vanhise.]  THE    CORDILLERAS.  303 
cases  litliological  and  structural  resemblances  furnish  a  strong  aid, 
which,  when  followed  up,  not  infrequently  throw  the  evidence  in  favor 
of  one  or  the  other  of  the  great  zones  of  quartzites  j  but  in  many  cases 
such  resemblances  are  meager,  and  the  references  are  made  upon  theo- 
retical grounds,  being  upon  slight  evidence,  or  even  personal  impres- 
sions received  in  the  field. 
King,7  in  1878,  describes  many  of  the  Nevada  ranges. 
In  the  Gosi-Ute  range  the   Archean  rocks  are  granite,  granite-por- 
phyries, and  crystalline  dolomites,  all  of  which  are  interlaminated  and 
are  chemically  allied  to  those  of  the  Humboldt  range.     That  the  gran- 
ite-porphyries are  interstratified  with  the  marbles  confirms  the  proba 
bility  of  their  being  metamorphic. 
The  Archean  of  the  Humboldt  range,  with  the  exception  of  a  small 
body  of  granite,  is  composed  of  a  conformable  series  of  gneisses,  gneiss- 
[)id  schists  which  are  sometimes  hornblendic,  dolomitic  limestones,  and 
quartzites,  all  of  which  dip  to  the  west.  It  is  evident  by  the  entire  ab- 
sence of  easterly  dipping  Archean  and  Paleozoic  rocks  that  a  fault 
similar  to  that  at  the  Wasatch  has  cut  down  the  core  of  the  range 
from  north  to  south,  and  that  the  eastern  half  is  depressed  below  the 
evel  of  the  Quaternary  plain.  The  White  Cloud  peak  granite  bears  a 
singular  resemblance  to  some  of  the  Huronian  granitoid  rocks,  also 
conceived  to  be  metamorphic.  The  granite  appears  to  underlie  con- 
formably the  series  of  schists.  The  gneisses  of  Clover  peak  can  not  be 
listinguished  in  hand-specimen  from  a  granite,  except  that  there  is  an 
ndistinct  parallelism  of  its  dark  constituents.  Between  this  stage  and 
;he  truly  schistose  gneisses  there  is  every  possible  transition.  The 
imestone  series  is  not  over  50  or  60  feet  thick,  in  beds  from  half  an  inch 
;o  6  feet.  Intercalated  with  the  limestones  are  gneiss  and  porphyries 
rery  like  those  in  the  Gosi-Ute  range.  The  upper  beds  pass  through  a 
ransition  into  the  pure  quartzites.  The  Humboldt  Archean  schists 
lave  a  family  likeness  with   those  of  the   Farmington  region   of  the 
asatch  and  those  of  the  Medicine  Bow. 
In  the  Cortez  range  a  central  body  of  granite  is  invaded  by  syenites, 
overlain  on  the  west  by  a  quartzite,  which  is,  for  the  sake  of  conven- 
nce,  referred  to  the  Weber. 
In  the  Shoshone  range  the  stratified  series  dip  away  from  the  central 
ass,  which  has  rather  the  appearance  of  an  intrusive  core.  From 
heir  likeness  to  other  known  Archean  rocks,  and  for  want  of  reasons 
o  the  contrary,  these  schists,  together  with  the  granite,  are  referred  to 
he  Archean.  Regular  parallel  divisional  planes  are  seen  in  the  gran- 
be,  so  as  to  give  it  an  appearance  of  stratification,  but  as  it  penetrates 
he  schists  in  the  form  of  a  dike,  there  is  no  doubt  of  its  eruptive 
rigin. 
In  the  Havallah  range,  associated  with  the  older  granites,  are  intru- 
ive  granite  bodies,  but  such  occurrences  are  exceptional  along  the 
>£ ea  of  the  fortieth  parallel. 
