﻿54 
  EEPOET 
  UNITED 
  STATES 
  GEOLOGICAL 
  SURVEY. 
  

  

  through 
  which 
  it 
  flows, 
  mostly 
  belong 
  to 
  the 
  Dakota 
  group 
  of 
  the 
  Cre- 
  

   taceous, 
  Jurassic 
  shales 
  and 
  even 
  the 
  top 
  of 
  the 
  red 
  beds 
  sometimes 
  

   showing 
  beneath 
  them 
  in 
  the 
  canon. 
  

  

  At 
  the 
  point 
  we 
  take 
  up 
  the 
  Dolores 
  again, 
  it 
  is 
  flowing 
  toward 
  the 
  

   northwest. 
  It, 
  however, 
  soon 
  tarns 
  and 
  flows 
  northeast, 
  at 
  right 
  angles 
  

   to 
  the 
  axes 
  of 
  two 
  anticlinal 
  folds, 
  cutting 
  directly 
  across 
  them. 
  The 
  

   anticlinal 
  axes 
  are 
  occupied 
  by 
  creeks 
  on 
  both 
  sides 
  of 
  the 
  river. 
  There 
  

   are 
  smaller 
  streams 
  in 
  the 
  synclinal 
  valleys, 
  but, 
  as 
  seen 
  from 
  Lone 
  Cone 
  

   and 
  the 
  Sierra 
  la 
  Sal, 
  they 
  are 
  not 
  of 
  much 
  importance, 
  and 
  their 
  di- 
  

   rection 
  was 
  not 
  definitely 
  determined. 
  

  

  The 
  valley 
  of 
  the 
  Dolores 
  was 
  probably 
  outlined 
  before 
  the 
  formation 
  

   of 
  the 
  anticlinal 
  folds, 
  and 
  therefore 
  the 
  anticlinal 
  and 
  synclinal 
  valleys, 
  

   whose 
  drainage 
  is 
  tributary 
  to 
  the 
  Dolores, 
  are 
  of 
  later 
  origin 
  than 
  the 
  

   valley 
  of 
  the 
  Dolores. 
  The 
  underlying 
  rocks 
  of 
  these 
  folds 
  are 
  the 
  red 
  

   beds, 
  with, 
  perhaps, 
  Upper 
  Carboniferous 
  beneath. 
  Of 
  the 
  latter, 
  how- 
  

   ever, 
  we 
  cannot 
  be 
  certain 
  until 
  the 
  river 
  has 
  been 
  examined 
  in 
  detail. 
  

   Above 
  the 
  red 
  beds, 
  Jurassic 
  shales 
  occur. 
  

  

  After 
  passing 
  through 
  the 
  most 
  eastern 
  of 
  the 
  folds, 
  the 
  Dolores 
  is 
  

   joined 
  by 
  the 
  San 
  Miguel, 
  and 
  flows 
  north 
  for 
  a 
  short 
  distance, 
  and 
  then 
  

   turns 
  to 
  the 
  northwest, 
  holding 
  that 
  course 
  to 
  its 
  mouth 
  in 
  the 
  Grand. 
  

   All 
  this 
  distance 
  it 
  is 
  in 
  canon, 
  from 
  1,500 
  feet 
  to 
  3,000 
  feet 
  deep. 
  At 
  the 
  

   mouth 
  of 
  West 
  Creek, 
  flowing 
  from 
  the 
  Unaweep 
  Caiion, 
  the 
  walls 
  are 
  

   about 
  2,500 
  feet 
  high. 
  This 
  increases 
  as 
  we 
  go 
  down 
  stream 
  to 
  a 
  cer- 
  

   tain 
  point, 
  and 
  again 
  decreases. 
  The 
  canon 
  walls 
  are 
  of 
  sandstones 
  

   and 
  shales. 
  The 
  top 
  of 
  the 
  canon 
  is 
  a 
  bluff 
  face 
  of 
  blood-red 
  massive 
  

   sandstone, 
  surmounted 
  by 
  pink 
  sandstones 
  more 
  massive 
  in 
  appearance 
  

   but 
  softer. 
  These 
  belong 
  to 
  the 
  red 
  beds. 
  Below 
  them 
  are 
  alternations 
  

   of 
  blood-red 
  sandstones 
  and 
  shales. 
  Below 
  these 
  are 
  pink 
  sandstones 
  

   and 
  red 
  shales, 
  with 
  gypsum. 
  As 
  we 
  descend 
  the„ 
  sandstones 
  become 
  

   con 
  glom 
  critic. 
  The 
  dip 
  is 
  about 
  5° 
  toward 
  the 
  east, 
  or, 
  perhaps, 
  a 
  lit- 
  

   tle 
  north 
  of 
  east 
  as 
  we 
  go 
  north. 
  The 
  drainage 
  on 
  the 
  west 
  side 
  of 
  the 
  

   Dolores 
  will 
  be 
  considered 
  under 
  another 
  head. 
  

  

  Between 
  the 
  San 
  Miguel 
  and 
  West 
  Creek, 
  coming 
  from 
  pnaweep 
  Caiion, 
  

   are 
  two 
  large 
  creeks 
  heading 
  in 
  the 
  crest 
  of 
  Uncompahgre 
  Plateau, 
  and 
  

   'flowing 
  into 
  the 
  Dolores. 
  

  

  Standing 
  on 
  the 
  crest 
  and 
  looking 
  down 
  upon 
  this 
  country 
  we 
  see 
  a 
  

   great 
  number 
  of 
  mesas, 
  separated 
  by 
  deep 
  canons. 
  Although 
  along 
  the 
  

   Dolores 
  there 
  is 
  an 
  eastern 
  dip, 
  still 
  there 
  appears 
  to 
  be 
  also 
  an 
  inclination 
  

   to 
  south 
  of 
  east. 
  Between 
  the 
  crest 
  and 
  the 
  Dolores 
  there 
  is 
  a 
  slight 
  

   synclinal, 
  which 
  is 
  also 
  indicated 
  by 
  the 
  drainage. 
  

  

  Starting 
  from 
  the 
  San 
  Miguel 
  River, 
  a 
  short 
  distance 
  above 
  Its 
  mouth, 
  

   and 
  going 
  north 
  and 
  north\vest, 
  we 
  find 
  the 
  mesas 
  between 
  the 
  creeks 
  

   at 
  first 
  with 
  a 
  capping 
  of 
  'No. 
  1 
  Cretaceous. 
  This 
  gradually 
  disappears 
  

   as 
  we 
  approach 
  the 
  IJnaweep 
  Caiion, 
  and 
  north 
  of 
  it 
  the 
  red 
  sandstones 
  

   are 
  on 
  the 
  surface, 
  even 
  the 
  Jurassic 
  not 
  coming 
  in 
  again 
  until 
  we 
  ap- 
  

   proach 
  Grand 
  Eiver. 
  

  

  The 
  first 
  creek 
  flowing 
  into 
  the 
  Dolores 
  from 
  the 
  east, 
  north 
  of 
  

   the 
  San 
  Miguel, 
  rises 
  on 
  the 
  western 
  edge 
  of 
  the 
  crest 
  of 
  the 
  

   Uncompahgre 
  plateau 
  south 
  of 
  stations 
  28 
  and 
  32. 
  Between 
  the 
  

   head 
  of 
  this 
  creek 
  and 
  station 
  26 
  is 
  the 
  head 
  of 
  a 
  stream 
  flow- 
  

   ing 
  into 
  the 
  San 
  Miguel 
  just 
  above 
  its 
  mouth. 
  These 
  streams 
  cut 
  

   through 
  the 
  sedimentary 
  beds 
  to 
  the 
  archaean 
  rocks. 
  Cretaceous 
  

   No. 
  1, 
  caps 
  the 
  crest 
  dipping 
  towards 
  the 
  northeast. 
  As 
  we 
  go 
  

   from 
  station 
  20 
  to 
  station 
  27, 
  which 
  is 
  nearly 
  700 
  feet 
  lower, 
  we 
  pass 
  

   over 
  the 
  edges 
  of 
  Lower 
  Dakota 
  and 
  Jurassic 
  shales 
  until 
  at 
  station 
  27 
  

   we 
  are 
  on 
  the 
  red-beds, 
  the 
  upper 
  layers 
  of 
  which 
  are 
  light-colored. 
  

  

  