﻿248 
  REPORT 
  UNITED 
  STATES 
  GEOLOGICAL 
  SURVEY. 
  

  

  Group 
  (6, 
  general 
  section). 
  In 
  the 
  depression 
  between 
  the 
  two 
  mesas 
  

   we 
  have 
  therefore 
  the 
  following 
  section 
  : 
  

  

  1. 
  Escarpment 
  of 
  Pinon 
  Mesa, 
  lower 
  stratum 
  of 
  group 
  1 
  80 
  feet. 
  

  

  Soft, 
  yellowish, 
  coarse-grained, 
  cross-bedded 
  sandstone, 
  

   containing 
  layets 
  of 
  large 
  pebbles 
  of 
  quartz 
  and 
  other 
  rocks. 
  

   Very 
  slight 
  dip 
  to 
  the 
  east. 
  

  

  2. 
  Bad 
  Land 
  formation, 
  " 
  Puerco 
  7narls,^^ 
  group 
  2 
  : 
  . 
  . 
  800 
  feet. 
  

  

  Principally 
  soft 
  sand 
  clays 
  and 
  marls, 
  highly 
  colored 
  with 
  

   reds, 
  yellows, 
  and 
  purples, 
  growing 
  gray 
  below 
  and 
  contain- 
  

   ing 
  noiasses 
  of 
  soft 
  sandstone 
  and 
  at 
  the 
  base 
  grading 
  into 
  the 
  

   next 
  group. 
  

  

  Upper 
  Coal 
  series, 
  group 
  3 
  , 
  800 
  feet. 
  

  

  Four 
  hundred 
  feet 
  of 
  greenish 
  clay 
  with 
  beds 
  of 
  brown 
  

   sandstone; 
  200 
  feet 
  of 
  shale 
  with 
  beds 
  of 
  brown 
  sandstone 
  ; 
  

   250 
  feet 
  of 
  shale 
  and 
  shaly 
  sandstone 
  bearing 
  a 
  heavy 
  seam 
  

   of 
  soft, 
  brown 
  lignite, 
  apparently 
  about 
  30 
  feet 
  in 
  thickness. 
  

   The 
  dip 
  here 
  rises 
  to 
  20°. 
  

  

  Pictured 
  Cliff 
  sandstone, 
  group 
  4 
  130 
  feet. 
  

  

  Thirty 
  feet 
  white 
  sandstone, 
  followed 
  by 
  100 
  feet 
  of 
  brown- 
  

   ish 
  and 
  yellowish 
  sandstones 
  and 
  shales. 
  Dip 
  20° 
  ; 
  strike 
  

   somewhat 
  irregular. 
  

  

  Sand 
  shales 
  and 
  bedded 
  sandi, 
  group 
  5 
  350 
  feet. 
  

  

  Dip 
  falls 
  again 
  to 
  3° 
  or 
  4P. 
  These 
  are 
  followed 
  by 
  the 
  

   sandstones 
  of 
  the 
  Mesa 
  Verde. 
  

  

  Mesa 
  Verde, 
  Upper 
  Escarpment 
  sandstone, 
  group 
  6 
  140 
  feet. 
  

  

  One 
  hundred 
  and 
  forty 
  feet 
  of 
  yellowish, 
  fine-grained 
  

   sandstone, 
  bearing 
  a 
  few 
  seams 
  of 
  shale. 
  This 
  is 
  the 
  strong- 
  

   est 
  stratum, 
  excepting, 
  i^erhaps, 
  the 
  sandstones 
  of 
  the 
  Da- 
  

   kota 
  group, 
  in 
  my 
  entire 
  section, 
  and 
  where 
  it 
  remains 
  is 
  a 
  

   governing 
  element 
  in 
  the 
  topography 
  of 
  the 
  country 
  ; 
  rising 
  

   at 
  a 
  gentle 
  angle 
  from 
  the 
  low 
  country 
  of 
  the 
  La 
  Plata 
  val- 
  

   ley, 
  it 
  reaches 
  the 
  upper 
  level 
  of 
  the 
  Mesa 
  Verde 
  and 
  flattens 
  

   out 
  forming 
  the 
  floor, 
  or 
  rather 
  the 
  capping 
  stratum 
  of 
  that 
  

   mesa. 
  The 
  sloping 
  eastern 
  face 
  has 
  been 
  cut 
  by 
  a 
  number 
  

   of 
  sharp, 
  deep 
  canons, 
  which 
  drain 
  out 
  to 
  the 
  La 
  Plata 
  and 
  

   San 
  Juan. 
  In 
  these 
  the 
  strata 
  of 
  the 
  Middle 
  Goal 
  Group 
  are 
  

   exposed. 
  

  

  3i€sa 
  Verde, 
  Coal 
  Measures, 
  group 
  7 
  500 
  feet. 
  

  

  Following 
  the 
  escarpment 
  sandstones 
  are 
  200 
  feet 
  of 
  strata 
  in 
  which 
  

   lignite 
  and 
  carbonaceous 
  shale 
  seem 
  to 
  predominate 
  ; 
  bedded 
  irregu- 
  

   larly 
  with 
  these 
  are 
  many 
  irregular 
  seams 
  or 
  masses 
  of 
  soft 
  sandstones. 
  

   There 
  is 
  no 
  single 
  seam 
  of 
  coal 
  above 
  a 
  few 
  feet 
  in 
  thickness, 
  and 
  there 
  

   is 
  probably 
  no 
  workable 
  seam 
  in 
  the 
  whole 
  series. 
  

  

  There 
  is 
  a 
  remarkable 
  lack 
  of 
  persistency 
  in 
  individual 
  strata, 
  and 
  

   sections 
  taken 
  a 
  few 
  rods 
  apart 
  across 
  corresponding 
  horizon 
  would 
  

   resemble 
  each 
  other 
  only 
  in 
  the 
  most 
  general 
  features. 
  Beneath 
  the 
  

   coal 
  bearing 
  series 
  are 
  about 
  300 
  feet 
  of 
  irregularly 
  stratified 
  sandstones, 
  

   clays, 
  and 
  shales. 
  In 
  the 
  entire 
  section 
  no 
  fossils 
  sufficiently 
  well 
  pre- 
  

   served 
  for 
  identification 
  were 
  found 
  excepting 
  the 
  ordinary 
  Halymenites. 
  

  

  VALLEY 
  OF 
  THE 
  SAN 
  JUAN. 
  

  

  The 
  Eio 
  San 
  Juan 
  is 
  one 
  of 
  the 
  most 
  important 
  tributaries 
  of 
  the 
  Eio 
  

   Colorado, 
  and 
  joins 
  that 
  stream, 
  according 
  to 
  Professor 
  Powell, 
  in 
  

   Utah, 
  85 
  miles 
  west 
  of 
  the 
  Colorado 
  line 
  and 
  12 
  miles 
  north 
  of 
  the 
  north- 
  

   ern 
  border 
  of 
  Arizona. 
  It 
  is 
  some 
  200 
  miles 
  in 
  length, 
  and 
  flows 
  in 
  a 
  gen- 
  

  

  