THK    CORDILLERAS.  779 
but  there  is  no  certain  evidence,  in  the  absence  of  fossils,  by  which  it 
can  be  equated  with  either. 
The  fauna  of  the  Chuar  group,  although  so  meager,  furnishes  the 
largest  number  of  fossils  yet  found  in  the  pre-Cambrian.  While  not 
sufficient  to  give  a  basis  for  correlation,  it  gives  legitimate  hope  that 
a  more  satisfactory  pre-Cambrian  fauna  may  be  found  in  the  future. 
SECTION  4.     UTAH. 
SUMMARY    OF   LITERATURE. 
UINTA    MOUNTAINS. 
Marsh,83  in  1871,  states  that  in  the  Uinta  Mountains  is  an  exten- 
sive series  consisting  of  reddish  sandstones  and  quartzites,  sometimes 
metamorphosed  and  apparently  without  fossils.  The  series  is  re- 
ferred provisionally  to  the  Silurian  on  the  ground  that  resting  con- 
formably upon  it  are  limestones  bearing  Carboniferous  fos>ils. 
Hayden,34  in  1872,  states  that  in  the  Uintas  from  the  red  beds  of 
the  Triassic  to  the  oldest  quartzites  no  unconformity  was  detected. 
The  whole  series  has  a  thickness  of  10,000  feet  or  more;  of  this  the 
lower  8,000  consists  of  sandstones  and  quartzites.  Although  no  fos- 
sils were  found,  the  upper  part  of  these  8,000  feet  is  believed  to  be 
Silurian  and  to  pass  down  without  a  break  to  the  rocks  of  Huronian 
age.  The  quartzites  are  like  the  Sioux  Falls,  Dakota,  quartzites, 
which  are  associated  with  the  pipestone  referred  by  TTall  to  the 
Huronian.  In  the  Uinta  series  is  an  excellent  illustration  of  a  grad- 
ual transition  from  unchanged  to  metamorphic  rocks. 
Powell,14  in  1874,  describes  in  the  Uinta  Mountains  crystalline 
schists  upon  which  rest  unconformable  Carboniferous  rocks. 
Powell,18  in  187G,  describes  the  Uinta  sandstones,  shales,  and 
qtiartzites,  1*2,500  feet  thick,  as  resting  unconformably  below  the 
Lodore  group.  Again,  unconformably  below  the  Uinta  sandstone  is 
the  Red  Creek  quartzite  associated  with  hornblendic  and  micaceous 
schists,  10,000  feet  thick.  It  is  evident  that  the  metamorphism  of  the 
Red  Creek  quartzite  is  anterior  to  the  deposition  of  the  Uinta  group, 
for  the  beds  of  the  latter,  especially  near  the  junction,  are  chiefly 
made  up  of  fragments  of  the  former:  hence  the  unconformity  is  vcry 
great,  and  the  quartzite  was  a  lofty  headland  in  the  old  Uinta  sea 
perhaps  20,000  feet  high — when  the  lowest  member  of  the  Uinta 
sandstone  was  formed.  The  period  of  erosion  separating  tin4  Uinta 
sandstones  from  the  Carboniferous  beds  was  sufficient  to  carry  away 
at  least  8,000  feet  of  the  former,  and  how  much  more  can  not  be  said. 
This  unconformity  is  seen  at  Whirlpool  Canyon  and  the  Canyon  of 
Lodore,  the  difference  of  dip  between  the  two  groups  being  from  4° 
to  0°,  and  the  members  of  the.  Lodore  group  steadily  overlapping  the 
