784  PRE-CAMBRIAN    GEOLOGY   OF    NORTH   AMERICA. 
granites  are  some  remnants  of  Archean  quartzites  and  schists,  which 
have  a  general  strike  northeast  and  dip  from  45°  to  60°  W.  At  the 
mouth  of  Little  Cottonwood  Canyon  they  consist  of  a  body  of  quartz- 
ites  about  1,000  feet  in  thickness.  These  quartzites  are  different 
from  the  Cambrian  quartzites  of  Big  Cottonwood  Canyon;  they 
contain  mica  in  varying  quantity,  and  where  this  is  abundant  ap- 
proach a  true  mica  schist.  Toward  the  mouth  of  the  canyon  the 
mica  is  replaced  by  hornblende.  Between  the  Cottonwood  canyons 
are  about  2,000  feet  of  Archean  slates,  quartzites,  hornblende  schists, 
and  mica  schists.  The  Cambrian  slates  above  the  granites  of  the 
Cottonwood  stand  at  an  angle  of  45°,  dipping  to  the  northeast.  It 
is  difficult  to  tell  whether  the  granite  should  be  considered  as  a  part 
of  the  main  granite  body,  which  it  does  not  resemble  very  closely,  or 
as  belonging  with  the  later  outbursts  of  granite  porphyries  and 
diorites  which  intersect  the  sedimentary  beds  of  this  region.  These 
dikes  are  very  numerous,  especially  around  the  Clayton  Peak  mass 
and  in  the  region  where  the  mineralization  of  the  beds  has  been 
most  developed.  One  of  these  in  the  Wasatch  limestones  is  a  dike  20 
feet  wide  of  syenitic  granite  porphyry.  The  Paleozoic  beds  of  the 
Cottonwood  canyons,  which  fold  around  and  partly  cover  the  granite 
bodies,  have  been  subjected  to  intense  compression  and  local  meta- 
morphism  and  cut  by  intrusive  dikes  and  mineral  veins. 
The  Farmington  Archean  body  is  composed  of  a  conformable  series 
of  gneisses,  mica  gneisses,  and  quartzites,  12,000  or  15,000  feet  thick, 
which  clip  westerly  at  about  15°  or  20°.  The  lowest  part  of  the  series 
is  coarse  and  structureless,  but  it  grades  up  into  an  evenly  bedded 
rock. 
Hague,35  in  1877,  describes  the  northern  Wasatch  region  and  the 
region  north  of  Salt  Lake.  The  geological  structure  of  the  Front 
Range  remains' of  the  same  type  as  to  the  south,  but  the  Archean 
rocks  are  less  abundant.  In  the  lower  canyon  of  Weber  River  are 
rocks  like  the  Farmington  Archean  body,  which  have,  however,  a 
westerly  dip  of  40°.  The  Cambrian  quartzite  of  Ogden  Peak  lies 
unconformably  on  the  edge  of  the  Archean  beds.  In  Ogden  Canyon 
the  quartzite  is  occasionally  conglomeratic,  containing  pebbles  of 
quartzite  and  jasper.  These  pebbles  are  sometimes  flattened  and 
elongated  in  almond-shaped  bodies,  and  are  frequently  distorted  and 
banded  into  curious  forms.  Sometimes  two  or  more  pebbles  are 
pressed  together  so  as  to  form  apparently  one  mass.  The  flattened 
pebbles  appear  with  their  longer  axes  in  parallel  planes. 
King,36  in  1878,  states  that  on  the  west  side  of  the  Wasatch  is  a 
fault  which  has  thrown  the  layers  downward  from  3,000  to  40,000 
feet.  The  Archean  rocks  occupy  the  core  of  the  range.  Above  these 
is  unconformably  exposed  in  the  Cottonwood  canyons  a  conformable 
series  of  Paleozoic  strata   30,000   feet  thick.     The  nucleus  of  the 
