﻿168 
  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  194 
  3 
  

  

  known 
  to 
  operators. 
  One 
  explanation 
  was 
  that 
  the 
  gas 
  formed 
  in 
  

   the 
  earth 
  much 
  as 
  steam 
  is 
  formed 
  in 
  a 
  boiler 
  and 
  that 
  the 
  pressure 
  

   resulted 
  from 
  the 
  confinement 
  of 
  the 
  gas. 
  The 
  theory 
  most 
  commonly 
  

   held 
  was 
  that 
  the 
  weight 
  of 
  the 
  overlying 
  rocks 
  caused 
  the 
  compres- 
  

   sion 
  of 
  the 
  gas, 
  and 
  the 
  resulting 
  pressure 
  was 
  accordingly 
  called 
  "rock 
  

   pressure." 
  Lesley 
  (1885) 
  exhaustively 
  studied 
  this 
  theory 
  and 
  dem- 
  

   onstrated 
  that 
  the 
  pressure 
  of 
  gas 
  did 
  not 
  accord 
  with 
  the 
  weight 
  of 
  

   the 
  overburden. 
  Orton 
  seems 
  to 
  have 
  been 
  the 
  first 
  geologist 
  clearly 
  

   to 
  understand 
  the 
  function 
  of 
  artesian 
  pressure 
  in 
  relation 
  to 
  the 
  

   pressure 
  of 
  oil 
  and 
  gas 
  in 
  the 
  same 
  stratum. 
  He 
  says 
  (1888, 
  p. 
  99) 
  : 
  

  

  In 
  the 
  porous 
  rock 
  that 
  contains 
  them 
  there 
  is 
  always, 
  outside 
  of 
  the 
  pro- 
  

   ductive 
  fields, 
  a 
  body 
  of 
  water, 
  and 
  in 
  almost 
  every 
  instance, 
  salt 
  water. 
  This 
  

   water 
  occupies 
  the 
  rock 
  as 
  it 
  rises 
  to 
  day 
  in 
  its 
  nearest 
  outcrops. 
  Communi- 
  

   cating 
  there 
  with 
  surface 
  water 
  or 
  with 
  rainfall, 
  a 
  head 
  of 
  pressure 
  is 
  given 
  

   to 
  the 
  gas 
  and 
  oil 
  that 
  are 
  held 
  in 
  the 
  traps 
  formed 
  by 
  the 
  anticlinals 
  or 
  

   terraces 
  into 
  which 
  the 
  stratum 
  has 
  been 
  thrown. 
  The 
  amount 
  of 
  pressure 
  would 
  

   thus 
  depend 
  on 
  the 
  height 
  to 
  which 
  the 
  water 
  column 
  is 
  raised, 
  in 
  case 
  con- 
  

   tinuous 
  porosity 
  of 
  the 
  stratum 
  can 
  be 
  assumed. 
  

  

  Later 
  Orton 
  (1890) 
  published 
  a 
  paper 
  on 
  the 
  origin 
  of 
  the 
  rock 
  

   pressure 
  of 
  the 
  Trenton 
  limestone 
  which 
  laid 
  the 
  foundation 
  for 
  all 
  

   later 
  studies 
  in 
  dynamic 
  geology 
  as 
  related 
  to 
  oil 
  and 
  gas. 
  

  

  SUMMARY 
  

  

  The 
  preceding 
  review 
  of 
  the 
  status 
  of 
  petroleum 
  geology 
  in 
  1890, 
  

   though 
  brief, 
  may, 
  nevertheless, 
  demonstrate 
  that 
  this 
  division 
  of 
  the 
  

   science 
  had 
  been 
  placed 
  on 
  a 
  sound 
  foundation 
  by 
  the 
  pioneer 
  work 
  

   of 
  the 
  men 
  whose 
  writings 
  have 
  been 
  cited. 
  The 
  difficulties 
  which 
  they 
  

   encountered 
  and 
  the 
  differences 
  of 
  opinion 
  which 
  developed 
  among 
  

   them 
  were 
  in 
  large 
  measure 
  the 
  result 
  of 
  an 
  endeavor 
  to 
  oversimplify 
  

   their 
  science. 
  

  

  The 
  tracing 
  in 
  detail 
  of 
  the 
  evolution 
  of 
  these 
  various 
  ideas 
  and 
  

   theories 
  and 
  of 
  their 
  development 
  into 
  those 
  which 
  make 
  up 
  the 
  present 
  

   content 
  of 
  petroleum 
  geology 
  would 
  unduly 
  extend 
  this 
  paper. 
  The 
  

   writer 
  accordingly 
  passes 
  to 
  a 
  review 
  of 
  its 
  present 
  status 
  without 
  

   attempting 
  to 
  follow 
  closely 
  all 
  the 
  changes 
  in 
  thought 
  during 
  the 
  

   intervening 
  period. 
  

  

  GENESIS 
  OF 
  PETROLEUM 
  

   GENERAL 
  PROBLEM 
  

  

  Starting 
  with 
  an 
  accumulation 
  of 
  factual 
  information 
  concerning 
  

   the 
  nature 
  and 
  occurrence 
  of 
  petroleum, 
  and 
  following 
  the 
  scientific 
  

   method 
  of 
  thought, 
  petroleum 
  geologists 
  have 
  sought 
  to 
  discover 
  the 
  

   sources 
  from 
  which 
  it 
  has 
  come 
  and 
  the 
  manner 
  in 
  which 
  it 
  has 
  origi- 
  

   nated. 
  Most 
  of 
  them 
  have 
  held 
  the 
  opinion 
  that 
  oil 
  and 
  gas 
  have 
  been 
  

  

  