﻿468 
  J. 
  Bar 
  veil 
  — 
  Upper 
  Devonian 
  Delta 
  of 
  the 
  

  

  Inferences 
  Regarding 
  Climate. 
  

  

  The 
  relations 
  between 
  climate 
  and 
  terrestrial 
  deposits 
  have 
  

   been 
  discussed 
  by 
  the 
  writer 
  elsewhere,* 
  and 
  the 
  conclusions 
  

   reached 
  in 
  that 
  paper 
  will 
  be 
  utilized 
  as 
  a 
  point 
  of 
  departure 
  

   in 
  this. 
  

  

  The 
  idea, 
  which 
  may 
  be 
  traced 
  to 
  Russell, 
  that 
  red 
  in 
  sedi- 
  

   ments 
  is 
  a 
  mark 
  of 
  derivation 
  from 
  a 
  deeply 
  decayed 
  regolith, 
  

   has 
  widely 
  pervaded 
  American 
  geological 
  literature 
  and 
  com- 
  

   petes 
  with 
  the 
  European 
  view 
  that 
  red 
  is 
  significant 
  of 
  ancient 
  

   aridity. 
  The 
  first 
  interpretation 
  has 
  been 
  adopted 
  by 
  Willis 
  

   in 
  his 
  reconstruction 
  of 
  Upper 
  Devonian 
  times 
  ; 
  the 
  second 
  

   has 
  been 
  utilized 
  by 
  a 
  number 
  of 
  British 
  and 
  Continental 
  geolo- 
  

   gists 
  who 
  have 
  written 
  of 
  the 
  Devonian 
  deserts 
  of 
  Europe 
  as 
  

   recorded 
  by 
  the 
  Old 
  Red 
  Sandstone. 
  The 
  redness 
  of 
  the 
  

   Devonian 
  rocks 
  of 
  northwestern 
  Europe, 
  made 
  of 
  waste 
  from 
  

   northwestern 
  lands 
  now 
  largely 
  under 
  the 
  sea, 
  has 
  led 
  Walther 
  

   to 
  name 
  this 
  now 
  dismembered 
  continent, 
  " 
  the 
  Old 
  Red 
  North- 
  

   land." 
  But 
  the 
  present 
  writer 
  has 
  argued 
  elsewheref 
  at 
  length 
  

   that 
  redness 
  in 
  rocks 
  is 
  not 
  necessarily 
  evidence 
  of 
  redness 
  of 
  

   the 
  original 
  sediment 
  ; 
  the 
  latter 
  may 
  have 
  been 
  red, 
  brown, 
  

   yellow, 
  or 
  yellowish 
  gray. 
  All 
  that 
  is 
  necessary 
  is 
  the 
  presence 
  

   of 
  ferric 
  oxide, 
  hydrous 
  or 
  anhydrous. 
  If 
  in 
  the 
  course 
  of 
  

   geologic 
  time 
  the 
  water 
  is 
  driven 
  out, 
  the 
  coloring 
  matter 
  will 
  

   necessarily 
  become 
  red. 
  Furthermore, 
  certain 
  red 
  rock 
  forma- 
  

   tions 
  have 
  originated 
  under 
  conditions 
  which 
  show 
  that 
  high 
  

   rainfall 
  with 
  seasonal 
  dryness 
  is 
  competent 
  to 
  produce 
  this 
  

   color 
  as 
  well 
  as 
  aridity. 
  Other 
  formations 
  show 
  that 
  rapid 
  

   mechanical 
  erosion, 
  with 
  imperfect 
  decay, 
  may 
  be 
  associated 
  

   with 
  redness 
  as 
  well 
  as 
  the 
  contrary 
  condition 
  of 
  deep 
  decay 
  

   over 
  a 
  land 
  of 
  low 
  relief. 
  In 
  fact 
  the 
  latter 
  is 
  probably 
  the 
  

   least 
  common 
  condition 
  associated 
  with 
  thick 
  formations 
  of 
  

   red 
  sandstone 
  and 
  shale. 
  To 
  cite 
  a 
  few 
  examples 
  which 
  bear 
  

   out 
  these 
  statements 
  of 
  varied 
  conditions 
  of 
  origin 
  : 
  It 
  is 
  seen 
  

   that 
  the 
  Amazon 
  and 
  the 
  Congo 
  are 
  now 
  depositing 
  red 
  marine 
  

   muds 
  off 
  their 
  mouths 
  from 
  climatic 
  regions 
  marked 
  by 
  tropic 
  

   heat 
  and 
  seasonal 
  rainfall. 
  The 
  Potomac 
  formations 
  of 
  the 
  

   Atlantic 
  Coastal 
  Plain, 
  of 
  Comanchean 
  age, 
  are 
  marked 
  by 
  

   brilliant 
  red 
  and 
  orange 
  beds 
  associated 
  with 
  blue 
  and 
  white 
  

   clays 
  and 
  abundant 
  plant 
  remains. 
  The 
  Newark 
  formations 
  

   of 
  Triassic 
  age 
  are 
  red 
  to 
  brown 
  sandstones 
  and 
  shales 
  with 
  

   much 
  feldspar 
  and 
  muscovite 
  showing 
  imperfect 
  decomposition. 
  

   Coal 
  beds 
  occur 
  in 
  this 
  terrane 
  in 
  Virginia 
  and 
  North 
  Carolina. 
  

   The 
  Siwalik 
  formations 
  of 
  India 
  contain 
  a 
  fossil 
  record 
  which 
  

   disproves 
  aridity 
  and 
  accumulated 
  under 
  physiographic 
  con- 
  

  

  * 
  Jour. 
  Geol., 
  xvi, 
  1908, 
  pp. 
  159-190, 
  255-295, 
  363-384. 
  

  

  •f-The 
  Climatic 
  Significance 
  of 
  Color. 
  Jour. 
  Geol., 
  xvi, 
  1908, 
  pp. 
  285-294. 
  

  

  