﻿PEALE.] 
  CREST 
  OF 
  UNCOMPAHGSE 
  PLATEAU. 
  55 
  

  

  They 
  rest 
  on 
  grauitoid 
  rocks 
  which 
  show 
  beneath 
  the 
  station, 
  and 
  in 
  

   narrow 
  strips 
  extending 
  up 
  the 
  creeks. 
  Crossing 
  the 
  narrow 
  strip 
  of 
  

   granite 
  we 
  find 
  the 
  Jurassic 
  shales 
  in 
  immediate 
  superposition 
  to 
  the 
  

   gneiss. 
  We 
  have 
  then 
  here 
  a 
  faulted 
  fold. 
  A 
  very 
  short 
  distance 
  north, 
  

   the 
  red-beds 
  show 
  beneath 
  the 
  Jurassic 
  on 
  both 
  sides 
  of 
  the 
  strip 
  of 
  

   granite, 
  and 
  still 
  farther 
  along 
  the 
  granite 
  is 
  concealed, 
  the 
  red-beds 
  

   continuing 
  across. 
  

  

  At 
  station 
  28, 
  there 
  is 
  a 
  break 
  again, 
  but 
  it 
  is 
  impossible 
  to 
  say 
  

   whether 
  there 
  is 
  any 
  faulting 
  or 
  simply 
  a 
  fold 
  with 
  the 
  layers 
  partially 
  

   removed. 
  Granite 
  appears 
  along 
  the 
  creek 
  and 
  branches 
  draining 
  the 
  

   country 
  immediately 
  about 
  station 
  28. 
  The 
  most 
  northern 
  or 
  western 
  

   branch 
  of 
  the 
  creek 
  we 
  have 
  been 
  discussing, 
  rises 
  in 
  an 
  amphitheatre 
  

   a 
  little 
  north 
  of 
  west 
  from 
  station 
  28. 
  The 
  floor 
  of 
  this 
  amphitheatre 
  

   is 
  gueissic, 
  and 
  its 
  walls 
  red 
  sandstone. 
  Beyond 
  it, 
  between 
  it 
  and 
  the 
  

   creek, 
  flowiog 
  from 
  station 
  32, 
  the 
  fold 
  of 
  the 
  red 
  beds 
  is 
  continuous 
  

   and 
  unbroken. 
  The 
  upper 
  portion 
  of 
  the 
  Triassic 
  beds 
  in" 
  this 
  region 
  

   are 
  light-colored, 
  in 
  fact 
  in 
  many 
  places 
  they 
  are 
  almost 
  white, 
  and. 
  it 
  is 
  

   only 
  by 
  noticing 
  their 
  structure, 
  which 
  remains 
  the 
  same 
  whatever 
  the 
  

   color, 
  and 
  watching 
  the 
  change 
  in 
  color, 
  with 
  their 
  position 
  in 
  relation 
  

   to 
  the 
  remaining 
  strata, 
  that 
  we 
  can 
  identify 
  them. 
  Another 
  point 
  to 
  

   be 
  noted 
  here 
  is 
  that 
  they 
  are 
  direct 
  Ij^ 
  superimposed 
  on 
  the 
  archsean 
  

   rocks. 
  Between 
  stations 
  32 
  and 
  35, 
  the 
  drainage 
  flows 
  to 
  the 
  west 
  and 
  

   southwest 
  to 
  a 
  creek, 
  whose 
  valley 
  is 
  parallel 
  to 
  that 
  of 
  the 
  Dolores, 
  al- 
  

   though 
  the 
  stream 
  flows 
  in 
  exactly 
  the 
  opposite 
  direction 
  until 
  joined 
  

   by 
  the 
  creek 
  from 
  station 
  32, 
  when 
  it 
  turns 
  and 
  flows 
  due 
  west 
  to 
  the 
  

   Dolores. 
  Between 
  this 
  creek 
  and 
  the 
  Dolores 
  are 
  three 
  small 
  streams 
  

   which 
  cut 
  deep 
  canons 
  in 
  the 
  red 
  beds, 
  leaving 
  mesas 
  between 
  capped 
  

   with 
  No. 
  1 
  Cretacious 
  toward 
  the 
  south. 
  Farther 
  north 
  only 
  Jurassic 
  

   forms 
  the 
  capping. 
  The 
  Dakota 
  sandstones 
  have 
  been 
  eroded 
  and 
  re- 
  

   moved. 
  

  

  We 
  now 
  return 
  to 
  the 
  crest. 
  The 
  rocks 
  on 
  station 
  32 
  are 
  a 
  portion 
  of 
  

   the 
  Dakota 
  group, 
  an 
  isolated 
  remnant 
  of 
  sandstones 
  that 
  once 
  must 
  

   have 
  covered 
  this 
  entire 
  country. 
  North 
  and 
  northwest 
  of 
  the 
  station 
  

   they 
  appear 
  to 
  be 
  entirely 
  absent, 
  while 
  to 
  the 
  east 
  and 
  northeast 
  there 
  

   are 
  similar 
  fragments 
  capping 
  the 
  higher 
  levels. 
  The 
  creek 
  rising 
  west 
  

   of 
  station 
  32 
  flows, 
  at 
  first 
  west, 
  then 
  southwest, 
  and 
  finally 
  west'again 
  

   to 
  the 
  Dolores. 
  We 
  have 
  already 
  seen 
  that 
  south 
  of 
  this 
  creek 
  the 
  red 
  

   beds 
  are 
  continuous, 
  the 
  monoclinal 
  fold 
  being 
  perfect. 
  In 
  this 
  short 
  

   interval, 
  then, 
  there 
  is 
  no 
  crest 
  to 
  the 
  plateau. 
  North, 
  however, 
  it 
  again 
  

   shows, 
  its 
  direction 
  being 
  about 
  north 
  40° 
  west, 
  instead 
  of 
  north 
  60° 
  

   west, 
  as 
  it 
  is 
  farther 
  south. 
  The 
  red 
  -beds 
  are 
  the 
  surface-rocks 
  on 
  the 
  

   edge, 
  a 
  strip 
  of 
  granitic 
  rock 
  showing 
  belOw. 
  This 
  is 
  very 
  irregular, 
  

   the 
  lower 
  portion 
  of 
  the 
  red 
  beds, 
  or 
  perhaps 
  some 
  older 
  strata, 
  ex- 
  

   tending 
  over 
  it 
  in 
  many 
  places. 
  The 
  latter 
  probably 
  represent 
  the 
  

   upper 
  beds 
  of 
  the 
  Carboniferous, 
  better 
  shown 
  on 
  the 
  Dolores 
  Eiver. 
  

  

  The 
  crest 
  near 
  station 
  33 
  and 
  the 
  plateau 
  just 
  below 
  the 
  station 
  

   are 
  drained 
  by 
  a 
  branch 
  of 
  West 
  Creek 
  of 
  Unaweep 
  CaQon. 
  There 
  are 
  

   several 
  branches 
  flowing 
  southwest 
  to 
  the 
  main 
  stream, 
  which 
  flows 
  to 
  

   the 
  northwest 
  until 
  it 
  receives 
  all 
  its 
  tributaries, 
  when 
  ife 
  flows 
  west 
  into 
  

   West 
  Creek. 
  Between 
  Unaweep 
  Canon 
  and 
  this 
  Creek 
  is 
  an 
  almost 
  

   square 
  piece 
  of 
  country, 
  including 
  about 
  16 
  square 
  miles. 
  " 
  There 
  are 
  

   three 
  high 
  points 
  in 
  it, 
  the 
  highest 
  of 
  which 
  is 
  about 
  3,000 
  to 
  4,000 
  feet 
  

   above 
  the 
  level 
  of 
  the 
  West 
  Creek. 
  The 
  capping 
  is 
  of 
  stratified 
  rocks, 
  

   probably 
  Triassic. 
  Beneath 
  them 
  the 
  archaean 
  rocks 
  appear 
  on 
  the 
  

   east, 
  north, 
  and 
  west. 
  On 
  the 
  south 
  a 
  tongue 
  of 
  stratified 
  rocks 
  appears 
  

   to 
  connect 
  with 
  the 
  strata 
  on 
  the 
  south 
  side 
  of 
  the 
  creek 
  from 
  station 
  

  

  