﻿G. 
  H. 
  Stone 
  — 
  Asphaltum 
  of 
  Utah 
  and 
  Colorado. 
  151 
  

  

  hardened 
  outflow 
  is 
  known 
  as 
  outflow 
  or 
  overflow 
  asphalt. 
  

   The 
  maltha 
  is 
  found 
  in 
  small 
  pools, 
  or 
  spread 
  over 
  the 
  ground 
  

   and 
  often 
  penetrates 
  the 
  spaces 
  between 
  the 
  broken 
  rock 
  of 
  the 
  

   talus 
  or 
  sub-soil 
  in 
  a 
  complex 
  network 
  of 
  stringers, 
  small 
  veins 
  

   and 
  sheets. 
  2. 
  ITintaite 
  or 
  Gilsonite. 
  A 
  brittle, 
  easily 
  soluble 
  

   and 
  fusible 
  mineral. 
  3. 
  Wurtzilite, 
  a 
  shining, 
  tough 
  mineral, 
  

   fusible 
  and 
  soluble 
  with 
  great 
  difficulty.* 
  

  

  Geological 
  Age 
  of 
  the 
  Deposits. 
  — 
  A 
  fissure 
  vein 
  of 
  wurtzi- 
  

   lite 
  is 
  reported 
  to 
  be 
  found 
  in 
  a 
  region 
  where 
  none 
  of 
  the 
  

   U. 
  S. 
  geological 
  maps 
  show 
  rocks 
  later 
  than 
  the 
  Jurassic 
  or 
  

   early 
  Cretaceous, 
  and 
  the 
  same 
  is 
  true 
  of 
  one 
  area 
  of 
  asphaltic 
  

   sandrock. 
  I 
  have 
  not 
  examined 
  these 
  deposits 
  and 
  leave 
  their 
  

   age 
  an 
  open 
  question. 
  All 
  the 
  fields 
  of 
  sand 
  asphalt 
  that 
  I 
  

   have 
  visited 
  are 
  plainly 
  of 
  Tertiary 
  age. 
  Most 
  of 
  them 
  are 
  in 
  

   the 
  Green 
  River 
  beds, 
  some 
  may 
  be 
  in 
  the 
  upper 
  part 
  of 
  the 
  

   Wasatch, 
  and 
  the 
  thick 
  beds 
  found 
  in 
  the 
  Ashley 
  valley 
  appear 
  

   to 
  be 
  near 
  the 
  base 
  of 
  the 
  very 
  late 
  Tertiary 
  formation 
  marked 
  

   on 
  Hayden's 
  maps 
  as 
  Uinta 
  and 
  on 
  that 
  of 
  Dr. 
  C. 
  A. 
  "White, 
  

   (Xinth 
  Ann. 
  Report 
  Director 
  U. 
  S. 
  G. 
  S., 
  87-88) 
  named 
  

   Brown's 
  Park. 
  The 
  black 
  asphaltic 
  or 
  bituminous 
  shales 
  (marls) 
  

   are 
  of 
  Green 
  River 
  age. 
  The 
  bituminous 
  limestones, 
  so 
  far 
  

   as 
  I 
  have 
  observed 
  them, 
  are 
  of 
  Green 
  River 
  and 
  some 
  per- 
  

   haps 
  are 
  of 
  Upper 
  Wasatch 
  age. 
  The 
  outcrop 
  of 
  the 
  fissure 
  

   veins 
  of 
  uintaite 
  and 
  some- 
  of 
  the 
  wurtzilite 
  are 
  in 
  the 
  Brown's 
  

   Park 
  rocks 
  and 
  therefore 
  these 
  veins 
  were 
  opened 
  and 
  filled 
  

   after 
  the 
  Brown's 
  Park 
  epoch 
  — 
  obviously 
  in 
  case 
  of 
  outflow 
  

   asphalt 
  we 
  have 
  to 
  determine 
  not 
  only 
  the 
  date 
  of 
  origin 
  of 
  the 
  

   tarry 
  bitumen 
  but 
  also 
  the 
  date 
  of 
  outflow. 
  These 
  fissure 
  

   veins 
  will 
  be 
  referred 
  to 
  again. 
  

  

  The 
  Bituminous 
  Rocks 
  and 
  Coal 
  Beds. 
  — 
  In 
  one 
  place 
  in 
  

   the 
  Ashley 
  valley 
  a 
  coal 
  bed 
  about 
  two 
  feet 
  thick 
  has 
  an 
  under- 
  

   day 
  a 
  few 
  inches 
  thick, 
  and 
  that 
  rests 
  directly 
  on 
  the 
  asphaltic 
  

   sand 
  rock. 
  The 
  coal 
  is 
  a 
  fair 
  specimen 
  of 
  the 
  Tertiary 
  coals 
  

   of 
  the 
  region. 
  It 
  is 
  free 
  burning, 
  not 
  caking, 
  and 
  no 
  bitumen 
  

  

  * 
  For 
  a 
  full 
  description 
  of 
  Uintaite 
  and 
  Wurtzilite 
  and 
  their 
  relations 
  to 
  alber- 
  

   tite, 
  grahamite 
  and 
  elaterite, 
  see 
  article 
  by 
  Professor 
  W. 
  P. 
  Blake, 
  Proceedings 
  of 
  

   American 
  Institute 
  of 
  Mining 
  Engineers, 
  Feb. 
  1890. 
  I 
  have 
  recently 
  learned 
  of 
  

   a 
  locality 
  where 
  the 
  wurtzilite 
  is 
  said 
  to 
  soften 
  under 
  heat 
  so 
  as 
  to 
  be 
  drawn 
  out 
  

   into 
  strings 
  that 
  tend 
  to 
  shorten. 
  This 
  grade 
  is 
  very 
  near 
  elaterite 
  in 
  behavior 
  

   and 
  perhaps 
  is 
  identical 
  with 
  it. 
  The 
  Ute 
  Indians 
  have 
  camped 
  on 
  almost 
  all 
  the 
  

   uintaite 
  and 
  wurtzilite 
  in 
  this 
  country. 
  The 
  valley 
  of 
  the 
  DuChesne 
  River, 
  also 
  

   those 
  of 
  the 
  Lower 
  White 
  and 
  adjacent 
  parts 
  of 
  the 
  Green 
  River, 
  are 
  crossed 
  by 
  

   numerous 
  fissure 
  veins 
  of 
  these 
  minerals, 
  though 
  wurtzilite 
  is 
  more 
  often 
  found 
  

   as 
  an 
  out-flow 
  product 
  in 
  the 
  talus 
  and 
  scattered 
  drift 
  than 
  in 
  fissures. 
  Both 
  

   wurtzilite 
  and 
  uintaite 
  are 
  found 
  in 
  a 
  great 
  variety 
  of 
  situations. 
  It 
  is 
  uncertain 
  

   whether 
  the 
  hardening 
  of 
  the 
  outflow 
  into 
  one 
  or 
  the 
  other 
  of 
  these 
  minerals 
  is 
  

   due 
  more 
  to 
  original 
  differences 
  in 
  the 
  chemical 
  composition 
  of 
  the 
  outflows 
  or 
  

   to 
  the 
  physical 
  conditions 
  under 
  which 
  they 
  hardened 
  after 
  the 
  outflow. 
  I 
  have 
  

   not 
  heard 
  of 
  both 
  minerals 
  being 
  derived 
  from 
  the 
  same 
  outflow. 
  So 
  far 
  as 
  at 
  

   present 
  known 
  the 
  facts 
  seem 
  to 
  indicate 
  that 
  they 
  are 
  derived 
  from 
  malthas 
  of 
  

   different 
  chemical 
  composition. 
  

  

  