﻿E. 
  B. 
  Branson 
  — 
  Geologic 
  Section 
  in 
  Missouri. 
  275 
  

  

  The 
  Chouteau 
  was 
  rather 
  extensively 
  eroded 
  before 
  the 
  

   Burlington 
  seas 
  advanced. 
  This 
  is 
  shown 
  by 
  the 
  thick- 
  

   ening 
  and 
  thinning 
  of 
  the 
  formation, 
  and 
  by 
  the 
  top 
  part 
  

   always 
  being 
  absent 
  where 
  the 
  formation 
  is 
  thin. 
  Also 
  

   it 
  is 
  not 
  uncommon 
  to 
  find 
  Burlington 
  resting 
  on 
  Devo- 
  

   nian 
  or 
  older 
  formations 
  with 
  no 
  Chouteau 
  or 
  Sylamore 
  

   present. 
  Only 
  rarely 
  is 
  there 
  evidence 
  of 
  unconformity 
  

   where 
  contacts 
  of 
  Chouteau 
  and 
  Burlington 
  are 
  exposed. 
  

  

  The 
  Burlington 
  Limestone 
  (Osagian). 
  — 
  The 
  Burling- 
  

   ton 
  limestone 
  is 
  continuous 
  from 
  St. 
  Louis 
  County 
  to 
  

   Jackson 
  County, 
  the 
  counties 
  of 
  St. 
  Louis 
  and 
  Kansas 
  

   City. 
  Its 
  nearest 
  outcrop 
  to 
  Jackson 
  County 
  is 
  about 
  

   40 
  miles 
  east. 
  It 
  ranges 
  from 
  20 
  feet 
  thick 
  to 
  190 
  feet 
  

   thick 
  and 
  is 
  much 
  the 
  same 
  lithologically 
  everywhere, 
  

   save 
  that 
  the 
  lower 
  10 
  to 
  30 
  feet 
  are 
  brown 
  in 
  the 
  eastern 
  

   end 
  of 
  the 
  section. 
  For 
  more 
  than 
  half 
  of 
  its 
  extent 
  it 
  

   rests 
  on 
  the 
  Chouteau, 
  for 
  perhaps 
  one-fourth 
  of 
  its 
  

   extent 
  on 
  the 
  Sylamore, 
  and 
  over 
  small 
  areas 
  on 
  Snider 
  

   Creek, 
  Callaway, 
  Kimmswick, 
  and 
  Joachim. 
  The 
  irreg- 
  

   ularity 
  in 
  thickness 
  is 
  due 
  to 
  erosion 
  of 
  the 
  top, 
  and 
  well 
  

   sections 
  seem 
  to 
  show 
  that 
  it 
  thickens 
  westward 
  from 
  the 
  

   place 
  where 
  it 
  dips 
  under 
  in 
  Pettis 
  County. 
  

  

  The 
  Salem 
  Limestone 
  (Meramecian). 
  — 
  The 
  Salem 
  

   limestone 
  outcrops 
  only 
  rarely 
  but 
  occurs 
  over 
  wide 
  

   areas 
  in 
  small 
  patches. 
  At 
  Boonville, 
  in 
  Cooper 
  County, 
  

   its 
  outcrops 
  are 
  well 
  known 
  and 
  in 
  Boone 
  County 
  Broad- 
  

   head 
  6 
  found 
  it 
  outcropping 
  15 
  to 
  20 
  feet 
  thick 
  in 
  one 
  

   place. 
  Archimedes, 
  in 
  cherts, 
  occur 
  in 
  hundreds 
  of 
  

   places, 
  scattered 
  along 
  the 
  section, 
  but 
  the 
  writer 
  has 
  not 
  

   seen 
  outcrops 
  of 
  rock 
  bearing 
  Archimedes, 
  excepting 
  at 
  

   Boonville 
  and 
  Broadheads' 
  locality. 
  Only 
  a 
  short 
  dis- 
  

   tance 
  east 
  of 
  the 
  section 
  several 
  other 
  Mississippian 
  for- 
  

   mations 
  occur 
  but 
  they 
  were 
  either 
  eroded 
  away 
  or 
  were 
  

   not 
  deposited 
  west 
  of 
  St. 
  Louis 
  County. 
  

  

  The 
  Pennsylvanian. 
  — 
  At 
  the 
  eastern 
  end 
  of 
  the 
  section 
  

   patches 
  of 
  Pennsylvanian 
  fire-clay 
  and 
  sandstone 
  occur 
  

   rarely 
  at 
  the 
  tops 
  of 
  the 
  hills, 
  a 
  little 
  shale 
  comes 
  in 
  a 
  

   few 
  places 
  at 
  the 
  tops 
  of 
  the 
  hills 
  where 
  the 
  section 
  

   crosses 
  Boone 
  County, 
  and 
  from 
  western 
  Pettis 
  County 
  

   westward 
  nothing 
  below 
  Pennsylvanian 
  outcrops. 
  The 
  

   Pennsylvanian 
  is 
  represented 
  by 
  the 
  Cherokee, 
  Henri- 
  

   etta, 
  and 
  Pleasonton 
  formations 
  and 
  by 
  the 
  Warrensburg 
  

   sandstone 
  which 
  was 
  deposited 
  in 
  a 
  valley 
  in 
  the 
  Chero- 
  

   kee 
  and 
  on 
  Henrietta 
  shales. 
  

  

  6 
  Geol. 
  Survey 
  of 
  Missouri, 
  vol. 
  12, 
  p. 
  383. 
  

  

  Am. 
  Jour. 
  Sci.— 
  Fourth 
  Series, 
  Vol. 
  XLIX, 
  No. 
  292.— 
  April, 
  1920. 
  

   20 
  

  

  