vanhise.]  DISCUSSIONS    OF    PRINCIPLES.  503 
by  an  eruptive  contact  or  whether  the  crystalline  complex  is  older  than 
the  clastic  series,  the  latter  being  deposited  upon  it. 
In  Nova  Scotia  the  great  gold-bearing  series  of  the  Atlantic  coast,  of 
unknown  thickness,  mapped  by  the  Canadian  Survey  as  Cambrian, 
may  be  pre-Cambrian  as  terms  are  here  used.  It  contains  the  evidence 
of  life  in  Eophyton,  but  this  does  not  forbid  regarding  it  as  Algonkian 
in  our  sense  of  the  term.  The  series  may  be  as  high  as  the  Cambrian, 
or  it  may  be  the  equivalent  of  one  or  more  of  the  pre-Cambrian  series. 
In  this  region  the  relations  of  the  granites  and  gneisses  to  the  gold- 
bearing  slates  are  such  as  to  demonstrate  with  a  reasonable  degree  of 
probability  that  the  granites  are  intrusive,  although  they  have  been 
regarded  by  certain  writers  as  metamorphic.  This  fact  suggests  that 
a  part  of  the  granite  of  the  fundamental  complex  of  southern  New 
Brunswick  and  Cape  Breton  may  also  be  a  later  eruptive,  but  even  if 
this  were  the  case  it  would  not  demonstrate  the  absence  of  an  earlier 
granite-gneiss  series. 
NEWFOUNDLAND. 
In  Newfoundland  is  a  clear  case  of  a  great  series  of  rocks  of  perhaps 
10,000  feet  thick,  referred  to  the  Huronian  by  Murray,  which  is  a  part 
of  the  Algonkian.  Here  is  found  the  Oleuellus  fauna  in  the  basal  Cam- 
brian rocks,  and  these  are  separated  by  an  unconformity  from  the  under- 
lying clastic  series,  in  which,  however,  has  been  discovered  two  or  three 
fossils  of  a  low  type.  What  the  relations  of  this  lower  slate  series  are 
to  the  crystalline  granite-gneiss  which  has  been  referred  to  the  Lau- 
rentian  is  uncertain.  No  evidence  is  available  showing  that  lower 
than  this  slate  series  are  any  elastics.  Certain  of  the  granites  of  the 
island  of  Newfoundland  are  iiitrusives  of  later  age  than  the  slates,  some 
of  them  being  as  recent  as  Carboniferous;  so  that  it  is  not  impossible 
that  many  of  the  granites,  syenites,  and  porphyries  referred  to  the  Lau- 
rentian  may  be  of  far  later  age. 
THE  BLACK  HILLS. 
In  the  Black  hills  is  a  great  series  of  slates,  quartzites,  quartzose 
conglomerates,  mica-schists,  and  mica-gneisses  of  unknown,  although 
probably  of  great,  thickness.  These  are  cut  both  by  intrusive  granites 
and  basic  rocks  of  Algonkian  age  and  by  eruptives  of  later  time.  All 
of  the  clastic  rocks  are  more  or  less  metamorphosed  by  the  contact  and 
dynamic  action  to  which  they  have  been  subjected,  and  adjacent  to  the 
great  batholites  of  granite  they  have  become  thoroughly  crystalline. 
In  degree  of  folding,  crystalline  character,  and  mineral  composition 
they  resemble  the  Lower  Huronian  of  the  lake  Superior  region  nearer 
than  any  other  series.  They  are  separated  from  the  Potsdam  sand- 
stone by  a  very  great  unconformity,  that  formation  resting  upon  them 
in  a  wholly  unfolded  condition,  while  the  prominent  secondary  struc- 
tures of  the  underlying  series  are  nearly  vertical  and  the  bedding  is  in 
a  series  of  sharp  folds.    No  pre- Algonkian  rocks  are  here  known. 
