﻿Appalachian 
  Geosyncline. 
  469 
  

  

  ditions 
  which 
  disprove 
  derivation 
  from 
  the 
  deep 
  regolith 
  of 
  

   a 
  mature 
  topography. 
  The 
  red 
  clays 
  of 
  the 
  Siwalik 
  were 
  on 
  

   the 
  contrary 
  laid 
  down 
  under 
  comparatively 
  similar 
  conditions 
  

   to 
  those 
  which 
  now 
  give 
  rise 
  to 
  the 
  lighter-colored 
  alluvium 
  of 
  

   the 
  Indo-Gangetic 
  flood 
  plain, 
  or 
  the 
  yellow 
  floods 
  of 
  the 
  

   Chinese 
  rivers, 
  or 
  the 
  muddy 
  waters 
  of 
  the 
  American 
  Missouri. 
  

   Lastly, 
  the 
  frequent 
  association 
  of 
  red 
  beds 
  with 
  salt 
  and 
  gyp- 
  

   .sum 
  shows 
  especially 
  in 
  the 
  Permian 
  that 
  redness 
  frequently 
  

   accompanies 
  aridity. 
  

  

  The 
  determination 
  of 
  the 
  climatic 
  conditions 
  under 
  which 
  a 
  

   terrestrial 
  formation 
  was 
  laid 
  down 
  must 
  therefore 
  depend 
  

   upon 
  the 
  analysis 
  of 
  a 
  combination 
  of 
  characters, 
  and 
  this 
  

   becomes 
  especially 
  necessary 
  when 
  the 
  marks 
  of 
  climatic 
  

   extremes, 
  as 
  glacial 
  deposits 
  on 
  the 
  one 
  hand, 
  or 
  evaporation 
  

   deposits 
  on 
  the 
  other, 
  are 
  absent 
  from 
  the 
  formation. 
  

  

  Turning 
  to 
  those 
  features 
  of 
  the 
  Upper 
  Devonian 
  delta 
  

   which 
  are 
  significant 
  as 
  to 
  climate, 
  the 
  most 
  broadly 
  distinctive 
  

   is 
  the 
  characteristic 
  redness 
  of 
  the 
  Catskill 
  shales, 
  and 
  the 
  gray 
  

   or 
  green 
  colors 
  of 
  the 
  cleaner 
  sandstone 
  members. 
  In 
  this 
  

   the 
  Catskill 
  resembles 
  the 
  Siwalik 
  formation 
  and 
  could 
  have 
  

   been 
  deposited 
  under 
  similar 
  physiographic 
  and 
  climatic 
  con- 
  

   ditions 
  to 
  those 
  prevailing 
  in 
  northern 
  India 
  in 
  Neocene 
  times, 
  

   rapid 
  erosion 
  in 
  high 
  mountains, 
  deposition 
  on 
  river 
  plains 
  

   marked 
  by 
  warmth 
  and 
  seasonal 
  rainfall. 
  

  

  The 
  red 
  shales 
  are 
  associated 
  especially 
  with 
  mud-cracking, 
  

   and 
  by 
  contrast 
  with 
  the 
  gray 
  and 
  olive 
  shales 
  of 
  the 
  Chemung 
  

   show 
  that 
  the 
  oxidation 
  was 
  due 
  to 
  periodic 
  drying 
  of 
  the 
  flood 
  

   plain 
  and 
  aeration 
  of 
  the 
  soil. 
  The 
  lack 
  of 
  oxidation 
  of 
  the 
  

   iron 
  in 
  the 
  sandstones, 
  in 
  spite 
  of 
  its 
  lesser 
  quantity, 
  suggests 
  

   that 
  more 
  abundant 
  ground-waters 
  in 
  the 
  sands 
  may 
  have 
  kept 
  

   out 
  the 
  air 
  and 
  permitted 
  the 
  organic 
  matter 
  to 
  accomplish 
  its 
  

   effects, 
  or 
  perhaps 
  that 
  here 
  the 
  ratio 
  of 
  organic 
  matter 
  was 
  in 
  

   excess 
  of 
  the 
  ferric 
  oxide. 
  The 
  oxidizing 
  conditions 
  in 
  general 
  

   were 
  nearly 
  balanced 
  by 
  those 
  of 
  deoxidation 
  as 
  seen 
  by 
  the 
  

   contrast 
  in 
  color 
  of 
  the 
  shales 
  deposited 
  under 
  permanent 
  

   water 
  and 
  the 
  yellow 
  or 
  green 
  pattern 
  occasionally 
  observed 
  in 
  

   the 
  filling 
  of 
  mud-cracks. 
  

  

  A 
  few 
  rare 
  carbonaceous 
  streaks 
  have 
  been 
  observed 
  in 
  the 
  

   Catskill 
  and 
  the 
  plant 
  impressions 
  are 
  in 
  places 
  found 
  in 
  deoxi- 
  

   dized 
  shales. 
  Coaly 
  and 
  pyritiferous 
  plant 
  fossils 
  are 
  also 
  pre- 
  

   served 
  in 
  some 
  of 
  the 
  olive 
  sandstones. 
  In 
  other 
  strata 
  mere 
  

   lustrous 
  red 
  streaks 
  show 
  the 
  marks 
  of 
  vegetation, 
  implying 
  

   that 
  the 
  oxidation 
  of 
  the 
  organic 
  matter 
  was 
  commonly 
  by 
  the 
  

   free 
  oxygen 
  of 
  the 
  air, 
  since 
  the 
  destruction 
  of 
  the 
  organic 
  

   matter 
  did 
  not 
  deoxidize 
  the 
  adjacent 
  ferric 
  oxide. 
  

  

  The 
  climatic 
  conditions 
  of 
  the 
  Upper 
  Devonian 
  were 
  equable 
  

   and 
  widespread 
  as 
  seen 
  by 
  the 
  similarity 
  of 
  deposits 
  and 
  of 
  

  

  