336  PRE-CAMBRIAN"  ROCKS    OF    NORTH   AMERICA.  [bull.  86. 
dino  mountains  the  main  mass  is  granite,  accompanying  gneiss,  mica- 
schist,  talcose  schist  and  primitive  clay-slate.  The  Biver-Side  and 
Half- Way  mountains  consist  of  granite  and  gneiss.  At  the  Mojave 
range  is  a  series  of  Azoic  rocks  consisting  of  fine  grained  granite, 
syenite,  hornblende- schist  and  quartzite.  At  the  Panamint  range  are 
primitive  limestone  and  clay-slate  as  accompaniments  of  the  granite. 
Eruptive  gneiss  is  found  in  the  Coahuila  valley  which  has  metamor- 
phosed the  limestone  on  either  side.  The  gneiss  shows  by  the  position 
of  its  mica  plates  a  stratification  parallel  to  the  limestone  layers,  indi- 
cating the  effect  of  pressure  during  the  consolidation  of  the  injected 
rock  mass.  Eruptive  syenite  occurs  in  the  Buena  Yista  and  Inyo  ranges 
and  eruptive  granite  at  Dead  mountains  and  in  the  Opal  ranges.  Occa- 
sionally 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  sandstone  resembling  to  some 
extent  granite,  but  the  uniform  grain,  friability,  and  rusty  surface  of 
the  fragments  elucidate  its  true  nature. 
Newberry,54  in  1876,  states  that  in  the  Aquarius  range  the  Carbon- 
iferous strata  rest  directly  upon  the  granite.  In  the  Cerbat  mountains 
gray  granitic  rocks  are  found  upon  which  rest  unchanged  Carboniferous 
strata.  In  the  mountains  of  the  lower  Colorado  metamorphic  rocks  are 
abundant,  consisting  of  gneiss,  mica-slate  and  clay-slate,  talcose  slate 
and  limestone,  the  latter  highly  metamorphosed  and  crystalline,  form- 
ing marble,  so  far  as  observed,  wholly  destitute  of  fossils.  This  meta- 
morphic limestone  of  the  Sierra  is  suspected  to  be  Carboniferous. 
Conkling,83  in  1877,  states  that  the  ridge-like  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,84  in  1878,  describes  portions  of  western  Nevada  and  east- 
ern California,  including  a  part  of  the  Sierra  range,  and  finds  little 
aside  from  metamorphic  and  igneous  rocks.  Granite  is  found  at  many 
localities. 
Becker,85  in  1888,  states  that  granite  underlies  the  Coast  ranges  and 
the  Sierra  Nevada.  The  evidence  in  California  is  in  favor  of  the  hy- 
pothesis that  the  main  mass  of  the  underlying  granite  is  primeval. 
While  it  is  not  absolutely  certain  that  Archean  rocks  occur  in  Califor- 
nia, the  unquestionable  occurrence  of  the  Archean  in  Arizona,  together 
with  the  similarity  of  the  rocks  of  southeastern  California  to  those  of ) 
the  adjacent  territory,  make  it  probable  that  San  Bernardino  county  iJ 
largely  Archean.  In  the  Gavilan  range  the  lowest  sedimentary  forma- 
tion is  a  crystalline  limestone,  associated  with  which  are  rocks  of  the 
Archean  gneiss  type.  It  is  possible  that  it  is  a  member  of  the  Knox- 
ville  series  more  metamorphosed  than  usual,  but  it  appears  more  proba- 
ble that  it  is  a  remnant  of  some  older  formation  which  has  perhaps 
