﻿66 
  

  

  SANTA 
  MARIA 
  OIL 
  DISTRICT, 
  CALIFORNIA. 
  

  

  Another 
  intrusion 
  of 
  probable 
  post-Monterey 
  age 
  forms 
  a 
  single 
  

   outcrop 
  m 
  the 
  bus 
  7 
  miles 
  northeasl 
  of 
  Point 
  Conception. 
  It 
  is 
  a 
  

   dike 
  ol 
  basic 
  porphyrsr 
  related 
  to 
  basalt. 
  On 
  one 
  side 
  of 
  the 
  outcrop 
  

   the 
  bases 
  ol 
  horizontally 
  lying 
  rough 
  pentagonal 
  columns 
  are 
  well 
  

   expose. 
  . 
  It 
  is 
  not 
  known 
  whether 
  the 
  sedimentary 
  rocks 
  through 
  

   which 
  I 
  lus 
  ,s 
  m. 
  ruded 
  belong 
  to 
  the 
  Monterey 
  or 
  the 
  upper 
  part 
  of 
  the 
  

   Vaqueros. 
  * 
  

  

  GEOLOGIC 
  HISTORY. 
  

  

  EARLIEST 
  PERIODS. 
  

  

  The 
  general 
  geologic 
  aspect 
  of 
  the 
  Santa 
  Maria 
  district 
  is 
  that 
  of 
  a 
  

   region 
  „I 
  comparatively 
  recent 
  geologic 
  formations. 
  Tertian' 
  rocks 
  

   in 
  places 
  covered 
  by 
  Pleistocene 
  deposits, 
  are 
  predominant, 
  those 
  

   oi 
  Cretaceous 
  and 
  Jurassic 
  age 
  less 
  widespread, 
  and 
  older 
  formations 
  

   entirely 
  absent. 
  The 
  Tertiary 
  has 
  received 
  almost 
  all 
  the 
  attention 
  

   in 
  the 
  present 
  study 
  and 
  little 
  can 
  be 
  said 
  of 
  the 
  history 
  of 
  the 
  region 
  

   previous 
  to 
  that 
  period. 
  The 
  much-disturbed 
  and 
  metamorphosed 
  

   Jurassic 
  sediments 
  (Franciscan), 
  intruded 
  by 
  serpentine, 
  form 
  the 
  

   basement 
  of 
  the 
  whole 
  region, 
  but 
  outcrop 
  only 
  very 
  locally 
  In 
  Cre- 
  

   taceous 
  time 
  a 
  considerable 
  thickness 
  of 
  marine 
  sediments 
  was 
  laid 
  

   down, 
  but 
  these 
  deposits 
  were 
  probably 
  not 
  greatly 
  disturbed 
  before 
  

   the 
  beginning 
  of 
  deposition 
  in 
  the 
  Tertiary. 
  To 
  the 
  present 
  time 
  they 
  

   have 
  remained 
  unmetamorphosed 
  and 
  no 
  more 
  affected 
  by 
  moun- 
  

   tain-making 
  forces 
  than 
  later 
  formations. 
  Igneous 
  intrusions, 
  how- 
  

   ever, 
  took 
  place 
  at 
  different 
  times 
  in 
  the 
  Cretaceous 
  

  

  EOCENE 
  PERIOD. 
  

  

  tint 
  f 
  l 
  gfe 
  A 
  W 
  1S 
  '° 
  nS 
  ° 
  f 
  the 
  Tertia 
  ^> 
  with 
  the 
  P^le 
  excep- 
  

   ™L 
  w 
  ? 
  !f. 
  0Cene 
  ' 
  are 
  re 
  P 
  resented 
  by 
  marine 
  sediments, 
  the 
  

   ThlJT 
  w 
  1S 
  tlm 
  \ 
  havin 
  g 
  been 
  taken 
  up 
  by 
  sedimentation, 
  

   been 
  tTl 
  TT" 
  the 
  . 
  Cretaceous 
  *nd 
  Eocene 
  rocks 
  have 
  not 
  

   been 
  studied. 
  Sedimentation 
  began 
  at 
  some 
  time 
  in 
  the 
  Eocene 
  

   not 
  yet 
  determined, 
  in 
  the 
  southern 
  portion 
  of 
  the 
  region 
  mapped 
  

   and 
  continued 
  nearly 
  to 
  the 
  end 
  of 
  the 
  Eocene, 
  when 
  if 
  ceased 
  "for 
  a 
  

  

  cedint 
  ttr 
  fT", 
  gtk 
  U 
  WaS 
  Pr 
  ° 
  bably 
  in 
  the 
  P 
  eriod 
  i 
  ust 
  Pre- 
  

   ceding 
  hat 
  of 
  the 
  deposition 
  of 
  the 
  Eocene 
  sediments 
  that 
  the 
  forces 
  

  

  began 
  to 
  work 
  which 
  caused 
  the 
  structural 
  features 
  south 
  of 
  the 
  

   wfsrT 
  r 
  \ 
  h6 
  ^t" 
  Rafael 
  M 
  ° 
  UntainS 
  n0W 
  stand 
  t0 
  assu 
  ™ 
  an 
  east- 
  

  

  eSJw 
  ; 
  J" 
  T 
  ^ 
  may 
  haVe 
  b6en 
  f0rmed 
  the 
  depression 
  

   extemlmg 
  east 
  and 
  west 
  across 
  the 
  region 
  now 
  occupied 
  by 
  the 
  

  

  Coast 
  Ranges, 
  which 
  afforded 
  a 
  basin 
  of 
  deposition 
  for 
  the 
  Eocene 
  

  

  and 
  possibly 
  a 
  connection 
  between 
  the 
  ocean 
  and 
  the 
  basins 
  in 
  which 
  

  

  TZ 
  tn! 
  6 
  v 
  me 
  T 
  Were 
  dep 
  ° 
  Sited 
  in 
  the 
  interior 
  - 
  A 
  lar 
  ge 
  part 
  

  

  1 
  ,% 
  T 
  Mountains 
  is 
  composed 
  of 
  Eocene 
  strata 
  which 
  

  

  have 
  been 
  lifted 
  up 
  along 
  east-west 
  lines 
  of 
  structure. 
  The 
  main 
  

  

  