tan  hise.]  THE    CORDILLERAS.  333 
quently  difficult  to  determine  the  stratification  even  where  extensive 
excavations  have  been  made.  However  much  the  slates  have  been 
disturbed  during  their  period  of  upheaval,  they  assume  the  slaty 
structure  in  continuous  or  parallel  lines  extending  over  considerable 
distances — in  the  present  instance  for  more  than  70  miles — the  inclina- 
tion being  nearly  vertical. 
Blake,51  in  1856,  states  that  the  contorted  gneisses  of  the  Aquarius 
mountains  are  metamorphic.  In  the  Aztec  mountains  the  horizontal 
Carboniferous  strata  show  that  it  was  an  ancient  granitic  uplift.  The 
specimens  of  granite  are  of  a  red  or  rose  color,  few  or  none  being  white 
or  light  gray,  in  this  respect  contrasting  strongly  with  the  collection 
made  from  the  Sierra  Nevada  and  the  Bernardino  Sierra,  as  well  as 
from  those  of  the  Great  basin  and  along  the  Mojave  river.  The  meta- 
morphic rocks  are  in  all  probability  not  older  than  the  Silurian  or  Car- 
boniferous. This  is  certainly  the  case  in  the  Aquarius  mountains.  In 
the  rapid  reconnaissance  of  these  disturbed  and  metamorphic  rocks  it 
was  not  possible  to  bestow  the  attention  upon  them  which  their  ob- 
scured condition  demands,  and  it  is  therefore  not  possible  to  assign  a 
dividing  line  between  the  truly  erupted  granitic  rocks  and  those  which 
simulate  them  but  in  reality  are  of  sedimentary  origin. 
Newberry,75  in  1856,  states  that  in  the  coast  mountains  are  found 
occasional  protrusions  of  granite  and  serpentine.  The  great  mass  of 
the  Sierra  Nevada  is  composed  of  plutonic  or  volcanic  rock,  granite, 
gneiss,  mica- schists  and  porphyries,  traps,  trachyte,  etc.,  with  aurifer- 
ous talcose  slates  and  veins  of  quartz.  The  western  slope  of  the  Cas- 
cade mountains  in  one  place  where  crossed  is  composed  of  trappean 
and  metamorphic  rocks. 
Antisell,76  in  1856,  states  that  in  the  Coast  range  the  igneous  rocks 
that  form  the  axis  are  of  two  kinds,  granitic  and  tr  achy  tic.  While  alto- 
gether distinct  in  their  extreme  types,  when  they  approach  each  other 
in  position  and  age  they  merge  these  separate  differences.  The  gran- 
ites of  the  Sierra  Nevada  are  anterior  to  the  Eocene  and  posterior  to 
the  later  Paleozoic.  All  of  the  observed  sedimentary  rocks  were  post- 
Cretaceous.  Granitic  and  primary  metamorphic  rocks  are  mentioned 
as  occurring  at  several  places  in  the  Coast  range,  and  in  the  Cordil- 
leras in  many  localities.    At  one  locality  hornblende-gneiss  is  found. 
Blake,77  in  1857,  states  that  granite  is  found  at  points  along  the 
coast  from  Monterey  to  near  the  Golden  Gate.  At  the  Tejon,  in  the 
Sierra  Nevada,  the  rocks  now  generally  classed  as  metamorphic,  such 
as  gneiss,  mica- schists,  hornblende-slate  and  chlorite- slate,  are  pre- 
dominant. While  these  rocks  are  probably  a  metamorphosed  sedi- 
ment, the  linear  arrangement  of  the  minerals  is  not  regarded  as  satis- 
factory evidence  of  it.  This  structure  also  appears  when  the  rocks 
are  so  far  fused  as  to  obliterate  the  original  planes  of  stratifi- 
cation, and  therefore  the  words  strata  or  stratification  in  relation  to 
these  rocks  are  avoided,  but  to  designate  the  lines  or  layers  of  minerals 
