﻿OIL 
  OF 
  THE 
  SANTA 
  MARIA 
  DISTRICT. 
  113 
  

  

  in 
  the 
  porous 
  mass 
  and 
  they 
  may 
  have 
  acted 
  as 
  preservatives 
  of 
  the 
  

   organisms 
  to 
  some 
  extent. 
  

  

  As 
  regards 
  the 
  age 
  of 
  the 
  oil, 
  it 
  is 
  stated 
  by 
  F. 
  W. 
  Clarke 
  a 
  that 
  the 
  

   process 
  of 
  formation 
  of 
  the 
  oil 
  from 
  organic 
  sources 
  may 
  not 
  be 
  slow, 
  

   but, 
  on 
  the 
  other 
  hand, 
  comparatively 
  rapid. 
  It 
  is 
  usually 
  thought, 
  

   however, 
  that 
  the 
  process 
  of 
  distillation 
  is 
  slow 
  and 
  is 
  continued 
  

   during 
  a 
  long 
  time. 
  The 
  petroleum 
  in 
  the 
  Monterey 
  may 
  have 
  been 
  

   formed 
  immediately 
  after 
  the 
  deposit 
  was 
  laid 
  down, 
  or 
  the 
  pro- 
  

   duction 
  of 
  it 
  may 
  be 
  still 
  in 
  progress. 
  There 
  is 
  evidence, 
  however, 
  

   in 
  the 
  presence 
  of 
  burnt 
  shale 
  in 
  a 
  Pleistocene 
  deposit 
  (see 
  p. 
  52), 
  

   in 
  the 
  old 
  and 
  eroded 
  deposits 
  of 
  asphalt, 
  and 
  in 
  the 
  presence 
  in 
  cer- 
  

   tain 
  asphalt 
  deposits 
  of 
  the 
  bones 
  of 
  extinct 
  Pleistocene 
  mammals 
  6 
  

   which 
  were 
  caught 
  in 
  tar 
  springs 
  in 
  Pleistocene 
  time, 
  that 
  much 
  of 
  

   the 
  oil 
  at 
  least 
  was 
  formed 
  in 
  the 
  Monterey 
  and 
  disseminated 
  to 
  the 
  

   surface 
  a 
  long 
  time 
  ago. 
  The 
  accumulation 
  and 
  dissemination 
  of 
  the 
  

   oil 
  has 
  probably 
  gone 
  on 
  continuously 
  ever 
  since 
  its 
  first 
  formation, 
  

   the 
  two 
  processes 
  taking 
  place 
  simultaneously. 
  There 
  may 
  be 
  por- 
  

   tions 
  of 
  the 
  formation 
  from 
  which 
  the 
  hydrocarbon 
  content 
  has 
  not 
  

   yet 
  been 
  extracted 
  in 
  the 
  form 
  of 
  oil, 
  whereas 
  other 
  portions 
  may 
  

   no 
  longer 
  contain 
  any 
  of 
  the 
  oil 
  in 
  its 
  original 
  disseminated 
  condi- 
  

   tion. 
  The 
  metamorphism 
  that 
  gave 
  rise 
  to 
  the 
  harder 
  shales 
  may 
  

   have 
  had 
  the 
  effect 
  of 
  driving 
  out 
  the 
  oil 
  more 
  completely 
  than 
  it 
  

   has 
  been 
  separated 
  from 
  the 
  softer 
  shale, 
  and 
  thus 
  aided 
  its 
  accumu- 
  

   lation, 
  although 
  this 
  is 
  conjectural. 
  

  

  The 
  general 
  conclusion 
  is 
  that 
  in 
  the 
  Santa 
  Maria 
  district 
  the 
  

   organic 
  material 
  in 
  the 
  Monterey 
  shale 
  that 
  may 
  have 
  acted 
  as 
  the 
  

   source 
  of 
  the 
  oil 
  was 
  without 
  a 
  doubt 
  adequate 
  in 
  amount 
  for 
  the 
  

   production 
  of 
  the 
  vast 
  quantity 
  of 
  petroleum 
  now 
  present, 
  and 
  that 
  

   the 
  forms 
  included 
  in 
  greatest 
  abundance, 
  the 
  diatoms, 
  were 
  the 
  

   chief 
  source, 
  although 
  animals 
  and 
  perhaps 
  other 
  plants 
  also 
  con- 
  

   tributed 
  largely. 
  

  

  PHYSICAL 
  PROPERTIES. 
  

   GENERAL 
  STATEMENT. 
  

  

  The 
  Santa 
  Maria 
  district 
  yields 
  four 
  distinct 
  grades 
  of 
  petroleum, 
  in 
  

   addition 
  to 
  the 
  heavy 
  oil 
  which 
  flows 
  from 
  springs 
  or 
  collects 
  as 
  

   asphalt 
  deposits. 
  These 
  petroleums 
  vary 
  widely 
  in 
  their 
  physical 
  

   and 
  chemical 
  properties 
  and 
  as 
  a 
  consequence 
  are 
  utilized 
  in 
  many 
  

   different 
  ways, 
  the 
  lighter 
  oils 
  usually 
  for 
  refining, 
  the 
  heavier 
  for 
  

   fuel, 
  road 
  dressing, 
  etc. 
  

  

  The 
  oil 
  as 
  it 
  comes 
  from 
  the 
  wells 
  contains 
  varying 
  quantities 
  of 
  

   gas, 
  often 
  amounting 
  to 
  a 
  considerable 
  percentage. 
  The 
  two 
  prod- 
  

  

  a 
  The 
  data 
  of 
  geochemistry 
  (in 
  preparation 
  for 
  publication 
  by 
  the 
  United 
  States 
  Geological 
  Survey). 
  

   b 
  Bull. 
  U. 
  S. 
  Geol. 
  Survey 
  No. 
  309, 
  1907, 
  pp. 
  154-155. 
  

  

  