780  PRE-CAMBRIAN   GEOLOGY   OF    NORTH   AMERICA. 
upper  members  of  the  Uinta  and  cutting  off  more  than  2,000  feet  of 
the  latter.  At  the  Canyon  of  Lodore  the  Uinta  sandstone  also  pro- 
trudes into  the  Lodore  shales.  On  the  northeast  side  of  Owiyukuts 
Plateau  the  Uinta  sandstones  are  seen  to  disappear,  having  been  cut 
off  by  erosion  before  the  deposition  of  the  limestone,  and  there  is 
from  1,000  to  2,000  feet  more  of  the  Uinta  sandstone  at  one  end  of 
the  ridge  than  at  the  other.  The  unconformity  can  also  be  seen  in 
the  canyon  of  Junction  Mountain,  and  has  been  observed  on  the  south 
side  of  the  Uinta  Mountains  in  a  canyon  cut  by  the  tributaries  of  the 
Uinta  River.  It  is  suggested  that  the  Uinta  sandstones  may  be  con- 
sidered as  Devonian — an  opinion  which  would  be  yielded  upon  the 
slightest  paleontological  evidence  to  the  contrary. 
The  Red  Creek  quartzite  is  believed  to  be  Eozoic.  This  Eozoic  is  in 
large  part  a  pure  white  quartz,  but  is  intimately  associated  with 
irregular  aggregations  of  hornblendic  and  micaceous  schists.  These 
schists  were,  perhaps,  argillaceous  strata  between  the  thicker  strata 
of  pure  siliceous  sandstone.  The  whole  group  has  been  greatly  meta- 
morphosed, so  as  almost  to  obliterate  the  original  granular  or  sedi- 
mentary structure  so  far  as  is  apparent  to  the  naked  eye.  Besides 
the  recrystallization,  they  have  been  profoundly  plicated  or  impli- 
cated, so  that  it  is  only  in  a  general  wa}^  that  any  original  stratifi- 
cation can  be  observed 
The  great  mass  of  the  Uinta  Range  is  of  the  Uinta  sandstone.  In- 
tercalated with  these  are  shales,  argillaceous  material,  and  semicrys- 
talline  quartzite;  the  whole  group  is  exceedingly  ferruginous  and 
contains  seams  of  clay  ironstone.  While  weeks  and  months  were 
spent  in  the  search,  no  fossils  were  found  in  the  Uinta  group.  The 
Uinta  Mountains  as  a  Avhole  have  been  produced  by  the  degradation 
of  a  great  upheaved  block,  having  its  axis  in  a  general  east-west 
direction.  The  upheaval  is  partly  a  flexed,  partly  a  faulted  one,  the 
major  part  of  the  faulting  and  the  steeper  inclinations  being  on  the 
north  side. 
Emmons  (S.  F.),35  in  1877,  describes  the  Uinta  Mountains  as  a 
remarkably  simple  and  regular  uplift  of  an  immense  thickness  of 
conformable  strata,  the  regularity  being  disturbed  only  about  a  small 
area  of  Archean  rocks  at  the  eastern  end.  These  old  rocks,  occurring 
along  Red  Creek  and  covering  a  comparatively  small  area,  are  quartz- 
it  es,  white  mica  schists,  and  hornblende  schists,  with  a  local  develop- 
ment of  paragonite  beds,  and  they  correspond  most  nearly  to  those 
classed  as  Huronian  in  the  Rocky  Mountains.  The  beds  are  steeply 
inclined  and  have  suffered  intense  compression  and  distortion.  The 
general  section  is  that  of  a  double  anticline. 
On  these  older  rocks  are  seen  the  conformably  gently  dipping 
Weber  quartzites,  and  the  succeeding  beds  were  then  deposited  around 
the  shores  of  an  Archean  island.     Above  the  Archean  is  a  thickness  of 
