﻿252 
  REPORT 
  UNITED 
  STATES 
  GEOLOGICAL 
  SURVEY. 
  

  

  Lower 
  Escarpment, 
  and 
  the 
  Goal 
  Gronp 
  series 
  occupies 
  the 
  slope 
  

   between. 
  

  

  The 
  section 
  of 
  the 
  Mesa 
  Verde 
  Group 
  as 
  exposed 
  in 
  the 
  Hogback 
  just 
  

   north 
  of 
  the 
  river 
  is 
  as 
  follows 
  : 
  ' 
  

  

  Upper 
  Escarpment 
  sandstone, 
  group 
  6 
  200 
  feet. 
  

  

  Yellowish-brown 
  massive 
  sandstone, 
  with 
  impressions 
  

   of 
  Ralymenites. 
  

   Middle 
  Goal-measures, 
  group 
  7. 
  

  

  90 
  feet 
  clay 
  shale 
  and 
  shaly 
  sandstone. 
  

   8 
  feet 
  orange-colored 
  sandstone. 
  

   8 
  feet 
  sandy 
  shales. 
  

  

  16 
  feet 
  sandstone, 
  with 
  seams 
  of 
  clay 
  and 
  lignite. 
  

   10 
  feet 
  arenaceous 
  clays 
  and 
  shales. 
  

  

  30 
  feetlignitic 
  beds, 
  containing 
  many 
  seams 
  of 
  fire-clay, 
  shale, 
  and 
  

   sandstone. 
  

  

  100 
  feet 
  calcareous 
  sandstones, 
  with 
  thin 
  seams 
  of 
  limestone 
  and 
  

   beds 
  of 
  iron 
  concretions. 
  

  

  375 
  feet 
  greenish, 
  purplish, 
  and 
  gray 
  clays, 
  containing 
  many 
  irregu- 
  

   lar 
  seams 
  of 
  sandstone, 
  shales, 
  and 
  concreDionary 
  seams 
  of 
  iron 
  ore 
  

   and 
  limestone 
  ; 
  also, 
  some 
  coal 
  indications. 
  

  

  5 
  feet 
  sandstones, 
  containing 
  fossil 
  leaves.* 
  Fossil 
  horizon 
  I^o. 
  4. 
  

   40 
  feet 
  clays 
  and 
  calcareous 
  shales, 
  with 
  stratum 
  at 
  base, 
  containing 
  

   fossil 
  leaves. 
  Fossil 
  horizon 
  No. 
  5. 
  

   30 
  feet 
  be^s 
  of 
  shale, 
  with 
  thin 
  coal 
  seams. 
  

   30 
  feet 
  sandstones, 
  with 
  seams 
  of 
  clay 
  shale. 
  

  

  Lower 
  Escarpment 
  sandstones, 
  group 
  8 
  180 
  feet. 
  

  

  100 
  feet 
  massive 
  fine-grained 
  sandstone, 
  whitish 
  above. 
  

   80 
  feet 
  yellowish 
  sandstones, 
  alternating 
  with 
  shales, 
  containing 
  

   Inoceramus 
  Barabini, 
  Tellina 
  scitula, 
  and 
  Trapezium 
  truncatum. 
  Fossil 
  

   horizon 
  No. 
  5. 
  

  

  Beneath 
  this 
  comes 
  the 
  great 
  series 
  of 
  Middle 
  Cretaceous 
  shales. 
  

   Before 
  completing 
  this 
  section 
  I 
  became 
  impressed 
  with 
  the 
  seeming 
  

   correspondence 
  between 
  certain 
  of 
  its 
  members 
  and 
  portions 
  of 
  the 
  sec- 
  

   tion 
  farther 
  up 
  the 
  river. 
  I 
  immediately 
  set 
  to 
  work 
  to 
  determine, 
  if 
  

   possible, 
  whether 
  or 
  not 
  a 
  displacement 
  and 
  consequent 
  duplication 
  

   occurred. 
  As 
  this 
  is 
  a 
  matter 
  of 
  considerable 
  interest 
  and 
  has 
  an 
  im- 
  

   portant 
  bearing 
  upon 
  the 
  vertical 
  extent 
  and 
  distribution 
  of 
  the 
  strata, 
  

   I 
  shall 
  give 
  here 
  all 
  the 
  more 
  important 
  facts 
  bearing 
  upon 
  it. 
  If 
  a 
  fault 
  

   occurs, 
  it 
  is 
  certainly 
  along 
  the 
  axis 
  of 
  the 
  San 
  Juan 
  fold, 
  which 
  fold 
  I 
  

   have 
  traced 
  entirely 
  across 
  my 
  district 
  without 
  being 
  able 
  to 
  detect 
  a 
  

   displacement. 
  The 
  exposures 
  of 
  the 
  strata 
  are 
  more 
  than 
  ordinarily 
  

   complete, 
  and 
  there 
  is 
  no 
  place 
  between 
  the 
  mouth 
  of 
  the 
  La 
  Plata 
  and 
  

   the 
  gateway 
  through 
  the 
  Great 
  Hogback, 
  in 
  which 
  the 
  strata 
  cannot 
  

   clearly 
  be 
  traced. 
  A 
  sudden 
  change 
  of 
  dip 
  occurs 
  along 
  the 
  east 
  base 
  

   of 
  the 
  Hogback, 
  (see 
  Fig. 
  1, 
  Plate 
  XXXVIII), 
  but 
  it 
  is 
  apparently 
  not 
  

   associated 
  with 
  any 
  dislocation. 
  Yet 
  there 
  is 
  a 
  marked 
  similarity 
  between 
  

   the 
  outcrops 
  east 
  and 
  west 
  of 
  this 
  fold, 
  sufiQcient 
  at 
  least 
  to 
  cause 
  one 
  to 
  

   suspect 
  that 
  a 
  fault 
  may 
  have 
  occurred 
  having 
  the 
  downthrow 
  on 
  the 
  west 
  

   as 
  is 
  indicated 
  in 
  Plate 
  XXXVIII, 
  Fig. 
  2, 
  by 
  which 
  there 
  would 
  be 
  a 
  

   double 
  outcrop 
  of 
  the 
  Mesa 
  Verde 
  Group. 
  The 
  Lower 
  Escarpment 
  Group 
  

   (8) 
  resembles 
  the 
  Pictured 
  Cliff 
  Group 
  (4), 
  and 
  beneath 
  each 
  is 
  a 
  bed 
  of 
  

   brown 
  sandstone 
  containing 
  fossils; 
  a 
  few 
  species 
  are 
  common 
  to 
  both 
  

   horizons. 
  Above 
  each 
  of 
  these 
  sandstone 
  groups 
  is 
  a 
  group 
  of 
  coal- 
  

  

  'Described 
  in 
  Report 
  of 
  United 
  States 
  Geological 
  and 
  Geographical 
  Survey 
  of 
  the 
  

   Territories 
  for 
  1874, 
  page 
  360. 
  

  

  