﻿256 
  KEPORT 
  UNITED 
  STATES 
  GEOLOGICAL 
  SURVEY, 
  

  

  In 
  the 
  foreground 
  are 
  shown 
  the 
  west 
  walls 
  of 
  the 
  Mancos 
  Canon 
  

   The 
  upper 
  and 
  steeper 
  portions 
  are 
  composed 
  of 
  the 
  Lower 
  Escarpment 
  

   sandstone, 
  and 
  the 
  slopes 
  and 
  base 
  of 
  the 
  shales 
  of 
  the 
  Middle 
  Creta- 
  

   ceous. 
  The 
  Coal 
  Group 
  and 
  the 
  Upper 
  Escarpment 
  sandstones 
  have 
  

   been 
  removed 
  by 
  erosion, 
  so 
  that 
  the 
  mesa-top 
  is 
  a 
  smooth 
  floor, 
  formed 
  

   by 
  the 
  upper 
  surface 
  of 
  the 
  Lower 
  Escarpment 
  beds. 
  This 
  floor, 
  al- 
  

   though 
  unusually 
  firm, 
  seems 
  to 
  be 
  yielding 
  very 
  rapidly 
  to 
  the 
  eroding 
  

   forces. 
  Many 
  side-canons 
  are 
  eating 
  their 
  way 
  into 
  the 
  very 
  center 
  of 
  

   the 
  mass, 
  and 
  large 
  fragments 
  have 
  already 
  been 
  entirely 
  or 
  partially 
  

   severed. 
  These 
  fragments 
  or 
  outliers 
  are 
  always 
  interesting 
  and 
  pictu- 
  

   resque 
  objects, 
  and 
  may 
  here 
  be 
  seen 
  in 
  all 
  stages 
  of 
  formation 
  and 
  decay. 
  

   Some 
  still 
  retain 
  their 
  tablelike 
  caps 
  and 
  are 
  a 
  number 
  of 
  square 
  miles 
  

   in 
  area 
  ; 
  others 
  stand 
  as 
  majestic 
  columns, 
  whose 
  vertical 
  sides 
  are 
  fan- 
  

   tastically 
  carved 
  and 
  colored 
  ; 
  others 
  are 
  so 
  far 
  reduced 
  that 
  they 
  are 
  

   mere 
  needles 
  that 
  totter 
  over 
  their 
  slender 
  bases, 
  while 
  innumerable 
  

   piles 
  and 
  heaps 
  of 
  earth 
  mark 
  the 
  sites 
  of 
  those 
  from 
  which 
  the 
  capitols 
  

   and 
  columns 
  have 
  long 
  since 
  fallen. 
  Beyond 
  the 
  canon-cut 
  mesa 
  is 
  the 
  

   group 
  of 
  mountains 
  which, 
  on 
  most 
  of 
  the 
  old 
  maps, 
  is 
  called 
  the 
  Sierra 
  

   Late. 
  It 
  is 
  a 
  small 
  group 
  of 
  low 
  trachytic 
  summits 
  that 
  stands 
  quite 
  

   alone, 
  and 
  with 
  its 
  rounded 
  and 
  conical 
  forms 
  presents 
  a 
  very 
  striking 
  

   contrast 
  to 
  the 
  flat, 
  square-cut 
  table-lands 
  that 
  surround 
  it. 
  Between 
  

   the 
  Mesa 
  Yerde 
  and 
  this 
  group 
  of 
  mountains, 
  as 
  may 
  be 
  seen 
  in 
  the 
  

   drawing, 
  there 
  is 
  a 
  wide, 
  deep 
  puerta 
  eroded 
  from 
  the 
  Cretaceous 
  l 
  ales. 
  

   This 
  depression 
  connects 
  the 
  valleys 
  of 
  the 
  San 
  Juan 
  and 
  Lower 
  Mancos 
  

   with 
  those 
  of 
  the 
  McElmo 
  and 
  Dolores. 
  

  

  From 
  this 
  station 
  the 
  line 
  of 
  Upper 
  Escarpment 
  cliffs 
  extends 
  south- 
  

   east 
  to 
  the 
  point 
  where 
  the 
  mesa 
  connects 
  with 
  the 
  San 
  Juan 
  Hogback, 
  

   a 
  distance 
  of 
  nearly 
  20 
  miles. 
  The 
  line 
  of 
  Lower 
  Escarpment 
  cliffs 
  is 
  

   nearly 
  parallel 
  with 
  the 
  Upi)er, 
  and 
  is 
  a 
  few 
  miles 
  farther 
  south. 
  This 
  

   line 
  is 
  very 
  much 
  broken 
  by 
  deep 
  indentations, 
  and 
  a 
  large 
  number 
  of 
  

   isolated 
  buttes 
  lie 
  to 
  the 
  south. 
  The 
  ciifl^s, 
  however, 
  are 
  quite 
  precipitous, 
  

   and 
  cannot 
  be 
  ascended 
  at 
  any 
  point 
  without 
  great 
  difficulty. 
  Between 
  

   the 
  base 
  of 
  these 
  cliffs 
  and 
  the 
  Rio 
  San 
  Juan 
  there 
  is 
  a 
  low, 
  smooth 
  

   plain, 
  eight 
  to 
  ten 
  miles 
  in 
  width, 
  which 
  is 
  quite 
  barren. 
  

  

  The 
  Mancos 
  River, 
  on 
  emerging 
  from 
  the 
  caiion, 
  turns 
  to 
  the 
  westward 
  

   and 
  flows 
  obliquely 
  across 
  this 
  low 
  belt. 
  The 
  exposed 
  rocks 
  are, 
  through- 
  

   out, 
  the 
  shales 
  and 
  shaly 
  limestones 
  of 
  the 
  Middle 
  Cretaceous 
  or 
  Colorado 
  

   group. 
  The 
  section 
  given 
  in 
  Fig. 
  2, 
  Plate 
  XL, 
  will 
  show 
  the 
  relations 
  

   of 
  the 
  cliffs 
  of 
  the 
  Mesa 
  Verde 
  to 
  the 
  valley 
  of 
  the 
  San 
  Juan. 
  

  

  West 
  of 
  the 
  Mancos 
  the 
  cliffs 
  have 
  their 
  southwestern 
  termination 
  

   in 
  a 
  sharp 
  angle. 
  From 
  this 
  they 
  extend 
  to 
  the 
  north 
  in 
  a 
  gentle 
  curve, 
  

   and 
  finally 
  sweep 
  around 
  to 
  the 
  point 
  at 
  which 
  the 
  Mancos 
  enters 
  the 
  

   caiion 
  on 
  the 
  north. 
  This 
  part 
  of 
  the 
  mesa, 
  viewed 
  from 
  the 
  west, 
  is 
  

   very 
  imposing. 
  In 
  many 
  places 
  the 
  greater 
  part 
  of 
  the 
  Mesa 
  Verde 
  

   Group 
  (including 
  both 
  escarpments 
  and 
  the 
  Coal 
  Group 
  between, 
  the 
  

   latter 
  being 
  chiefly 
  sandstone 
  here) 
  comes 
  forward 
  together, 
  forming 
  a 
  

   series 
  of 
  bold 
  cliffs 
  upward 
  of 
  a 
  thousand 
  feet 
  in 
  height. 
  Beneath 
  th 
  s 
  

   are 
  exposed 
  nearly 
  a 
  thousand 
  feet 
  of 
  the 
  shales 
  of 
  the 
  Colorado 
  Grou 
  >. 
  

   These 
  weather 
  into 
  most 
  fantastic 
  forms. 
  They 
  are 
  soft 
  and 
  homogene- 
  

   ous, 
  and 
  the 
  water 
  from 
  the 
  occasional 
  rain-falls 
  carves 
  out 
  innumerable 
  

   little 
  sinuous 
  washes, 
  which, 
  in 
  descending, 
  come 
  together, 
  forming 
  deep 
  

   gullies. 
  These 
  keep 
  on, 
  joining 
  others, 
  until 
  the 
  main 
  drai,nage-course 
  

   of 
  the 
  valley 
  is 
  reached. 
  Between 
  this 
  net- 
  work 
  of 
  washes 
  are 
  corre- 
  

   sponding 
  ridges, 
  which, 
  in 
  a 
  favorable 
  light, 
  give 
  to 
  the 
  mesa-face 
  the 
  

   appearance 
  of 
  an 
  elaborate 
  and 
  very 
  artistic 
  piece 
  of 
  ornamental 
  carv- 
  

   ing. 
  

  

  J 
  

  

  