﻿304 
  W. 
  A. 
  Verwiebe 
  — 
  Correlation 
  of 
  the 
  

  

  below. 
  The 
  two 
  limestones 
  are 
  somewhat 
  exaggerated 
  in 
  order 
  

   to 
  make 
  them 
  more 
  prominent. 
  They 
  are 
  usually 
  six 
  inches 
  to 
  

   two 
  feet 
  thick 
  but 
  may 
  be 
  less 
  and 
  are 
  sometimes 
  absent. 
  A 
  

   third 
  limestone 
  of 
  exactly 
  the 
  same 
  nature 
  as 
  the 
  Meadville 
  

   limestones 
  is 
  found 
  about 
  the 
  middle 
  of 
  the 
  Sharpsville. 
  It 
  

   will 
  be 
  noted 
  that 
  along 
  the 
  state 
  line 
  between 
  Ohio 
  and 
  

   Pennsylvania 
  the 
  Meadville 
  already 
  begins 
  to 
  show 
  a 
  con- 
  

   siderable 
  proportion 
  of 
  thin 
  sandstones. 
  These 
  increase 
  in 
  

   number 
  toward 
  the 
  east. 
  But 
  toward 
  the 
  west 
  the 
  opposite 
  

   takes 
  place 
  and 
  the 
  Royalton 
  formation, 
  which 
  represents 
  it 
  

   toward 
  its 
  upper 
  part, 
  has 
  only 
  a 
  small 
  percentage 
  of 
  sandstone 
  

   layers. 
  

  

  Sharpsville 
  formation: 
  This 
  formation 
  was 
  named 
  after 
  the 
  

   village 
  of 
  that 
  name 
  which 
  lies 
  a 
  few 
  miles 
  north 
  of 
  Sharon 
  on 
  

   the 
  Shenango 
  River. 
  It 
  consists 
  largely 
  of 
  sandstone, 
  though 
  

   shale 
  layers 
  may 
  occur 
  ; 
  furthermore 
  muddy 
  sediment 
  is 
  so 
  

   thoroughly 
  mixed 
  with 
  the 
  sand 
  grains 
  that 
  the 
  sandstone 
  is 
  

   very 
  impure. 
  Frequently 
  the 
  formation 
  is 
  divided 
  into 
  two 
  

   subequal 
  parts 
  by 
  a 
  limestone 
  layer 
  like 
  those 
  in 
  the 
  Meadville 
  

   formation, 
  which 
  is 
  on 
  the 
  average 
  one 
  foot 
  in 
  thickness. 
  

  

  In 
  tracing 
  the 
  formation 
  toward 
  the 
  east 
  it 
  was 
  found 
  more 
  

   and 
  more 
  difficult 
  to 
  separate 
  it 
  from 
  the 
  Orangeville 
  below. 
  

   Toward 
  the 
  west 
  it 
  becomes 
  more 
  shaly 
  and 
  finally 
  also 
  loses 
  

   its 
  identity 
  in 
  the 
  Cuyahoga 
  terrane. 
  It 
  is 
  distinctly 
  recog- 
  

   nizable 
  as 
  far 
  west 
  as 
  the 
  Warren 
  (Ohio) 
  region, 
  but 
  becomes 
  

   indefinite 
  beyond 
  that. 
  

  

  Orangeville 
  formation: 
  Lying 
  just 
  beyond 
  the 
  border 
  of 
  

   Pennsylvania 
  in 
  Trumbull 
  County, 
  Ohio 
  is 
  Orangeville. 
  Here 
  

   a 
  series 
  of 
  soft, 
  argillaceous, 
  bluish 
  gray 
  shales 
  are 
  exposed 
  to 
  

   which 
  I. 
  C. 
  White 
  gave 
  the 
  name 
  Orangeville. 
  They 
  are 
  

   interbedded 
  to 
  a 
  slight 
  extent 
  with 
  thin 
  sandstones. 
  Iron 
  is 
  

   present 
  in 
  the 
  form 
  of 
  marcasite 
  concretions 
  and 
  the 
  solution 
  

   of 
  these 
  causes 
  the 
  formation 
  to 
  present 
  a 
  rather 
  rusty 
  outcrop. 
  

   When 
  followed 
  toward 
  the 
  east 
  the 
  sandy 
  layers 
  become 
  more 
  

   abundant 
  and 
  in 
  the 
  region 
  of 
  the 
  Allegheny 
  River 
  form 
  the 
  

   largest 
  part 
  of 
  the 
  formation. 
  Toward 
  the 
  west 
  the 
  opposite 
  

   holds 
  true, 
  also 
  the 
  layers 
  toward 
  the 
  base 
  become 
  more 
  carbo- 
  

   naceous, 
  blacker, 
  tougher, 
  and 
  more 
  fissile. 
  This 
  phase 
  in 
  its 
  

   typical 
  development 
  is 
  called 
  the 
  Sunbury 
  shale. 
  Whenever 
  

   the 
  Orangeville 
  is 
  encountered 
  it 
  is 
  found 
  to 
  contain 
  an 
  

   abundant 
  though 
  not 
  varied 
  fauna 
  which 
  consists 
  of 
  the 
  follow- 
  

   ing 
  species 
  : 
  

  

  Lingula 
  melie, 
  Hall 
  

   Lingula 
  membranacea, 
  Winchell 
  

   Discina 
  newberryi, 
  Hall 
  

   Discina 
  pleurites, 
  Meek 
  

  

  