502  PRE-CAMBRIAN   GEOLOGY   OF   NORTH   AMERICA. 
SUMMARY     OF    PRESENT    KNOWLEDGE. 
SOUTHERN  NEW  BRUNSWICK. 
Dr.  G.  F.  Matthew  has  kindly  prepared  this  summary  of  the  pre- 
Cambrian  succession  of  southern  New  Brunswick : 
From  the  base  up  the  series  are: 
1.  An  undetermined  mass  of  feldspathic  and  ehloritic  and  hornblende  schists, 
with  very  little  limestone.     Intrusive  into  division  2. 
2.  "  Upper  series  of  the  Laurentian,"  with  heavy  masses  of  limestones, 
quartzites,  etc.    This  has  been  termed  Grenvillian. 
These  two  groups  are  injected  with  masses  of  quartz  diorite,  protogene,  sye- 
nites, gabbros,  and  diorites,  many  of  the  latter  altered  to  serpentine.  These  in- 
trusions are  more  ancient  than  any  succeeding  elastics,  as  they  nowhere  cut  the 
latter. 
Unconformity. 
3.  A  great  series  consisting  in  the  lower  part  chiefly  of  ehloritic  and  feld- 
spathic schists  and  in  the  upper  of  various  argillites,  dark-gray  slates,  gray- 
wacke,  and  bedded  diorites.  (The  hydro-mica  schists,  feldspathic  schists,  and 
argillites  of  the  eastern  part  of  St.  John  County  appear  to  be  the  lower  part  of 
the  series.)  This  series  has  been  called  Huronian  in  the  geological  reports;  it 
is  probably  Murray's  Intermediate  system  of  Newfoundland.  It  extends  along 
the  north  side  of  the  Long  Reach  of  St.  John  River,  and  southwestward  into 
the  islands  of  Passamaquoddy  Bay,  with  prevailing  southwesterly  dips. 
4.  The  Kingston  series  or  terrane.  This  is  entirely  an  effusive  series,  made  up 
of  diorites  and  hornblendic,  micaceous,  and  feldspathic  schists,  the  last  especially 
toward  the  top.  It  occupies  the  peninsula  between  the  Long  Reach  and  Kenne- 
becasis  River,  extending  northeast  and  southwest  from  there.  As  it  separates 
from  No.  3  going  westward,  it  is  supposed  to  be  an  unconformable,  later  series. 
The  Coldbrook  and  Etcheminian  terranes  being  regarded  by  me  as  Cambrian, 
I  know  of  no  later  pre-Cambrian  terrane  Or  formation  in  this  area  than  the 
Kingston  series. 
The  Coldbrook  series  is  closely  related  to  the  Etcheminian,  always  underlies 
it,  and  is  not  altered  so  that  its  rocks  become  crystalline,  further  than  they 
may  have  been  as  volcanic  rocks.  In  Cape  Breton  a  volcanic  series,  similar  in 
aspect,  and  lying  between  Etcheminian  and  Grenvillian,  contains  unaltered 
argillites  or  clay  slates  with  fossils  of  Cambrian  type  (Lingulella,  Lingulepis, 
OboJus.  Acrothyra,  etc.).  We  therefore  can  not  separate  the  Coldbrook  from 
the  Cambrian. 
I  question  whether  the  so-called  Coastal  series  of  previous  classifications  can 
be  regarded  as  an  independent  series,  or  while  a  portion  of  it  may  be  such,  a 
great  deal  should  be  referred  to  other  horizons.  The  rarity  of  fossils,  or  ob- 
scured relations  to  the  Paleozoic  sediments,  has  been  the  reason  for  referring  to 
this  group  much  that  is  probably  Paleozoic,  especially  in  the  view  that  the  Cold- 
brook and  Etcheminian  are  both  Paleozoic. 
Correlations — Divisions  3  and  4,  following  usage  in  other  districts, 
are  provisionally  correlated  with  the  Algonkian.  The  rocks  of  di- 
vision 1  are,  according  to  Matthew,  mainly  intrusive  into  the  Gren- 
ville  of  division  2.  The  correlation  of  the  Grenville  of  this  district 
presents  the  same  problems  as  that  of  the  original  Laurentian  and 
Hastings  districts,  where  it  may  be  noted  there  is  still  doubt  as  to 
a  By  the  authors. 
