vanhise.]  THE    CORDILLERAS.  281 
LITERATURE   OF  THE   TETON   RANGE. 
Bradley,18  to  1873,  describes  the  central  nucleus  of  the  Teton 
mountains  as  consisting  of  granites,  gneisses,  and  schists  wliich  vary 
greatly  in  ch aracter.  No  rock  succession  was  ascertained .  The  granite 
is  in  thick  solid  beds  and  the  other  rocks  are  much  broken  and  tilted 
in  various  ways,  and  are  crossed  in  every  direction  by  innumerable 
large  and  small  veins,  mostly  of  quartz,  but  a  few  of  granite.  There 
is  a  general  strike  in  an  east  and  west  direction.  Trap-like  rocks  are 
inteiiaminated  with  the  gneiss  and  granite,  Avhich  suggest  that  they 
may  be  dikes,  but  they  are  evidently  conformable  with  the  layers  and 
were  either  contemporaneous  sheets  or  else  subsequent  intrusives. 
St.  John,  17  in  1879,  describes  Archean  rocks  as  constituting  the  nu- 
cleal  ridge  of  the  Teton  mountains.  The  major  portion  of  them  are 
metamorphics  of  a  gneissic  or  schistose  variety.  The  Archean  strata 
of  the  Teton,  Wyoming  and  Gros  Ventre  ranges  are  divided  into 
Huronian  and  Laurentian.  With  the  former  are  placed  the  quartzites, 
micaceous  and  chloritic  slates  forming  heavy  deposits  several  thousand 
feet  in  thickness  and  developed  only  in  the  southwest,  while  with  the 
Laurentian  are  the  gneisses,  various  schistose  rocks,  and  granite.  In 
the  southwest  part  of  the  Teton  district  is  a  narrow  tongue  of  quartz- 
ites which  are  placed  with  the  Primordial,  but  may  be  Huronian. 
SUMMARY  OF   RESULTS. 
The  rocks  referred  to  the  Archean  by  the  various  authors  can,  with 
considerable  certainty,  be  considered  pre-Cambrian,  as  the  region  is  one 
in  which  no  folding  has  taken  place  since  the  beginning  of  Paleozoic 
time,  and  the  various  members  of  the  Paleozoic  are  found  in  uncon- 
formable contact  with  the  underlying  crystallines  at  many  points.  -It 
is  not  necessary  to  assume,  as  was  done  by  Endlich,  that  a  portion  of 
the  metamorpnism  of  the  Archean  took  place  subsequent  to  Paleozoic 
time,  for  the  indurated  quartzites  so  often  found  in  direct  contact  with 
the  crystalline  strata  have  probably  been  thus  hardened  by  the  now 
well  known  process  of  cementation.  The  quartzites  which  so  closely 
resemble  the  unaltered  granite  are  doubtless  recomposed  rocks  which 
have  been  cemented  in  the  same  manner. 
Whether  among  the  pre-Oambrian  rocks  in  these  various  ranges  of 
mountains  there  are  any  which  are  now  of  a  distinctly  clastic  character  is 
uncertain.  Those  between  fort  Stambaugh  and  the  central  Wind  river 
mass  spoken  of  as  metamorphic  slates,  and  the  rocks  described  by  St. 
John  in  the  southwestern  part  of  the  Teton  district  as  consisting  of 
quartzites,  micaceous  and  chloritic  slates,  may  very  likely  be  of  this 
character,  but  it  is  not  certain  that  the  latter  do  not  belong  to  the  Cam- 
brian, for  nothing  is  said  of  their  relations  to  the  recognizable  Paleozoic s. 
The  separation  of  the  rocks  into  Laurentian  and  Huronian,  or  into 
Prozoic,  Laurentian  and  Huronian,  as  is  done  by  Endlich,  is  purely  litho- 
logical.    They  are  all  thoroughly  crystalline,  and  have  been  assumed  by 
