﻿PEALE.l 
  GUNNISON 
  RIVER 
  EAST 
  CREEK. 
  45 
  

  

  on 
  the 
  west 
  side 
  of 
  station 
  31. 
  Almost 
  its 
  entire 
  course 
  is 
  in 
  Triassic 
  

   sandstones. 
  

  

  Near 
  the 
  Gannisou, 
  when 
  the 
  dip 
  of 
  the 
  strata 
  increases, 
  Jurassic 
  

   shales 
  capped 
  with 
  Dakota 
  sandstones 
  appear 
  above 
  the 
  white, 
  soft 
  sand- 
  

   stone 
  that 
  marks 
  the 
  upper 
  limit 
  of 
  the 
  Triassic 
  beds. 
  It 
  is 
  possible 
  

   that 
  a 
  narrow 
  strip 
  of 
  gueissic 
  rock 
  may 
  show 
  near 
  the 
  bed 
  of 
  the 
  

   stream 
  before 
  it 
  reaches 
  the 
  river. 
  At 
  the 
  Gunnison 
  it 
  is 
  in 
  the 
  

   red-beds. 
  We 
  did 
  not 
  have 
  time 
  to 
  follow 
  its 
  whole 
  course, 
  which 
  must 
  

   be 
  done 
  before 
  all 
  the 
  details 
  of 
  the 
  region 
  through 
  which 
  it 
  flows 
  can 
  

   be 
  stated. 
  It 
  seems 
  to 
  carry 
  considerable 
  water, 
  although 
  much 
  of 
  it 
  

   sinks 
  when 
  it 
  gets 
  into 
  the 
  sandy 
  soil 
  before 
  reaching 
  the 
  Gunnison. 
  It 
  

   is 
  very 
  irregular 
  in 
  its 
  course 
  near 
  the 
  head, 
  differing 
  in 
  this 
  respect 
  from 
  

   the 
  creek 
  next 
  south 
  of 
  it. 
  '^ 
  

  

  The 
  next 
  creek 
  we 
  take 
  up 
  is 
  East 
  Creek 
  in 
  the 
  Unaweep 
  caiion. 
  It 
  

   is 
  much 
  shorter 
  than 
  the 
  Dominguez 
  and 
  at 
  a 
  much 
  lower 
  level, 
  not 
  

   being 
  on 
  the 
  plateau, 
  although 
  some 
  of 
  its 
  branches 
  rise 
  there. 
  Its 
  level 
  

   is 
  shown 
  by 
  the 
  base-line 
  of 
  the 
  caiion 
  in 
  Plate 
  IV, 
  Fig. 
  2. 
  It 
  rises 
  

   about 
  1,200 
  feet 
  below 
  the 
  level 
  of 
  the 
  plateau 
  in 
  a 
  broad 
  prairie-like 
  

   divide, 
  on 
  the 
  western 
  side 
  of 
  which 
  rises 
  the 
  stream 
  flowing 
  to 
  the 
  

   Dolores 
  Eiver. 
  Its 
  course 
  at 
  first 
  is 
  about 
  northeast 
  for 
  about 
  ten 
  miles. 
  

   In 
  this 
  part 
  of 
  its 
  course 
  it 
  has 
  one 
  branch 
  from 
  the 
  plateau 
  on 
  the 
  south 
  

   and 
  two 
  from 
  the 
  north. 
  These 
  branches 
  flow 
  with 
  a 
  comparatively 
  

   gentle 
  descent 
  until 
  they 
  reach 
  the 
  edge 
  of 
  the 
  caiion 
  when 
  they 
  plunge 
  

   over 
  the 
  granite 
  wall. 
  When 
  we 
  passed 
  through 
  the 
  caiion 
  in 
  August 
  

   these 
  streams 
  were 
  all 
  dry. 
  The 
  rate 
  of 
  fall 
  of 
  the 
  valley 
  for 
  this 
  part 
  of 
  

   its 
  course, 
  is 
  105 
  feet 
  per 
  mile. 
  The 
  upper 
  part 
  of 
  the 
  creek 
  is 
  entirely 
  

   in 
  gneissic 
  rocks 
  which 
  rise 
  in 
  i^erpendicular 
  walls, 
  and 
  are 
  probably 
  

   half 
  a 
  mile 
  apart. 
  On 
  top 
  of 
  the 
  archcean 
  rocks 
  are 
  red 
  sandstones 
  dip- 
  

   ping 
  to 
  the 
  east 
  at 
  an 
  angle 
  of 
  4° 
  to 
  5^, 
  gradually 
  decreasing 
  to 
  the 
  west 
  

   and 
  increasing 
  as 
  we 
  go 
  east. 
  The 
  granite 
  exposure 
  becomes 
  less 
  and 
  

   less 
  as 
  we 
  go 
  down 
  stream. 
  The 
  red 
  saudstones 
  having 
  a 
  greater 
  incli- 
  

   nation 
  than 
  the 
  fall 
  of 
  the 
  stream, 
  the 
  bed 
  of 
  the 
  creek 
  passes 
  into 
  the 
  

   red 
  sandstones, 
  the 
  granitic 
  rock 
  ending 
  as 
  a 
  narrow 
  tongue 
  a 
  short 
  dis- 
  

   tance 
  below 
  station 
  5J-. 
  

  

  Immediately 
  under 
  station 
  Si 
  the 
  course 
  of 
  the 
  creek 
  changes 
  to 
  due 
  

   north, 
  which 
  it 
  keeps 
  for 
  four 
  miles, 
  when 
  it. 
  gradually 
  turns 
  eastward, 
  

   until 
  it 
  flows 
  into 
  the 
  Gunnison, 
  with 
  its 
  original 
  course. 
  Its 
  fall 
  now 
  

   is 
  at 
  the 
  rate 
  of 
  about 
  150 
  feet 
  to 
  the 
  mile. 
  It 
  is 
  in 
  caiion 
  for 
  9 
  miles, 
  

   cutting 
  at 
  first 
  through 
  soft, 
  variegated 
  Jurassic 
  shales. 
  Two 
  miles 
  

   above 
  the 
  mouth 
  a 
  large 
  branch 
  comes 
  in 
  from 
  the 
  plateau 
  rising 
  east 
  

   ' 
  of 
  station 
  41, 
  at 
  an 
  elevation 
  of 
  8,600 
  feet. 
  The 
  elevation 
  at 
  the 
  Gun- 
  

   nison 
  is 
  4,635 
  feet, 
  a 
  fall 
  of 
  3,965 
  feet 
  in 
  a 
  distance 
  of 
  about 
  20 
  miles« 
  

   The 
  greater 
  part 
  of 
  the 
  fall 
  is 
  in 
  the 
  last 
  10 
  miles, 
  where 
  the 
  creek 
  de- 
  

   scends 
  rapidly 
  in 
  a 
  narrow 
  caiion. 
  In 
  the 
  upper 
  portion 
  of 
  its 
  course 
  

   the 
  rocks 
  are 
  red 
  sandstones, 
  in 
  which 
  it 
  soon 
  cuts 
  a 
  deep 
  caiion. 
  

   Emerging 
  from 
  this, 
  it 
  joins 
  the 
  southern 
  branch, 
  and, 
  keeping 
  on 
  in 
  

   its 
  original 
  direction, 
  cuts 
  across 
  the 
  lower 
  part 
  of 
  the 
  Dakota 
  group 
  

   to 
  the 
  Gunnison, 
  which 
  it 
  joins 
  in 
  a 
  valley, 
  marking 
  a 
  break 
  in 
  the 
  

   caiion 
  of 
  the 
  Gunnison. 
  Bordering 
  this 
  stream 
  are 
  the 
  variegated 
  Jurassic 
  

   shales. 
  Although 
  the 
  creek 
  descends 
  at 
  the 
  average 
  rate 
  of 
  nearly 
  200 
  

   feet 
  per 
  mile, 
  which 
  rate 
  is 
  largely 
  increased 
  as 
  its 
  crosses 
  the 
  mono- 
  

   clinal 
  fold, 
  it 
  in 
  reality 
  ascends 
  geologically, 
  the 
  red 
  beds 
  first 
  sinking 
  

   out 
  of 
  sight, 
  and 
  next 
  the 
  Jurassic 
  shales, 
  until 
  the 
  Dakota 
  sandstones 
  

   are 
  at 
  last 
  the 
  bordering 
  rocks. 
  W^e 
  have 
  already 
  seeii 
  this 
  to 
  be 
  the 
  

   case 
  in 
  other 
  streams 
  to 
  the 
  south. 
  Looking 
  up 
  these 
  creeks 
  from 
  a 
  

   point 
  on 
  the 
  opposite 
  side 
  of 
  the 
  Gunnison, 
  we 
  see 
  before 
  us 
  a 
  broad 
  

  

  