﻿82 
  REPORT 
  UNITED 
  STATES 
  GEOLOGICAL 
  SURVEY. 
  

  

  plateau 
  there 
  is 
  a 
  tongue 
  of 
  Jurassic 
  and 
  Cretaceous 
  rocks 
  extending 
  

   from 
  the 
  Gunnison 
  to 
  the 
  western 
  side 
  of 
  the 
  plateau 
  a 
  few 
  miles 
  north 
  

   of 
  the 
  canon. 
  (See 
  Fig. 
  3, 
  Plate 
  IV.) 
  North 
  of 
  this, 
  the 
  surface 
  forma- 
  

   tion 
  is 
  the 
  cross-bedded 
  white 
  sandstone 
  of 
  the 
  Upper 
  Trias, 
  dip]3ing5<^ 
  

   to 
  the 
  northward, 
  with 
  granite 
  showing 
  on 
  the 
  bottoms 
  of 
  the 
  canons 
  

   of 
  the 
  streams 
  flowing 
  toward 
  the 
  Grand. 
  The 
  upper 
  member 
  of 
  the 
  

   series 
  is 
  subject 
  to 
  much 
  change, 
  becoming 
  red 
  and 
  salmon 
  colored 
  as 
  

   we 
  approach 
  the 
  Grand, 
  where 
  isolated 
  patches 
  of 
  Jurassic 
  shales 
  cap 
  

   buttes 
  composed 
  of 
  these 
  sandstones. 
  Between 
  this 
  upper 
  member 
  of 
  

   the 
  Trias 
  and 
  the 
  granite, 
  are 
  laminated 
  blood-red 
  sandstones, 
  separated 
  

   in 
  places 
  by 
  a 
  band 
  of 
  white 
  sandstone. 
  The 
  latter 
  becomes 
  pink 
  and 
  

   blood-red 
  as 
  we 
  follow 
  it 
  northward, 
  and 
  the 
  laminated 
  sandstones 
  

   change 
  to 
  massive 
  sandstones 
  with 
  a 
  few 
  shales 
  at 
  the 
  base. 
  The 
  thick- 
  

   ness 
  is 
  as 
  follows 
  : 
  

  

  Feet, 
  

  

  Oross-bedded 
  sandstone 
  somewhat 
  laminated 
  at 
  base, 
  yellow, 
  

  

  white, 
  or 
  salmon 
  colored 
  300-400 
  

  

  Massive 
  sandstone, 
  blood-red 
  in 
  color, 
  with 
  shales 
  at 
  base 
  rest- 
  

   ing 
  on 
  granite 
  400 
  

  

  700-800 
  

  

  The 
  lemon-yellow, 
  pink, 
  and 
  salmon-colored 
  sandstones 
  are 
  composed 
  

   generally 
  of 
  very 
  fine 
  material, 
  and 
  the 
  buttes 
  into 
  which 
  they 
  have 
  

   been 
  eroded 
  present 
  most 
  beautiful 
  examples 
  of 
  rock-coloring. 
  On 
  the 
  

   sides 
  of 
  the 
  buttes 
  great 
  caves 
  have 
  been 
  worn 
  into 
  the 
  rock, 
  and 
  

   others 
  have 
  the 
  form 
  of 
  pinnacles 
  and 
  towers. 
  

  

  On 
  the 
  western 
  side 
  of 
  the 
  plateau 
  there 
  is 
  a 
  fault 
  of 
  about 
  800 
  feet, 
  

   with 
  the 
  beds 
  below 
  tipped 
  up 
  against 
  the 
  granite. 
  The 
  area 
  between 
  

   the 
  crest 
  of 
  the 
  plateau 
  and 
  the 
  Dolores 
  is 
  occupied 
  mainly 
  by 
  red 
  beds, 
  

   with 
  Jurassic 
  and 
  Lower 
  Cretaceous 
  strata 
  appearing 
  as 
  we 
  approach 
  

   Grand 
  Eiver. 
  Between 
  the 
  Dolores 
  and 
  the 
  Salt 
  Mountains 
  the 
  red 
  

   beds 
  again 
  are 
  the 
  surface 
  formation, 
  with 
  the 
  exception 
  of 
  several 
  

   small 
  areas 
  of 
  Jurassic 
  and 
  the 
  Carboniferous 
  area 
  of 
  Sindbad 
  Valley. 
  

   This 
  valley 
  lies 
  on 
  the 
  line 
  of 
  a 
  fold 
  extending 
  from 
  a 
  point 
  south 
  of 
  

   the 
  Dolores 
  to 
  the 
  Grand 
  and 
  northwest 
  of 
  the 
  Grand. 
  As 
  explained 
  

   in 
  a 
  previous 
  chapter, 
  in 
  the 
  valley 
  which 
  we 
  named 
  Sindbad 
  there 
  is 
  a 
  

   fault, 
  with 
  the 
  ends, 
  of 
  Carboniferous 
  strata, 
  tipped 
  up 
  against 
  the 
  red 
  

   beds 
  on 
  the 
  west 
  side. 
  The 
  following 
  is 
  a 
  section 
  on 
  the 
  east 
  side 
  of 
  

   the 
  valley, 
  on 
  Salt 
  Creek, 
  which 
  drains 
  the 
  basin 
  : 
  

  

  Feet. 
  

  

  1. 
  Light-red 
  sandstones, 
  massive 
  ) 
  qi^q 
  

  

  2. 
  Dark-red 
  shales 
  j 
  

  

  3. 
  Massive 
  blood-red 
  sandstone 
  - 
  700 
  

  

  4. 
  Brown 
  sandstones 
  with 
  interlaminated 
  red 
  shales 
  300 
  

  

  1, 
  600 
  

  

  5. 
  Finh 
  and 
  red 
  gypsiferous 
  shales 
  and 
  sandstones, 
  conglomeritic 
  

  

  at 
  the 
  base 
  700 
  

  

  Layer 
  No. 
  5 
  was 
  included 
  in 
  the 
  section 
  of 
  Permian 
  beds, 
  page 
  71. 
  

  

  The 
  section 
  on 
  the 
  Dolores 
  is 
  like 
  that 
  of 
  Salt 
  Creek, 
  except 
  that 
  the 
  

   beds 
  are 
  lighter 
  colored 
  near 
  the 
  base 
  and 
  contain 
  large, 
  angular 
  frag- 
  

   ments 
  of 
  granite. 
  On 
  Grand 
  Eiver, 
  north 
  of 
  tlie 
  Sierra 
  la 
  Sal, 
  I 
  made 
  

   the 
  following 
  section. 
  Tbe 
  tbickuesses 
  were 
  measured 
  by 
  angles 
  taken 
  

   with 
  the 
  gradienter, 
  as 
  it 
  was 
  impossible 
  to 
  descend 
  the 
  clifl's 
  to 
  measure 
  

   the 
  strata 
  in 
  detail. 
  

  

  