498  PRE-CAMBRIAN    GEOLOGY    OF    NORTH    AMERICA. 
pre-Huronian.  The  great  unconformity  in  the  district  is  between  the 
Laurentian  and  the  Huronian,  not  between  the  Huronian  and  the 
Cambrian. 
Matthew,27  in  1895,  gives  the  following  pre-Cambrian  succession 
near  St.  John,  New  Brunswick : 
A.  Laurentian  : 
1.  Portland  group,  including  division  2,  with  probably  parts  of  division  1 
in  other  localities  than  St.  John. 
2.  Intrusive  granite  and  quartz  diorite ;  perhaps  later  than  the  position  here 
assigned  to  it. 
B.  Huronian  : 
3.  Coldbrook  group  or  division  3,  of  volcanic  rocks. 
4.  Coastal  group  or  division  4,  of  volcanic  and  sedimentary  rocks,  in   its 
upper  part  probably  equivalent  to  the  next  group. 
5.  Etcheminian  or  Basal  series,  of  sedimentary  rocks,  underlying  the  St. 
John  group. 
6.  Kingston   group   or   division   5,    of  metamorphosed    volcanics.     Of   very 
uncertain  relations ;  may  be  post-Cambrian. 
The  Huronian  in  southern  New  Brunswick  is  in  large  part  made 
up  of  surface  volcanic  rocks.  The  lower  part,  or  Coldbrook  group, 
is  almost  exclusively  volcanic;  the  upper  part,  or  Etcheminian,  is 
clastic,  while  the  intermediate  Coastal  contains  both  volcanic  and 
sedimentary  members.  The  effusive  rocks  include  lavas,  breccias,  and 
tuffs,  and  with  them  may  be  placed  a  holocrystalline  soda  granite 
which  is  probably  either  an  intrusion  or  a  very  thick  surface  flow. 
The  Etcheminian  series  rests  unconformably  upon  the  Coldbrook 
series  and  unconformably  below  the  St.  John  group,  which  is  for  this 
district  placed  at  the  base  of  the  Cambrian.  The  igneous  rocks  com- 
prise effusives,  including  quartz  porphyry,  felsite  porphyry,  diabase, 
and  feldspar  porphyrites,  and  dike  rocks,  which  include  diorite  por- 
phyrite,  diabase,  and  augite  porphyrite.  Each  of  these  is  described 
in  detail. 
Matthew,28  in  1899,  describes  a  Paleozoic  terrane  beneath  the  Cam- 
brian in  St.  John  and  Kings  counties,  New  Brunswick,  on  Cape 
Breton,  and  near  Smith  Sound,  Newfoundland.  This  terrane  is  un- 
conformably below  Cambrian  strata  bearing  Paradoxides  and  Pro- 
tolenus  fauna,  and  is  given  the  name  Etcheminian.  The  faunal  fea- 
tures as  distinguished  from  the  Cambrian  are  the  great  preponder- 
ance of  tube  worms,  absence  or  rarity  of  trilobites,  minuteness  of  the 
gasteropods  except  Patellidse,  minuteness  of  the  brachiopods,  and 
minuteness  of  the  crustaceans. 
Walcott,29  in  1899,  states  that  in  NewT  Brunswick  certain  rocks 
placed  by  Matthew  below  the  Middle  Cambrian  contain  fossils  which 
may  be  pre-Cambrian. 
He  also  believes  the  Etcheminian  terrane  of  New  Brunswick  and 
Newfoundland,  called  pre-Cambrian  by  Matthew,  to  be  of  Lower 
Cambrian  age.    His  evidence  is: 
