﻿364 
  JOURNAL 
  OF 
  THE 
  WASHINGTON 
  ACADEMY 
  OF 
  SCIENCES 
  VOL. 
  12, 
  NO. 
  15 
  

  

  tripoli 
  and 
  earthy 
  yellow 
  soil. 
  It 
  closely 
  resembles 
  the 
  Elbrook 
  

   limestone 
  of 
  Cumberland 
  County 
  and 
  is 
  correlated 
  with 
  it. 
  The 
  

   Waynesboro 
  formation, 
  a 
  purplish 
  sandy 
  shale 
  which 
  lies 
  between 
  

   the 
  Tomstown 
  and 
  Elbrook 
  formations 
  in 
  Cumberland 
  County 
  but 
  

   which 
  dies 
  out 
  northeastward 
  near 
  the 
  Susquehanna 
  River, 
  is 
  evi- 
  

   dently 
  not 
  present 
  in 
  this 
  area. 
  Because 
  of 
  poor 
  exposures, 
  the 
  thick- 
  

   ness 
  of 
  the 
  Elbrook 
  formation 
  cannot 
  be 
  determined 
  but 
  it 
  is 
  estimated 
  

   to 
  be 
  about 
  500 
  feet. 
  

  

  The 
  Elbrook 
  is 
  succeeded 
  by 
  a 
  series 
  of 
  limestones 
  comprising 
  

   thick 
  pure 
  light 
  gray 
  limestones 
  which 
  are 
  apparently 
  largely 
  Cryp- 
  

   tozoon 
  reefs, 
  thin-bedded 
  finely 
  laminated 
  wavy 
  limestones 
  of 
  related 
  

   organic 
  origin, 
  sandy 
  conglomerate 
  beds 
  which 
  weather 
  to 
  pitted 
  

   porous 
  sandstone, 
  and 
  dark 
  blue 
  impure 
  dolomite. 
  This 
  formation 
  

   corresponds 
  to 
  the 
  Conococheague 
  limestone 
  of 
  Cumberland 
  County. 
  

   As 
  many 
  of 
  its 
  beds 
  weather 
  to 
  earthy 
  yellow 
  soil 
  similar 
  to 
  that 
  of 
  

   the 
  Elbrook 
  dolomite 
  it 
  cannot 
  readily 
  be 
  distinguished 
  from 
  that 
  

   formation 
  on 
  upland 
  surfaces. 
  It 
  is 
  estimated 
  to 
  be 
  900 
  feet 
  thick. 
  

  

  Overlying 
  the 
  Conococheague 
  are 
  well-bedded 
  pure 
  blue 
  limestones 
  

   and 
  magnesian 
  limestones 
  containing 
  gasteropods. 
  The 
  fossils 
  and 
  

   the 
  lithologic 
  characters 
  determine 
  the 
  formation 
  to 
  be 
  Beekmantown. 
  

   The 
  Beekmantown 
  limestone 
  is 
  estimated 
  to 
  be 
  about 
  2,000 
  feet 
  thick. 
  

  

  The 
  Beekmantown 
  limestone 
  is 
  overlain 
  by 
  a 
  dark 
  gray 
  shale, 
  

   gray, 
  green, 
  and 
  purple 
  slates, 
  and 
  soft 
  greenish 
  impure 
  sandstone. 
  

   The 
  dark 
  shales 
  contain 
  graptolites 
  of 
  Normanskill 
  type 
  and 
  have 
  

   at 
  their 
  base 
  thin 
  crinoidal 
  limestones 
  which 
  are 
  also 
  fossiliferous. 
  

   It 
  is 
  probably 
  at 
  least 
  1,000 
  feet 
  thick. 
  It 
  is 
  named 
  Cocalico 
  shale 
  

   from 
  the 
  creek 
  which 
  exposes 
  the 
  shale 
  where 
  its 
  relation 
  to 
  the 
  under- 
  

   lying 
  Beekmantown 
  limestone 
  is 
  well 
  shown. 
  

  

  South 
  of 
  the 
  Hellam-Chickies 
  Hills 
  and 
  Welsh 
  Mountain 
  there 
  is 
  

   a 
  dark 
  slaty 
  and 
  conglomeratic 
  limestone 
  formation 
  that 
  develops 
  

   to 
  great 
  thickness 
  south 
  of 
  Lancaster 
  and 
  eventually 
  supplants 
  all 
  

   other 
  limestones. 
  Eleanora 
  Bliss 
  Knopf 
  and 
  Anna 
  I. 
  Jonas 
  have 
  

   called 
  it 
  in 
  manuscript 
  the 
  Conestoga 
  limestone. 
  It 
  has 
  been 
  traced 
  

   and 
  studied 
  by 
  them 
  from 
  Lancaster 
  southward 
  to 
  Quarr}'ville 
  and 
  

   into 
  Chester 
  Valley, 
  but 
  its 
  relations 
  are 
  not 
  there 
  revealed. 
  It 
  was 
  

   named 
  Conestoga 
  limestone 
  because 
  of 
  excellent 
  outcrops 
  along 
  

   Conestoga 
  Creek, 
  south 
  of 
  Lancaster. 
  The 
  Conestoga 
  limestone 
  is 
  

   made 
  up 
  of 
  thin-bedded 
  dark 
  slaty 
  limestone, 
  coarse 
  conglomerate 
  

   or 
  breccia 
  of 
  limestone 
  and 
  marble 
  pebbles 
  and 
  fragments, 
  thin-bedded 
  

   blue 
  crystalline 
  limestone, 
  and 
  thin, 
  dark, 
  graphitic 
  slate. 
  Its 
  total 
  

  

  