﻿6 
  REPORT 
  UNITED 
  STATES 
  GEOLOGICAL 
  SURVEY. 
  

  

  The 
  party 
  completed 
  about 
  six 
  thousand 
  square 
  miles 
  in 
  the 
  West, 
  

   being 
  obliged, 
  after 
  the 
  trouble 
  with 
  the 
  Indians, 
  to 
  leave 
  un 
  worked 
  a 
  

   small 
  corner 
  in 
  the 
  Northwest, 
  requiring 
  about 
  five 
  days 
  to 
  be 
  completed. 
  

   This 
  piece 
  of 
  ground 
  joins 
  directly 
  on 
  to 
  Mr. 
  Gannett's 
  uncompleted 
  

   area, 
  and 
  lies 
  entirely 
  west 
  of 
  the 
  Colorado 
  line. 
  In 
  going 
  to 
  and 
  from 
  

   the 
  work, 
  six 
  full 
  weeks 
  were 
  si3ent 
  in 
  marching. 
  Mr. 
  Chittenden 
  worked 
  

   about 
  six 
  thousand 
  five 
  hundred 
  square 
  miles, 
  and 
  made 
  eighty-four 
  

   main 
  stations. 
  

  

  The 
  geological 
  examination 
  by 
  Mr. 
  Holmes 
  was 
  fruitful 
  of 
  most 
  im- 
  

   portant 
  results. 
  His 
  investigations 
  were 
  extended 
  from 
  Colorado 
  into 
  

   portions 
  of 
  Utah, 
  Arizona, 
  and 
  New 
  Mexico. 
  

  

  In 
  1874, 
  Dr. 
  Endlich 
  examined 
  the 
  district 
  lying 
  to 
  the 
  east, 
  so 
  that 
  

   Mr. 
  Holmes 
  took 
  up 
  the 
  work 
  where 
  he 
  left 
  off 
  at 
  108° 
  west 
  longitude, 
  

   and 
  carried 
  it 
  without 
  difficulty 
  to 
  109° 
  30'. 
  In 
  general, 
  the 
  geology 
  is 
  not 
  

   greatly 
  complicated. 
  The 
  section 
  of 
  stratified 
  rocks 
  exposed 
  extends 
  

   from 
  the 
  Tertiary 
  to 
  the 
  Carboniferous, 
  including 
  about 
  2,000 
  feet 
  

   of 
  the 
  former 
  and 
  slight 
  exposures 
  merely 
  of 
  the 
  latter. 
  About 
  9,000 
  

   feet 
  of 
  measures 
  passed 
  under 
  examination. 
  Of 
  other 
  rocks, 
  there 
  

   are 
  — 
  four 
  small 
  areas 
  of 
  trachyte, 
  one 
  limited 
  area 
  of 
  metamorphic 
  

   rock, 
  and 
  a 
  few 
  unimportant 
  dikes. 
  

  

  Beginning 
  at 
  the 
  east. 
  Dr. 
  Endlich's 
  section 
  on 
  meridian 
  108° 
  includes 
  

   the 
  entire 
  series, 
  begiuni-ng 
  with 
  the 
  Lower 
  Carboniferous 
  in 
  the 
  north 
  

   and 
  extending 
  up 
  into 
  the 
  Tertiary 
  at 
  the 
  south. 
  The 
  strike 
  is 
  east 
  and 
  

   west, 
  the 
  dip 
  south 
  from 
  5° 
  to 
  45°. 
  Working 
  to 
  the 
  westward, 
  Mr. 
  

   Holmes 
  found 
  the 
  whole 
  series 
  flattening 
  out, 
  *. 
  e., 
  approaching 
  a 
  hori- 
  

   zontal 
  position. 
  At 
  the 
  same 
  time, 
  a 
  gentle 
  rise 
  toward 
  the 
  northwest 
  

   brings 
  the 
  Cretaceous 
  rocks 
  to 
  the 
  surface, 
  or 
  at 
  least 
  up 
  to 
  the 
  general 
  

   level 
  of 
  the 
  country. 
  The 
  Tertiary 
  formations 
  are, 
  therefore, 
  confined 
  to 
  

   the 
  southeast. 
  From 
  Station 
  I, 
  an 
  outcrop 
  of 
  the 
  light-colored 
  sandstone 
  

   belonging 
  to 
  the 
  base 
  of 
  this 
  series 
  could 
  be 
  traced 
  along 
  its 
  entire 
  

   course 
  through 
  the 
  district. 
  

  

  The 
  heaviest 
  seam 
  of 
  coal 
  examined 
  in 
  these 
  beds 
  is 
  26 
  feet 
  in 
  thick- 
  

   ness. 
  It 
  is 
  rather 
  light 
  and 
  impure 
  on 
  the 
  surface, 
  but 
  probably 
  of 
  

   moderately 
  good 
  quality. 
  A 
  number 
  of 
  less 
  important 
  seams 
  were 
  

   also 
  observed. 
  

  

  West 
  of 
  the 
  Eio 
  La 
  Plata, 
  the 
  Upper 
  Cretaceous 
  beds 
  are 
  raised 
  to 
  a 
  

   higher 
  plane 
  by 
  a 
  slight 
  monoclinal 
  fold, 
  after 
  which 
  they 
  spread 
  out 
  

   to 
  the 
  west, 
  forming 
  the 
  Mesa 
  Verde. 
  This 
  mesa 
  extends 
  nearly 
  to 
  

   the 
  San 
  Juan 
  on 
  the 
  south, 
  west 
  beyond 
  the 
  Rio 
  Mancos, 
  and 
  north 
  to 
  

   the 
  middle 
  of 
  the 
  district, 
  an 
  area 
  of 
  more 
  than 
  700 
  square 
  miles. 
  On 
  

   these 
  three 
  sides, 
  the 
  mesa 
  breaks 
  abruptly 
  off 
  in 
  lines 
  of 
  irregular, 
  

   escarped 
  cliffs, 
  generally 
  from 
  1,000 
  to 
  2,000 
  feet 
  >n 
  height. 
  

  

  The 
  striking 
  features 
  of 
  this 
  series 
  are 
  the 
  exposures 
  of 
  two 
  horizons 
  

   of 
  massive 
  sandstoues. 
  The 
  upper 
  forms 
  the 
  top 
  of 
  the 
  mesa; 
  the 
  lower, 
  

   1,000 
  feet 
  below, 
  produces 
  a 
  subordinate 
  shelf. 
  Shales 
  intervene 
  be- 
  

   tween 
  the 
  sandstones 
  of 
  the 
  Lignitic 
  and 
  the 
  upper 
  sandstones 
  of 
  the 
  

  

  