﻿RESUME. 
  123 
  

  

  The 
  formations 
  involved 
  in 
  the 
  geology 
  of 
  the 
  district 
  include 
  the 
  

   Franciscan 
  (Jurassic?) 
  sandstone, 
  shale, 
  glaucophane 
  schist, 
  jasper, 
  

   and 
  intruded 
  serpentine; 
  Knoxville 
  (lower 
  Cretaceous) 
  conglomerate, 
  

   sandstone, 
  and 
  shale; 
  pre-Monterey 
  (which 
  may 
  include 
  both 
  Cre- 
  

   taceous 
  and 
  older 
  Tertiary) 
  conglomerate, 
  sandstone, 
  and 
  shale; 
  

   Tejon 
  (Eocene) 
  sandstone, 
  shale, 
  and 
  conglomerate; 
  Yaqueros 
  (lower 
  

   Miocene) 
  conglomerate, 
  sandstone, 
  and 
  shale; 
  Monterey 
  (middle 
  

   Miocene) 
  diatomaceous 
  and 
  flinty 
  shale, 
  limestone, 
  calcerous 
  shale, 
  

   and 
  volcanic 
  ash; 
  Fernando 
  (Miocene-Pliocene-Pleistocene) 
  con- 
  

   glomerate, 
  sandstone, 
  and 
  shale; 
  and 
  Quaternary 
  gravel, 
  sand, 
  clay, 
  

   and 
  alluvium. 
  The 
  sedimentary 
  formations 
  of 
  Tertiary 
  and 
  early 
  

   Quaternary 
  age 
  have 
  a 
  combined 
  maximum 
  thickness 
  of 
  at 
  least 
  

   13,200 
  feet. 
  

  

  A 
  variety 
  of 
  igneous 
  rocks 
  of 
  Cretaceous 
  and 
  Tertiary 
  age, 
  mostly 
  

   intrusive, 
  outcrop 
  over 
  small 
  areas. 
  

  

  The 
  Monterey 
  shale 
  (middle 
  Miocene) 
  is 
  the 
  original 
  and 
  chief 
  

   oil-bearing 
  formation, 
  the 
  petroleum 
  having 
  originated 
  and 
  remained 
  

   in 
  it 
  in 
  large 
  quantities. 
  Some 
  has 
  escaped 
  by 
  seepage 
  and 
  collected 
  

   in 
  the 
  overlying 
  Fernando 
  formation 
  or 
  the 
  Quaternary 
  terrace 
  de- 
  

   posits, 
  or 
  has 
  been 
  dissipated. 
  The 
  oil 
  is 
  supposed 
  to 
  accumulate 
  in 
  

   fractured 
  zones 
  and 
  porous 
  sands 
  in 
  the 
  lower 
  portion 
  of 
  the 
  Monterey, 
  

   where 
  brittle 
  shale 
  predominates, 
  anticlines 
  furnishing 
  the 
  most 
  favor- 
  

   able 
  conditions 
  for 
  accumulation. 
  The 
  Monterey 
  shale 
  is 
  in 
  large 
  

   part 
  of 
  organic 
  origin, 
  being 
  especially 
  rich 
  in 
  diatoms, 
  and 
  the 
  oil 
  

   is 
  supposed 
  to 
  be 
  a 
  product 
  of 
  the 
  plant 
  and 
  animal 
  remains 
  inclosed 
  

   in 
  it. 
  The 
  quantity 
  of 
  these 
  remains 
  originally 
  deposited 
  with 
  this 
  

   formation 
  is 
  sufficient 
  to 
  account 
  for 
  a 
  vast 
  amount 
  of 
  derived 
  oil. 
  

  

  Two 
  structural 
  S3^stems 
  prevail 
  in 
  the 
  district, 
  the 
  features 
  in 
  the 
  

   northeastern 
  portion 
  striking 
  northwest 
  and 
  southeast, 
  those 
  in 
  the 
  

   southern 
  portion 
  striking 
  east 
  and 
  west, 
  and 
  those 
  in 
  the 
  intervening 
  

   region 
  trending 
  in 
  a 
  direction 
  intermediate 
  between 
  the 
  two. 
  Few 
  

   faults 
  of 
  importance 
  were 
  noted 
  in 
  the 
  field. 
  The 
  productive 
  terri- 
  

   tory 
  lies 
  in 
  a 
  region 
  of 
  more 
  or 
  less 
  gentle 
  folds 
  in 
  the 
  central 
  part 
  of 
  

   the 
  area, 
  most 
  of 
  the 
  wells 
  being 
  located 
  along 
  or 
  near 
  anticlines. 
  

  

  The 
  wells 
  range 
  in 
  depth 
  from 
  1,500 
  to 
  more 
  than 
  4,000 
  feet. 
  In 
  

   the 
  Santa 
  Maria 
  and 
  Lompoc 
  fields 
  they 
  obtain 
  oil 
  from 
  zones 
  of 
  

   fractured 
  shale, 
  and 
  possibly 
  in 
  certain 
  places 
  from 
  sandy 
  layers 
  in 
  

   the 
  lower 
  portion 
  of 
  the 
  Monterey 
  formation. 
  The 
  production 
  of 
  the 
  

   individual 
  wells 
  ranges 
  from 
  5 
  to 
  3,000 
  barrels 
  per 
  day, 
  the 
  average 
  

   being 
  between 
  300 
  and 
  400 
  barrels. 
  The 
  oil 
  ranges 
  in 
  gravity 
  from 
  

   19° 
  to 
  35° 
  Baume, 
  the 
  greater 
  part 
  of 
  it 
  being 
  about 
  25° 
  to 
  27°. 
  In 
  

   the 
  Arroyo 
  Grande 
  field 
  the 
  oil 
  comes 
  from 
  sandstone 
  at 
  the 
  base 
  

   of 
  the 
  Fernando 
  and 
  is 
  of 
  14° 
  gravity. 
  There 
  is 
  in 
  all 
  these 
  fields 
  

   much 
  undeveloped 
  territory 
  which 
  offers 
  great 
  promise 
  of 
  being 
  

  

  