﻿CHAPTER 
  II. 
  

  

  SURFACE 
  GEOLOGY— 
  LOS 
  PINOS 
  AGENCY 
  TO 
  UNCOMPAH- 
  

   GEE 
  VALLEY— 
  GUNNISOX 
  EIVEE 
  AND 
  UNCOMPAHGEE 
  

   . 
  PLATEAU. 
  

  

  The 
  country 
  lying 
  on 
  tlie 
  south 
  side 
  of 
  the 
  Gunnison 
  Eiver, 
  extending 
  

   from 
  Cochetopa 
  Creeli 
  westward 
  to 
  the 
  Uncompahgre 
  Eiver, 
  was 
  par- 
  

   tially 
  described 
  in 
  the 
  report 
  for 
  1874, 
  when 
  speaking 
  of 
  the 
  Gunnison 
  

   Eiver. 
  The 
  principal 
  streams 
  here, 
  as 
  we 
  go 
  westward, 
  are 
  the 
  follow- 
  

   ing 
  : 
  White 
  Earth 
  Eiver, 
  Lake 
  Fork, 
  and 
  the 
  Cimmaron 
  and 
  Cebolla 
  

   Creeks, 
  which 
  unite 
  to 
  form 
  one 
  stream 
  before 
  they 
  join 
  the 
  river. 
  All 
  

   these 
  streams 
  head 
  far 
  up 
  in 
  the 
  San 
  Juan 
  Mountains, 
  and 
  the 
  geological 
  

   features 
  of 
  the 
  country 
  about 
  their 
  sources 
  will 
  be 
  found 
  detailed 
  in 
  Dr. 
  

   Endlich's 
  report 
  for 
  1874. 
  Their 
  courses 
  are 
  api^roximately 
  parallel, 
  

   being 
  a 
  few 
  degrees 
  west 
  of 
  north. 
  There 
  seems 
  to 
  be 
  a 
  slight 
  slope 
  in 
  

   th€ 
  country 
  toward 
  the 
  north, 
  although 
  the 
  various 
  volcanic 
  strata 
  ap- 
  

   pear 
  to 
  be 
  horizontal. 
  On 
  the 
  north 
  side 
  of 
  the 
  Gunnison 
  the 
  dip 
  is 
  

   . 
  toward 
  the 
  south, 
  the 
  cause 
  being 
  found 
  in 
  the 
  eruptive 
  peaks 
  of 
  the 
  West 
  

   Elk 
  Mountains, 
  as 
  has 
  been 
  fully 
  explained 
  in 
  the 
  report 
  for 
  1874. 
  To 
  

   the 
  southward, 
  in 
  Dr. 
  Endlich's 
  district, 
  the 
  dip 
  although 
  very 
  gentle, 
  

   is 
  toward 
  the 
  north 
  and 
  northeast. 
  

  

  Almost 
  all 
  this 
  region 
  is 
  covered 
  with 
  volcanic 
  rocks, 
  which 
  are 
  cut 
  

   by 
  the 
  streams 
  into 
  mesas 
  extending 
  in 
  long 
  narrow 
  tongues 
  toward 
  

   the 
  north. 
  Along 
  the 
  Gunnison 
  they 
  are 
  for 
  the 
  most 
  part 
  underlaid 
  by 
  

   breccia. 
  As 
  far 
  as 
  observed, 
  this 
  breccia 
  does 
  not 
  underly 
  the 
  trachytic 
  

   flows 
  everywhere, 
  but 
  only 
  along 
  the 
  principal 
  streams 
  and 
  near 
  the 
  

   Gunnison, 
  especially 
  on 
  the 
  north. 
  In 
  several 
  places 
  between 
  the 
  main 
  

   creeks 
  I 
  noticed 
  the 
  trachyte 
  resting 
  immediately 
  on 
  the 
  same 
  gneissic 
  

   rocks 
  which 
  are 
  so 
  well 
  exposed 
  along 
  the 
  Gunnison 
  in 
  its 
  caiion. 
  

  

  Leaving 
  the 
  Los 
  Pinos 
  Indian 
  agency, 
  we 
  followed 
  the 
  wagon-road 
  

   which 
  leads 
  to 
  Lake 
  City, 
  (a 
  new 
  mining 
  town 
  on 
  the 
  Lake 
  Fork 
  of 
  the 
  

   Gunnison,) 
  as 
  far 
  as 
  the 
  Lake 
  Fork. 
  Our 
  first 
  station 
  was 
  made 
  on 
  the 
  

   west 
  side 
  of 
  White 
  Earth 
  Eiver, 
  on 
  a 
  granitic 
  hill. 
  This 
  was 
  about 
  two 
  

   miles 
  north 
  of 
  Wilson's 
  Station 
  7 
  of 
  1874. 
  

  

  "WHITE 
  EARTH 
  EIVER. 
  

  

  We 
  entered 
  the 
  valley 
  of 
  the 
  White 
  Earth 
  at 
  the 
  mouth 
  of 
  Beaver 
  

   Creek, 
  one 
  of 
  its 
  eastern 
  tributaries. 
  Here 
  the 
  White 
  Earth 
  has 
  a 
  

   valley 
  extending 
  four 
  miles 
  down 
  the 
  river, 
  in 
  which 
  the 
  stream 
  winds 
  

   so 
  much 
  that 
  its 
  length 
  is 
  about 
  twice 
  that 
  of 
  the 
  valley. 
  The 
  valley 
  

   will 
  probably 
  average 
  about 
  half 
  a 
  mile 
  in 
  width, 
  and 
  is 
  i^artly 
  settled. 
  

   Above 
  this 
  valley, 
  the 
  creek 
  is 
  in 
  Dr. 
  Endlich's 
  district, 
  and 
  has 
  been 
  

   described 
  by 
  him. 
  Below, 
  it 
  is 
  in 
  caiion 
  until 
  it 
  reaches 
  the 
  Gunnison. 
  

   It 
  here 
  flows 
  through 
  granitic 
  rocks, 
  which 
  are 
  capped 
  with 
  trachyte, 
  a 
  

   coarse 
  breccia 
  being 
  interposed 
  as 
  we 
  approach 
  the 
  river. 
  About 
  half- 
  

   way 
  down 
  the 
  valley, 
  on 
  the 
  west 
  side, 
  is 
  a 
  group 
  of 
  springs, 
  or, 
  more 
  

   correctly, 
  two 
  groups, 
  one 
  of 
  cold 
  and 
  the 
  other 
  of 
  warm 
  springs. 
  

  

  First 
  group. 
  — 
  This 
  group 
  has 
  two 
  springs, 
  the 
  waters 
  from 
  which 
  

  

  37 
  

  

  