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6
:ONTRIBUTIONS FROM THE GEOLOGICAL DE-
PARTMENT OF COLUMBIA COLLEGE.
No. XXX.
The Effusive and Dyke Rocks near
St. John, N. B.
Th
esis
I
M T.MITTKI) HY
VV. D. MATTHEW. A, 1].. I'h. IJ., M. A..
FkLLoW IX (ilCOI.ixiV,
Til paitial fullilincnt of the rf(|iiiieiiiciits
: for till-
)ef;ree of I)oct(ir of I'liilosopliy, in the I'liiveisity Fiteult\ of I'uk Scifiicc of
C'oluiiil>ia Colh'ue. H!).").
|IU'liriiiti.Ml I'ldiu till- TuANs. New Ymi;k At AH. Sri . \iv . 1>-T. I'liilf- \ii -xvii. l-'i'-'>. A H.
(■;• '
I
i I,
THE EFFUSIVE AND DYKE ROCKS NEAR ST.
JOHN. N. B.
W. D. Matthew.
Ufiiil l)y title, March 17th. l^'.i.').
TABLE OF CONTENTS.
IXTROnrCTION.
Pre-Caiul)iian volcaiiics alonji the Eastern coast of North America
Review of work done on New Brunswick volcanics.
Chissificatiou of pre-Canihrian in New Brunswick.
Laurentian or Portland group.
188
I
TRANSACTIONS OF TIIK
Al'U. 15,
Hiiiuiiian iiicliiilin;: tlii' {'(ildlirook. Coa>tiil. I\iiii:>tnn and Ktcln i.iiniau
finni|i>.
Till \\\)[iiv limit of the pre-Canil'iiaii in N'l-w l!iun>\\icl<.
t'lussilicatiiin i>f tln' volcanic rocU tyjic-i.
Tin: Kri'i si\i: i;(i( Ks (IK Tin: CoLDr.HunK. Oia^tal axii Ivn iik.mixian
(iKOll'S.
(Jnaitz-|i<iiiiliyiy. fclsitc-]i<iiiili\r.\ ami asli-rncks.
Dialiasc and iiorpliyiitc.
Mctainorjtldsni.
Tin: Sdi) \-(ii{AMTi:. with an analysis.
Tin: KiMisTiix (iijui r,
('(i.MI'AinsilXs.
DvKi: ildcKs.
l)ioritc-ii(ir]iliyiitc, with an analysis.
I )I A I! ASK.
(^•naitz-dialiasc, with an analysis.
Angitu-piniihyritc.
ADKITIONAT. NoTKs (IN TIIK LaIKKNTI AN IMu KS.
(>Tin:i; volcanic i;(k ks in Nkw r,i;iNs\\ k k.
SfM.^IAKV.
I'r.ATKs XII-XVI at end (il vnhinif.
I
LITEKAT'vl;!:.
1. Kcimits of the (ieolfifiical Survey of the I'm^ ince df New llinnsw ick,
]S3!)-l:{. liy Aliraliain Ges.-tr.
•2. ( ilisei vatiiins on the Cienlii^^y ui Smi.tiiern Xt'W Biiinswick, liy l^. W.
Bailey, (i. F. Matthe\s and C. 1'. JIaitt.
3. On the Azoic ,ind I'alaeo/uic Rocks ot .<c)\ithcrn New Brunswick, hy fl.
F. Matthew, (^iiar. .Tour. (ieol. S(k.'. XXI.. l-J-.'.
4. Keniavks on ti;" A^c and Kehitions of the Metainoiiihic Iv'ocks of New
Biiiiiswiek iind Maine. ii,\ Oeo. F. Mattiie\\ aiu! L. \V. P>iiiley. I'ldc. Am.
Ass. Adv. Sei. 1>'(I!), 1T!>.
5. Preliminary lieport on tlie (ieolo^y of .'Southern New Binnswick. L. W.
Bailey and (,. V. Matthew. Can. liefil. Siu. Iteji. l-Td-l. \>. IJ.
(i. .Summary of (ieolo^ieal Observations in .Southern Xew Brunswick, l>y
L. AV. Bailey and (i. F. Matthew. Can. Geol. .>^ur. Kep. 1874-5, p. S4.
7. Keport of (ieolojiical Ohservations in ,<outheni New Brnnswick. hy L.
AV. Bailey, G. F. Alatthew -and K, W. Ells. Can. Cieol. Snr. Kep. l.-<7.)-0, p.
348.
S. Keport on the l'i-e-Siluiian ( Huronian ; and Camliriau or Primordial
^Silurian Kocks of Southern X'ew Brunswick, liy L. "NV. Bailey. Can. Geol.
Bur. I!ep. 1877-H, p. 1-34 DI).
f). Report on the Upper Silurian and Kinuston i Hnronian i of Southern
New P>ruiis\viek. liy (;. F. Matthew. lb. )). l-(! E.
/.
1805.]
NEW YORK ACADEMY OF SCIENCES.
IS't
■1
>*
1(1. l;ti"irt nil till- (i(iil(i;;\ (if Sdiitliciii New I'li iiiisu ick, cinliiaciiii: llic
coiintii's (tf Cliarlotti', Sunlmiy, (^>iicfii>. Kinys, St. Jolni mid AIIm n, 1p\ I,.
W. Hailc.v. a. V. Matilicw ami \l. W. I.lls. Can. (ii-ol. Sm. l:r|i. 1-7- !•, ji,
!-•.'(; IJ.
11. On till' I'i((;;if.xs of (ici.lM^iioai Iiivistiiiatiiiii in New liniiww ick l-^Tc-
1— (t. l.y L. W. ISailiv, Vvm: Am. Ass. Adv. Sfi. Hst. j.. llo.
rj. On tin- rniuriss nl ( ii'oluiiical Iii\ cstijiatiKii in Ni'w J'.i iinsw ick. Tiaiis.
Jfoy. S(K\ Can. l-^!l, VII., Sec. 1. :i-I7.
1:5. Canil>rian Oij:aiiisiiis in Acadia. I)y (i. F. .Mattlicw in 'I'lans. 1,'ny. Soc.
Can. l-iMi), Sec. 1, p. i;{,-).
It. Conflation PaiuTs. Arcluuan and Aii:iiiikian, l>y C. K. Van Ili-c V.
►S. (icol. Siir. I'.iiU. -^(i. !-!)•>.
15. .Mattlicw, W. !».. Intrusive Kocks iicai St. John, X. I!. Trans. N. V.
Ac. ^ci. XIII., l-T). l-!ll.
Ki. Outlets of tlie St. Joliii Iv'iver, hy (i. V. Mattlieu . Nat. Hist. Soc.
New liruns. Hull. XII., I-tri.
Tilt.' prt'sont i»:i|ier is .-i coiitiiuiatioii of :i pctioiriapliit' study
of tlic iiriR'oiis focks iu'!ii' St. John, X. I>. Tlic intnisivc rocks
ill tin.' iiiiim.'(li!itc' iic'i<rlilioi'hood of tin." city have iilivady I'C'cii
(lisciissod ;* it ix'inains to (It'scrilje tlie siirfaee volcanic- ami
dykes, and to add some iK.tcs as to tlic fiirtlicr extension of ilie
iiitriisives.
Pre-Cambriaii \olcanic rocks are known to exist at various
points alonu: tlie flanks of the inetaniorithic licit of eastcin Xoith
America. Although more or less clearly recoouized as sucli in
many of the earlier surveys, their certain deteriiiinations could
usually lie made only liy the aid of thin sections, and accord-
ingly it is only -within the last few years that their exact char-
acter has been definitely kiiown.^ The late Dr. Geo. II. Williams,
in an article in the Journal of (icolooy,t has called attention to
their wide (listriVintion and iin|iortance, and to their close re-
semlilance to modern ert'nsives, except where altered by meta-
morphism. Dr. Williams gives a very full and complete sum-
mary of their occurrence in Newfoundland, Nova Scotia and
New Brunswick, the eastern townships of Quebec, in Maine,
New Hampshire and eastern Massachusetts, in the South Moun-
tain of I'ennsylvania and Maryland, and along the Blue Ridge
as far south as Georgia. There is, however, a great dearth of
petrographic descriptions of these rocks, most of the determina-
tion having been made in the field only. Besides the well known
♦Trans. N. V. .Vftid. Sci. XIII., is."..
t.Iour. (leol. II.. 1.
I
190
TUANfi.ACTIoNS ol' YUl'.
A I'M. 1.')^
IJ.'iscoint on till' South Moiin-
)l" W.'Klswoitli.;': DilltTi :iiiil
work «)t' Dr. Williiinis*^ :iii(l Mi-is
tain volt'tuiics. and tlif --tnilii's
Sfars in tlif Boston IJasin, iJu' i)Mly "U'Sfiiptions of ancient I'llii-
sive rocI<s from tiio I'astorn coast ot" wiiicii tlio writer Iviiows arc
the recent article of I)r. Hayiev •" on tiie s|iin'rulitic fejsites from
A'inal Haven. Me., ami a few (lescriplions of porphyries from t he
i-astorn townships liy Dr. Adams**. There is, no donlit, other
work of the kind in i)repar.ition. .and tpiite [jroltahly other pnli-
iished descriptions exist, which have escaped this review; still
the scantiness of petroij;raphic descriptions of these early vol-
canics of the oast coast, in comparison with those from other
parts f)f the United iStates, is rather remarkahle.
In .Southern New IJrnnswiek the so-called Ilui'onian li.as liccn
l)elicved from the tirst to he in lariie }iart voh-anic, and w:is so
descril)ed in the reports of the different surveys.
The lirst systematic survey was made 1)y Dr. Alir.ah.am (Jes-
ner for the I'rovincial (Jovernnient in ls;;8-4:2, its results iie-
\n<r luil'lished in Hve reports dated 1S8J*— 13, inclusive. Dr. Ges-
nei' was Lrreatly impressed with the important part which had
l)een })layed in Southern New Brunswick l>y volcanic foi'ces,
which, however, he was inclined to over-rate, ascribinj.^ to them
many of the etfects due to erosion. Speakiii<j: of the soutlu-rn
[)ait of the province he says:
"At the southeastern l)a«e of this .'levated region " (the irran-
ite area which divides Southern from Central New Brunswick)
"the slates and limestones of the transition series, and the sand-
stones and conglomerates (jf the secondary' formations, are
placed in their usual order of succession, wherever they have not
heeii broken up and buried by extensive eruptions of volcanic
matter. All these rocks have been })enetrated l)y large and
numerous dikes of traj). basalt ;ind pophyry (.s/c), and tlie sur-
face of the country with all the islamls in the Passamacjuoddy
Bay exhibit the cleai'est evidences of having been the theatre of
violent eartlKjuakes and intense volcanic action. "ft
Althouyh some of the massive roeks which Dr. Ges
ner in
be-
lieved igneous have been sinci' shown to be of seilimentai'y ori-
gin, yet his estimate of the importance of eruptive rocks in this
* Aiiier. .)()\ir. Sei. XI. IV.. l^.i.
t.Idur. (tuol., T.
t Hull. .Mn«. Ciiinp. zr.ol. Ilarv.. V.. J?.'): I'ri"-. Host. Sor. Xut. IIi^^t.. XXI., 2sx.
5 Hull. Mu<. ((inip. Zim.I. Univ.. VII.. \<;x
n Hull. Mas. Cijiiip. ZiMil. Iliirv.. XVI., Xo. '.I: Hull. Ksse.'i hiM. XXVI.. IHetc.
" (ifiil. Sue. AiiKT.. r.MltiuMiv Muftinir. Det'.. 1'>'.U.
** Can. (it'i)l. .-ur. lU'lPoit uf l^:'.'.i. p. ].'.
ttHepiirt on^;i;t, p. 12.
I
Jii
1805
NI'^V Vi'KK ACADEMY ">F SCIENCES.
T.'l
'V:
|>iiit of llic I'loviiicf still lidids Kooil, IJiit it i^ evident I'loiii
tlu! tone ol' liis writiiii; t li;it lie (•on>i(Iereil t lu' xoleiinic out Imr^ts
lis of fill' Inter dnte tliiin tli:ir now ii^^iLnied to tlieni. I'oi' he con-
nects tlit'se (list iiihanees with recorded e;ut JKiUMkes ;ind cliMUues
of level in New Hrunswiek within hi-toiic times, :ind even pic-
tnies !i nnni'ier ol' snifpo^ed vole;inie cone> iiciif (Jivat S:dnuiii
River. e.Mst of (in.'U'o.'
In the I)oniiuion (lOveiniiiL'nt Survey Ueports. I>i-. I.. W .
Hailey iind (i. F. M:dtliew recoiriiize the i-xisteiice cd' i:re;it
iinioiints ot' volciinie !ish. ;is widl tis innssive hi vus. iioi|ih\ lit ic
and vt'siciiliir. ISiit the ".n-ciiter piirt of the series, eonsistini: of
fiue-iri'nined rocks denoted !is /(7.<//c jind jnlrin'ilf.r. reiiKiined to
the hist of doiilit fill oriirin. with :iii iipiiMrent ti'ndency in I>r.
IJiiiley's later ri'poit ( 1>«TT-!S). written nftei' a most careful and
thorough study of the volcanic hills, to consider them as lariii'ly
sedinu'iitui'v rocks, tiioiiirh formeil under special conditions f)f
deposition:! wliik' I)r. Klls+ considers them as volcanic. In
his latest paper liearini!' on this siiliject ^ I)r. Bailey points out
the need of microscopic sections f)f these rocks, lioth to make
sure of their eharactei' and perhaps to determine also whctiier
certain memliers are of pre-Camlirian a^e or are identical witli
very simihu' rocks of later ori;j;in. He summarizes the charac-
ter and relations of tiie |iie-('aml>rian rocks as follows:
" Anioiiii' thesi' Arch;ean rocks at least two <rreat groups (d"
sediments are to he distinguished, which, in a general wsiy. Iiear
many features of rest'uihlancc to those which in other parts of
Canada are known sis the Laiirentian and lIiiroiii:in systenis.
At the same time it is impossilile . . . not to see that . . .
there are eiiiially striking ditl'erences. . . especially seen in
the greater i)r(jportionate amount of distinctly stratiiit-d rocks,
such !is slates and (luartzites, in the eomi)arative alisence of
coarsely crystalline deposits of crystalline minerals and ore
beds, and in the much greater regularity ami uniformity of the
whole . . . Another desideratum in connection with these
two ancient systems is a better understanding of their time re-
lations to each other, for tiiough no doubt is entertained by the
author as to the fact that the felsitic and schistose rocks refer-
red to the lluronian are more recent than the granitoid and
gneissic rocks and the great Ijclts of crystalline limestone
which have been regarded as Laurentian, a coutrarv view has
*Keiniit of'lslu, p. 'J1.
t<'nn. "rLMil. Sur. Ktip. I>T7->-. p. I. I', li. In ii Incit-iKilf iit llii- j'iiu;i-. In. Si-luyii
0(iiii)iiir(.'s this M'lif^^ 111 till' iinciiiit vdli'iiiiii' incks nf luiiilimd iiml \VnU«. uilli uliiili
lie lioliovi"- they tiiv iilunticiil in miL'in.
111... p.il D."
iTrims. Key. .S<ic, ('an,. l"<»'.i. \'nl. \'I1.. Sii , i. p. :;.
102
TRANSACTIONfl OF Tlli:
[a I'll. 1.'),
▼ "
liccii t;iUt'ii Ipv iitliri'-; while iicitlici' Iim-< .•my siitislactory <'Oii-
tiifl of till' two luniiMt ioiis Ih'cii <)1i>it\ fil. nor :iii iiistjiiirc in
wliicii till' roii^loiiHTiiti'-^ of (lie oiu' !irr iimiiiL'stiijiKilily iiwhIl- ii|)
of inMtcri.'il lU'rivtul fi'oni the otluT."*
('f)II»'('tions iiiMilf diiriiiy: tlii' |)!ist tliri-c smnnu'ix :iinl s|ii<lii'il
liy tilt' .'lid of till' iiiii-roM'o|)t.' luivi- amply coiiliriiu'il tlir views
Ih'M .'IS to tile voleMiiie origin of tlie irroiiter pfirt of the
" Miiroiiian."" It will lie seen that a coiisideralile variety of
igneous rocks is represented, iiieliidiiit; lavas ami ash loeks oiiee
pi'eeisely like those of niodein times and not i^reatly altered liy
niet.'iniorphisni. Many of the line irraiiied feUites and nnich of
the petrosilex. however, eaniiot Ite eert.'iinly determined, evi'ii
with the aid of thin sections; lint jiidijjinif from the almost coni-
jilete alisence amonir them of ilistinetly reeoiiiii/.alile sediments,
it is prolialile tlmt llif ijrfnli'r jiorf nf' l/w ilniihlt'n} mifn sIkihIiJ
hi' riiiisi(Ii'n'</ IIS nltiTi'iI u.<lii\-< or liill'.<.
The pre-Canil»rian of Southern New Uninswick falls naturally
into two ijfreat divisions: !i lf)werone composed of gneisses, linu;.
stones, ipiartzites and \arions schistose rocks, nsiially liiLdily
cryst.'illine, lint of ilistinetly sedimentary chanicter ; and an
iippei' one composed chietly of volcanic products, fading out
above into more normal sedimentary lieds which are as a rule
much less altered than those of the lower series. Tlu- lower
{xroup has lieeii compared to the Lanreiitian ; the upper has lieen
called llui'onian ; lint lioth these names are dropped in the later
Survey Ileports and replaced tiy numliers tor the dill'erent
•iroups. In the present paper they may be occasionally used as
indicatin<j; this two-fold division, lint not implyinu: any correla-
tion in the present restrictetl sense of the terms.
The Laurentian series includ(!S divisions 1 ami 2 of the later
reports; the lirst l)ein<r ijranitic gneiss and ^irranite, which is. near
St. Jolin at least, intrusive in Hivision -', and may be placed
provisionally between it and the volcanic series. Division 2 is
clearly sedimentary, and s!,ows a varying amount of regional
metaniorphism, being at tii'ies com|)ar;itively little altei'ed.
The upper series or
groups. These are
Hu
ronian inc
lud
es a
t least three
siin-
1. ColilbrmA' (Div. 3). This is comi)Osed almost entirely of
volcanic rocks — lava>
ashes and tulfs. The most aliundant
types of rock are felsites and " petrosilex "' (fine-grained, llinty
quartz-felsite), often porphyritic and accompanied by much ag-
glomerate and liner grained ash-rocks into which they seem to
grade. Dr. IJailey also mentions various sedimentary rocks from
!<.'
* I. lie. I'it.. \>.
r
I
1MI>.').
XliW VOKK ACADEMY nf SCIKXCES.
lit:;
\v
? J
tlii"* iriiiiip: ;iltli«)iii:li tlif sections cxMiiiiiU'il liy tin- itrc^ciit
writt-r li.'ivf -M) t';ir t';iilt'il to -.linw iiiiy 'li'^t iiK'tly iinii-vulc'iiiic
(•l;i«*tif«*. Tilt' ( 'oliUn'nok is cNiioscit ovci' m i'<tiisi(|,.|;ili|,. ;irf!i
imrtln'M'-t Mini i';i>t ul" tlic city. iiiiikiiiLr ii|i tlic irit'Mtcr pMit of tlic
|iir-(':iiiilii'i!iii liills ill tiiiit diiTftioii. wlifif it^ lu'>l »'X|Misiirfs
III'. To till' west it i-i of h'ss ini|iort!iiict'.
•2. (Jiiiis/nl fHiv. 4). Ovfilyiii;!; the Colfllirook is Miiotlicr
Mi'iit's of rocks, iiiort' alti'r*'(l in its ty|Mc;il c\iio^iiH'«, tliiiii liic
lower Ltidiip. Its lower ptirt * is iii.'nle ii|, of volcniiic rocks en-
tirely siniiliir to those of the ('ohllirook. from which the writer
li;is not Iteen :il>le to ilistiiimiish it. TIk' ii|i|>cr |i;iit. however, is
composed chielly of seilinieiitiiries. with some volc.'iiiics intcr-
lieilileil. I'lie previiiliiii'' schistose sinicliin' of most of the rocks
of this yronp in the :irt'!i exiimiiicd renders it very dilliciilt to
dcterniiiic their iwitiirc without the :iid of -i thin section in c;ic!i
iiidividnnl ciise; heiici^ the pro|)ortion of volciinic rock is not
very Well known. It is often dilllcnlt. indeed, even with m thin
s«'ctioii. to s;iy whether ;\ rock of this kiiul is ;ilteri(l lcl>ite, or
!xsh, or volciiiiie dultris rccomposed l»y wuter nnd Mpproxinnitiiiii
normal sediments.
.'). h'iiii/stoii (\)'\\'. ,')). This is a more Mltcrcil >eries than eithci'
of the other two. . and occupies a st riji of land sonic live miles
wide, lionmk'd on either side liy a fault liuc.t and not less than
"0 miles in length. Its rocks emlu'ace rccoiiui/alilc surface \ol-
canics. porphyritic lavas and fclsitic ash rocks, and also :dtered
types, lui.sic and .'U'id schists, some of which were certainly of
volcanic oriirin. and i|iiitc ])rolpal»ly all. The icl.ntions of the
Kiiiirston to the other pre-(':imliriau rocks are very uncert.ain.
Dr. Hailey says :
"The same uncertainty rests upon the a^e of the so-called
Kinjjjston <;'roup of southern New Uruuswick, and which in its
western extension liecomes in part at least continuous with that
to which Prof. Shaler assigns the name of • the Cainpohello
Series.' l>y that author they arc reiranled aslteinu' Lower
Canilirian. but as lieds of very similar character occur within a
very short <listance of the known Camlirian of St. John, and vet
bear very little resemblance to it. this supposition seems un-
tenable. As they are certainly older than the Silurian, and in
.all probability not Cambrian, they must lie re^iircU'd as prt-
C'ambriaii, the view ailopted in the Survey Keports, or as ('.'im-
bro-Siluriaii."";{:
''Asdi'liiK-.l by I'ruf. Itnilcy in thy Fieport for l^TT-'<
tii. !•". Mattluw, null. Nut. Hi-t. Soc, N". M. XII.. h',,
; Trrns. liny. .-uc. ran. I--'.i. Si'i-. I, ]>. ^.
IIU
TRAN.SACrrOXS (IF THE
[ai"R. 15,
The thickness of this series is very great ; at New Iliver tlie
section is over eleven thousand feet.'*' supposed to have been de-
dei)Osited in a gradually sinliing area, bounded by tiie faults on
each side. The immense erosion which this this scries has snf-
fereil probably is the key to its more altered character, the rocks
now at the surface havinix l»een very deei)ly buried.
4. ElfhcmiiiUni.i This is a series underlying the Cambrian
slates in most of their exposures, and nnconformable both to
them ami to the Cold1>rook rocks on which it rests. The rocks
are wholly sedimentary in their ty])ic.'il exposures, but are lie-
lieved by G. F. Matthew to have l)een rapidly deposited by the
working over of the softer volcanic beds, an(l to indicate .a time
of dying volcanic activity. There is reason to lielieve that part
of the diabase which lies below the Camlu'ian at8t..Ioiin is piost-
Etcheminian ([tossibly post-Cambrian as well). This series is
considered by the last named author to lie proliably eipiivalcnt
to the upi)er i)art of the Coastal : if so it has considerable directly
volcanic material in it.
To sum up. the pre-Cambrian near St. John includes the fol-
lowing groups :
A. — Laihkntia.v.
1. Portland yrndji. including I>iv. 2. with probably parts of
Piv, I in other localities than St. John.
2. Iiil)-usin' (jranitc and (piartz-diorite ; perhaps later th.in
the position here assigned to it.
B. — III RdNIAN.
,'5. Coldhrook- rp-o)!/! or Div. 3, of volcanic rocks.
4. (Jixistal ijroitji or Div. 4. of volcanic and sedimentary rocks,
in its upper ])art jirobably equivalent to the next group.
5. Etrlii'minidii or Hanoi S('n'ct<, of sedimentary rocks, under-
Iviiiil the St. John jrroui).
fi. Kiiif/xfon f/roi(p or Div. 5, of metamorphosed volcanics.
Of very uncertain relations; may lie post-Camlirian.
UiM'EH Limit of the Pre-Cambrian.
The Cambrian is here considered to l>e limited by the uncon-
formit.v at the base of the St. John group. The criterion
given by\Mr. Walcott for determining the base of the Cambrian,
namely the lower limit of the Olenellus fauna, cannot here lie
applied, as Olenellus has not been found in ^ew Brunswick,
though a large pre-Paradoxidean fauna of very jjrimitive type
*G. F. .Matthew, (an. tieol. Snr. Ri'ii. lss7-><. p. 4E.
t Trans. INiy. Sue. Can. iss;), See. 1, p. l:r>.
I Al'R. 15,
Ikiver the
e l)C'en de-
' niults on
es lias suf-
, tilt' rocks
Camlirian
L' l)otli to
The rocks
mt ore 1 ic-
ed by the
ate a time
■ that part
lin is post-
s series is
;'finivalciit
le directly
cs the fol-
V parts of
ater than
ary rocks,
ip."
ks, mider-
volcaiiics.
.he iincon-
criterion
Camlirian,
Dt here ])e
Ininswick,
itive type
1805.]
NEW YOKK ACADEMY OF SCIENCES.
10.:
Mr. Aaleott f includes the Etchoninian, which contain^ a L
fossils, none satisfactory us determining its relations i„ the
he Camhnan period. In this case it would heconie ;, st ,
we.M. ?;;■ T> I '''"•'''" ''\' '"^'-""^ ''' the unconforniitv C
the Ltchenunian and the ro/,.„r/r rocks beneath "and
vhotherthelattermight not also be inclu.led in the Lowe Ca
bnun. Between the Laur-ntian and all the later rocks tl ere -
cha.acters and the lack of conformity in di,) in manv places
Satistactory conglomerates are. as mjoht l,e expected, lackin-^
ock nearest the contact is a breccia (volcanic); but it is „„t
known whether any of these contacts are not obseuml
thrust-planes. That the St. John group is .sepa latcd f Vo tl e
Liuirentian l>y a gre.at In-eak there is ^iod evidence- a c i-
merateat.ts b.nse ha- been observed to contain p ■ ,l',l s "tl .
Laurentian rocks. j ' ^
Cj,Assiri(ATio.\.
It has been thought most convenient in the i>resent paper to
diseuss the igiK-ous rocks of the Coldlu'ook. Coa.tal and Fiche-
minian together, divid.ing them accor.lino- to j-livsical eha ' c-
ters, and subsequently to take up the Kingston rocks as mJta-
T/"i .;?.?.' "'r.^^ ^'"'^"- ^' '^ '"^^"""^ t'''^t the division into
Arul and Jln.^r Aj/.sn-rs. used by Dr. Williams for the j.rneous
rocks of South Mountain, is a very convenient one to iMnplov
here, the intermediate tyj.es being Ijut poorlv represented. The
<lykes elearly recognizable as such, are diseussed sei.arateh-
as IS aiso an occurrence of soda granite which has l)een referred"
to the Huroniau m the Survey Reports. ]„ order to give some
clear understanding of the character of the rocks included under
these divisions they nave been placed in groups which in the
sections studied are fairly .listinct one from another It has
no been possible to make any mcII foun,le<l generalizations as
to the distinctness of these groups in point of time, still less as
to tlieir succession. The arrangement is as follows :
A. — Acid Etfii!<irc.<.
EfKISMK lldCKs.
I. Quartz rorjJi ;,,•;/. Compact, (luartzose. full of
orysts.
pheno-
* Tliesf Triinsiii tiou«. ViA. xiv.. Ajiiil, Ivc.
t •nnelntion I'lipi-r-f tiiiibrinii. I", s. i,. s. isnll.. M.
tTiiiiis. H(iy. Soc. (',•111., K^'.i. St'c. 1. |,, i:;:i.
VM
TRANSACTIONS OF THE
[APR. 15,
2. Felnilf jiur/iln/r;/. Few idu'iiocrvsts, niJiiiy characters of
surraee flows. This iiichidi's nearly all tlu' acid ctfusives, and
laps over «)n the one hand into (luartz-porphyry and on the
other into an acid porphyritc.
i;. — Ill/sir Ej/n.^iv.-i.
1. Diahiiiii'. This is the chief type.
2. Fel(Upar-iinri>hiiriti'f^.\\w\\\i.\\\\g a few l)a.sic lavas, strongly
porphyritic. pnrplish in color.
Dyke Rocks. Only basic dykes are known.
1. Dinri/r-ixirjihi/rift' and Camptoiiite.
2. Di(ih(i.-<(' an<1 various porpliyrites.
3. Aii</ifi'-jiit/-jilii/i-i/i'.
Soda (iuANiTK.
(^1 AHTZ-I'dUVUVUV.
Two occurrenc'S in the <^uaeo Hills, one on the I'pper Qnaca
Road, the other near (lolden (irove. seem to merit special no-
tice. The porphyry is even grained, eomi)act and homogeneous,
Avith abundant phenocrysts of (jnartz and orthoclase. the tjuartz
predominating. No characters of surface flows were o'jserved ;
the rock ap[)ears not to grade into the felsites and ash-rocks in
which it occurs, and may be in both cases an intrusive sill or a
heavy dyke of i)ost-Coldbrook age. It is very similar in cliaracter
to the quartz-i)orphyrv ('• claystone-porphyry""). which occurs
at the base of the Siluro-Devonian in Western St. John County
(Dipper Harbor Ror'^\
Under themicrosc 'ms rock shows abundant ([uartz pheno-
crysts, somewhat cor at times, but usually with well marked
crystal outlines. Tli i^how -.hat seems to be a polysynthetie
twinning, very line and Mintly marked, visible in sections a))-
proximately basal. This may be the rhombohedval twinning
mentioned by Prof. Rosenbusch * as occurring in quartz-
porphyry. The orthociase phenocrysts are rather less abun-
dant than quartz ; they are usually once twinned, and present
no sjiecial feature worthy of note. Dark silicates are absent in
the sections examined. Iron ores occur in scattered granules.
The i/rnH)uIma.ti< is microgranitic and of very even texture, com-
posed of (piartz and untwinned feldspar.
The color of this I'ock in its fresjiest occurrence is a bright
pinkish-red ; near (tolden Grove it is pale green, weathering to
brown, and much altered.
Mikio-k. I'liy~. iUt Mus^iKiii lif^ti'iiii?. ii. arifi.
189.").]
NEW YORK ACADEMY OF SCIENCES
107
I
N/<
FKLsiTK-iM.iti'iiviiV. PI. XII., XIII.,!ui(l Fig-. A p. lltO.
Umlor tlii.s <ri'oiip iiuiv lie placed tlie majority of the etl'iisives
of the Hiironiaii. Most of tiie "' feUites " ami • petl•o^*ilex " of
the Canadian Snrvey lleports are either porphyry or i)orpliyry-
ash ; and some of tlie roeks described as sandstone, etc., prove
on the evidence of thin sections to belong here. The centnil
and most abundant type is a iinartz-frce porphyry with scat-
tered i)henocrysts of orthoelase ami piagioclase in a micro-
granitic or mierofelsitic gronndmass. (Quartz phenocrysts occur
in a few sections; in otliers the amount of twinned feldspar in-
creases relatively to tlie untwinned till the rock is. strictly
speaking, a porplivrite. Flow structure is seen in most of the
sections, and ti'ichites, spheruliles, ])erlitic cracks and other
characteristically volcanic structures have lieen observed. IJrec-
cias are abundantly found, sometimes very coarse, the fragments
l)eing six inches to two feet in diameter. Finer grained rocks,
sometimes distinguishable as composed of sharp-eilged ;ingular
fragments, more often not determinable, are still more comuKin.
From the absence of any accompanying rocks of distinctly sedi-
n)entary character it is perhaps safest to place these as in most
cnsfs tine ashes ortutt's.
This group of rocks bears every indication of being of strictly
su|)erficial origin. Their texture is more or less irregular; they
are frecjuently vesiculai' and tlow-brecciated, with few scattered
and often broken phenocry^<ts, being contrasted in these char-
acters with the compact, smooth ar.d uniform appear ee and
abundance of phenocrysts seen in the last group.
Quariz i»lienocrvsis occur (piite rarely, are often broken, but
seldom notably resorbed. The (juartz in the groundmass is more
important. In i)erhaps a third of the sections examined it
seems to be an essential constituent, distinguishable from the
feldspars by its l.)rigliter polarization colors ; it is granular and
rarely at all intergrown in granophyric forms. In many cases
it is certainly a devitriticati<jn product, as is shown Ijy the rem-
nants of original glassy structures still traceable.
Or/horlase phenocrysts are found sparsely scattered in all the
sections. They are never very large, mostly 1-4 mm. in length,
are rarely resorbed, but not uncommonly broken and the frag-
ments displaced. The\- are usually twinned after the Carlsbad
law, in one case after the Baveno. The orthoelase in the grouml-
mass is mostly irranular. but jiart of the rod-like feldspar in the
groundmass of some sections may be monoclinic
PlffjiDchmr is in some sections more abundant than orthoelase,
and rarelv entirely fails. Its crystals are less regular in outline
108
TRANSACTIONS OF THE
[APR. 15,
thiiii till' ortliochisf. In tlu' uroundinass it soincthnc'S occurs in
granuhi;' Ibnn, bcinn' tlicn in sonic cases, prohaliiy in all, of sec-
ondary orijj;in (the rock beinjr a consolidated ash). More gener-
ally it is seen as little rods lying in a granular mixture of less
uell individualized feldsj)athic material.
The /'eyro)iia(incf<i(tn )<ilica/es are almost entirely wanting.
This may be due in part to alteration, but they evidently were
never in any considerable qnanity. In one instance (Sik'c. .'UO
from east of Coldl»rook Station), a quartz bearing porphyry
^vith an unusual abundance of phenocrysts, biotite has been ob-
served, now colorless from alteration, but still retaining its
optical ciiaracters and form.
Magnetite and other iron ores occur commonly, mostly in
very sm;dl grains. It is frequently titaniferous, as shown liy its
■Weathering to leucoxene.
The special interest of this group of rocks lies in the charac-
teristic structures noticeable in them. These afford conclusive
proof that the rocks were ejected on the surface and i)rol>ably
in part under water, and that they were originally ver^- like
modern volcanic products — acid lavas, scoriaceous, glassy and
brecciated towards the surface, more compact and porphyritic
below.
/V/'////rr?'oe/-.s (PI. XIII.. Fig. 1) appear to be preserved in sev-
eral specimens, Imt in one only were they clearly and certainly-
determined. This is part of a " felsite "' outcrop on the Ham-
mond River below Uj)ham ; this felsite is strongly tlow-lined,
somewhat brecciated and spherulitic in parts. The perlitic
cracks are preserved in some brilliantly polarizing mineral
(ealcite ?), and are most easily seen with crossed nicols, though
they are visible in ordinary light.
In the same tiow are the best preserved examples of largo spher-
ulites that I have seen from New Brunswick (PI. XII., Fig. 1).
These are rather irregular in form, seldom complete, but retain
a radial structure. They shot out from various solid bodies
in the magma, feldsi)ar phenocrysts, grains of magnetite, etc.,
paying no regard in their growth to the flow-lines already ex-
isting. The rods of (piartz and feldspar seem now to be broken
down into elongated granules with straight lateral edges ( Fig. A);
l»ut there is no evidence in the specimen that this Avas not the
original structure of the sphernlites. The groundmass in which
they occur is microgranitic, and. along with the sphernlites
themselves, is filled with minute tricliites. seen in Fig. A. com-
posed of one or more curving black needles shooting out from
a grain of magnetite. These needles are now partly broken up
into a succession of granules, like a string of l)eads ; in other
1805.]
NEW YORK ACADEMY OF SCIEXCES.
109
piii-ts tlioy lire imoliauiicil. Tlu-y iu'l- eviik'iilly c'lirlicr lliaii the
splicrulites, for they show a ironoral flirection follo\vin<r that of
tlie flow lines, without le^ard toti\o sphiTulitic structure.
Microspherulites, siiowiuu;- the revolving cross undei' crossed
uieols have been observed in a red felsite from Ilanfoid liiook,
collected by G. F. .Matthew. Nodular felsites, in which tlie
radial structure is not >een, occur in several plact's. This struc-
ture in English rocks is i»elit've(l by some authorities to lie gen-
erally secondary, arising from a [irogressive altei'ation of the rock
jiroceeding from a central vesicle or sonic point of weakness.
From the traces of radial structure preserved, it seems jirobable
that, in some instances at least^the noilules in New Brunswick
felsites ari' altered spherulito-- of large size. At Siianklin, near
leral
)Ugh
■)her-
•etain
lodies
etc.,
, ex-
oken
>g-. A);
ot the
vhich
iilites
com-
from
en <ip
other
Fl<i. A. Ti'icIiik'.-< ill sjtho-iiiilir fehile. S/n'C. nO/^.
tied loo dict)))efcrs.
Ma<liu-
<^uaco, is a bright red iiodidar felsite forming an outlier in Sub-
carlioniferous shale. It is lithologically like the volcanic hills
near by, and probal)ly of the same age. The nodules in this
rock are strongly marke<l in tlu' weatlieied sjtecimens. from the
aliundance of hematite in their outer zones; they often fall out
of the matrix on slight weathering, lieing apjiarently more silici-
tied and better able to resist alteration. They have usually .a
central tilling of feldspatliic material free from iron ; the iron
has collected chietly at their surfaces. In thin sections traces
of a radial structure seems to be preserved in the arrangement
of the secondary hematite Hakes, The whole substance of the
rock is much silicified, but both in the transparent centres and
200
TRANSACTHiXS OF TlUi
[APR. lo,
in tlic lU'i'ply stJiiiied oiitsitli' :i inimitc pilitic stnictiii'c is iv-
tiiiiic'd, ;ii)i):ii'c'iitly of {L'l(ls[iMr roils arniiiiiCil iippioxiinutely [nw-
iillt'l to tlie How liiifs. If tilt' iiitinuviit rciujiiiis of radial struc-
ture n,re not illusory, this would seem to indicate either :
1. That a radial .splierulitic structure could form in a rock
already in lar<:c part crystallizeil, or
2. That this pilitic sti'ucture of the irroundmass may be of
secondary oriixin.
Of these two. the former supposition seems to the writer the
more prohaMe one.
The Survey Reports mention in <>"eneral terms.* and in one
case more particularly, gradations of thesf felsites into tin'
holocrystalline rocks with which they are in i)laces associated.
l>r. Ells speaks of thesf holocrystallines as liasal ])ortions of
volcanic tlows : I)r. IJaileyf considers that north of the (iermaine
JJrook as an extrei e case of metamorpliism. The present
Avriter has not yet Ijeen able to obtain a comi)lete scries sliow-
'u\<x this cradntion. tiiou^di a i)artial one was made at Germaiue
Ih'ook. But in none of the felsites sectioned is there evidence
of gradation into crystalline rocks, either by slower cooling or
subsefiuent metamorpliism. That such deeper-seated fades of
the Huronian igneous rocks exist there can be no doulit, and it
■would probably lie revealed by more extended study.
The acid hrcrcinx and asJi-i'oclt'S are very abundant. Coarse
felsite breccias occur east of Coldbrftok. where they contain
larger romnled or pear-shaited masses, proliably volcanic bombs:
on the road skirting the south tiank of Bloomsbury Mountain,
here comiioseil of a pale greenish-gray silicified felsite. strongly
tlow-lined and iierhaps a devitrified glass; at Titus' Mill on the
Hammond River, here being jtartly a devitrilied glass lu'eccia ;
in a railway cutting near Henry Lake, and elsewhere. The finer
breccias or coarse ash-rocks are sometimes schistose, as for
instance, a greenish-gniy breccia not far east of ColdVirook.
With increasing lineness they are more and more altered and
less easy to recognize, the finc-graineil. lliiity felsites and petro-
silex showing no characteristic structures which can be consid-
ered original.
These tine-graiiied rocks often sliow aggregations of chloritic
material in rounded or irregular spots with fairly well defined
outline. Aside from this tliey are uniformly micro-crystalline
in structure, made up of feldspar with a quarter or less admix-
ture of quartz, and scattered magnetite grains. Occasional large
grains and por[)hyritic crystals of feldspar are seen in some
.specimens.
* Klls, 1S77-N.
tHiiiley, ISTT---. Iiiscus-e.l in tln~ pui'f' vi'idi^'i' >i"lii fri'.'iuiti.'.
I
1805.]
NKW ViiUK ACADEMY Ol' .^ClKNCi:,-
:2(il
1
I
I)i.vi;.\>K.
Hxci-jil llio fflsiti's this is tlio most ;il)iiiiil;iiit ruck of tln' Cold-
brook irroup. and fonns also a considcralilo part of the rocks iv-
fcrrcd to tho Coastal scries in ]SST-S. It occurs as siirfaoe tlows
as well as intriuk'd sills and dykes. At Ilacfhorsc Point, east
of St. Joim City, it crops out on the shore as a heavy dyke in
the coarse L^'een and red sandy slates that are overturned on Hie
line L>rev slates of the St. John jiroup.* This dyke has Icikeil
the adjoinin^f slate into a liornstone very like the edues of the
iijjueoiis rock itself, and the contact of the two is not easy to dis-
tinLrmsJi. Dr. Gesner in l!^40t mentions it as a dyke, lint snp-
l»oses that it has fused the slate near liy. and thus elfaced the
line of contact. The Survey llei)orts]; do not I'ecounize it as a
<lyke. luit consider it, apiiareutly. as an altered sediment or ash-
rock. In thin section, however, it is unmistakalily .a dialtase.and
on careful examination the lino of contact with the slates was
traced on each side. Under the microscope this contact is per-
I'ectly sliar[i and clear, the iirneous rock lieiuix dense, almost
opacpie, with scattered [)laij;ioclase iihenociysts. The slate does
not show much chaufre ; the iiarallel arran<rement of the <rrnnules
is not noticalile. and minute i^rains of a lu-iurhtly itoiarizini:- min-
eral are developed near the edge. The diabase of the central
parts of the dyke is tolerably fresh ; the ausiitc occasionally
shows crystal outlines, Imt mostly moidds the feldspar. No
olivine was observed, but a peculiar oil-green substance, indis-
tinctly fdn'ous or matted, with a high refractive index and bright
aggregate fiolarization, appears occasionally, and is probably an
alteration jiroduct of olivine, perhaps allie<i to I5ecke"s y(/7//('.
At some little distance back from the shore, near the jieuiteu-
tiary. the dialiase crops out again, here being in jiart a snrface
tlow. finer grained and stron;;ly -icular. and separated Iiy a
sharp line of contact from the ccjarser. non-vesicular diabase
lying northwest of it. The latter contains included masses of
wiiite-weathering Hinty felsite, which seem to l>elong just north
of it, and are very like the sup[iosed asli-rf)cks underlying the
Etcheminian nortli of the city.
From the foregoing it is clear that a part of the diabase, the
dyke on the shore and the heavier dyke or sill back of it, nuist
be later than the slate and felsite through which they cut. Of
the relative age of the vesicular diabase there is no good evi-
dence ; though it appears to be older than the sill. The slate is
* Trans. Koy. Soc. Can. iNiO. Sec. 1. i'. VJ7.
t <ie()l. Sin, I'mv. Xcw linins.. Rep. isio. \>. 11.
tiu'ol. Siir. Canadii. He)'. 1>71. 1'. MT.
•202
TRA.\.'« ACTIONS cF THE
[APR. ].'),
eonsidori'd EtclK'inininii l>y (i. V. Mattlii'w* ; liencc this diabiiso
is i)Ost-Klc!u'inini;m. pussilily (';iiiilirian or inter.
I'rovisioiinlly it iiiay 'u' |il;u'i'<l ;is prc-CnniliriiUi.
Tilt' iliiiliMst' is Mifiiin wcil fX|>o->tMl on tin- wt-st, side of tlie ii;ir-
bor of St. .Folwi, in :i series of liills on tlie snutlieast bordiT of
tlic Cambrian valley. It is ni:i<le np, as tar as ean be seen, of a
niiMibef of surface tlows, wliich are aceonipanied by a little slate,
api>arently intei'bedile(l. -md were perhaps partly sl)nMiariiie.
The characters of surface tlows ean l)e seen in some others of tiie
many outcrops that occur in all parts of the Iluroiiian hills,
Fui. B. Vt'ficli^ in iUahcttte. .•<howiiig (njatc-likc bdnduKj of
frJdapar (?) and chlorite. Maijnifit'd 70 diameters. Sjiec. 150.
others are more probaltly intrusive sills. All are normal dia-
base, without olivine, and with an almost colorless augite. The
vesicles are mostly lined with cpiartz, and filled with chlorite,
sometimes with hornblende. The chlorite is very often spheru-
litic and shows the beautiful Berlin-blue polarization color.
Secondary growths of a mineral which seems to be plagioclase
are known; it is not twinneil. but ai)pears to be sometimes opti-
cally continuous with the feldspar rods around the vesicle. It
* Trims. Roy. .Soc. Cnnndn. IT'.H). Sec. I. \<. r.'T.
^
K. I'"),
u' liar-
iUt of
n, of a
> sliite,
iKirine.
< of the
1 hills.
I8O0
NEW YORK AfADE.MV lU' ,-;CIEXCE.S.
203
is ;it tiint's iiiterjirowii in altoniatu concentric layers witli tlic
chlorite of the vesieh's, as is shown in Fi>,'. 11.
I>asie '(>•/' /vx'/x occnr almmlantly and can sometimes lie seen
to he made np of diabase fniLMiients. lint most of tiicni ;ire too
far altered to be ceitaiidy ideulilied.
I'dlirilVHITES.
Untler tiie uronp may be placed a considerable number of out-
crops of strongly pvjrpliyritic busic clfusives. mostly of purplish
bhicU color and not certainly known to urade into the dialcises.
They form heavy beds, apparently thick surface Mows, very
ve-^icuiar for the ifiost part and containin«i- phcnocrvsts of
idauiocla^e which in one case, a porphyrite from south of (iolden
Grove, are remarkably fres! md ylassy.
Under the microscope ilicy show a somewhat ophitic line-
l^raineil nrroundnuiss composed of feldspiir rods, minute iriains
of auuite tind magnetite in which are scattered the feldspjir
l)iieuocrvsts, those in the rock from Golden (Jnnx' bein<i of the
inicroli.)if habit, w.ater clear, repeatedly twiuneil and sonfewhat
corroded. No anirite pheiiocrysts were seen. Fu a porphyrite
from near Henry Lake the vesicles are tilled with a zeolite, de-
terminetl as thompsonite on its micro-ciuiractcM's.
di)i(j of
<„'<: 150.
inal dia-
The
hlorite,
spheru-
color.
rioclase
les opti-
cle. It
Mktamhuimiis.m.
The alteration as seen in these Coldbrook ami Coastal rocks
is very varied in amount. Drritri jiidtion is univers;d ; in no
instance lias any trace of remaiuiiiir glass been identitied. The
resultant inicroerystalliuc mass varies in texture from a micio-
felsite, in wliicli the minerals are scarcely distinguishable to a
moderately tine microgranite. in which are local accumulations
of coarser grains. Siu'aring occurs sometimes in the poi'phyries,
quite generally in the ash-rocks. In the Coastal especially, it is
usually so much developed as to produce a schist. The last
named alteration is accompanied by the production of great
amounts of epidote ; this mineral occurs less abundantly in the
massive Hoavs. Uralitic hornblende is a freipient alteration pro-
duct of the diabase, retaining usually the form of the augite
which it replaces. In no observed case is the change carried
so far, either in the acid or basic rocks, as to produce a strongly
schistose or subgneissic structure. It is not intended to assert
that such rocks may not occur locally, but only that they are
evidentlv not usual.
204
TKANSACTIONS (U Till:
[aI'U. 15,
ScPA-iiHAMTK. IM. XVI. :m(l XVII.
A liiizli riiliTf strctchiiii: froiii Ilnrtliiiiivillf on tlic (icnnniiie
Hiook to thf ureal luiid in tin- II:uuuioihI UiMr lidow rplmu)
consists of jv rc'iljrranitic rockoallctl syenite (liornbende-jrianite)
])\ tiu' Snrvcy oilift-is, Imt wliicii on microscopic study Jippc.'irs
to lie :ui auirite-soda-iiianite. 'I'iie (Jerniaini' IJroolc and llnni-
inond Iliver run at the fool of its sleep eastern slope; on liie
otlu'i' side lies a liroken country, little opeiu'd up. The rock
was consi(]ered liy I'rof. jlailey as an extienieiy nietauioiphosed
phase of the breccias and felsites which surround it ; and he cites
instances of the transition of the one into the other, which the
writer has not yet been ablo t() completely follow. *
In rcirard to I'lof. IJailey's conclusion, il must be observed
that microscope sections have failed to show any extreme nu'ta-
morphism in the ("oldbroctk or C'o.'istal irronps. They have i'w-
(pieiitly a secondary cleavage developed, which often amounts
to an imperfi'ct schistosity. Hut of the entire re-formation of
tile minerals in the I'ock so as to make a irneiss, still less a uran-
ile. I have seen no instance in the })ost-Laurentian rocks of this
re<rion. If the rock is not a subseiiuent intrusion, tiie view of
Hr. Ells, stated with regard to a numlter of such areas of crys-
talliue rocks occurrinir near the borch-rs of the volcanic ai'eas,
seems moru acceptable, t He regards them as b(,'ing basal parts
of volcanic flows, their crystalline character being due to slow
cooling.
Prof. Bailey describes the passage from felsite into "syenite,"
as follows :
'' With the dark grey petrosilex are irregular beds of pale red
and red felsite, which in approaching Titus' Mill become at the
same time more freipient and more crystalline. In some por-
tions . . . a'distinct but usually highly contorted stratification
is discernible, but other portions are quite homogeneous, and by
admixture of a dark green mineral resembling hornblende be-
come imperfect syenites. ... It is su|)posed that these syenitic
hills . . . are simply the petrosilex and breccia in a more
altered form. That they are in great jiart of fragmentary ori-
gin is very evident, and even where apparently most crystalline
a rounding of the grains of (paartz, and the occurrence of irreg-
ular cavities or vesicles suggests that all have been produced by
like agencies.'" ^
The microscopic appearance of the " syenite " throws consid-
* Geol. Snr. Can. Rep., IS-7-7S. \>. S, PD.
t <ieol. Snr. (1111. Ki'|i.. ls"-->. p. :;. li.
{ Loc. cit.
,'K. lo,
l«i».j.]
NDW YORK ACAUEMV OF .SCIENCE!*.
l'( I.')
rmaine
l'l)li!\in
liuiiti')
I H:un-
oii the
u' rock
pliosi'd
u' citi'S
ifli the
hservod
iL' iiR'ta-
!ivi' tVo-
luoimts
ition of
< !\ i^iniii-
* oi" thiw
view ot"
of crvs-
c areas,
;!il pni'ts
to slow
yeiiite,"
lule red
;it the
ine por-
fieiition
II nd Ity
iide l»e-
syenitic
:i more
:u'y ori-
.stulline
of irreg-
uoed by
cousid-
eial)h' iR-w liirht on its oiijrin. in thin •-(•ffion (I'l. X\'I.. \\<^.
I) it Mpiifiirs !is !i r.'itlicr eoaix- Imt \ivy f\L'n-;uM!Hnid >(»d:i-
^rranite, apparently of itrneous origin, tlie (piart/. often granopiiy-
lie (wlieiice tlie loiUKling of its grains of wiiicii Pr. IJaih'V
spt-aks); till' (hulv silicatt'> arc angite and hrown ami grei'n iioin-
liliinh'. the two hitter apparently st'condary after angite. 'I'lic
fcldspiir is partly idioniorphic. partly granophyric or u^r.inilic.
Towiirds the edges of the ma^s the rock liccomcs finc-gT'iincd.
and shows in thin section ( IM. XVI.. tig. '2) :\ mass of intcrl.'ic-
ing rods of feldspar with comp!irativ«'ly little ((nartz. and angite
In small irregidar grannies. The characters eiteil are sntlicient
to show that tlii> rock has cooled from fusion. l)id it oceiii' in
the midst of highly metamorphie rocks. gnei>ses and crystalline
schists, it might well he snpposed that its fusion was hut an ex-
treme phase of nictaniorphism. lint in view of the slightly al-
tered character of the roek^ surnjiinding it. it seems almost cer-
tain that tile fusion was followed hy a notahle displacement. and
the rock is therefore !i stranger in its present association and
must he classed as igneous. '|'he pei'iplieral phases, as l\\v ;is
noted, accord with this view ; we tind there a rock approaching
a jiorphyi'y in structure, instead f>f a gneis>. How nearly the
granite is connected with the felsites iironnd it, it is not now
possilile to say.
Mil- roan, i>lc rliararfi'i'.'i. The rock is an fiiif/itf.nntla-ip-din'ff^,
containing at niost. peihtips. one-third free (luartz, and a vary-
ing .amount, sometimes (iiiite small, of ferromagnesian silicates.
In its centrsd jiarts it is strongly granofihyric (IM. X\'II.); to-
wards the edges it loses that feature and finally hecomes fine-
grained with a rod-like form to tlu' feldspars, and almost no
quartz.
The ijiKirh. calls for no especial comment. It is. as noted,
largely intergrown with the feldspar; when not so.it a])[iears to
have heen the last constituent of the rock to form, never show-
ing crystal outlines.
The /'I'hh/Kir is partly a twinned teldsjyar. apiiarently anor-
thoclase, and partly untwinned. Much of it is so altered l>y
kaolinization that its !mtnre cannot he determined; the more
altered parts are made almost opacjue liy the presence of minute
red Hakes (hematite ^j. The untwinned feldspar rai'cly shows
crystal outlines and is often intergrown with (piartz. The
twinned felds]);ir shows an ('XceedinglN line and regular twin-
ning with :i small extinction .nngle. and occurs mostly in idio-
morjihie crystals iml>edded in the ([uartz-orthoclase mass.
From the regularity and fnu'uess of its twinning this feldspnr is
considered to he more prohahly anorthoclase than a line grained
plagioclase.
liOO
THAXfJACTIo.N'S of lilt:
[aph. 15,
I'csiilcs the :iiioilIinrl;i>c, ;i low oryHtiih of the onliimry
|)l:iuMot;liif*c' t.vjK' wi-rc uhsi'iveil.
AiK/iti' occiirH ill poorly iU!V<'1o|h'<1 c'lystJiU or iiT»';j;iiliir •j;iiiiiiH,
:illin>>t colorless :iii(l witli no Miipiirciit picocliroisiii. It in
iiiosilv ;iltf)'('i| to lioriililciiilf, cliloiitc or ciiidote. In tin*
stronjily irnmopliyric spcfiiiienH the nii<,nli; mihI other lerntiiisi;;-
iieNiiin silieiites :ire in very sunill iinioiiiit.
Jli-'iir,, linrnhh'Dilr. A jt.'de Inown lioriiblemle, witli n very
lii^li extinetioii ansile, 'Ib^ nmxiiniiin, occmii'h in niodenile
Miiionnt. It is in piut at least seeon<l:uy jifter aiifrite, Imt some
of it seems to sliow its own crystal outlines, and if so. may he
considered ori«.dnal. Its pleochroisin is;
j1 — taint lirowiii-.li yellow,
t) — pale ifddi>li Inown,
r — pMle yellowish Itrown,
a>ti>r.
Gi'i'i'n jKirnhU'iuh'. This is in varyinix quantity, and appears
to he in all cases paramorphie after aii^'iti' and hrowii liorii-
hlende. It has the usual colors and pleochroisni of iiralitic liorii-
lileiide. thoii;i;li its strnctiire is jtlinost compact. The stii<j;es in
the alteration of the aniiite appear to be,
1. IJrown horidilende,
■2. (Jrecii hornblende, sometimes bleached before passing into
:5. Chlorite.
Epidote oecurs as an alteration iiiodiict, but apparently not
of this series ; the conditions of its formation must have been
dillerent. In some sections no aujrite or brown hornblende is
found, but only an agj^reirate of <rreen hornblende, epidote and
chlorite.
Jfi'iti/i' is an abundant accessory, in the usual loii<; prisms,
which are rather more abundant in the (piartz.
Miii/iirtifr occurs in small irreirular masses and is in part
titaniferous. J'l/rih' is occasionally to be noticed.
Ziri'on !ii)pears in every section examined in crystals of scpiare
cross section. In the concentrates these are seen to be inacle up
of the unit jirism and pyramid, rarely showin*; their edges in
the sliifhtest degree moditied. This character of the crystals is
much in contrast with the rather abundant zircons of the intru
sive granite-diorites of the Laureiitian. The latter have the unit
and second-order prism and unit [lyramid much moditied 1'3' <le-
velopinent of several other faces, giving them a ronnded outline,
while the zircons of the soda-granite are sharp-ed<:ed and clear*
cut. The ditlerence in character may perhaps be ilneto the con-
ditions of .ioliilifving, more probalily to the chemical composi-
tion of the magma.
I
•u. 15,
dimU'V
liriiiii**,
It in
in tin;
!i very
odi'iivte
lit sdine
in:iv '»«
181t.j
NEW VnUK ACAKK.MV nl SCIENCE:"
JOT
iVIl lioiii-
itic lioni-
stiiti*.'^ ill
isiiig into
[eiitly not
•ivf hwn
(loto anil
(T |)rismfi,
in i'iirt
ofs(iu:ire
f intuk- \\\y
edges in
rystiils is
the intni
. the nnit
umI I'y <k'-
outliiie,
Mud flean
I) the oon-
composi-
VI
(■(
In tlie t(»nct'ntr:iteH n IVw <j;i!iins nif tonnd of a niinei;il with
ultiaiimiiiu'-lihie color. iiinl pleucliroiMii iiltrninuriiK' to lohuloHs.
Tllis is thoilgllt to he |ii(thMlily (I soil:1-lio| nhhllde, iiliieil t»»
}r|iiiieo|)h!Uie. Its rct'r:u't ion iukI polari/.atioii iiuliees iiif alunit
thoHe of lioriihh'iide ami it Ih (;') hiivxitil ; hut its properties
fonld no! lie fnrtlifr (leteriiiine(l.
The iiciiplier.'il pliMscs of tile soila-;:ranite are not llioroiljihly
known. The eoinplete gradation from it into the felsite-hreeeiu
desciilti'd l>y Hr. Itailcy ;is occ lining :\\ Titus' Mill, the writer
ha> not >tueeee(lcd in lindiiig. At otlu-r points the granite was
Heeii to he llne-giMiiie<l and to have lost Its oliarneteristio hriglit
red enlor. it was not at all giicissie. however, nor was it strf)iigly
porpliyiitie, and of fiiithtr transition ln'twi'eii it and the feUites
no traee wiis seen.
I'nder the microscope (l'\.. X\'I., lig. 2) this line-grained facies
shows a more or less paiiidi'>ni<irphie structure of feldsp.ar crys-
liils which exhihit .a decided tendency towards the rod-like form.
One or two large crystals appear to he porphyritie in the rest t)f
the mass. The feldspar is largely plagioelase, tin- rest orthoclase,
no aiiort hoclase heiiig certainly rei'ogni/.ahh' in the sections.
Augitei' appears in minute grains scattered all through the
muss; they are too small to show well tin characteristic optical
properties, .and have little or no crystal outline.
.An analysis was made of the suda-granite from aiio\e Titus'
Mill. spec. fiCil. This wns a fairly average specimen, moder-
ately graiiophyric. with an unusually Large anioiiiit of dark sili-
cates present. The following results were olitained (coluinu I.; :
Analyses or .^opa-ukamtes.
I. Titus' Mill. I'pham. N. 1$.
II. Kekeipiahic Lake, Minn. U. S. (Jrant.
III. Pigeon Toint. Minn. W. S. Ihiyley.
I. " II. III.
(I I,
SiOa (M.Hfi (II.T!> 6«.'^t Ti.i-i
TiO.j u.Tu u.(i:i 0.40
AI,(), ir).(C' ls.-,>;» 1:1.04
Fe.O, 'i.-y-i .").(iu 2.27 (i.«M
FpO l.Ol u.si; O.-iu 3.17
ISInO U.ls u. 10 (i.oii
Cao 2.()i 2.(;:i .i.'.n o.tMi
]SIk<> 1.43 l.ol ().>^1 O.-y^
NaO 3.92 :{.!« 5.14 H.44
K o 2.37 *J.3.j 2.s() 4.1)7
(•('), 0."i
I'.o, ti O.-Ju
Loss on ijiii. 1.73 1.7H 0.4(i l.-il
0!).>^!) 100.0.") 100.37
ft*
1
208
TRANSACTIONS OF THE
[aI'R. lo,
With this .'iiiiilvsis nro plnct'il for compnrison analyses of
aiiofthooliisf o;i'aiiitL'S from Ivi'lvLMHiiibic Lake'- (II.) and Pi<>:t'on
J'oiiitt in Minnesota (III.). The Upham rociv agrees fairly well
in composition with that from Keke([nal)ic Lake, being some-
what lower in alkalies and alumina and higher in iron percent-
age. Dr. Grant describes the latter rock as dnll pink in color,
feldspathic, with abujidant augite an<l conijjaratively little (juartz,
!ind siiows that it is an intrusive rock, exhibiting porpliyritic
facies. It would seem to be less altered than our rock, and con-
sequently has a much larger proportion of augite; otherwise the
resemlilance is (|uite close.
The residts of separation witii potassio-mereuric iodide solu-
tion were as follows :
>p. 'A
•>..-, l_-j.,-,7
•)
•2.ru—-2.e,-2
•Jfi
•i.lW -•,>.(!?
»1
•.>.(;7— -.'.70
i
•J.7(»— •J.7;3
(i
e.7:!— :!.lf>
10
> :5.l(i
,>i
100
The part falling between 2.02 and 2.(57 was chietly (juartz and
impure feldspar. The feldsi)ar between 2..")7 and 2.()2 was
analyzed with the followiiiii results:
.'<iO,, (16. 02;
MgO, not det. ;
A1,0.„ - Fe.O,, 21.:2:2; CaO, O.w-J:
Xa.O, «,7;5; KjO, 2.10.
In its outwanl appearance and in many det.'iils of its struc-
ture this soda-granite is very like the " re<l rock " of I'igeon
Point, in Minnesota, so fully described by W. S. Ba3de\\;{; Dr.
Bayley determined the red rock as an anorthoclase granite with
l)orphyritic phases.
Dr. Bayley shows that the red rock is to be considered as a
contact proiluct resulting from the complete fusion of red sand-
stones l)y an intrutled gabbro. If the view held by Trof L. W.
Bailey as to the origin of the soda-granite be correct, there is a
further likeness to the Pigeon Point rcick, as the metamorphism
which could jn-oduce a rock of such type must be supposed
pushed to the point of fusion. For reasons alread}' stated, how-
ever, the writer is unable to take this view, and would consider
it ratiier as an igneous rock of unknown relations to the felsites.
, — i . — ™ — 1 . .
* Minn, (ieiil. Survey. Ann. Rep. WV2. p. U.
+ Anier. Jonr. Science c.) XXXVII.. M. See iilso r. s. li. s. I'.iill. lO'.i.
; Hull. lOii, U. S. (i. S.
I
I'R. 15,
181»o.!
NEW YOKK ACADEMY OF SCIENCES.
200
vses of
Pigeon
rly well
(T some-
[^>ercent-
n color,
. (luartz,
phyritic
:uk1 con-
wise the
ide soln-
uavtz ivnd
2.t')'i was
.10.
its stnic-
of Pigeon
unite witu
ered as a
red sand-
lOf. L. W.
there is a
morphism
supposed
tated.hovv-
d consider
the lelsites.
/"w
I
The KixdSTfiN Group.
This group presi-nt^ :i series of volcanic rociis parallel to
those of the Coldbrook, l)ut far more altered. The acid mem-
bers are strongly sheared, often unrecognizal^le as volcanic, and
with a great development of secondary micas, making a quart/.-
ose or felilspathic mica-seiiist. .Some of these schists retain
their porphyritic crystals with clear cut edges and compani-
tively little altered, tliouirh the ground mass is all recrystalli/.eil.
Ash rocks, now changed to tlinty fclsites. are sometimes still re-
cognizable, but no doubt most of them are too much metamor-
phosed to be determiuiMl.
The basic rocks of the series are even more changed. Though
mostly less cleavctl, they are coarsely crystalline hornblende
schists, witii no traces of their original structure visible under
the microscojie. Kemnants of the porphyritic feldspars some-
times still appear as while spots scattered through the dark
sciii.<t. but their original form is lost.
These remarks apply to the New River e-.posures. the oidy
ones examined liy the writer. A moditieation of tliem might
be necessary on study of other areas of Kingston rocks v.iiich
show certainly a greater variation in the amount of metamor-
phism than is seen at New Piiver.
COMI'AIUSONS.
In their original character and degree of i)reservatiou the
New l{run>wick etfusives may best be compared with those of
South .Mountain. The volcanics of the Boston IJasiu, as far as
the writer has seen them, seem to be more dense and massive,
less shattered and epidotized and more crj^stailine than ours.
In tield characters there is a considerable resemblance to the
volcanic series along the Maine coast, at Eastport and Mount
Desert; but I have seen no jietrographic descriptions of these.
The rocks .jf the Coldbrook group seem to be much less
sheareil than almost all of the South Mountain rocks, to which
our Coastal volcanics show a closer reseniltlance in this respect.
The Coldbrook felsites are also of liner grain, their recrystalli-
zation not having i)roceede<l (piite as far. The characteristic
structures of volcanic rocks, as has already been detailed, they
possess in great perfection, the only structure of which I have
not seen satisfactory examph's being chain spherulites.
It is worthy of note that all these •'ancient volcanic rocks,"'
as Dr. Williams hapjiily termed them, lie unconformably vinder-
Tran-saction> N. v. Ai All. S. I.. Vol. XIV., sii;. II. May 'Js, Is'.i.i.
a1
•210
TRANSACTIONS OF THE
[Al'R. 15,
nt'iilli ralii'ozoic strata. Wliethor they vav consiiU'i-cd as the
lowest nieinUer of the Paheozoie series or the iippennost one of
the pre-Camhriaii rocks wouhl seem to depend chieHy on what
may be taken as the base of the Palneozoie. In New ]>runswick
it is ratiier more than elsewhere convenient to consider them
as at nil events pre-Camlrian, and to take the very persistent
coarse grey sandstone at the base of the Wt. John <rroni» as the
dividinir line. This would leave 1»oth the volcanic s'eries and the
Etcheminian among tiiejire-Cambrian rocks. Nevertheless their
age is probably not greatly different from the so-called Cambrian
cttnsives Ivinir southwest of them.
TlIK DYKE.S.
In all the rocks referred to the '• Laurentian.'" we find a great
al/undance of dykes. In the later rocks they are few in num-
ber. In the volcanic series the\' are, naturally, not easy to re-
cognize : a nundjer of supposed sills are known, but of small
dykes cro^^sing the bedding of the rocks very lew. The Etche-
minian contains one certain dyke, and probably others. In the
St. John Group one dyke is reported from near the city, but I
have not seen specimens of it. Though none have )»een met in
the Devonian slates, a few occur in the Sub-carboniferous.*
The vast majority of the dykes in Laurentian rocks, as well as
the dyke and sill in the Etcheminian, are ordinary diahase,n\ov(^
or less altered and often porphyritic. With these occur several
dykes which can be grouped under Prof. Rosenbusch's term of
Dinrifr-porphip-ifc, though they border on camptonite. The
Sub-Carboniferous dykes, with one or two occurring in older
rooks, are avyitt'-jioyjihi/ritc. Some d^'ke rocks appearing to be
of other t^pes are known, but are all so altered as to be unrec-
ognizable.
As a rule no general trend is to be distinguished in the direc-
tion of the diabase dykes. An exception is seen at Pleasant
Point, where the granite is seamed with dykes, most of which
are perfectly straight and parallel, with a north-west and, south-
ea.st direction, parallel to the great cross-fault of the Short
Reach
DioRiTK-PoRi'HYRiTE. PI. XIV. Figs. 1 and 2.
Under this name may be grouped a number of dykes varying
a good deal in character, but all distinguished by a grouudmass
consisting of shar[ily idiomorphic hornblendes, lath-shaped feld-
*These notes npiily merely to the neishboiiiooil of St. Joliu.
»i
a'R. 15,
1895.]
NEW YORK ACADEMY OF SCIENCES.
211
.IS the
t one of
on what
unswick
lev tlieni
jrsistcnt
ip as the
and the
OSS their
'auibviau
1 a great
in nnui-
isy to re-
of small
he Etche-
. In the
ity, but I
>n met in
ous. ■
as well as
hose, more
ur several
's term of
lite. The
in oilier
ring to be
be unrec-
the direc-
Pleasant
t of which
md, south-
the Short
:es varying
roundniass
haiieil feld-
spars and some interstitial quartz, with phenoerysts chietly feld-
spar, sometimes hornlilende. occasionnlly quartz. They arc
holocrvstalline. rather fine ";rained, and distini»'uishal)le macro-
scoi)ically from dial)ases by their paler gray color, granular tex-
ture, and often by the short hornblende rods which stand out
on weathered surfaces. The texture is mostly uniform, but in
two cases is extremely irregular in different i)arts of the same
dyke. They are singularly like the basic segregations in the
granite, which latter tiiey cut in several places, and are jierhaps
to be connected with it as the last member of the intruded series,
injected after the rest had solidified.
Under the microscope they show numerous well formed crys-
tals of liornhlonlc, varying in size according to the width of the
dyke, with prismatic faces always well developed, often also with
good terminal faces. The prismatic faces are ?h, usually //. rarely
o. The terminal faces are not safely determinable, but ajiparently
r is present, and also a steef) inramid or clino-dome. In the
less altered specimens (203, 204, (103, G08) the hornblende is
brown, showing a strong pleochroism :
a — brownish-yellow.
b — brown.
r — greenish-brown.
The extinction angle is high, not less than IT-, and the colors
are scarcely so deep or so .'ed tinte<l as those of basaltic horn-
l)]ende. It appears therefore to be a brown variety of the com-
mon kind.
Green hornblende sometimes ai)pears as a secondary rim at
the edges of the brown crystals, more commonly as a paramor[)h
after them ; all stages of the change can be seen in diflerent crys-
tals, the alterati*^ n beginning at the edges or in cracks; Iii
either case the orienta.ion of the two varieties is the same, and
their extinction identical.
In the more altered dykes (00,22.5,284 and 336), the horn-
blende is entirely green, its pleochroism being
a — pale brownish yellow,
t — green,
C — bluish green.
The outlines tend to become less distinct with increasing
metamorphisni.
In spec. 284, from a small dyke, there are, instead of the usual
corrode«l feldspar phenoerysts, abundant long rods of green
hornblende, from 0.2 to O..'^ mm. diameter, and several millime-
M
•212
TRANSACTIONS OF THE
[APR. 15,
iH:
teis in leiiiitli. They :ue not noticc.ibly corroded. Strictly
spoalvin^. tills rock is a rdmii/onitr, hnt its loal .itlinities seem
to be nitii tlie diorite-}iori)Iiyrites. Spec. 608 also shows por-
phyritie hornblendes, brown, like those of the srroundniass,
alonix with the feldspar phenocrysts.
Fi Idspar i)henocrysts are i)resent in all but one of the sec-
tions. They are much corroded and kaolinized and snrrounded
by a rim of clear feldspar, probably secondary, at least later
than the greater part of the groundmass. When not too much
altered, they can be seen to be a very basic plagioclase with ex-
tinctions up to at least 40 . indicating api)roximately bytownite.
Twinning after the Carlsbad and All)ite laws is observed, the
latter polysyntheiic. The crystals are stroiioly zonal towards
the edges, tlu' clear outer rim becominir rajiidly more acid till it
is an oligoclase with nearly straigiit extinction. The zonal out-
side aM(l decaye(l core .'ire not always coterminous, the latter
being often more or less zonal. There is no evidence that the
clear outer rim formed later than the consolidation of the rock ;
the decay of the feldspar within may well be due to its different
composition. But it certainly formed after the greater part of
the groundmass had crystallized out.
The feldspar of tiie groundmass is comjjosed in jiart of lath-
shaped crystals, with the extinction angi.^ of labradorite, zonal
at the edges like the phenocrysts, but not corroded, though often
decayed at the centre. The rest of the feldspar occurs as zonal
rims to llie laliradorite rods and as irregular grains packed in
among them. It is always fresh, and judging from its extinc-
tion angles its composition varies from an "id lal)radorite to
oligoclase or even albite.
Qvnrtz occurs as a phenocryst in spec. S-Sfi and shows well de-
fined crvstal outlines, somewhat corroded, not much broken up.
It occurs in the groundmass of all the dykes, though never in
very large amount, and is then of the same age as the clear felil-
spar forming the zonal rims and irregnlar grains, that is, the last
constituent to crystalize.
JffK/netile and pijriti' occur in small, well formed crystals.
Ajiafite is rare. The hornblende of the concentrates api)ears to
show transition to an ultramarine blue variety, probably a soda-
hornblende.
/•Voir .<triictirrr is very well seen in -;)me of those d3'kes, as
shown in PI. III., fiir. 2.
1895.]
NEW YORK ACADEMY OF SCIENCES.
213
All Miifilysis of tlic (liorilo porpliyrito, spec. tl()3, y^ixw tlic fol-
lowing results
i
Si (),
H.!N
'11 o".
O..Vi
A] , O,
17.7(i
Fi.;, <),,
:>.14
IV ()
«..V^
Ca ()
^^.:5(;
M- ( )
•,'.0!t
Nil , ( >
• I. 77
K.O
2.0-<
Fi.\t(l CO.
0. "^'j
Loss on iunii ion
1.50
100.5-^
I am iiol aware tliat this rock iia-^ licoii i'eport('(l bcfoiv from
Nortii America.
PlADASE.
It seems veiy likely that this t,rroii|) of ilykes is connected
witii tile great surface fiows underlyiiiij- tlie Cambrian slates. ami
of" HiH'onian" ao;e. There is a tsreiit variety in their character,
the majority lieinu normal dialiase, but many ha^iiio; the feld-
spar in two or three oenoi'ations, and some showing porphyritie
aiio'ites.
The normal diabase has a colorless or almost colorless aiigito,
well twinned feldspar rods and inagnetitt' in small, irregular
grains. It is nstially considerably altered, the angite being
either nralitizcd or chloritized. In about half the dykes green
hornblende, nralitic or compact, has entirely replaced the au-
gite, ■^till retaining the outward form of the original mineral.
Some of the dialiases are (piite porphyritie. the plagioclase
phenocr3-sts being short and stout, the groumimass containing
small twinned rods and sometimes apparently a third genera-
tion. These appear to lie more feldspathic than the rest.
Contact action has not been noticed except on the limestones.
These are bleached by even small dykes for aViout 3 or 4 mm.
from the edge; and in the case of a fifteen foot dyke near
King's Mill, Fairville (spec. 63). there is a development within a
few millimetres of the edge, of epidote. titanite and pale green
liornblende of tremolitic habit — b and r very jiale green, a color-
less. These constituents entirely replace the lime just along the
contact. The diabase itself has the usual contact cliai'acter.
A single dyke {'f) in the lower Coastal rocks west of the Cohl-
brook Marsh shows a departure from the ordinary type eiioiigh
to merit special notice. It is ratiier coarse-grained, tii' •:iiag-
214
TRANSACTIONS OF THE
I APR. 15,
netiti' ill iimisiuiUy lar<j;e grains with a teiulciicy towards skele-
tal foniis. Till' aiiiziti' is (luitc strongly colored, and there is
a not iiniinpoi'tiiiit amount of free ijiKniz (See PI. XV., Fig. 2).
The microscopic' description is as follows :
Aii/p'fi' nearly or quite as almndandant as the plagioclase,
violet-lirown, slightly hut ilistinctly pleochroic, mostly moulding
the feldsiiiir, occasionally idioinorphie.
ri(n/iochific in large, rather short lath-shaped crystals, idio-
niorphic with respect to the aiigite, water-clear, coarsely twinned.
Extinctions are ahout those of labradorite.
Mdiini'Utt' is in unusually large grains, mostly of the peculiar
skeletal forms which are sometimes referred to titaniferons iron ;*
idioinorphie with resi)ect to the feldspar and most, if not all of
the augite, l»ut with edges and angles freqnently rounded.
Ajxtlifi' in long slender needles varying from .05 mm. in di-
ameter down to indeterminable minuteness; included in all other
constituents, though rarely in the magnetite.
Quartz in allotriomorphic grains, moulding the feldspar
nnd augite, forms a not iinimi)ortant constituent of the rock.
It would seem to he original, judging from the unusnal freshness
of the rock, the size and nniformity of the quartz-grains, and
the presence of apatite needles in them as abundantly as in the
feldspar.
An analysis of this diabase gave the following results :
Si O ,
•I(i.<il
Ti 0,
(I..").")
Al, 03
l.-).:$4
Fe, ();,
>*.4()
FeO
H.14
Mn
o.sn
Ca
9.27
MfiO
.5.-J7
Na2
3.04
K,
1.41
L0S.S oil igiiitiou
1.41
9i).C3
The presence of free quartz in so basic a rock is unusual
The large size of the magnetite crystals, however, probably in-
dicates that the early stages of cooling were slow, giving time
for the basic constituents to crystallize out more completely
than usual, leaving at the end a more acid residue, which was
able to slightly corrode the first formed crystals of magnetite,
and produced some free quartz on crystallization. The same
phenomenon is seen in the diorite-porphyrite.
* The aimlysiis. however, fails lo show any eousi(lenil)le iiinount of titnnie aoiil.
J-
1805.]
NEW YORK ACADEMY oF SCIENCES.
•2i:
AnilTK-l'iilil'llVlHTE.
Tlie dykes in Suli-carlionitV'roiis saiuUtoin' at Poverty Hall
Point appear to lie of tiiis rook. The |)lieni)('rvsts are eliielly
anirite. the larger ones lieinir i'ntirely,tiie smaller ones frequently
chloritized. They present the usual short stout erystals charac-
teristie of anirite, ami are quite almndant. Augite oeeurs also
in the irroundmass. but is mostly destroyed. Mdiimlitf is
aliuudant in small crystals. Oliriiie phenocrysts oeeur rarely.
The /ildi/iocldsi^ is oonlined to tlie ^M'oumlmass and is in small
lath shaped erystals. A niie.'iceous mineral occurring- in small
plutes in the "rroundmass is i)erhapK an altereil hioiite. and is
(piite abundant.
With these Cari)oniferous dykes may lie [jlaeed from litholo<i-
ioal resemblance spec. 1 4S. a dyke in the volcanic series at Lily
Lake, known as labrad()rile-|)()ri)liyrite. It contains lar<re phen-
ocrysts of completely altei'cd lelils[iar. Spec. 2.')1 is perliai)s
also related, showinji ausfite and occasional feldspar phenocrysts
and a much altered Lrroiuidmass which contains m great abund-
ance of i)lates of .altered l)iotite (J) in ;i fehlspaihic base now
apparent!}' recrystallized and granular.
AdIHTKiNAI. XoTKS on TIIK Lai IlKNTIAN llncKS.
Seme further note*^ may be made as t(j the Laurentian arenas
in a few places otside of the district studied last year; though
no general examination was made of them.
A more mas>ive gneiss than has yet been noticed occurs l(e-
\-ond Sutton Station, on the Canadian Pacilic P^ailw.ay ; it is
strongly feldspathic, bande(l, ami contains a bed of limestone.
The iuti'Msive granites occur both east and west of the mapi)ed
district. To the southwest are also large masses of granite of a
ditferent type, non-porphyritic, much altered, and perhaps older
than the Indiantown granite At Musquash the contact is ex-
poseil between it and the Devono-Silurian limestone. The gran-
ite is here clearly seen to be the older rock.
The gabltro (olivine-norite) hill north of Dolin's Lake presents
less vari:ition in feldspai contents than tiie small Indiantown
exposure. Its grain varies greatly, crystals being sometimes 2"
across, sometimes finely granular and almost ophitic (i'l. XV.,
Fig. 1), as in spec. 474. This section fails to show olivine; it
is made u[) of colorless angite, weakly pleochroic hypersthene,
biotite.and basic ]ilagioclase, the latter giving a maximum extinc-
tion of about of!'-', and occurring in more or less lath-shapeil
crystals, which hoAvever do not distinctly ai)pear to be older than
the bisilicates.and are certainly in })art younger. The biotite is
later than much of the feldspar. M.ignetite and apatite occur
2lt>
TRAN'SACTIONs OF TllK
[aI'K. 15,
seatterin^^ly. 'I'liis phase of the iiorite appears lo occur as a
lieavv (lyUc or intrusive kiioli in the main mass.
Tlie relations ol'tiie norite to the snrrouiuling rocks could not
be (letermiiied. It is cut l»_v three sets of dykes.
1. Eurite and cranitc-veiiis. prol'nldy connected with the
granite.
2. Diahase.
3. Augite-porphyrite. older than the dialiase. and very much
decayed.
OtIIKK VoLt ASMC Rocks in NkW ]}l<l NSWK K.
The foregoing article deals with but a small part of the vol-
canic rocks of New Brunswick. IJesides the extension of the
C'oldl)rook and Kingston groups to tiie northeast and south-
west, and other detached areas lying further inland, there is a
great body of pre-Cand>rian rocks, chicHy volcanic, in the
northern part ot the Province, forming a consideraljle part of
the broken and unsettled country about the heatlwaters of the
Tolji(iue. Xepisi(iuit and Northwest Miramichi rivers. In seve-
ral of the later formations, also, great quantities of volcanic
material occur, notably in the Silurian of Passaniatiuoddy Bay,
at the base of the Itevoniai; arouiu^ the shores of Baie Chaleur,
in the Sub-carboniferous at the Blue Mountains near the To-
bique River, and around the head of Grand Lake, and in the
Triassic at (^uaco and Graml Ma nan Island. No petrographic
study of any of these rocks has yet been made, and they aflord
a fruitful tield for future investigation. The' great areas of De-
vonian granites extending across the centre of the Province
from the southwest nearly to the northeast lioundarv would
also v*ell repay study, especially with regard to their well
marked contact phenomena.
Si MMARY.
The Iluronian in Southern New Brunswick is in large part
made up of surface volcanic rocks. The lower part or Cold-
brook group is almost exclusively volcanic ; the upper part or
Eteheminian is clastic, while the intermediate Coastal contains
both volcanic and sedimentary members. The etfusive rocks
include lavas, l)reccias and tuffs, and with them may be placed a
holocrystalline soda-granite wiiich is probably either an in-
trusion or a ver}' thick surface tlow.
The rock types represented may be conveniently divided into
acid and 1)asie, the intermediate varieties lieinu little developed.
The acid rocks are more aliundant. They are chietly felsite-por-
phyry and show all the characteristic structures of surface
18'. to
NKW YORK ACAbEMY u\- SCIENCES.
217
flows. Vt'siclL'"^. tlow-liiii'- jiiiil tlow-liiffciii nrc very comiiuiii,
and till- st'iittcivd plu'iiocrv sts juv often \>vo\- -n :iml ilis|il;u'('(l.
SpliLMiilitie ami iierlitic striiotiuvn, triehiti'S aixl skcli'tijii crvs-
tills aio somctinu's cxcoUciitly prc^eiviMl. Tlic It.'isio locUs urc
eliit'tiy diiiluisi.'. mid su'c in ptut :is ImIc as tlu- KtclifUiinian.
Breccias and tutl's are veiy almndant. The alteration is not ex-
cessive except in the tntfs. ninny of wiiich are now nnrecotriiiz-
al'le. Tile massive rocks are coiupletely devitriliiMJ Imt other-
wise not much changed; schistose clea\af!;e is marked in the
more liitrhly nietamorpliic areas, hut is izeiierally absent.
The soda-granite is a (luartz-anorthochise rock with auirite
and lioriihlende as tlie dai'k silicates. It shows a xerystroiiir
•rranophyric structure in the central part, hut i> liner ,<rrained
and suniewhtit porphyritic towards the edocs.
The dyke rocks ,'ire all hasic and predoniiiiMiitly dialiase ; Imt
a nunilier Itelonsx to the rare type of diorite-porphyrite. Tiie
latter is a |>anidiomorphic rock with feldsi)ar. hrown liornhlende
and suliordiuate iiiiartz. 'I'lie atic of tiie dyke^ is prolialily pre-
(.'amlirian. '■ t-xceptin;: a few of dili'erent type from the rest.
In concludinir, I wish to express my acknowlediinients to
Prot". J. F. Kemp, for his assistance and advice in ctirryiiiL; out
this study, f am also much indehted to my father, Mr. (?. V.
Matthew, especially as regards the details of local ircolojry.t
♦Aiiil hencf imy niclo tliiil they cut udiiM be still ciirliei'. Tlicy iiic \iry iilnmilimt
in tilt' iiitrucivf u'taiiito ni-iir ttu' I'-ity. iiiiil liiiotly mi tlii< iicciiutit flic Jtur <<( ilu- i.Tiiii
iti- «Hs i>ifivisicpiinlly (iliK Til MS i'r>'-< iiiiiliiiiiii. It scfins wull tn iiiiiUc tlii« imiiil lU'iir.
us it liiis lu'eii iiii-stiili.'il ill u ici'i'iit nlpstnict nCtliu iirtii'U' (lospriliim; tlif !.'rauiti.'s.
+ iti'iildiricnl lit'inirtiiiriu. <'iiliiuiliiii Cdlk't't'. Apnl. Is'.C).
I'l.ATi; XII.
n... 1. S,,,.rn,it>r .,,■„,,,„; „. ,,,.1 ,VNi„.-,„.,|.l,y,y , a,M.l,si,li.„ , f,„„. „„.
';","""""' '''^'■' '"■'"» >l'l'i"M, X. I!. Tl,iss.rti.M. ,HlHms un.ln
iHul.n nM::,„li,.,tin„ u.ll prr^rv..,! tiichitrs tlinM,M|,„„t |„„|, ,|„.
■<|'lHT.iliiu.;,ncl iiMn-spliniiliii.' piiit^Mf th,. rock i S,... V\u \ „ ].,<))
>pi<. Cfil. .Mii;.'iiiii(d :;t ili;nii(t.i>.
n.. - i;,,l uU,l,.,„„;,luini (trnchyt,.). slM,wi„n nMs,,,, i„ „„,... „..„ni,-
n..n>:l.,-.. ,.lH.n,K.,.Ws.,n,.ll n.,l-lil<.. ..,,s,als arnl snu.lUn.ins
"•;' -' <'"nn,l,..l. IIM. glassy ni. ..ial has 1,....,. ..l,an«-.l t..
-"-n..,..ls„e. ■n,ronlv..,l„.,n,i,u., Jsa^.n,aun.,i,..a„,ls,...„,Ml-
"•''"" -•'■l'li"'iiiu in |M,tu„..„f ,l„.ortl„.rlas.. ,,1,,. .,v.N
>l»'c. ,-.7."). ^ 4:.'(liaiii.
Thanh. N. Y Ar.\n. S( i.
Vni,. XIV . I'l, Ml
It) fiiiiii till'
slidws iiiiiln
out liutll lili-
it;. I, p ]!•!•).
Iii«'c uciicrii-
>iiiiiill grains
('liaiiut'<l til
anil si'coihI-
ilirlliKTVStH.
I'Ki. 1.
Fk;. •-'.
-V
''I.ATK XIII.
•■"'•f i>n's,-,v.,l i„ , l„.i.,l„K , ^•' '"'''"'•■ '•••'<■'<« an. „
Tkans
^MIlllKllliI
•■, wliicli
was ii(,f
ii'silcx )
i
.\:ii
Fi(i. 1,
I'Ki.
M
.^Stt.
(!
Flo. 1
,„;„le to »P"l>J'.ll IS h^rl.tly shadlMl.
Pl(i. -i.
lade to ivpiesciit Hu' vm.ni * •■■"■-■>-•. -All atteinjn is also
"-"-•vsts. T ,;"T ^^"'^7--' "-a,e,l .o„'s of the
■Waek. Spec. 6.K x!!^;;;;;" " * """ "" -^-'^iteis„J
P'-"<'.y-; .lu.M..am in ,:";!, ;:r^"^^''-- """ -i-t. as
-*^^^^i''^i«H„aivi..a.ai^i: ry^^oisr"'"''''--
Tkan>
XIV
I'l.ATi; w
n-. I. rn„.,,„,,„,x„,,,, ^, ,,,,,,,..., „„..,,,vin....al,l.n,., |, •. ,,,,,
i-t.t.Ms n,nTsnuH l,y l,..avy parallH li„,.s. ,la,io,.laM. I.^ li..l,
"•s : a„„t.. an.I In, ...,., I,,.,,.. ,. im.,„la,. .-nK.Ks, ,i.e ,,vpn
;■'"■ ^"T.""'':^' '"- -"'"--^i"" -ith i„,u;„.,n...i; i
"""■lMn.ll,.l,n,lsol„,a,.m.,it... S,,..,.. ,:;;, , tT dia,,,.
N'ar.ssl.H,.,lu,t.,,,a,.aIi..l li,u..,,K. au.it.. I.vinv.„la,...,u.s
r .^ r ''' '"'"""■^ n in „„. n.,.,.,.. S.......
PLATK XVT.
Fi<i. 1. Sotht-f/rinilti. ftom Titus' Mill. The feldspar is stipi)l(Ml, the lino
twinniiij: (»f the anortlKK'lasc, lirinj: niJifsciitcd wlicio visihlc by
piinillel lines. Sonip attoinj)! is niatlc to sliow tlic (•(iiii]iarativc
alteration of tlie feldspar bv the lieavine.s.s of the stijiplinji. Horn-
blende is iei)resented by diajionally eiossin;!: i)arallel lines. (Quartz
is un.shaded and niaf^netite is dead blaek. Spec. (Kil. X 1*^ diaiii.
FH!. ',». Snihi-ijranitr {\w "jrained and porphyritic. From the llanmiond
River below I'pbani. Shadiny: as in the last li^nre, but au^fite
is represented by ineiiidar lines. Spec. (Kif!. X :!7 diani.
Tkans. N. Y. A( ah. Sci.
Vol,. XIV., I'l,. XV[.
Ill'
in
vc
•II-
i-t/
rii.
nd
itr
Fkj. 1.
Fkj. •
I
PLATE XVII.
Fl((. 1. di-iniiijiln/rli' stiiiritin- in soda-niiiiiitc I'ldni near Ilardin^^villo. Tlic
fi'I(ls])ai' is rtiircsciitcil liy parallel lioii/ontal liiU's; the (luartz is
unsliailcd; llic limiihlciuk' is ii'iut'si'iitcd liy (lia^onallv crossinj;
lines, zircdii hv iire;i;idar lu'a\ v criicks, and cliloritc by 'irntw
points. In tlic u]t])('r left liand <niadiant tlii' (|nart/, is mostly in
minute triuonal jirisms varionsly .shown liy dilTi rent sections. In
the upper I'iuhl hand (|uadrant tlie (|uait/. is ve.nulai' and minute
at the I'cntre, hut lieeomes coarse and incjiidar outside. In the
lower halt' the (|uait/, is seen radiatinu; out from a crystal of feld"
s|)ar, hecdniin;; coarser and more iri'enular as it continues its
growth. Tiie feldspar hetween thesi' quartz growths is in part
optically continuous with the central crystal. I'^om Spec. VtM.
X f^U diain.
'I"i;\\s. N. V \« AH. S( I.
Vc.i, XIV.. IM, XVII.
i
Fi.i. 1.
W. D. MATTHEW,
A. IJ., University of New Bninswicit, 1889.
Ph. B., Colmnhifi College, 1893.
M. A., Colunii)i!i College, 1894.
Fellow in Geology. Columbia College. 189:^-95.
Publications.
On Topaz from Japan. School of Mines Quarterly. \'<A.
XIV., p. 53, 1893.
Phosphate Nodules from the Camln-ian of Southern Xew
Brunswick. Trans. \. Y. Acad. Sci., XFI., 108, 1893.
A Study of the Scale-charaeters of the Northeastern Ameri-
can Sjiecies of Guscuta. Bull. Torrey Bot. Club, XX. 310
1893.
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