vanhise]  THE    CORDILLERAS.  291 
wood  granites  are  some  remnants  of  Archean  quartzites  and  schists, 
which  have  a  general  strike  northeast,  and  dip  from  45°  to  60°  to  the 
westward.  At  the  month  of  the  Little  Cottonwood  canyon  they  con- 
sist of  a  body  of  quartzites  about  1,000  feet  in  thickness.  These  qua  rtz 
ites  are  different  from  the  Cambrian  quartzites  of  the  Big  Cottonwood 
canyon :  they  contain  mica  in  varying  quantity,  and  where  this  is 
abundant  approach  a  true  mica-schist.  Toward  the  mouth  of  the  can- 
yon the  mica  is  replaced  by  hornblende.  Between  the  Cottonwood 
canyons  is  about  2,000  feet  of  Archean  slates,  quartzites,  hornblende- 
schists,  and  mica  schists.  The  Cambrian  slates  above  the  granites  oi 
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  oi 
the  main  granite  body,  which  it  does  not  resemble  very  closely,  or  with 
the  later  outbursts  of  granite-porphyries  and  diorites  which  intersect 
the  sedimentary  beds  of  this  region.  These  dikes  are  very  frequent, 
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  in- 
tense compression  and  local  metamorphism,  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  dip  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,0  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  southward,  but  the  Archean  rocks 
are  less  abundant.     In  the  lower  canyon  of  the  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 
pn  the  edge  of  the  Archean  beds.     In  the  Ogden  canyon  the  quartzite 
s  occasionally  conglomeratic,  containing  pebbles  of  quartzite  and  jas- 
er.    These  pebbles  are  sometimes  flattened  and  elongated  in  almond- 
haped  bodies,  and  are  frequently  distorted  and  banded  into  curious 
forms.     Sometimes  two  or  more  pebbles  are  pressed  together  so  as  to 
brm  apparently  one  mass.    The  flattened  pebbles  appear  with  their 
onger  axes  in  parallel  planes. 
King,7  in  1878,  states  that  on  the  west  side  of  the  Wasatch  is  a  fault 
vhich  has  thrown  the  layers  downward  from  3,000  to  40,000  feet.  The 
Lrchean  rocks  occupy  the  core  of  the  range.  Above  these  is  uncon- 
brmably  exposed  in  the  Cottonwood  canyons  a  conformable  series  of 
aleozoic  strata  30,000  feet  thick.  The  nucleus  of  the  Archean  rocks 
n  the  Cottonwood  area  is  a  mass  of  granite  and  granite-gneiss.    This 
