﻿Appalachian 
  Geosyncline. 
  443 
  

  

  sandy, 
  with 
  sandstones, 
  gray, 
  argillaceous 
  and 
  gritty. 
  On 
  the 
  

   eastern 
  side 
  of 
  the 
  geosyncline 
  the 
  gray, 
  arenaceous 
  members 
  

   dominate 
  the 
  formation, 
  especially 
  its 
  upper 
  part, 
  and 
  the 
  red 
  

   shale 
  sinks 
  to 
  not 
  over 
  twenty 
  per 
  cent 
  of 
  the 
  section. 
  On 
  the 
  

   west, 
  however, 
  the 
  shale 
  rises 
  in 
  quantity, 
  though 
  it 
  is 
  not 
  so 
  

   universally 
  red. 
  

  

  Many 
  of 
  the 
  sandstones 
  are 
  feldspathic 
  ; 
  others 
  are 
  spangled 
  

   with 
  mica. 
  They 
  are 
  apt 
  to 
  be 
  clearly 
  separated 
  below 
  from 
  

   the 
  shales, 
  but 
  grade 
  into 
  red 
  or 
  maroon 
  sandstones 
  and 
  red 
  

   shales 
  above. 
  Soft, 
  argillaceous 
  sandstones, 
  deep 
  red 
  to 
  pale 
  

   red 
  in 
  color, 
  form 
  an 
  intermediate 
  type, 
  grading 
  toward 
  the 
  

   shales. 
  The 
  sandstones 
  also 
  grade 
  in 
  the 
  other 
  direction 
  into 
  

   hard 
  siliceous 
  grits 
  of 
  greenish 
  color 
  on 
  fresh 
  fracture. 
  These 
  

   on 
  the 
  east 
  attain 
  a 
  great 
  development 
  and 
  become 
  con- 
  

   glomeratic 
  from 
  the 
  presence 
  of 
  small 
  scattered 
  pebbles 
  of 
  

   white 
  quartz. 
  A 
  few 
  horizons 
  of 
  coarser 
  and 
  purer 
  con- 
  

   glomerates 
  also 
  occur. 
  The 
  sandstones 
  give 
  rise 
  to 
  ledges, 
  the 
  

   weathered 
  surfaces 
  revealing 
  oblique 
  bedding 
  of 
  most 
  of 
  the 
  

   strata 
  and 
  the 
  whole 
  etching 
  into 
  outcrops 
  which 
  have 
  been 
  

   likened 
  to 
  piles 
  of 
  boards. 
  I. 
  C. 
  White 
  gives 
  a 
  vivid 
  descrip- 
  

   tion 
  of 
  the 
  bedding 
  characters 
  for 
  northeastern 
  Pennsylvania, 
  

   as 
  follows 
  : 
  

  

  "The 
  sandstone 
  beds 
  vary 
  in 
  thickness 
  from 
  2' 
  to 
  10' 
  and 
  are 
  

   characteristically 
  false 
  or 
  current-bedded. 
  The 
  lamination, 
  as 
  

   exhibited 
  in 
  the 
  cliffs, 
  is 
  very 
  curious. 
  Each 
  of 
  the 
  horizontal 
  

   beds 
  are 
  crossed 
  obliquely 
  by 
  lines 
  an 
  inch 
  or 
  two 
  apart, 
  weathered 
  

   into 
  furrows. 
  The 
  slope 
  of 
  the 
  furrows 
  in 
  one 
  bed 
  will 
  be 
  in 
  one 
  

   direction 
  ; 
  that 
  of 
  the 
  beds 
  above 
  and 
  below 
  in 
  the 
  opposite 
  

   direction. 
  The 
  ends 
  of 
  the 
  furrows 
  meet 
  along 
  the 
  horizontal 
  

   lines 
  of 
  stratification 
  at 
  an 
  acute 
  angle. 
  Consequently, 
  when 
  a 
  

   considerable 
  number 
  of 
  these 
  sandstone 
  beds, 
  lying 
  upon 
  one 
  

   another, 
  are 
  exposed 
  to 
  view, 
  the 
  whole 
  face 
  of 
  the 
  cliff 
  is 
  sculp- 
  

   tured 
  in 
  zigzags 
  from 
  top 
  to 
  bottom. 
  

  

  "This 
  false 
  bedding 
  sometimes 
  shows 
  regularly 
  straight 
  and 
  

   parallel 
  lines 
  ; 
  at 
  other 
  times 
  the 
  lining 
  is 
  curved 
  and 
  the 
  laminae 
  

   overlap 
  each 
  other 
  at 
  the 
  bottom 
  ; 
  but 
  at 
  the 
  top 
  they 
  are 
  cut 
  off 
  

   square."* 
  

  

  Ripple-marking 
  is 
  but 
  rarely 
  observed. 
  Although 
  the 
  sand- 
  

   stones 
  may 
  be 
  sharply 
  separated 
  in 
  many 
  instances 
  from 
  the 
  

   shales 
  below, 
  and 
  different 
  strata 
  show 
  oblique 
  truncation, 
  they 
  

   do 
  not 
  commonly 
  exhibit 
  channeling 
  effects. 
  Not 
  infrequently, 
  

   however, 
  they 
  contain 
  fragments 
  of 
  red 
  shale, 
  originally 
  no 
  

   doubt 
  as 
  plastic 
  mud, 
  showing 
  in 
  that 
  manner 
  that 
  scour 
  and 
  

   fill 
  did 
  go 
  on. 
  

  

  *The 
  Geology 
  of 
  Susquehanna 
  and 
  Wayne 
  Counties, 
  Second 
  Geol. 
  Surv., 
  

   Pa., 
  G-5, 
  p. 
  60, 
  1881. 
  

  

  