﻿T. 
  E. 
  Savage— 
  Devonian 
  Formation 
  of 
  Illinois. 
  175 
  

  

  since 
  the 
  stratigraphic 
  relations 
  of 
  the 
  Camden 
  chert 
  (of 
  

   similar 
  age) 
  in 
  western 
  Tennessee 
  indicate 
  its 
  post- 
  

   Oriskany 
  age, 
  and 
  there 
  is 
  a 
  lack 
  of 
  any 
  hiatus 
  between 
  

   the 
  Clear 
  Creek 
  chert 
  and 
  undoubted 
  Onondaga 
  strata, 
  

   the 
  Clear 
  Creek 
  chert 
  is 
  now 
  referred 
  to 
  the 
  basal 
  por- 
  

   tion 
  of 
  the 
  Ulsterian 
  (Onondaga) 
  series. 
  

  

  Dutch 
  Creek 
  Sandstone. 
  — 
  The 
  Clear 
  Creek 
  chert 
  is 
  

   almost 
  everywhere 
  overlain 
  by 
  a 
  sandstone 
  which 
  

   records 
  an 
  uplift 
  either 
  farther 
  west 
  in 
  the 
  Ozarkian 
  

   region 
  of 
  Missouri 
  or 
  to 
  the 
  south 
  in 
  Llano 
  or 
  Appala- 
  

  

  Fig. 
  2. 
  

  

  

  

  

  

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  JJrSfe'xi.fli 
  

  

  

  

  "-vW 
  

  

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  * 
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  Fig. 
  2. 
  — 
  View 
  of 
  Clear 
  Creek 
  chert 
  in 
  quarry 
  near 
  Tamms, 
  in 
  Alexander 
  

   County. 
  A 
  vertical 
  face, 
  180 
  feet 
  high, 
  is 
  here 
  exposed. 
  

  

  chia. 
  This 
  sandstone 
  ranges 
  from 
  10 
  to 
  12 
  feet 
  to 
  as 
  

   much 
  as 
  30 
  or 
  more 
  feet 
  thick, 
  and 
  consists 
  of 
  iron- 
  

   stained, 
  reddish-brown 
  or 
  yellow, 
  rather 
  coarse 
  grains 
  

   of 
  quartz 
  sand 
  cemented 
  with 
  iron 
  oxide, 
  in 
  layers 
  10 
  

   to 
  24 
  inches 
  thick. 
  It 
  outcrops 
  in 
  many 
  places 
  in 
  Union 
  

   and 
  Alexander 
  counties 
  at 
  the 
  horizon 
  immediately 
  

   above 
  the 
  Clear 
  Creek 
  chert. 
  It 
  may 
  be 
  appropriately 
  

   referred 
  to 
  as 
  the 
  Dutch 
  Creek 
  sandstone 
  on 
  account 
  of 
  

   the 
  fact 
  that 
  good 
  exposures 
  occur 
  along 
  Dutch 
  creek 
  in 
  

   the 
  southwest 
  part 
  of 
  Union 
  County. 
  In 
  places 
  this 
  

   sandstone 
  contains 
  numerous 
  moulds 
  and 
  casts 
  of 
  such 
  

   fossils 
  as 
  Pleurodictyon 
  problernaticum, 
  two 
  or 
  three 
  

  

  