﻿450 
  J. 
  Barrett 
  — 
  Upper 
  Devonian 
  Delta 
  of 
  the 
  

  

  In 
  this 
  region 
  of 
  marine 
  deposition 
  the 
  sands, 
  by 
  virtue 
  of 
  

   their 
  cleanness 
  and 
  porosity, 
  carry 
  brine 
  and 
  oil. 
  Some 
  gyp- 
  

   sum 
  is 
  also 
  known 
  from 
  the 
  Waverly 
  group 
  of 
  Ohio. 
  In 
  the 
  

   eastern 
  half 
  of 
  the 
  state, 
  however, 
  marine 
  fossils 
  and 
  these 
  other 
  

   associations 
  are 
  not 
  present. 
  From 
  a 
  thickness 
  of 
  some 
  hun- 
  

   dreds 
  of 
  feet 
  in 
  the 
  western 
  part 
  of 
  Pennsylvania, 
  it 
  increases 
  

   eastward, 
  reaching 
  a 
  maximum 
  of 
  about 
  2,000 
  feet 
  in 
  the 
  east- 
  

   ern 
  central 
  part 
  of 
  the 
  state. 
  

  

  Sections 
  or 
  the 
  Catskill-Pocono 
  Formations 
  on 
  the 
  

   Schuylkill 
  River, 
  Pennsylvania. 
  

  

  The 
  published 
  descriptions 
  of 
  the 
  Catskill 
  do 
  not 
  conclu- 
  

   sively 
  prove 
  its 
  mode 
  of 
  origin 
  and 
  are. 
  especially 
  lacking 
  in 
  

   the 
  mention 
  of 
  the 
  mapks 
  of 
  subaerial 
  exposure. 
  Consequently 
  

   the 
  writer 
  in 
  his 
  Held 
  observations 
  has 
  paid 
  especial 
  attention 
  

   to 
  features 
  and 
  places 
  of 
  significant 
  character, 
  aiming 
  to 
  see 
  

   especially 
  if 
  the 
  marks 
  of 
  subaerial 
  exposure 
  were 
  probably 
  

   absent 
  or 
  merely 
  difficult 
  to 
  observe. 
  For 
  reasons 
  which 
  have 
  

   been 
  discussed, 
  the 
  mode 
  of 
  origin, 
  if 
  of 
  the 
  nature 
  of 
  a 
  sub- 
  

   aerial 
  delta 
  plain, 
  is 
  least 
  open 
  to 
  doubt 
  in 
  regions 
  where 
  the 
  

   deposit 
  is 
  thickest 
  and 
  farthest 
  removed 
  from 
  the 
  marine 
  facies. 
  

   Excellent 
  exposures 
  have 
  recently 
  been 
  made 
  by 
  the 
  work 
  on 
  

   the 
  Lackawanna 
  railroad 
  in 
  straightening 
  the 
  tracks 
  between 
  

   Scranton, 
  Pa., 
  and 
  Binghamton, 
  N. 
  Y. 
  An 
  examination 
  was 
  

   made 
  in 
  1913 
  of 
  these 
  fresh 
  cuttings 
  and 
  the 
  huge 
  fillings 
  of 
  

   fresh 
  rock 
  waste. 
  Numerous 
  carbonized 
  plant 
  impressions, 
  

   some 
  of 
  tree 
  trunks, 
  others 
  of 
  more 
  delicate 
  vegetation, 
  were 
  

   found 
  in 
  gray 
  sandstones. 
  Rainprints 
  and 
  mud-cracks 
  were 
  

   not 
  uncommon 
  in 
  the 
  red 
  shales 
  and 
  red 
  argillaceous 
  sandstones. 
  

   In 
  this 
  region, 
  however, 
  the 
  beds 
  are 
  nearly 
  flat 
  and 
  not 
  adapted 
  

   to 
  the 
  study 
  of 
  a 
  complete 
  section 
  of 
  the 
  formation. 
  On 
  the 
  

   eastern 
  side 
  of 
  the 
  southern 
  anthracite 
  coal 
  basin, 
  on 
  the 
  con- 
  

   trary, 
  the 
  folding 
  exposes 
  complete 
  sections 
  in 
  the 
  region 
  of 
  

   maximum 
  thickness 
  in 
  short 
  distances, 
  and 
  these 
  outcrops, 
  fur- 
  

   thermore, 
  are 
  those 
  in 
  Pennsylvania 
  which 
  lie 
  nearest 
  to 
  the 
  

   old 
  uplands 
  of 
  Appalachia 
  whence 
  the 
  sediments 
  were 
  derived. 
  

   For 
  these 
  reasons, 
  from 
  1908 
  to 
  1912 
  these 
  sections 
  of 
  the 
  Cats- 
  

   kill 
  and 
  Pocono 
  were 
  studied 
  in 
  detail 
  in 
  Schuylkill 
  County 
  

   of 
  Pennsylvania. 
  Three 
  branches 
  of 
  the 
  Schuylkill 
  River 
  

   cross 
  the 
  formation 
  in 
  steep-sided 
  gaps 
  ; 
  the 
  rocks 
  are 
  admira- 
  

   bly 
  exposed 
  by 
  the 
  cuttings 
  of 
  the 
  several 
  railroads 
  which 
  seek 
  

   every 
  entrance 
  into 
  the 
  anthracite 
  basins 
  ; 
  the 
  beds 
  stand 
  ver- 
  

   tical, 
  almost 
  uncomplicated 
  by 
  faults 
  or 
  minor 
  folds 
  and 
  through 
  

   a 
  thickness 
  of 
  three 
  miles 
  of 
  strata 
  record 
  the 
  succession 
  of 
  

   geologic 
  events 
  from 
  the 
  Middle 
  Devonian 
  into 
  the 
  Pennsyl- 
  

   vanian 
  period. 
  The 
  section 
  of 
  the 
  Pottsville 
  conglomerate 
  has 
  

  

  