﻿462 
  J. 
  Bar 
  veil 
  — 
  Upper 
  Devonian 
  Delta 
  of 
  the 
  

  

  are 
  more 
  nearly 
  balanced 
  in 
  this 
  transition 
  zone 
  than 
  in 
  the 
  

   true 
  Catskill 
  above, 
  as 
  shown 
  by 
  the 
  green 
  filling 
  of 
  some 
  of 
  

   the 
  mud-cracked 
  red 
  shales 
  and 
  the 
  tendency 
  to 
  variegation 
  in 
  

   color 
  in 
  these 
  basal 
  beds. 
  The 
  upper 
  Catskill 
  in 
  this 
  section 
  is 
  

   not 
  favorably 
  exposed 
  for 
  study. 
  The 
  shales 
  are 
  sandy 
  and 
  have 
  

   crumbled 
  in 
  weathering 
  until 
  the 
  original 
  characters 
  have 
  

   become 
  destroyed, 
  but 
  the 
  more 
  significant 
  base 
  was 
  still 
  at 
  

  

  Fig. 
  4. 
  

  

  Bedding 
  plane, 
  upper 
  surface 
  

  

  Irregular 
  sechon 
  ar 
  right-angles 
  to 
  Ismi-rificarion 
  

  

  Fig. 
  4. 
  Kootmarks 
  in 
  red 
  argillaceous 
  sandstone. 
  Lower 
  Catskill, 
  near 
  

   Frostburg, 
  Maryland. 
  The 
  fracture 
  surface 
  which 
  exposes 
  these 
  rootlets 
  

   is 
  irregular 
  but 
  roughly 
  at 
  right 
  angles 
  to 
  the 
  bedding 
  plane. 
  

  

  this 
  time 
  well 
  exposed 
  by 
  the 
  tunneling 
  and 
  cutting 
  for 
  the 
  

   railroad. 
  

  

  These 
  observations 
  from 
  Pennsylvania 
  to 
  Maryland 
  show 
  

   the 
  widespread 
  development 
  of 
  the 
  marks 
  of 
  subaerial 
  exposure 
  

   through 
  the 
  red 
  beds 
  of 
  the 
  Catskill. 
  Thev 
  are 
  not 
  marginal 
  

   or 
  shoreward 
  developments 
  within 
  the 
  Catskill, 
  but 
  may 
  occur 
  

   as 
  widely 
  as 
  the 
  red 
  rocks 
  themselves. 
  It 
  required 
  special 
  char- 
  

   acters 
  of 
  beds, 
  however, 
  to 
  clearly 
  preserve 
  the 
  cracks 
  in 
  the 
  

   original 
  deposition 
  and 
  fresh 
  exposures 
  are 
  necessary 
  for 
  their 
  

   observation. 
  The 
  red 
  color 
  is, 
  however, 
  something 
  which 
  is 
  

   not 
  readily 
  destroyed, 
  being 
  inherited 
  even 
  in 
  the 
  soil, 
  and 
  in 
  

   this 
  particular 
  formation, 
  in 
  widely 
  separated 
  localities, 
  it 
  is 
  

   seen 
  to 
  mark 
  the 
  disappearance 
  of 
  marine 
  faunas 
  in 
  gray 
  or 
  

   olive 
  shales 
  and 
  the 
  appearance 
  of 
  the 
  marks 
  of 
  subaerial 
  

   exposure. 
  Following 
  the 
  criteria 
  previously 
  discussed, 
  the 
  red 
  

   shales 
  mark, 
  in 
  the 
  Upper 
  Devonian 
  physiography 
  of 
  the 
  

   Appalachian 
  region, 
  the 
  subaerial 
  plain 
  of 
  a 
  far-reaching 
  delta. 
  

  

  