﻿Appalachian 
  Geosyncline. 
  

  

  461 
  

  

  such 
  as 
  is 
  common 
  in 
  the 
  Mauch 
  Chunk 
  and 
  Newark 
  forma- 
  

   tions. 
  On 
  a 
  number 
  of 
  the 
  surfaces 
  the 
  larger 
  patterns 
  of 
  

   cracks 
  are 
  gray-green, 
  contrasting 
  strongly 
  with 
  the 
  red 
  poly 
  

   gons. 
  On 
  one 
  of 
  these 
  the 
  smaller 
  secondary 
  cracks 
  on 
  the 
  

   same 
  surface 
  were 
  red, 
  contrasting 
  with 
  the 
  gray-green 
  of 
  the 
  

   larger 
  cracks. 
  One 
  of 
  these 
  mud-cracked 
  surfaces 
  is 
  shown 
  in 
  

   fig. 
  3, 
  taken 
  close 
  to 
  the 
  bottom 
  of 
  the 
  red 
  shale. 
  

  

  Fig. 
  3. 
  

  

  - 
  - 
  

  

  • 
  

  

  ?.■■■'■ 
  

   - 
  , 
  : 
  ... 
  . 
  

  

  

  

  

  

  fw 
  :; 
  ¥ 
  !? 
  l&5l 
  

  

  ■■■Vv 
  

  

  '"" 
  -• 
  iff**! 
  

  

  Fig. 
  3. 
  Mud 
  cracks 
  in 
  the 
  lower 
  Catskill 
  between 
  Cumberland 
  and 
  Frost- 
  

   burg, 
  Maryland. 
  The 
  cracks 
  are 
  filled 
  with 
  green 
  sand 
  in 
  a 
  red 
  shale. 
  Photo 
  

   taken 
  July 
  1, 
  1908. 
  

  

  Some 
  impressions 
  of 
  vegetation 
  occur 
  and 
  measure 
  up 
  to 
  five 
  

   inches 
  in 
  wddth, 
  but 
  most 
  of 
  them 
  are 
  of 
  small 
  fragments. 
  In 
  

   the 
  waste 
  from 
  the 
  tunnel 
  were 
  found 
  slabs 
  showing 
  current 
  

   marks, 
  rain 
  prints, 
  and 
  rootmarks. 
  A 
  drawing 
  of 
  a 
  specimen 
  

   of 
  rootmarks 
  is 
  shown 
  in 
  figure 
  4. 
  Thus 
  in 
  this 
  section, 
  as 
  on 
  

   the 
  Schuylkill 
  Biver, 
  the 
  close 
  relation 
  is 
  seen 
  between 
  the 
  

   marks 
  of 
  subaerial 
  exposure 
  and 
  the 
  change 
  of 
  color 
  from 
  olive 
  

   to 
  red, 
  but 
  the 
  conditions 
  involving 
  deoxidation 
  and 
  oxidation 
  

  

  Am. 
  Jour. 
  Sci.— 
  Fourth 
  Series, 
  Vol. 
  XXXVI, 
  No. 
  215. 
  

   31 
  

  

  -November, 
  1913. 
  

  

  