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  SANTA 
  MARIA 
  OIL 
  DISTRICT, 
  CALIFORNIA. 
  

  

  hut 
  the 
  Eocene 
  shales 
  in 
  which 
  it 
  is 
  characteristic, 
  or 
  in 
  which 
  

   it 
  occurs 
  in 
  appreciable 
  quantity 
  except 
  locally, 
  although 
  there 
  are 
  

  

  numerous 
  formations 
  which 
  would 
  be 
  capable 
  of 
  storing 
  oil 
  if 
  any 
  

   had 
  originated 
  in 
  them. 
  Moreover, 
  the 
  bituminous 
  Monterey 
  shale 
  

   of 
  the 
  Coast 
  Ranges 
  does 
  not 
  occur 
  consistently 
  above 
  or 
  below 
  

   any 
  one 
  formation 
  from 
  which 
  the 
  oil 
  could 
  have 
  been 
  derived. 
  It 
  

   lies 
  unconformably 
  upon 
  ancient 
  metamorphic 
  rocks; 
  granite 
  and 
  

   other 
  igneous 
  rocks; 
  Jurassic, 
  Cretaceous, 
  or 
  early 
  Tertiary 
  sedi- 
  

   ments; 
  or 
  conformably 
  over 
  lower 
  Miocene 
  beds, 
  according 
  to 
  local 
  

   conditions; 
  and 
  it 
  is 
  either 
  not 
  covered 
  by 
  later 
  deposits 
  or 
  is 
  buried 
  

   by 
  sediments 
  of 
  various 
  ages, 
  in 
  different 
  places. 
  

  

  The 
  decision 
  is 
  therefore 
  unavoidable 
  that 
  some 
  ingredients 
  of 
  the 
  

   Monterey 
  shale 
  gave 
  rise 
  to 
  the 
  oil, 
  and 
  the 
  question 
  arises 
  what 
  these 
  

   were. 
  The 
  organic 
  composition 
  of 
  the 
  strata 
  making 
  up 
  this 
  forma- 
  

   tion 
  is 
  discussed 
  on 
  pages 
  38-43, 
  where 
  a 
  number 
  of 
  animal 
  and 
  

   plant 
  forms 
  that 
  may 
  have 
  contributed 
  to 
  the 
  oil 
  are 
  enumerated. 
  

   The 
  writers 
  are 
  strongly 
  of 
  the 
  belief 
  that 
  the 
  petroleum 
  was 
  derived 
  

   largely 
  from 
  the 
  minute 
  organisms, 
  especially 
  the 
  plant 
  organisms 
  

   (diatoms), 
  which 
  are 
  present 
  in 
  such 
  abundance 
  in 
  these 
  shales. 
  The 
  

   chemists 
  Peckham 
  and 
  Clarke 
  believe 
  that 
  the 
  nitrogen 
  present 
  in 
  

   the 
  California 
  oil 
  proves 
  its 
  origin 
  from 
  animal 
  substance. 
  But 
  it 
  is 
  

   not 
  necessary 
  to 
  consider 
  that 
  this 
  petroleum 
  originated 
  entirely 
  

   from 
  either 
  animal 
  or 
  vegetable 
  matter; 
  it 
  is 
  more 
  probably 
  the 
  

   product 
  of 
  remains 
  of 
  both 
  kinds 
  combined, 
  much 
  of 
  the 
  nitrogenous 
  

   material 
  being 
  furnished 
  by 
  animal 
  tissue. 
  

  

  Other 
  small 
  organisms 
  of 
  a 
  low 
  order 
  present 
  in 
  the 
  Monterey 
  shale 
  

   besides 
  the 
  diatoms 
  are 
  Foraminifera 
  and 
  Radiolaria, 
  both 
  orders 
  of 
  

   marine 
  animals. 
  They 
  became 
  embedded 
  in 
  the 
  mass 
  of 
  the 
  organic 
  

   and 
  adventitious 
  silt 
  material 
  of 
  the 
  deposit 
  at 
  the 
  sea 
  bottom, 
  and 
  

   their 
  bodies 
  were 
  thus 
  preserved 
  with 
  the 
  hard 
  parts 
  and 
  may 
  have 
  

   become 
  a 
  source 
  of 
  hydrocarbons 
  and 
  nitrogen 
  for 
  the 
  petroleum. 
  

   The 
  fact 
  that 
  the 
  limestone 
  and 
  calcareous 
  shale 
  of 
  the 
  Monterey 
  are 
  

   usually 
  very 
  bituminous 
  suggests 
  the 
  conclusion 
  that 
  the 
  Foraminif- 
  

   era 
  were 
  great 
  oil 
  formers, 
  inasmuch 
  as 
  these 
  rocks 
  are 
  thought 
  to 
  be 
  

   made 
  up 
  largely 
  of 
  foraminiferal 
  remains, 
  although 
  of 
  course 
  the 
  

   calcareous 
  strata 
  may 
  owe 
  their 
  petroliferous 
  character 
  to 
  their 
  

   porosity. 
  In 
  many 
  places 
  the 
  body 
  of 
  the 
  limestone 
  is 
  full 
  of 
  minute 
  

   specks 
  of 
  oil 
  contained 
  in 
  cavities 
  about 
  the 
  size 
  of 
  the 
  interior 
  of 
  

   foraminiferal 
  skeletons, 
  and 
  these 
  specks 
  give 
  the 
  impression 
  that 
  the 
  

   oil 
  is 
  not 
  far 
  from 
  its 
  point 
  of 
  origin. 
  Albert 
  Mann, 
  of 
  the 
  United 
  

   States 
  Department 
  of 
  Agriculture, 
  makes 
  the 
  suggestion 
  that 
  possibly 
  

   Foraminifera 
  originally 
  made 
  up 
  a 
  greater 
  part 
  of 
  the 
  shales 
  than 
  

   now 
  appears 
  and 
  that 
  their 
  easily 
  destroyed 
  calcareous 
  tests 
  were 
  

   leached 
  out, 
  the 
  soft 
  parts 
  adding 
  their 
  quota 
  to 
  the 
  total 
  amount 
  of 
  

   petroleum 
  formed 
  and 
  owning 
  to 
  their 
  animal 
  character 
  helping 
  to 
  

  

  