288  PRE-CAMBRIAN    ROCKS    OF    NORTH    AMERICA.  [bull. 86. 
seen  at  Whirlpool  canyon  and  the  canyon  of  Lodore,  the  difference 
of  dip  between  the  two  groups  being  from  4°  to  G°,  and  the  members 
of  the  Lodore  group  steadily  overlapping  the  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  protrudes  into  the  Lodore  shales. 
On  the  northeast  side  of  O-wi-yu-kuts  plateau  the  Uinta  sandstones 
are  seen  to  disappear,  having  been  cut  off  by  erosion  before  the  depo- 
sition 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  un- 
conformity can  also  be  seen  in  the  canyon  of  Junction  mountain,  and 
has  been  observed  on  the  south  side  of  the  Uinta  mountains  in  a  can- 
yon cut  by  the  tributaries  of  the  Uinta  river.  It  is  suggested  that  the 
Uinta  sandstones  may  be  considered  as  Devonian,  an  opinion  which 
would  be  yielded  upon  the  slightest  paleontological  evidence  to  the 
contrary. 
The  Eed  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,  i>erhaps,  argillaceous  strata  between  the  thicker  strata  of 
pure  siliceous  sandstone.  The  whole  group  has  been  greatly  metamor- 
phosed so  as  almost  to  obliterate  the  original  granular  or  sedimentary 
structure  so  far  as  is  apparent  to  the  naked  eye.  Besides  the  recrys- 
tallization,  they  have  been  profoundly  plicated  or  implicated,  so  that  it 
is  only  in  a  general  way  that  any  original  stratification  can  be  observed; 
The  great  mass  of  the  Uinta  range  is  of  the  Uinta  sandstone.  In- 
tercalated with  these  are  shales,  argillaceous  material,  and  semi  crys- 
talline quartzite  5  the  whole  group  is  exceedingly  ferruginous  and  con- 
tains 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  whole  have  been  produced  by  the  degradation  of  a 
great  upheaved  block,  having  its  axis  in  a  general  east  and  west  direc- 
tion. 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.),6  in  1877,  describes  the  Uinta  mountains  as  a  remark- 
ably simple  and  regular  uplift  of  an  immense  thickness  of  conformable 
strata,  the  regularity  being  disturbed  only  about  a  small  area  of  Arch-: 
ean  rocks  at  the  eastern  end.  These  old  rocks,  occurring  along  Kedj 
creek  and  covering  a  comparatively  small  area,  are  quartzites,  Avhite 
mica-schists,  and  hornblende-schists,  with  a  local  development  of  parag- 
onite  beds,  and  they  correspond  most  nearly  to  those  classed  as 
Iluronian  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  locks  are  seen  the  conformably  gently  dipping  Weber 
quartzites,  and  the  succeeding  beds  were  then  deposited  around  the 
