﻿ExuLicH] 
  SANGRE 
  DE 
  CEISTO 
  CARBONIFEROUS. 
  117 
  

  

  distance 
  up 
  the 
  road, 
  where 
  they 
  strike 
  granite 
  with 
  their 
  edges, 
  but 
  after 
  

   that 
  is 
  passed 
  they 
  continue, 
  dipping 
  ia 
  the 
  same 
  direction 
  at 
  an 
  angle 
  

   of 
  about 
  30°. 
  Heavy 
  beds 
  of 
  a 
  blue 
  to 
  gray 
  limestone 
  here 
  set 
  in, 
  sepa- 
  

   rated 
  by 
  a 
  bed 
  of 
  dark-red 
  sandstone. 
  In 
  quality 
  and 
  texture 
  tlie 
  sand- 
  

   stones 
  of 
  this 
  pass 
  as 
  well 
  as 
  of 
  the 
  one 
  above 
  discussed 
  agree. 
  They 
  are 
  

   generally 
  of 
  middle 
  to 
  coarse 
  grain, 
  cemented 
  by 
  an 
  argillaceous 
  material. 
  

   Sometimes 
  the 
  cement 
  is 
  quartzitic. 
  Shaly 
  varieties 
  and 
  true 
  shales 
  are 
  

   not 
  wanting, 
  but 
  marls 
  do 
  not 
  occur, 
  so 
  far 
  as 
  I 
  have 
  observed. 
  As 
  we 
  

   proceed 
  eastward, 
  a 
  curious 
  curving 
  of 
  the 
  strata 
  takes 
  place, 
  no 
  doubt 
  

   in 
  some 
  connection 
  with 
  the 
  anticlinal 
  fold 
  farther 
  north. 
  Though 
  no 
  

   true 
  lold 
  of 
  that 
  kind, 
  the 
  effect 
  produced 
  is 
  virtually 
  the 
  same, 
  and 
  we 
  

   find 
  at 
  one 
  place 
  the 
  limestone 
  strata, 
  the 
  last 
  ones 
  in 
  the 
  upper 
  series, 
  

   dipping 
  at 
  an 
  angle 
  of 
  90°. 
  Prom 
  there 
  on, 
  however, 
  the 
  stratilicatiou 
  

   becomes 
  more 
  simple, 
  the 
  easterly 
  dip 
  gradually 
  diminishes, 
  until, 
  at 
  

   the 
  summit 
  of 
  the 
  Pass, 
  it 
  is 
  not 
  more 
  than 
  10° 
  to 
  12°. 
  A 
  section 
  will 
  

   explain 
  more 
  thoroughly 
  what 
  has 
  here 
  been 
  said. 
  (Section 
  II.) 
  We 
  

   have 
  in 
  it 
  but 
  the 
  three 
  rocks, 
  metamorphic, 
  granite 
  (a), 
  red 
  sandstone 
  

   with 
  its 
  quartzoseaud 
  shaly 
  varieties 
  {h), 
  and 
  limestone 
  (c). 
  The 
  latter 
  

   weathers 
  into 
  small 
  angular 
  fragments 
  in 
  part, 
  in 
  part 
  it 
  forms 
  large 
  

   bowlders 
  that 
  show, 
  upon 
  being 
  exposed 
  to 
  atmospheric 
  influences, 
  the 
  

   presence 
  of 
  silica, 
  in 
  the 
  shape 
  of 
  either 
  irregular 
  nodules 
  or 
  small 
  ramify- 
  

   ing 
  veins. 
  The 
  granite 
  is 
  red, 
  coarse-grained, 
  closely 
  resembling 
  in 
  its 
  

   lithological 
  constitution 
  that 
  of 
  station 
  6. 
  It 
  seems 
  probable, 
  that 
  the 
  

   very 
  heavy 
  mass 
  of 
  limestones 
  (d) 
  beyond 
  the 
  granitic 
  outcrop 
  may 
  

   correspond 
  to 
  ^7 
  of 
  Section 
  I, 
  but 
  it 
  was 
  impossible 
  to 
  trace 
  the 
  connec- 
  

   tion 
  from 
  a 
  distance 
  on 
  account 
  of 
  the 
  tery 
  dense 
  timber 
  covering 
  the 
  

   intervening 
  space. 
  It 
  is 
  in 
  this 
  limestone 
  that 
  the 
  apparent 
  anticlinal 
  

   occurs, 
  just 
  before 
  the 
  heaviest 
  beds 
  of 
  the 
  sandstone 
  set 
  in. 
  Owing 
  to 
  

   probably 
  a 
  slight 
  admixture 
  of 
  manganese, 
  a 
  portion 
  of 
  the 
  limestones 
  

   that 
  has 
  for 
  a 
  long 
  time 
  been 
  exposed 
  shows 
  a 
  very 
  dark 
  color, 
  strangely 
  

   in 
  contrast 
  with 
  the 
  bright 
  red 
  of 
  the 
  succeeding 
  sandstones. 
  All 
  

   through 
  the 
  limestones 
  represented 
  in 
  the 
  above 
  section 
  Carboniferous 
  

   fossils 
  were 
  found, 
  consisting 
  chiefly 
  of 
  the 
  species 
  Productus 
  semireticu- 
  

   latiis 
  and 
  Athyris 
  subtilita, 
  Spirifers^ 
  &c. 
  Not 
  only 
  do 
  they 
  occur 
  in 
  

   the 
  heavy 
  beds, 
  but 
  also 
  in 
  the 
  tbin 
  interstrata 
  between 
  the 
  sandstones. 
  

   Taking 
  into 
  consideration 
  this 
  fact, 
  together 
  with 
  the 
  occurrences 
  in 
  

   Sangre 
  de 
  Cristo 
  Pass, 
  there 
  is 
  left 
  no 
  doubt 
  in 
  my 
  mind 
  as 
  to 
  the 
  age 
  

   of 
  the 
  sandstones, 
  and 
  the 
  stand-point 
  taken 
  with 
  reference 
  thereto 
  in 
  

   1873 
  appears 
  to 
  be 
  fully 
  justified. 
  It 
  is 
  desirable 
  that 
  quarrying 
  should 
  

   be 
  done 
  in 
  the 
  sandstone 
  itself, 
  which, 
  I 
  presume, 
  would 
  lead 
  to 
  the 
  dis- 
  

   covery 
  of 
  Carboniferous 
  plants. 
  As 
  it 
  readily 
  yields 
  both 
  to 
  disin- 
  

   tegration 
  and 
  erosion, 
  the 
  delicate 
  impressions 
  left 
  by 
  ferns, 
  &e., 
  may 
  

   rapidly 
  be 
  effaced. 
  Faint 
  traces 
  resembling 
  plants, 
  more 
  particularly 
  

   Catamites 
  and 
  Sigillaria, 
  were 
  observed, 
  but 
  were 
  too 
  doubtful 
  to 
  be 
  ad- 
  

   mitted 
  as 
  positive 
  evidence. 
  

  

  East 
  of 
  station 
  114, 
  on 
  the 
  west 
  side 
  of 
  the 
  Sangre 
  de 
  Cristo 
  Eange, 
  

   the 
  red 
  sandstone 
  covers 
  a 
  considerable 
  area. 
  Numerous 
  strata 
  of 
  blue 
  

   limestone 
  are 
  inclosed 
  between 
  the 
  sandstones. 
  These 
  former 
  show 
  fos- 
  

   sils 
  in 
  abundance 
  : 
  Productus, 
  OrtMs, 
  Spirifer, 
  Crinoids^ 
  &c. 
  No 
  defi- 
  

   nite 
  arrangement 
  of 
  the 
  relative 
  position 
  of 
  limestones 
  could 
  be 
  deter- 
  

   mined, 
  and 
  it 
  seems 
  probable 
  that 
  they 
  were 
  deposited 
  v^herever 
  the 
  

   conditions 
  for 
  precipitation 
  and 
  conservation 
  were 
  most 
  favorable. 
  

  

  From 
  Indian 
  Creek 
  Pass, 
  the 
  elevation 
  of 
  which 
  is 
  9,774 
  feet, 
  the 
  red 
  

   sandstone 
  continues 
  southward 
  in 
  an 
  unbroken 
  line, 
  flanking 
  the 
  granite 
  

   of 
  the 
  range. 
  Its 
  strata 
  dip 
  due 
  west, 
  with 
  some 
  local 
  variation, 
  pro- 
  

   duced 
  either 
  by 
  recent 
  dislocations 
  or 
  such 
  disturbances 
  as 
  may 
  be 
  due 
  

  

  