﻿PEALE.J 
  GENERAL 
  INTRODUCTION. 
  35 
  

  

  a 
  fold, 
  while 
  on 
  the 
  Gunnison 
  side 
  there 
  is 
  a 
  monoclinal 
  fold. 
  The 
  red 
  

   beds 
  also 
  frequently 
  appear 
  as 
  the 
  floor, 
  the 
  Cretaceous 
  sandstones 
  cap- 
  

   ping 
  butte-like 
  prominences. 
  

  

  One 
  of 
  the 
  most 
  curious 
  features 
  of 
  the 
  region 
  is 
  the 
  Unaweep 
  Caiion, 
  

   extending 
  from 
  the 
  Gunnison 
  to 
  the 
  Dolores 
  Eiver. 
  It 
  is 
  evidently 
  the 
  

   bed 
  of 
  an 
  old 
  stream 
  which 
  flowed 
  either 
  towards 
  the 
  Gunnison 
  or 
  

   towards 
  the 
  Dolores. 
  At 
  present 
  there 
  are 
  in 
  it 
  two 
  creeks, 
  one 
  a 
  trib- 
  

   utary 
  of 
  the 
  Gunnison, 
  and 
  the 
  other 
  a 
  branch 
  of 
  the 
  Dolores. 
  The 
  latter 
  

   is 
  the 
  principal 
  stream. 
  At 
  the 
  divide 
  between 
  the 
  two 
  creeks 
  the 
  caiion 
  

   is 
  about 
  1,200 
  feet 
  deep, 
  900 
  feet 
  of 
  gneissic 
  rock 
  and 
  300 
  of 
  red 
  sand- 
  

   stones 
  resting 
  on 
  the 
  metamorphic 
  rock. 
  The 
  dip 
  of 
  the 
  sedimeutaries 
  

   is 
  towards 
  the 
  east, 
  and 
  as 
  they 
  gradually 
  become 
  lower 
  the 
  creek 
  

   is 
  geologically 
  higher. 
  The 
  granite 
  wall, 
  therefore, 
  becomes 
  lower 
  and 
  

   lower 
  until 
  the 
  streamjoius 
  the 
  Gunnison 
  in 
  the 
  sandstones 
  of 
  the 
  Dakota 
  

   group, 
  above 
  the 
  red 
  sandstones 
  and 
  shales, 
  (Triassic 
  and 
  Jurassic). 
  

   Towards 
  the 
  west 
  the 
  caiion 
  deepens 
  rapidly 
  until 
  it 
  is 
  3,000 
  feet 
  below 
  

   the 
  general 
  surface. 
  The 
  stream 
  cuts 
  across 
  the 
  line 
  of 
  folding 
  and 
  

   faulting 
  on 
  the 
  west 
  side 
  of 
  the 
  plateau, 
  and 
  enters 
  the 
  red 
  sandstones, 
  

   in 
  which 
  it 
  joins 
  the 
  Dolores. 
  These 
  sandstones 
  did 
  towards 
  the 
  west 
  

   until 
  we 
  cross 
  the 
  Dolores 
  and 
  approach 
  the 
  Sierra 
  la 
  Sal, 
  when 
  the 
  dip 
  

   changes 
  to 
  the 
  east. 
  

  

  North 
  of 
  the 
  Unaweep 
  Caiion, 
  between 
  it 
  and 
  Grand 
  Eiver, 
  the 
  Dakota 
  

   group, 
  which 
  prevails 
  to 
  the 
  southward, 
  is 
  almost 
  entirely 
  absent, 
  the 
  

   red 
  beds 
  forming 
  the 
  greater 
  part 
  of 
  the 
  surface. 
  There 
  is 
  a 
  series 
  of 
  

   caiions, 
  and 
  the 
  general 
  slope 
  is 
  toward 
  the 
  north. 
  The 
  western 
  line 
  of 
  

   faulting 
  continues 
  for 
  some 
  distance, 
  and 
  then 
  becomes 
  a 
  fold, 
  and 
  the 
  

   eastern 
  fold 
  becomes 
  at 
  first 
  a 
  fault, 
  and 
  again 
  a 
  fold 
  toward 
  the 
  north. 
  

  

  North 
  of 
  Grand 
  Eiver 
  is 
  a 
  wide 
  valley, 
  in 
  which 
  are 
  Cretaceous 
  rocks, 
  

   the 
  bluffs 
  bordering 
  it 
  being 
  of 
  Upper 
  Cretaceous 
  age, 
  beyond 
  which 
  are 
  

   Tertiary 
  strata, 
  forming 
  the 
  " 
  Book" 
  or 
  "Eoan" 
  Mountains, 
  which 
  are 
  in 
  

   reality 
  a 
  series 
  of 
  plateaus, 
  one 
  above 
  the 
  other, 
  with 
  clift-like 
  edges, 
  

   forming, 
  in 
  other 
  words, 
  a 
  series 
  of 
  terraces. 
  These 
  we 
  did 
  not 
  have 
  

   any 
  opportunity 
  to 
  examine, 
  and 
  only 
  noticed 
  them 
  from 
  a 
  distance. 
  

   Grand 
  Eiver, 
  below 
  the 
  mouth 
  of 
  the 
  Gunnison, 
  is 
  alternately 
  in 
  valley 
  

   and 
  caiion, 
  most 
  often 
  in 
  the 
  latter. 
  From 
  the 
  mouth 
  of 
  the 
  Dolores 
  it 
  

   is 
  in 
  deep 
  caiion, 
  in 
  fed 
  sandstone. 
  

  

  The 
  San 
  Miguel 
  Eiver 
  and 
  its 
  branches 
  cut 
  deep 
  and 
  narrow 
  caiions 
  

   through 
  the 
  Dakota 
  sandstones, 
  leaving 
  mesas 
  between 
  the 
  difi'erent 
  

   streams, 
  all 
  having 
  the 
  same 
  general 
  level. 
  As 
  we 
  approach 
  the 
  Dolo- 
  

   res, 
  the 
  Jurassic 
  shales 
  form 
  the 
  cappings 
  of 
  ihe 
  mesas, 
  the 
  Cretaceous 
  

   sandstones 
  being 
  completely 
  eroded 
  away. 
  Still 
  farther 
  north 
  the 
  

   caiions 
  increase 
  in 
  depth, 
  and 
  are 
  cut 
  through 
  massive 
  red 
  sandstones, 
  

   with 
  here 
  and 
  there 
  isolated 
  patches 
  of 
  Jurassic 
  beds 
  on 
  top, 
  like 
  huge 
  

   monuments, 
  while 
  in 
  the 
  bottoms 
  of 
  the 
  caiions 
  beds 
  of 
  Upper 
  Carbonif- 
  

   erous 
  age 
  sometimes 
  appear. 
  

  

  Between 
  the 
  San 
  Miguel 
  and 
  the 
  Dolores 
  the 
  Dakota 
  group 
  forms 
  the 
  

   floor. 
  West 
  of 
  this 
  are 
  several 
  broad 
  folds 
  whose 
  axes 
  are 
  parallel, 
  

   having 
  a 
  direction 
  about 
  northwest 
  and 
  southeast. 
  Sometimes 
  the 
  Do- 
  

   lores 
  Eiver 
  cuts 
  across 
  these 
  folds, 
  and 
  again 
  it 
  follows 
  the 
  axes, 
  gen- 
  

   erally 
  occupying 
  anticlinal 
  valleys. 
  The 
  rocks 
  here 
  are 
  Triassic 
  f 
  red 
  

   sandstones, 
  capped 
  with 
  remnants 
  of 
  Jurassic 
  shales. 
  All 
  this 
  country 
  

   is 
  extremely 
  dry, 
  only 
  the 
  larger 
  streams 
  carrying 
  water. 
  AVest 
  of 
  the 
  

   Sierra 
  la 
  Sal 
  we 
  could 
  see 
  roches 
  moutonnees 
  forms 
  cut 
  in 
  the 
  red 
  sand- 
  

   stones 
  which 
  prevail 
  there. 
  These 
  are 
  northeast 
  of 
  the 
  Canon 
  Colorado, 
  

   which 
  was 
  named 
  from 
  the 
  red 
  rocks 
  through 
  which 
  it 
  is 
  cut. 
  

  

  In 
  this 
  chapter 
  I 
  have 
  endeavored 
  to 
  give 
  simply 
  the 
  general 
  features, 
  

  

  