444  I  ONTBIBUTIONS    TO    ECONOMIC    GEOLOGY,   L906,    PART    1. 
Santa  Maria  Valley.  The  quality  is  ("specially  good  2  miles  north- 
west of  Schumann,  on  the  south  side  of  this  ridge.  This  deposit  is 
at  the  summit  of  the  Monterey  formation,  and  just  above  it  on  llu 
ridge  the  overlying  Fernando  beds  have  a  similar  diatomaceous  char-] 
acter,  although  of  less  purity.  The  total  area  of  line  diatomaceous 
material  in  this  region  would  not  exceed  2  square  miles. 
REGION    OF    THE    SANTA    MARIA    OIL    FIELD. 
Something  over  1  square  of  mile  of  Monterey  diatomaceous  shale 
is  exposed  in  the  region  of  the  Santa  Maria  oil  ("add  southeast  ofOrcutt. 
These  deposits  were  all  covered  at  a  not  very  remote  period  of  geologic 
time  by  Fernando  or  later  sediments  which  have  been  removed  hy 
erosion  in  the  canyons,  exposing  the  shale  beneath.  The  beds  arc 
considerably  tilted  and  jointed  over  most  of  the  area,  hut  in  the  region 
of  the  Pinal  wells  west  of  Pine  Canyon  deposits  of  fairly  pure  material 
of  considerable  thickness  are  i  xposed  in  ih<   road  cuts. 
CANADA    DEL    GATO    AM)    SISQUOC    AREA. 
Diatomaceous  shale  is  found  in  the  Fernando  formation  (of  upper 
Miocene  age  in  this  pari  of  the  formation)  in  the  region  between  the 
head  of  Howard  Canyon  and  a  point  on  the  plateau  south  of  Ko.xen 
Canyon  aboul  2  miles  southeast  of  Sisquoc  post-office.  The  area  over 
which  the  diatomaceous  shah1  is  exposed  is  aboul  5  miles  long,  witli 
an  average  width  of  about  1  '  miles,  thus  comprising  7'  square  miles. 
The  deposits  vary  in  thickness  from  60  to  aboul  -'5(H)  feet,  and  over  a 
considerable  portion  of  the  territory  lie  almost  horizontal.  Along  the 
southern  border  of  the  area  the  beds  dip  al  angles  as  high  as  35°.  The 
material  in  this  area  is  not  so  pure  as  the  diatom  shah1  found  in  the 
Monterey  (middle  Miocene),  a  fad  that,  coupled  with  its  remoteness 
from  thi^  railroad,  r<  riders  It  unlikely  thai  this  deposit  will  he  of  eco- 
nomic importance  for  a  long  time,  at  best. 
MOUNTAINS    NORTHEAST    OF   THE    SANTA    MARIA    VALLEY. 
Soft,  (laky  diatomaceous  shale  occurs  on  Tepusquel  Creek  about  2 
miles  up  from  the  Santa  Maria  Valley.  Soft  white  shale  is  also  found 
near  the  head  of  Rattlesnake  (*an\  on  about  2  miles  south  of  Tepusquet 
Peak,  and  again  south  of  Labrea  Creek  2  mile-  northeast  of  its  junction 
with  Sisquoc  River.  But  this  -hale  i.^  of  inferior  quality  to  that  at 
previously  mentioned  places,  nor  is  it  comparable  in  thickness  or 
extent.  The  major  portion  of  these  mountains  is  composed  of  strata 
older  than  the  upper  part  of  the  Monterey  format  ion  than  that  part , 
in  other  words,  in  which  the  soft  shale  occurs  most  abundantly. 
