﻿156 
  G. 
  H. 
  Stone 
  — 
  Asphaltum 
  of 
  Utah 
  and 
  Colorado. 
  

  

  of 
  the 
  limestones 
  or 
  certain 
  layers 
  of 
  the 
  shales, 
  we 
  may 
  also 
  

   assume 
  that 
  a 
  part 
  of 
  the 
  bitumens 
  originated 
  as 
  above 
  de- 
  

   scribed, 
  or 
  in 
  some 
  other 
  way 
  from 
  the 
  upward 
  passage 
  of 
  oils 
  

   through 
  the 
  fissures. 
  

  

  Such 
  an 
  hypothesis 
  certainly 
  accords 
  with 
  some 
  of 
  the 
  facts. 
  

   The 
  rocks 
  now 
  dip 
  from 
  the 
  Roan 
  Cliffs 
  northward 
  to 
  the 
  

   DuChesne 
  and 
  White 
  Rivers. 
  The 
  marginal 
  portions 
  of 
  the 
  

   rocks 
  that 
  were 
  laid 
  down 
  in 
  the 
  Tertiary 
  lake 
  of 
  this 
  region 
  

   have 
  been 
  removed 
  by 
  erosion. 
  This 
  is 
  the 
  region 
  where 
  a 
  

   non-conformity 
  would 
  be 
  exposed.* 
  While, 
  then, 
  we 
  do 
  not 
  

   know 
  with 
  certainty 
  that 
  the 
  rocks 
  at 
  the 
  southern 
  margin 
  of 
  

   the 
  Tertiary 
  lake 
  near 
  the 
  present 
  course 
  of 
  the 
  Green 
  river 
  

   dipped 
  northward 
  at 
  the 
  time 
  this 
  lake 
  began 
  to 
  exist, 
  yet 
  

   it 
  is 
  a 
  very 
  natural 
  supposition 
  that 
  they 
  did 
  so, 
  and 
  that 
  

   it 
  was 
  owing 
  to 
  an 
  uplift 
  toward 
  the 
  south 
  that 
  the 
  lake 
  

   was 
  formed. 
  If 
  reservoirs 
  of 
  oil 
  existed 
  in 
  the 
  black 
  

   shales, 
  a 
  northward 
  dip 
  would 
  tend 
  to 
  prevent 
  their 
  escape 
  

   southward. 
  And 
  since 
  the 
  supposed 
  fissures 
  would 
  let 
  in 
  the 
  

   water 
  from 
  the 
  lake 
  as 
  well 
  as 
  let 
  out 
  the 
  oil, 
  it 
  is 
  easy 
  to 
  ac- 
  

   count 
  for 
  the 
  oil 
  rising 
  to 
  the 
  surface 
  of 
  the 
  lake. 
  The 
  inter- 
  

   mittent 
  depositing 
  of 
  the 
  asphalt 
  could 
  then 
  be 
  accounted 
  as 
  

   due 
  to 
  alternate 
  opening 
  and 
  closing 
  of 
  the" 
  fissures, 
  such 
  as 
  

   would 
  be 
  possible 
  during 
  the 
  great 
  Uinta 
  uplift, 
  or 
  to 
  other 
  

   accidents 
  of 
  sedimentation. 
  

  

  Now 
  the 
  fissures 
  that 
  are 
  at 
  present 
  exposed 
  are 
  of 
  very 
  late 
  

   age, 
  being 
  made 
  after 
  the 
  latest 
  rocks 
  were 
  formed 
  in 
  this 
  

   basin, 
  and 
  after 
  the 
  lake 
  was 
  drained 
  by 
  the 
  Green 
  River, 
  and 
  

   when 
  the 
  Uinta 
  and 
  Wasatch 
  uplifts 
  were 
  far 
  advanced. 
  It 
  is 
  

   possible 
  that 
  they 
  are 
  the 
  continuations 
  upward 
  of 
  fissures 
  

   made 
  in 
  earlier 
  Tertiary 
  time, 
  or 
  we 
  may 
  suppose 
  there 
  were 
  

   earlier 
  fissures 
  that 
  were 
  at 
  the 
  last 
  covered 
  by 
  the 
  Brown's 
  

   Park 
  rocks. 
  The 
  present 
  fissures 
  are 
  filled 
  with 
  hard 
  asphalt 
  

   that 
  once 
  was 
  evidently 
  liquid, 
  and 
  indeed 
  the 
  asphalt 
  grows 
  

   softer 
  as 
  we 
  go 
  down 
  in 
  the 
  veins 
  and 
  in 
  places 
  is 
  somewhat 
  

   viscous, 
  even 
  quite 
  near 
  the 
  surface. 
  Where 
  I 
  have 
  examined 
  

   these 
  veins 
  there 
  is 
  no 
  sign 
  that 
  this 
  liquid 
  has 
  passed 
  out 
  into 
  

   the 
  wall 
  rock 
  and 
  charged 
  it. 
  The 
  only 
  asphaltic 
  rock 
  exposed 
  

   in 
  the 
  country 
  bordering 
  the 
  fissures 
  is 
  of 
  very 
  low 
  grade, 
  and 
  

   there 
  is 
  a 
  very 
  large 
  amount 
  of 
  this 
  impoverished 
  rock 
  in 
  that 
  

   region. 
  There 
  are 
  no 
  known 
  fissure 
  veins 
  in 
  the 
  country 
  

   where 
  the 
  asphaltic 
  sand 
  rock 
  is 
  rich. 
  Thus 
  there 
  is 
  no 
  field 
  

   evidence 
  of 
  the 
  passage 
  of 
  asphalt 
  outward 
  from 
  the 
  fissures, 
  

   but 
  strong 
  indications 
  that 
  the 
  sand 
  rocks 
  were 
  drained 
  of 
  their 
  

   maltha 
  to 
  fill 
  the 
  fissures.f 
  

  

  * 
  Such 
  a 
  nou 
  -conformity 
  exists 
  at 
  the 
  Grand 
  Mesa 
  east 
  of 
  Grand 
  Junction, 
  

   Colo., 
  where 
  the 
  Tertiary 
  beds 
  overlie 
  the 
  Laramie. 
  

  

  f 
  At 
  two 
  places 
  in 
  the 
  Ashley 
  valley 
  there 
  are 
  very 
  rich 
  areas 
  of 
  sand 
  asphalt 
  

   at 
  the 
  foot 
  of 
  slopes 
  of 
  natural 
  dip, 
  as 
  if 
  the 
  maltha 
  had 
  flowed 
  down 
  the 
  slopes 
  

  

  