﻿Mississippian 
  of 
  Ohio 
  and 
  Pennsylvania. 
  

  

  309 
  

  

  Ohio 
  geology. 
  The 
  black, 
  rather 
  tough, 
  strongly 
  laminated 
  

   shales 
  to 
  which 
  it 
  is 
  applied 
  are, 
  though 
  thin, 
  a 
  well 
  marked 
  

   lithologic 
  unit. 
  When 
  traced 
  from 
  Ohio 
  into 
  Pennsylvania 
  

   this 
  formation 
  loses 
  its 
  distinctive 
  character 
  and 
  becomes 
  an 
  

   inseparable 
  portion 
  of 
  the 
  Orangeville 
  shale. 
  The 
  black 
  color 
  

   is 
  noticeable 
  as 
  far 
  east 
  as 
  the 
  longitude 
  of 
  Linesville 
  in 
  Craw- 
  

   ford 
  County, 
  but 
  the 
  hard 
  compact 
  texture 
  is 
  perceptible 
  some- 
  

   what 
  farther 
  east. 
  The 
  fauna 
  is 
  also 
  characteristic 
  and 
  is 
  the 
  

   same 
  as 
  that 
  of 
  the 
  Orangeville 
  formation. 
  

  

  Mississippian 
  as 
  a 
  whole. 
  

  

  The 
  correlation 
  of 
  the 
  formations 
  enumerated 
  has 
  been 
  given 
  

   in 
  connection 
  with 
  each. 
  In 
  conclusion 
  a 
  few 
  words 
  may 
  be 
  

   added 
  regarding 
  the 
  Mississippian 
  as 
  a 
  whole. 
  Figure 
  5 
  shows 
  

   a 
  number 
  of 
  typical 
  sections 
  across 
  the 
  region 
  under 
  discussion 
  

   which 
  will 
  indicate 
  the 
  variation 
  in 
  thickness 
  and 
  character 
  

   from 
  west 
  to 
  east. 
  The 
  first 
  section 
  (107) 
  has 
  a 
  considerable 
  

   portion 
  covered. 
  As 
  explained 
  elsewhere, 
  this 
  interval 
  most 
  

   probably 
  consists 
  of 
  Royalton 
  shales. 
  The 
  great 
  irregularity 
  

   in 
  thickness 
  is 
  explained 
  largely 
  by 
  the 
  unconformity 
  between 
  

   the 
  Mississippian 
  and 
  Pennsylvanian 
  systems, 
  still 
  there 
  is 
  evi- 
  

   dence 
  of 
  considerable 
  thinning 
  toward 
  the 
  east. 
  In 
  sections 
  

   31, 
  47, 
  and 
  74 
  the 
  Sharon 
  comes 
  to 
  rest 
  upon 
  formations 
  below 
  

   the 
  Shenango 
  sandstone 
  or 
  its 
  equivalent, 
  whereas 
  this 
  as 
  well 
  

   as 
  the 
  overlying 
  shale 
  forms 
  part 
  of 
  the 
  sections 
  farther 
  east. 
  

   Another 
  prominent 
  feature 
  is 
  the 
  tendency 
  to 
  increasing 
  

   coarseness 
  toward 
  the 
  east. 
  Ail 
  formations 
  show 
  this, 
  so 
  that 
  

   the 
  whole 
  system 
  changes 
  from 
  a 
  shaly 
  aspect 
  in 
  the 
  west 
  to 
  a 
  

   sandstone 
  and 
  conglomerate 
  facies 
  in 
  the 
  east 
  (along 
  the 
  Alle- 
  

   gheny 
  River). 
  Still 
  farther 
  east 
  the 
  whole 
  series 
  becomes 
  the 
  

   Pocono 
  formation. 
  The 
  following 
  table 
  gives 
  a 
  summary 
  of 
  

   the 
  formations 
  and 
  their 
  correlation 
  in 
  different 
  areas 
  : 
  

  

  Pennsylvania 
  

   east 
  

  

  r 
  Mauch 
  Chunk 
  

  

  Ohio 
  

  

  west 
  

  

  north 
  

  

  central 
  

  

  c 
  

  

  Greenbrier 
  

   (Burgoon) 
  

  

  r 
  Shenango 
  shale 
  "^ 
  

  

  Shenango 
  sandstone 
  

  

  s 
  { 
  Pocono 
  

  

  Logan 
  

  

  Meadville 
  

   Sharpsville 
  

  

  Orangeville 
  

  

  \ 
  Royalton 
  

  

  I 
  

   J 
  \ 
  Cuyahoga 
  

  

  Brecksville 
  | 
  

  

  Aurora 
  J 
  

  

  Sunbury 
  Sunbury 
  

  

  Corry 
  sandstone 
  

   Cussewago 
  shale 
  & 
  Berea 
  

   sandstone 
  

  

  Berea 
  

  

  