﻿PEALE] 
  UNCOMPAHGRE 
  PLATEAU— 
  KIO 
  DOLORES. 
  5o 
  

  

  and 
  heads 
  farther 
  back 
  ia 
  the 
  crest, 
  and 
  the 
  following 
  additional 
  beds 
  

   appear 
  beneath 
  : 
  

  

  5. 
  Blood-red 
  sandstones, 
  with 
  shales. 
  

  

  6. 
  Purplish 
  shales. 
  

  

  Between 
  the 
  two 
  creeks 
  just 
  referred 
  to, 
  the 
  continuity 
  of 
  the 
  Da- 
  

   kota 
  sandstone 
  (No. 
  1 
  in 
  the 
  section 
  jast 
  given) 
  is 
  broken, 
  and 
  on 
  the 
  

   west 
  side 
  of 
  the 
  fold 
  it 
  dips 
  steeply 
  to 
  tbe 
  west. 
  

  

  On 
  the 
  north 
  sideof 
  the 
  last-mentioned 
  creek 
  it 
  is 
  tipped 
  5° 
  past 
  the 
  ver- 
  

   tical, 
  (Fig. 
  1, 
  Plate 
  III,) 
  but 
  soon 
  regains 
  Its 
  original 
  inclination, 
  and 
  flat- 
  

   tens 
  out 
  on 
  the 
  San 
  Miguel 
  plateau, 
  which 
  in 
  this 
  region 
  consists 
  of 
  me- 
  

   sas 
  between 
  tbe 
  different 
  streams 
  tributary 
  to 
  the 
  San 
  Miguel. 
  The 
  

   upturned 
  edge 
  of 
  the 
  Dakota 
  sandstone 
  continues 
  for 
  some 
  distance 
  to 
  

   the 
  northwest, 
  the 
  strike 
  being 
  parallel 
  to 
  the 
  direction 
  of 
  the 
  crest. 
  In 
  

   many 
  places 
  there 
  appears 
  to 
  be 
  faulting, 
  with 
  the 
  edges 
  of 
  the 
  beds 
  

   thrown 
  down, 
  dragged 
  up, 
  so 
  that 
  it 
  is 
  difficult 
  at 
  first 
  sight 
  to 
  say 
  

   whether 
  there 
  is 
  simply 
  a 
  fault 
  or 
  an 
  abrupt 
  fold. 
  Farther 
  to 
  the 
  north, 
  

   however, 
  there 
  is 
  not 
  room 
  for 
  the 
  fold, 
  and 
  the 
  fault 
  is 
  more 
  plainly 
  

   seen. 
  The 
  ends 
  of 
  the 
  strata 
  that 
  are 
  dragged 
  up 
  dip 
  steeply 
  to 
  the 
  

   westward 
  and 
  -in 
  places 
  are 
  tipped 
  past 
  the 
  vertical. 
  

  

  Near 
  stations 
  27 
  and 
  28 
  the 
  line 
  of 
  outcrop 
  of 
  the 
  upturned 
  Dakota 
  

   sandstones 
  has 
  receded 
  to 
  the 
  westward, 
  and 
  the 
  upper 
  portion 
  of 
  the 
  

   group 
  forms 
  the 
  capping 
  of 
  mesas 
  between 
  the 
  branches 
  of 
  the 
  Sau 
  

   Miguel. 
  

  

  Both 
  stations 
  27 
  and 
  28 
  are 
  just 
  below 
  the 
  crest 
  of 
  the 
  Uncompahgre 
  

   plateau, 
  on 
  the 
  upper 
  part 
  of 
  the 
  red 
  beds, 
  (Triassic 
  "?.) 
  These 
  red 
  beds 
  

   rest 
  directly 
  on 
  the 
  granite. 
  West 
  of 
  the 
  stations, 
  and 
  at 
  a 
  lower 
  level, 
  

   the 
  edges 
  of 
  Jurassic 
  strata 
  are 
  exposed, 
  dipping 
  at 
  a 
  sharp 
  angle 
  to 
  

   the 
  westward, 
  and 
  also 
  resting 
  on 
  the 
  granite. 
  Here 
  we 
  will 
  leave 
  the 
  

   crest 
  of 
  the 
  Uncompahgre 
  plateau, 
  and 
  reserve 
  further 
  description 
  of 
  

   it 
  for 
  description 
  under 
  the 
  head 
  of 
  the 
  Dolores 
  Eiver, 
  as 
  it 
  overlooks 
  

   that 
  stream. 
  

  

  The 
  description 
  of 
  the 
  country 
  west 
  of 
  the 
  San 
  Miguel, 
  extending 
  to 
  

   the 
  Dolores, 
  will 
  have 
  to 
  be 
  reserved 
  until 
  it 
  is 
  more 
  thoroughly 
  inves- 
  

   tigated. 
  Enough 
  was 
  seen 
  to 
  demonstrate 
  the 
  presence 
  of 
  several 
  folds 
  

   whose 
  axes 
  are 
  approximately 
  northwest 
  and 
  southeast. 
  Immediately 
  

   west 
  of 
  the 
  San 
  Miguel 
  the 
  plateau 
  appears 
  to 
  rise 
  toward 
  the 
  west, 
  

   to 
  the 
  western 
  side 
  of 
  an 
  anticlinal 
  fold 
  that 
  is 
  low 
  and 
  broad. 
  There 
  

   is 
  also 
  a 
  slope 
  from 
  the 
  mountains 
  toward 
  the 
  north. 
  Near 
  the 
  mount- 
  

   ains 
  there 
  are 
  remnants 
  of 
  the 
  Cretaceous 
  shales 
  resting 
  on 
  the 
  Dakota 
  

   sandstones. 
  

  

  DOLORES 
  RIVER. 
  

  

  The 
  Eio 
  Dolores 
  has 
  its 
  origin 
  in 
  two 
  large 
  streams 
  that 
  rise 
  in 
  the 
  

   northwestern 
  part 
  of 
  the 
  San 
  Juan 
  Mountains. 
  The 
  North 
  Fork 
  risesiu 
  

   the 
  southern 
  face 
  of 
  the 
  group 
  named 
  San 
  Miguel 
  Mountains, 
  and 
  the 
  

   South 
  Fork 
  or 
  Bear 
  Eiver 
  drains 
  the 
  Bear 
  Eiver 
  group 
  of 
  mountains 
  and 
  

   the 
  country 
  between 
  it 
  and 
  the 
  La 
  Plata 
  Mountains. 
  The 
  course 
  of 
  the 
  

   Dolores 
  after 
  the 
  junction 
  of 
  the 
  two 
  forks 
  is 
  south. 
  It 
  then 
  turns 
  ab- 
  

   ruptly 
  west, 
  and 
  next 
  flows 
  north 
  a 
  short 
  distance, 
  and 
  then 
  to 
  the 
  north- 
  

   west 
  as 
  far 
  as 
  it 
  has 
  been 
  definitely 
  located 
  in 
  latitude 
  37° 
  45', 
  and 
  lon- 
  

   gitude 
  108° 
  45'. 
  Beyond 
  this 
  is 
  a 
  gap 
  in 
  the 
  work 
  of 
  30 
  miles 
  in 
  an 
  air- 
  

   line. 
  In 
  this, 
  however, 
  its 
  general 
  course 
  is 
  probably 
  northwest, 
  for 
  

   where 
  we 
  leave 
  it 
  and 
  where 
  we 
  take 
  it 
  up 
  again 
  that 
  is 
  the 
  direction 
  in. 
  

   "which 
  it 
  is 
  flowing. 
  

  

  The 
  geology 
  of 
  the 
  Upper 
  Dolores 
  and 
  its 
  tributaries 
  will 
  be 
  fully 
  de- 
  

   tailed 
  in 
  Mr. 
  Holmes's 
  report. 
  Suffice 
  it 
  to 
  state 
  here 
  that 
  the 
  rocks 
  

  

  