﻿GEOLOGY. 
  283 
  

  

  j^rincipal 
  branches, 
  were 
  seen 
  extending 
  some 
  distance 
  

   further, 
  rather 
  out 
  of 
  the 
  direct 
  line 
  of 
  the 
  trunk. 
  It 
  

   might 
  be 
  rash 
  to 
  assert 
  that 
  these 
  trees 
  lie 
  where 
  they 
  

   grew 
  ; 
  yet 
  they 
  present 
  strong 
  indications 
  that 
  such 
  is 
  

   the 
  fact. 
  

  

  The 
  but-end, 
  or 
  larger 
  extremity 
  of 
  the 
  principal 
  

   one, 
  although 
  exhibiting 
  no 
  distinct 
  roots 
  above 
  the 
  

   ground, 
  presents 
  that 
  curvature 
  or 
  enlargement 
  of 
  out- 
  

   line, 
  that 
  is 
  seen 
  at 
  the 
  base 
  of 
  a 
  standing 
  tree, 
  formed 
  

   by 
  the 
  expansion 
  of 
  the 
  roots 
  in 
  the 
  earth. 
  It 
  had 
  also 
  

   the 
  appearance 
  of 
  a 
  tree, 
  which, 
  being 
  considerably 
  ad- 
  

   vanced 
  in 
  a 
  state 
  of 
  decay, 
  had 
  been 
  broken 
  by 
  falling 
  

   across 
  a 
  rather 
  sharp 
  ridge 
  before 
  silicification 
  took 
  place. 
  

   It 
  now 
  lies 
  only 
  slightly 
  imbedded, 
  in 
  a 
  fine 
  white 
  

   sandy 
  soil. 
  

  

  In 
  the 
  lake 
  marl, 
  which 
  occupies 
  the 
  lacustrine 
  beds 
  of 
  

   the 
  drift 
  period, 
  we 
  find 
  a 
  few 
  fossil 
  testacea, 
  such 
  as 
  the 
  

   lymncea, 
  succinea, 
  cyclas, 
  two 
  species 
  of 
  planorbis, 
  and 
  a 
  

   very 
  small 
  paludina. 
  

  

  One 
  species 
  of 
  the 
  planorbis, 
  a 
  very 
  minute 
  one, 
  and 
  

   the 
  paludina 
  mentioned, 
  are 
  not 
  now 
  found 
  living 
  in 
  our 
  

   waters 
  ; 
  the 
  others 
  belong 
  to 
  existing 
  species. 
  

  

  The 
  testacea 
  of 
  the 
  loess, 
  or 
  loam, 
  referred 
  to 
  the 
  same 
  

   period, 
  are, 
  on 
  the 
  contrary, 
  all 
  terrestrial, 
  embracing 
  

   several 
  species 
  of 
  helices 
  or 
  snails, 
  all 
  of 
  Avliich, 
  it 
  is 
  be- 
  

   lieved, 
  are 
  yet 
  found 
  living 
  in 
  different 
  parts 
  of 
  the 
  Con- 
  

   tinent, 
  although 
  some 
  of 
  them 
  seem 
  to 
  have 
  disappeared, 
  

   or 
  to 
  have 
  now 
  no 
  living 
  representative 
  in 
  the 
  fauna 
  of 
  

   this 
  region. 
  

  

  Among 
  the 
  species 
  most 
  numerous, 
  may 
  be 
  enumerated 
  

   the 
  Helix 
  albolabris, 
  alternata, 
  concava, 
  elevata, 
  fraterua, 
  

   perspectiva, 
  profunda, 
  thyroides, 
  tridentata, 
  &c. 
  

  

  The 
  great 
  bone 
  bed 
  of 
  the 
  Mississippi, 
  or 
  the 
  depository 
  

  

  