﻿Appalachian 
  Geosyncline. 
  451 
  

  

  been 
  given 
  in 
  detail 
  by 
  David 
  White 
  ; 
  the 
  present 
  writer 
  has 
  

   elsewhere 
  described 
  this 
  section 
  of 
  the 
  Mauch 
  Chunk 
  forma- 
  

   tion, 
  and 
  here 
  is 
  added 
  a 
  detailed 
  view 
  of 
  the 
  Upper 
  Devonian 
  

   and 
  lower 
  Mississippian 
  strata. 
  

  

  The 
  Portage-Chemung 
  and 
  lower 
  Catskill 
  strata 
  are 
  best 
  dis- 
  

   played 
  on 
  the 
  main 
  branch 
  of 
  the 
  Schuylkill 
  River 
  between 
  

   Schuylkill 
  Haven 
  and 
  Pottsville. 
  The 
  upper 
  beds 
  of 
  the 
  

   Catskill 
  are 
  best 
  observed 
  on 
  the 
  Little 
  Schuylkill 
  south 
  of 
  

   Tamaqua, 
  fifteen 
  miles 
  northeast 
  of 
  the 
  other 
  section. 
  At 
  both 
  

   places 
  the 
  entire 
  thicknesses 
  can 
  be 
  measured, 
  but 
  the 
  beds 
  

   were 
  studied 
  in 
  detail 
  only 
  where 
  best 
  exposed 
  in 
  each. 
  It 
  is 
  

   quite 
  certain 
  that 
  in 
  this 
  distance 
  there 
  is 
  some 
  variation 
  in 
  

   total 
  thicknesses 
  and 
  no 
  exact 
  correlation 
  of 
  individual 
  mem- 
  

   bers, 
  but 
  this 
  error 
  in 
  passing 
  from 
  one 
  section 
  to 
  the 
  other 
  

   was 
  more 
  than 
  offset 
  by 
  the 
  advantages 
  found 
  in 
  studying 
  the 
  

   beds 
  for 
  the 
  purposes 
  of 
  this 
  article. 
  

  

  The 
  entire 
  distance 
  of 
  two 
  miles 
  through 
  the 
  Upper 
  Devonian 
  

   and 
  lower 
  Mississippian 
  was 
  controlled 
  by 
  tape 
  measurements 
  

   and 
  the 
  thicknesses 
  corrected 
  for 
  the 
  angles 
  between 
  the 
  courses 
  

   and 
  the 
  strike 
  and 
  dip. 
  The 
  details 
  were 
  fitted 
  on 
  to 
  this 
  con- 
  

   trol 
  by 
  pacing, 
  since 
  in 
  such 
  unfossiliferous 
  and 
  variable 
  beds 
  

   nothing 
  would 
  be 
  gained 
  by 
  the 
  minuter 
  accuracy 
  of 
  measur- 
  

   ing 
  individual 
  strata 
  by 
  tape 
  or 
  rule. 
  The 
  most 
  definite 
  hori- 
  

   zon 
  from 
  which 
  to 
  measure 
  in 
  this 
  section 
  is 
  the 
  top 
  of 
  the 
  

   Pocono 
  sandstone, 
  coarse 
  gray-white 
  sandstones 
  giving 
  way 
  at 
  

   this 
  level 
  to 
  the 
  thick 
  red 
  shales 
  of 
  the 
  Mauch 
  Chunk 
  forma- 
  

   tion. 
  This 
  was 
  therefore 
  taken 
  as 
  the 
  datum 
  plane 
  in 
  the 
  two 
  

   Schuylkill 
  County 
  sections. 
  

  

  The 
  printed 
  section 
  is 
  made 
  to 
  some 
  degree 
  graphic 
  by 
  off- 
  

   setting 
  the 
  lines 
  to 
  the 
  right 
  to 
  represent 
  the 
  gradations 
  in 
  

   texture 
  from 
  conglomerate 
  through 
  sandstone 
  to 
  shale. 
  The 
  

   color 
  is 
  a 
  significant 
  feature 
  and 
  this 
  is 
  brought 
  out 
  by 
  print- 
  

   ing 
  red 
  sandstones 
  and 
  shales 
  in 
  heavy-faced 
  type. 
  The 
  recur- 
  

   rence 
  of 
  evidences 
  of 
  subaerial 
  exposure 
  in 
  the 
  form 
  of 
  mud- 
  

   cracks 
  and 
  rainprintsis 
  made 
  prominent 
  by 
  marginal 
  asterisks. 
  

  

  POCONO— 
  CATSKILL 
  SECTION. 
  

  

  South 
  of 
  Tamaqua, 
  Pa., 
  on 
  the 
  Little 
  Schuylkill 
  River, 
  west 
  side. 
  

  

  Mauch 
  Chunk 
  Shale 
  and 
  Sandstone 
  Formation 
  with 
  below 
  

  

  Basal 
  Beds 
  as 
  follows 
  : 
  Thick- 
  ^ 
  top* 
  

  

  Red 
  sandstone 
  shading 
  to 
  gray 
  ; 
  the 
  highest 
  gray- 
  

   ish 
  sandstone 
  in 
  basal 
  Mauch 
  Chunk 
  28 
  

  

  Red 
  shale 
  __ 
  6 
  

  

  Red 
  sandstone 
  11 
  

  

  Gray 
  sandstone, 
  crossbedded 
  _ 
  21 
  

  

  Red 
  shale 
  1 
  

  

  Gray 
  sandstone, 
  crossbedded. 
  16 
  

  

  Red 
  shale 
  with 
  gradations 
  into 
  flaggy 
  red 
  

  

  sandstone. 
  The 
  base 
  of 
  the 
  Mauch 
  Chunk 
  63 
  146 
  

  

  