872  PRE-CAMBRIAN    GEOLOGY   OF    NORTH    AMERICA. 
Lawson,173  in  1893,  describes  the  Santa  Lucia  granite  of  Carmelo 
Bay  as  resting  unconformably  below  the  sedimentary  rocks  (Miocene) 
of  the  Carmelo  series.  At  the  base  of  the  latter  is  a  fine  basal  con- 
glomerate. Across  the  Bay  of  Monterey,  in  the  Santa  Cruz  Range, 
granite  without  doubt  of  the  same  geological  range  bears  a  similar 
relation  to  rocks  which  are  of  not  later  age  than  Cretaceous.  The 
granite  is  therefore,  at  the  latest,  of  pre-Cretaceous  age. 
Hershey,174  in  1901,  describes  the  schistose  rocks  of  the  Klamath 
Mountains  in  northwestern  California.  On  the  whole  it  seems  im- 
practicable to  fix  upon  any  particular  part  of  the  time  between  the 
Archean  and  the  Devonian  as  the  period  of  deposition  of  the  Klamath 
schists,  but  it  is  believed  that  the  evidence  favors  the  earlier  or  Algon- 
kian  portion  rather  than  the  Cambrian  or  Silurian  portion. 
Hershey,175  in  1902,  describes  the  results  of  a  brief  examination  of 
the  Fraser  Mountain  and  Sierra  Pelona  regions,  and  portions  of  the 
Tehachapai,  Sierra  Madre,  and  San  Bernardino  ranges,  together  with 
a  rather  extended  section  of  Mohave  Desert,  all  comprised  in  the 
counties  of  Los  Angeles,  Ventura,  Kern,  and  San  Bernardino,  of 
California.  The  crystalline  rocks  are  discriminated  under  the  follow- 
ing heads : 
1.  The  Pelona  schist  series. 
2.  The  gneiss  series. 
3.  The  rocks  of  Fraser  Mountain  and  vicinity. 
4.  The  Mesozoic  granites. 
5.  The  Ravenna  plutonic  series. 
6.  The  gneiss  near  Barstow. 
7.  The  quartzite-limestone  series  of  Oro  Grande. 
8.  The  schists  in  Cajon  Pass. 
The  Pelona  schist  series  and  the  adjacent  gneisses,  the  rocks  of 
Fraser  Mountain  and  vicinity,  and  the  gneiss  near  Barstow  are  tenta- 
tively correlated  with  the  Abrams  schist  of  the  Klamath  region  in 
a  general  way,  and  are  considered  pre-Paleozoic,  perhaps  in  part 
Archean  and  in  part  Algonkian. 
Hershey,176  in  1903,  discusses  the  structure  of  the  southern  portion 
of  the  Klamath  Mountains  of  California.  The  oldest  rocks  in  the 
mountains  west  of  Sacramento  River  are  the  Abrams  mica  schists, 
.1,000  feet  thick,  and  overling  it  the  Salmon  hornblende  schist, 
known  to  be  at  least  2,500  feet  thick,  both  of  them  supposed  to  be  of 
pre- Cambrian  age,  probably  Algonkian  and  possibly  Archean.  The 
Abrams  mica  schist  is  a  sedimentary  rock  and  the  Salmon  horn- 
blende schist  is  a  metamorphosed  volcanic  ash.  The  Klamath  schists 
form  the  central  ridge  of  the  Klamath  region.  They  are  bordered 
on  the  west  by  a  great,  unsymmetrical  geosyncline,  and  on  the  east 
by  the  western  limb  of  another  great  geosyncline.  The  first  geosyn- 
cline is  limited  on  the  west  by  another  belt  of  schist,  chiefly  the 
