782  PRE-CAMBRIAN    GEOLOGY    OF    NORTH    AMERICA. 
western  Uintas  is  12,000  feet  and  in  the  eastern  Uintas  14,000  feet. 
He  concludes  that  the  basal  quartzite  of  the  western  Uintas  is  surely 
not  "  Weber."  It  is  apparently  late  Cambrian,  and  possibly  in  part 
post-Cambrian,  lapping  up  against  the  margins  of  the  Paleozoic  con- 
tinent toward  the  east. 
Emmons,41  in  1907,  discusses  the  stratigraphy  of  the  Uinta  Moun- 
tains and  concludes  that  the  Uinta  quartzites  are  undoubtedly  of  pre- 
Cambrian  age.  They  occupy  a  position  corresponding  to  the  pre- 
Cambrian  series  in  the  Grand  Canyon,  which  Powell  included  under 
the  general  name  of  Grand  Canyon  series,  the  lower  member  of  which 
(the  Vishnu)  resembles  lithologically  the  Uinta  quartzite. 
Weeks,42  in  1907,  discusses  the  stratigraphy  and  structure  of  the 
Uinta  Range.  He  refers  the  Uinta  quartzite  formation  to  the  pre- 
Cambrian  and  correlates  it  with  the  great  quartzites  of  the  Wasatch 
and  other  ranges  of  Utah  and  eastern  Nevada,  whose  position  beneath 
the  Olenelliis  shales  of  the  lower  Cambrian  is  generally  recognized; 
also  with  the  pre- Cambrian  quartzites  of  the  Grand  Canyon.  He 
concludes  that  no  representative  of  the  Basement  Complex  is  known 
in  the  Uinta  region.  The  Archean  of  King,  Emmons,  and  Powell  is 
referred  to  the  upper  part  of  the  Uinta  quartzite  because  he  has 
traced  certain  beds  of  conglomerate  and  sandstone,  very  highly 
metamorphosed,  directly  into  Quartz  Mountain,  which  was  con- 
sidered by  Powell  and  Emmons  to  be  made  up  of  Archean  rocks. 
Their  reference  of  the  series  to  the  Archean  was  largely  due  to  the 
great  complexity  in  structure  near  Green  River.  Finally  he  concludes 
that  the  Uinta  quartzite  passes  up  into  the  lower  shales  (Cambrian) 
without  evidence  of  unconformity,  thus  differing  from  Powell,  who 
recognized  an  unconformity  at  the  top  of  the  Uinta  quartzite. 
AVASATCH  MOUNTAINS. 
Hayden,43  in  1872,  describes  a  nucleus  of  granite  in  the  Wasatch 
Mountains  and  on  the  canyon  of  the  Weber.  In  Box  Elder  Canyon 
are  gneisses,  quartzites,  and  slates.  In  Port  Neuf  Canyon  there  are 
exposed  at  least  10,000  feet  of  quartzite,  the  age  of  which  is  obscure, 
the  only  thing  indicating  its  position  being  that  Carboniferous  fossils 
are  found  in  the  upper  horizon. 
Silliman,44  in  1872,  regards  the  granite  of  Big  and  Little  Cotton- 
wood canyons  as  probably  metamorphic  from  conglomerates,  because 
it  has  conspicuous  patches  of  dark-colored  material  in  a  light-gray 
matrix,  and  because  with  a  glass  there  can  be  detected  a  sort  of  pebble- 
like roundness  in  the  quartz  of  the  granite. 
Hayden,45  in  1873,  describes  syenite  in  Little  Cottonwood  Canyon 
of  the  Wasatch,  at  the  base  of  the  series,  upon  which  rest  feldspathic 
gneissic  strata,  and  unconformably  upon  these  the  lower  quartzites. 
The  Wasatch  is  probably  a  complete  anticlinal  fold. 
