tiic rocks exposed show the following series from south to north: — Fine-grained diorites; hard gray granite and felsites; mica and hornblende schists; crushed granite; soft Iluronian micaceous scliists, striking E. 10 X., and dipping oO" to X. \V.; dark crystalline diorite with white blebs. The latter rock might be described as a porphyritic diorite. Some distance north of this series a belt of diorite crosses the lake near ^looi'e's house. The main bodv of the Ifuronian is encountered just north of AVawiatan Portage at the foot of Kenogainissee Lake. It is repre- sented lirst by a bidt of granite X. i>0° AV., followed by coarse green diorite and soft close-bedded whitc-weatlicring schist almost ver- tical and striking north-west. A niicrosco])ic examination of this rock shows a very fine-gi'ained ground mass of quartz and feldspar with porphyritic crvstals apparently of ])lagioclase, which would make the rock a poii)livrite schist. Below the rapids frw exposures are seen until we reach Onicemec or Pigeon Rapids. On this stretch, however, quartzose schists and some clay slate striking X. 7.")' W. occur. At the Pigeon Kapids greenish crystalline diorite i- mixed with dark gray quartzose schists and contains bands of (piartz carry- ing gold. Considerable intermixed calcite occurs here. Only a few exposures of siliceous schists are seen until the first of the Sandy Portages is reached (Ivish-ki-qua-mo). where is seen a hard gray quartzose schist (gray siliceous and dark blui-h gray clay-slate, according to Bell). Between this and the next portage occurs a green rock with wdiite spots. A section shows tlie white to be entirely altered feldspar and the green mostly chlorite arranged around the feldsi)ar. It is possibly a much altereil ])i)r- phyrite which contained a large amount of ferro-nuignesian matter. It strikes about east and west. At the second portage the rock at fflmi 28 the top is hard p-ay quartzosc gchist followed to the north by softer schists (nacreous, chlorotoid and talcoid schists, according: to Bel! i. Avith streaks of quartz, strike X. Mf AV. At the foot is a large dyl and slaty. Then occur dykes of green crystalline diorite. Half a mile further is dark gray (piartzite with iron pyrites and clear qiiartz grains, X. 80° AV. At the end of another half-mile a massive, light greenish gray siliceous schist resembling diorite rnn^ 1 Geol. Survey of Canada, Report, 1875-76, page 312 et teq. i^.-s north by softor rdiiip: to Bel! I. is a large dvke V vari-coloiiV( J J dccoinposabk' lutli-wcst. Dr. but it is (ioxibt- of quartz and > portagO!= till' On ascendiiii;- [ind then lianl it to the lake is seen. The ible size Avhieli 3 schists niv 'if strike a little X siiows a pro- biting nndnla- icnlar ])atelu'~. iea boino- verv Those schists ; out of Kamii- by a coarser tc of dark gray iw the Tvanii-- ter's invostig;!- recorded: — Oa re of ''massivf, : specular iron, is followed f^r both massive iorite. Half a ites and clear pr half-mile ,i ig diorite run-; 29 K. 75° W. (quartzose schist). At Sturgeon Portage, three and a half miles farther down we find hard greenish gray slaty diorire, K. 35° to 00" \V., cut by a great dyke of greenish gray slati-like crvsralline difjrite rnnning north and south. Six miles below the portage are seen ''soft grayish green calcareous talcoid schists, ^. 55' AV.'' Eight miles more bring us to outcrops of "gray diorite or volcanic ash, holding sliarn crystals terlv direction for abont eighty miles, crossing the Canadian Pacific Railway be- tAveen Pidout and AVoman Piver, and terminating near A 81 ists crop oiit, iLlonde schist rcccia. From l)out a milo siircs ^ gray 5111 the muutli orito, Xorrh al horiibloiulii the bay from irainod wliite iig- i^ome tiiic e rocks niiicli are followed leude granite, ; MatagaiuiiiiT and the rocks bay, are seen '; into liglitiT ne and a half si)lan and schistose diorites with iiyritc, soft white schists, and hard white spotted varieties, probably altered porphyrites. Fresh speci- mens are much greener than the surface samples, and under the 33 inicro«copo show fi.u-m-alncd iM.]vM- dceoinposition products and indistinct liii-lit i-Tccn chlorite wit', a little quartz. The second por- tnuc l.cy..nd this lake j.-in^ a stn-ani ll..\yin- into the Pishkann- fiania; on it occur hard ,i>Tay quartzose schists. The lluronian area crosses the rishkano-anui Uivev in thrrc narrow helt-. The most northerly has a width reen stdiisjs aver aiiinu' north-west in strike and dii)pini:' to the south-west. Near thr foot of ri:ania Lake the second belt crosses auy are not at all common towards thex-eutre. Thi> is also true of tlu^ altered basic enq)tlves, diorite schist, grconschists, etc. The (luartzose schists, cru^^hed granites and more acid rocks generally are far ujore characteristic of this belt than of the first, where aitere , oTcenschists re aci plagioclase, and with numerous liarnets in the more weathered parts; it varies in structure from massive to quite schistose and towards llic -outh-wesi corner is horiddendic and hiahlv pvritous. At the Lol)stick Portage is seen tirst a highlv horidilendic schist followed by streaks of dark gray schist with pyrite, whicdi is succeeiled by augite syenite and (piartz iiorjthyry. heconiing more granitic in appearance down stream. Augite syenite occurs about two miles tlown and is traversed l)v narrow bands of Rue black diabase, running in all dir(>ctions and showing beautiful examples of dislocation and niiiiiainre taultnig. This rock seems to pass into diorile or rathir alternates with diorites; a rock occurring above the Ibrcdi Portaiic itresents a much altered appearance and may he a syeiute or diorite with spheiie and mellilite. Above the Oil Can Portage a highly feldspathic augite syenite of coarse structure is seen; at the foot of the portaije the rock is somewhat the same hut contains ralhir more ])lagioclauiall veins of iine crystal- line calcite occur throughout this helt. At the head of the cany(-tn the rock is practically the same as at the Oil Can Portage. Three quarters of a mile down a snndl amount of an down tlu^ cliffs are nearly 200 feet high and are formed of dark gabhro nnxed Avith irregular masses of granite anar St. Peter's Portai>e some narrow hands of Tluronian rocks intersect the iiueiss; these consist of both dioritic and quart- /ose S(dn'st, hut it is douhtful if they are of sutHcient extent to ho cla-ssed as a lluroiuan area. The only other Iluronian belt is that lyinc,' to the westward of Trout Lake as dctennimd by Dr. Dell. The writer had no opportunity of .' this area and depends entirely on Dr. Bcdbs observations that the rocks here consist of '* rather dark coloured hornblendic schists, with an east and west strike." 35 eavy voek > of dark anite and aiiun^' of II vo estal)- iso at the out of the :)r. Bell's nur(»iiian nd quart- cnt to 1)0 westward r had no Dr. Bell's coloux'od SUMMARY. As a petroaraphieal series most of the rocks of those various rejiious may ho desorilxMl iis altered eniiitive<, hoth acid and basic, which have, for the most |)art, lieen suhjected to iuteii-e nietaiiim- phisiii. Mixed with them are other schists himinae dipiiinii' at iusih angles. While a great similarity exists between the ditl'ercnt areas there are, in a general way. some peculiarities belonging to each. The first or great area i-<, on the whole, more l)asic tlian the second, tlie rnost important rock being diorite with its (hn'ivatives diorite schi-t and greenschist. These basic rocks seem to form the centre of tlie area and the more acid representative". (]uart/.(>se schists, altenHJ porphyries, etc., appear to be distributed more towards the bordeis. The second area Is decidodlv umre acid with a preponderance of crushed granites, felsites, altered (piartz porphyries and acid schists. The third division ihow-i considerable diorite of a somewhat massive nature, froquontly fornnnii' hills, whicdi are tlankeil by the same series of schists as in the other regions. The lluroniau area of the Abitibi canyon is ([uite different from any oi those and must be roganh'd as a large eruptive dyke coini)os(>d princi]>ally (d" augite sveiute passing into gabbro. The schistose areas seem to be comparable to hawson's Ivee- watiu scries, at least in part. They mav aho be couii)ared to the gi-eonstone schist area of iMarquette. Their origin is i)robably similar to that of the regions mentioned and will not be discussed liere; the reader is referred to 15uUetiiis i'd (ISild) and SO (1S!)2) of tlio V. S. Geological Survev, ami to the lieport of the (ieological Survey of Canada^ Part '% 18S8. The sketch map accompanving this ]y.\])vv is compiled largoly from Dr. Bell's map of the region, corrected in ]daces by the more recent determinations on the base and meridian lines of Alexander Nivon, O.L.S., as well as hv the compass surveys con