﻿Twenhofel 
  — 
  Wreford 
  and 
  Foraker 
  Limestones. 
  409 
  

  

  The 
  Wreford 
  Limestone 
  Member. 
  

  

  The 
  Wreford 
  limestone 
  is 
  known 
  to 
  extend 
  from 
  north- 
  

   ern 
  Kansas 
  into 
  central 
  Oklahoma. 
  Throughout 
  the 
  

   Flint 
  Hills 
  of 
  Kansas 
  (The 
  Wreford 
  limestone 
  member 
  in 
  

   considerable 
  part 
  yielded 
  the 
  flint 
  after 
  which 
  the 
  hills 
  are 
  

   named) 
  the 
  thickness 
  varies 
  from 
  thirty-five 
  to 
  fifty-five 
  

   feet. 
  1 
  Near 
  the 
  Kansas-Oklahoma 
  line 
  it 
  is 
  much 
  thin- 
  

   ner. 
  Its 
  base 
  is 
  pretty 
  sharply 
  deliminated 
  from 
  the 
  

   underlying 
  shales/ 
  the 
  change 
  from 
  shale 
  to 
  limestone 
  

   being 
  quite 
  abrupt. 
  The 
  upper 
  limit 
  of 
  the 
  formation 
  

   does 
  not 
  appear 
  to 
  be 
  quite 
  so 
  sharply 
  defined. 
  

  

  Of 
  the 
  descending 
  sections 
  which 
  follow, 
  the 
  first 
  was 
  

   measured 
  about 
  one 
  mile 
  east 
  of 
  the 
  little 
  village* 
  of 
  

   Otto, 
  Cowley 
  County, 
  Kansas. 
  The 
  second 
  section 
  was 
  

   measured 
  about 
  eight 
  miles 
  nearly 
  due 
  north 
  of 
  the 
  first. 
  

   The 
  two 
  sections 
  serve 
  to 
  show 
  the 
  persistence 
  of 
  the 
  indi- 
  

   vidual 
  units 
  of 
  the 
  member 
  and 
  also 
  their 
  variations. 
  

  

  11. 
  Slabby 
  gray 
  limestone 
  weathering 
  into 
  rounded 
  dome- 
  

   shaped 
  surfaces. 
  Not 
  well 
  exposed 
  at 
  the 
  base. 
  Upper 
  layer 
  

   one 
  foot 
  thick 
  3 
  feet. 
  

  

  10. 
  Gray 
  limestone 
  with 
  yellow 
  and 
  gray 
  chert 
  in 
  lenticular 
  

   masses 
  parallel 
  to 
  the 
  bedding 
  planes. 
  Not 
  well 
  exposed 
  at 
  the 
  

   base 
  4 
  feet. 
  

  

  9. 
  Compact 
  gray 
  limestone, 
  coarser 
  grained 
  than 
  that 
  of 
  zone 
  

   8. 
  This 
  zone 
  contains 
  an 
  abundance 
  of 
  chert 
  concretions 
  of 
  

   which 
  many 
  attain 
  diameters 
  exceeding 
  two 
  feet. 
  The 
  concre- 
  

   tions 
  have 
  odd 
  and 
  peculiar 
  shapes. 
  Many 
  of 
  them 
  have 
  their 
  

   longest 
  axes 
  parallel 
  to 
  the 
  bedding 
  planes. 
  Others 
  have 
  them 
  

   vertical 
  or 
  inclined 
  to 
  these 
  planes. 
  Locally, 
  the 
  concretions 
  are 
  

   connected 
  with 
  those 
  adjacent, 
  and 
  places 
  have 
  been 
  observed 
  

   where 
  the 
  chert 
  composes 
  nearly 
  the 
  whole 
  of 
  the 
  zone. 
  The 
  

   chert 
  thoroughly 
  litters 
  the 
  ground 
  over 
  the 
  outcrop 
  of 
  the 
  zone 
  

   which, 
  as 
  a 
  general 
  feature, 
  occurs 
  on 
  the 
  rim 
  of 
  a 
  well-defined 
  

   rock 
  terrace. 
  Both 
  chert 
  and 
  limestone 
  are 
  fossiliferous. 
  the 
  

   fossils 
  for 
  the 
  most 
  part 
  being 
  fragments 
  of 
  shells 
  3 
  feet. 
  

  

  8. 
  Compact, 
  fine-grained, 
  yellowish 
  gray 
  limestone, 
  contain- 
  

   ing 
  a 
  great 
  deal 
  of 
  pale 
  blue 
  and 
  yellow 
  chert 
  which 
  is 
  thoroughly 
  

   and 
  intimately 
  intergrown 
  with 
  the 
  limestone. 
  The 
  chert 
  com- 
  

   poses 
  about 
  fifty 
  per 
  cent 
  of 
  the 
  rock, 
  but 
  the 
  ratio 
  varies 
  some- 
  

   what 
  with 
  locality. 
  On 
  weathered 
  surfaces 
  it 
  stands 
  out 
  in 
  

   irregular 
  relief. 
  Both 
  chert 
  and 
  limestone 
  contain 
  many 
  frag- 
  

   ments 
  of 
  fossils 
  2 
  feet, 
  8 
  inches. 
  

  

  1 
  Prosser, 
  C. 
  S. 
  : 
  Jour. 
  Geol. 
  vol. 
  10, 
  p. 
  713, 
  1902. 
  

  

  