﻿148 
  G. 
  H. 
  Stone 
  — 
  Asphaltum 
  of 
  Utah 
  and 
  Colorado. 
  

  

  Art. 
  XIII. 
  — 
  Note 
  on 
  the 
  Asphaltum 
  of 
  Utah 
  and 
  Colorado 
  / 
  

   by 
  George 
  H. 
  Stone. 
  

  

  During 
  the 
  past 
  year 
  the 
  writer 
  has 
  visited 
  all 
  the 
  known 
  

   asphalt 
  fields 
  of 
  western 
  Colorado 
  and 
  northeastern 
  Utah, 
  save 
  

   those 
  situated 
  within 
  the 
  reservations 
  of 
  the 
  Ute 
  Indians, 
  and 
  

   two 
  other 
  exceptions 
  noted 
  below. 
  It 
  is 
  intended 
  at 
  some 
  

   future 
  time 
  to 
  complete 
  a 
  map 
  of 
  the 
  asphalt 
  exposures 
  and 
  to 
  

   publish 
  a 
  more 
  detailed 
  account 
  of 
  them 
  than 
  is 
  possible 
  in 
  this 
  

   preliminary 
  paper. 
  

  

  Petrography 
  of 
  the 
  Deposits. 
  — 
  The 
  following 
  named 
  classes 
  

   of 
  deposit 
  are 
  represented 
  : 
  

  

  1. 
  Asphaltic 
  sand-rock, 
  known 
  also 
  as 
  sand-asphalt 
  and 
  bitu- 
  

   minous 
  rock. 
  This 
  is 
  the 
  most 
  abundant 
  of 
  all 
  the 
  asphaltic 
  

   deposits. 
  It 
  consists 
  of 
  a 
  sandstone 
  the 
  grains 
  of 
  which 
  are 
  in 
  

   contact 
  with 
  each 
  other 
  and 
  the 
  spaces 
  between 
  the 
  grains 
  are 
  

   wholly 
  or 
  partly 
  filled 
  with 
  asphaltum. 
  The 
  proportion 
  of 
  as- 
  

   phalt 
  varies 
  up 
  to 
  about 
  15 
  per 
  cent 
  by 
  weight 
  and 
  27 
  per 
  cent 
  ' 
  

   by 
  volume 
  Of 
  course 
  sandstones 
  will 
  contain 
  different 
  pro- 
  

   portions 
  of 
  asphalt 
  in 
  their 
  inter-granular 
  spaces 
  since 
  those 
  

   spaces 
  depend 
  on 
  the 
  sizes 
  and 
  shapes 
  of 
  the 
  constituent 
  

   grains 
  and 
  often 
  on 
  the 
  presence 
  of 
  other 
  cementing 
  sub- 
  

   stances. 
  When 
  a 
  bituminous 
  sandstone 
  contains 
  more 
  than 
  

   about 
  15 
  per 
  cent 
  of 
  asphalt, 
  it 
  may 
  be 
  assumed 
  that 
  it 
  has 
  not 
  

   been 
  under 
  pressure 
  of 
  superincumbent 
  rock 
  sufficient 
  to 
  cause 
  

   the 
  grains 
  to 
  come 
  in 
  contact 
  with 
  each 
  other.* 
  

  

  The 
  thickest 
  stratum 
  of 
  fully 
  charged 
  rock 
  that 
  I 
  have 
  seen 
  

   was 
  near 
  40 
  feet 
  in 
  thickness. 
  Usually 
  the 
  strata 
  of 
  high 
  grade 
  

   rock 
  are 
  not 
  more 
  than 
  4 
  to 
  10 
  feet 
  thick 
  and 
  they 
  alternate 
  

   with 
  lower 
  grade 
  or 
  barren 
  strata 
  of 
  sand-rock, 
  and 
  sometimes 
  

   with 
  marls, 
  shales 
  or 
  limestones. 
  Hence 
  the 
  amount 
  of 
  rich 
  

   rock, 
  — 
  " 
  pay 
  rock 
  " 
  — 
  has 
  often 
  been 
  enormously 
  over-estimated, 
  

   no 
  account 
  having 
  been 
  made 
  of 
  the 
  poor 
  strata. 
  This 
  is 
  par- 
  

   ticularly 
  the 
  case 
  with 
  some 
  of 
  the 
  published 
  accounts 
  of 
  the 
  

   asphalt 
  beds 
  of 
  the 
  valley 
  of 
  Ashley 
  Creek, 
  Utah. 
  

  

  2. 
  Bituminoios 
  Shales 
  or 
  Marls. 
  — 
  Black 
  or 
  blackish 
  marls 
  

   or 
  shales 
  cover 
  large 
  areas 
  both 
  in 
  Colorado 
  and 
  Utah. 
  The 
  

   richer 
  layers 
  have 
  the 
  smell 
  of 
  asphalt, 
  though 
  like 
  Wurtzilite, 
  

   they 
  are 
  difficultly 
  soluble. 
  The 
  specimens 
  examined 
  by 
  me 
  

  

  * 
  The 
  analyses 
  of 
  the 
  California 
  bituminous 
  rook 
  given 
  in 
  Seventh 
  Annual 
  

   Report, 
  Wm. 
  Irelan, 
  Jr., 
  State 
  Mineralogist, 
  Cal., 
  1887, 
  pp. 
  51-53, 
  show 
  from 
  

   1*10 
  to 
  8 
  per 
  cent 
  of 
  fixed 
  carbon, 
  and 
  of 
  volatile 
  carbonaceous 
  matter 
  from 
  940 
  

   to 
  46-20 
  percent, 
  with 
  small 
  proportions 
  of 
  lime, 
  etc. 
  An 
  asphaltic 
  sand 
  con- 
  

   taining 
  so 
  large 
  a 
  percentage 
  of 
  asphalt 
  as 
  afforded 
  by 
  some 
  of 
  these 
  analyses 
  

   would 
  probably 
  have 
  been 
  produced 
  by 
  a 
  relatively 
  small 
  quantity 
  of 
  sand 
  being 
  

   washed 
  or 
  drifted 
  on 
  to 
  an 
  outflow 
  of 
  soft 
  asphalt. 
  

  

  