THE   CORDILLERAS.  871 
the  injected  rock  mass.  Eruptive  syenite  occurs  in  the  Buena  Vista 
and  Inyo  ranges,  and  eruptive  granite  at  Dead  Mountains  and  in  the 
Opal  ranges.  Occasionally  in  the  San  Bernardino  Mountains  the 
granite  gives  rise  to  the  formation  of  beds  of  arkose,  a  rock  in  which 
granitic  debris  has  been  recemented,  forming  a  sort  of  granitic  sand- 
stone resembling  to  some  extent  granite,  but  the  uniform  grain,  fri- 
ability, and  rusty  surface  of  the  fragments  elucidate  its  true  nature. 
Newberry,9  in  1876,  states  that  in  the  Aquarius  Range  the  Car- 
boniferous strata  rest  directly  upon  the  granite.  In  the  Cerbat  Moun- 
tains are  found  gray  granitic  rocks  upon  which  rest  unchanged  Car- 
boniferous strata.  In  the  mountains  of  the  lower  Colorado  meta- 
morphic  rocks  are  abundant,  consisting  of  gneiss,  mica  slate  and  clay 
slate,  talcose  slate,  and  limestone,  the  latter  highly  metamorphosed 
and  crystalline,  forming  marble,  and  being,  so  far  as  observed,  wholly 
destitute  of  fossils.  This  metamorphic  limestone  of  the  Sierra  is  sus- 
pected to  be  Carboniferous. 
Conkling,169  in  1877,  states  that  the  ridgelike  line  of  the  eastern 
summit  of  the  Sierra  consists  entirely  of  granite,  flanked  in  several 
places  by  igneous  rocks.  In  the  western  summit  range  are  also  found 
granitic  rocks. 
Conkling,170  in  1878,  describes  portions  of  western  Nevada  and 
eastern  California,  including  a  part  of  the  Sierra  Range,  and  finds 
little  aside  from  metamorphic  and  igneous  rocks.  Granite  is  found 
at  many  localities. 
Becker,171  in  1888,  states  that  granite  underlies  the  Coast  Ranges 
and  the  Sierra  Nevada.  The  evidence  in  California  is  in  favor  of  the 
hypothesis  that  the  main  mass  of  the  underlying  granite  is  primeval. 
While  it  is  not  absolutely  certain  that  Archean  rocks  occur  in  Cali- 
fornia, the  unquestionable  occurrence  of  the  Archean  in  Arizona  and 
the  similarity  of  the  rocks  of  southeastern  California  to  those  of  the 
adjacent  territory  make  it  probable  that  San  Bernardino  County  is 
largely  Archean.  In  the  Gavilan  Range  the  lowest  sedimentary 
formation  is  a  crystalline  limestone,  associated  with  which  are  rocks 
of  the  Archean  gneiss  type.  It  is  possible  that  it  is  a  member  of  the 
Knoxville  series  more  metamorphosed  than  usual,  but  it  appears 
more  probable  that  it  is  a  remnant  of  some  older  formation  which, 
has  perhaps  undergone  repeated  metamorphism.  Aside  from  these 
the  earliest  metamorphic  rocks  of  the  coast  are  probably  Cretaceous. 
Mills,172  in  1892,  finds  in  the  Sierra  Nevada,  unconformable  below 
the  Mesozoic,  eruptive  granites  and  sedimentary  slates  and  quartzites. 
The  latter  in  places  rest  and  were  probably  deposited  upon  the  gran- 
ite, while  in  other  places  they  are  contemporaneous  and  embedded 
within  it.  The  quartzites  are  held  to  be  silicified  phases  of  the  slates. 
These  rocks  in  age  may  run  from  Archean  to  the  Paleozoic,  and  some 
of  them  may  be  early  Mesozoic. 
