﻿THE 
  TERTIARY 
  FORMATIONS 
  OP 
  VIRGINIA. 
  337 
  

  

  throughout 
  the 
  Tertiary 
  region 
  with 
  its 
  innumerable 
  ravines 
  and 
  shal- 
  

   low 
  valleys 
  of 
  excavation. 
  Whether 
  this 
  last 
  change 
  was 
  impressed 
  

   upon 
  the 
  surface 
  by 
  the 
  final 
  emergence 
  of 
  the 
  whole 
  territory 
  from 
  

   the 
  sea 
  to 
  its 
  present 
  level, 
  or 
  by 
  some 
  more 
  universal 
  denuding 
  flood 
  

   which 
  has 
  swept 
  the 
  continent 
  generally, 
  we 
  venture 
  not 
  to 
  decide 
  ; 
  

   though 
  the 
  comparatively 
  small 
  amount 
  of 
  transported 
  superficial 
  peb- 
  

   bles 
  and 
  boulders, 
  and 
  the 
  absence 
  of 
  any 
  which 
  can 
  be 
  traced 
  beyond 
  

   the 
  nearest 
  rocks 
  at 
  the 
  head 
  of 
  tide, 
  incline 
  us 
  to 
  attribute 
  the 
  denud- 
  

   ation 
  in 
  question 
  to 
  the 
  supposed 
  local 
  action 
  rather 
  than 
  to 
  the 
  other. 
  

  

  V. 
  EOCENE 
  FORMATION 
  OF 
  VIRGINIA. 
  

  

  36. 
  Though 
  some 
  attention 
  has 
  been 
  devoted 
  by 
  Mr 
  Conrad, 
  and 
  

   other 
  American 
  naturalists, 
  to 
  the 
  Tertiary 
  fossils 
  of 
  several 
  localities 
  

   in 
  Virginia, 
  as 
  yet 
  their 
  researches 
  have 
  been 
  limited 
  to 
  such 
  as 
  apper- 
  

   tain 
  to 
  the 
  subordinate 
  divisions 
  of 
  the 
  Tertiary 
  group, 
  arranged 
  by 
  

   Mr 
  Lyell 
  under 
  the 
  head 
  of 
  Pliocene 
  and 
  Miocene 
  ; 
  and 
  though 
  the 
  

   existence 
  of 
  an 
  Eocene 
  deposit 
  might 
  naturally 
  have 
  been 
  inferred, 
  no 
  

   locality 
  of 
  this 
  character 
  appears 
  to 
  have 
  been 
  known 
  to 
  them. 
  The 
  

   existence 
  of 
  an 
  extensive 
  Eocene 
  formation 
  in 
  eastern 
  Virginia 
  is 
  now 
  

   for 
  the 
  first 
  time 
  announced, 
  as 
  furnishing 
  an 
  interesting 
  step 
  in 
  the 
  

   progress 
  of 
  the 
  geological 
  inquiries 
  which 
  are 
  now 
  on 
  foot 
  by 
  legisla- 
  

   tive 
  authoritv 
  in 
  that 
  state. 
  

  

  37. 
  This 
  formation 
  appears 
  to 
  have 
  a 
  general 
  meridional 
  direction, 
  

   traversing; 
  the 
  state 
  from 
  the 
  Potomac 
  to 
  the 
  Roanoke. 
  It 
  is 
  inter- 
  

   sected 
  and 
  exposed 
  by 
  the 
  principal 
  rivers, 
  first 
  making 
  its 
  appearance 
  

   at 
  from 
  twenty 
  to 
  thirty 
  miles 
  below 
  the 
  primary 
  ridge. 
  The 
  most 
  

   interesting 
  locality 
  which 
  has 
  as 
  yet 
  been 
  visited, 
  and 
  that 
  from 
  which 
  

   the 
  fossils 
  have 
  been 
  most 
  abundantly 
  obtained, 
  is 
  on 
  the 
  James 
  river, 
  

   beginning 
  a 
  little 
  above 
  City 
  Point, 
  and 
  extending 
  nearly 
  in 
  a 
  conti- 
  

   nuous 
  manner 
  to 
  Coggins 
  Point, 
  a 
  distance, 
  following 
  the 
  flexures 
  of 
  

   the 
  shore, 
  of 
  about 
  eleven 
  miles. 
  At 
  Coggins 
  Point, 
  Torbay 
  and 
  

   Evergreen, 
  the 
  cliffs 
  have 
  a 
  height 
  varying 
  from 
  thirty 
  to 
  forty 
  feet. 
  

   At 
  the 
  base, 
  a 
  stratum 
  of 
  what 
  appears 
  at 
  first 
  to 
  be 
  a 
  blackish 
  clay 
  

   extends 
  nearly 
  horizontally 
  throughout 
  the 
  whole 
  distance, 
  rising 
  a 
  

   little 
  as 
  it 
  ascends 
  the 
  river. 
  Its 
  height 
  above 
  the 
  water 
  at 
  Coggins 
  

  

  VOL. 
  V. 
  4 
  K 
  

  

  