﻿BEYBICH— 
  OLIGOCEffE. 
  7 
  

  

  Basin, 
  fully 
  to 
  make 
  out 
  the 
  correlation 
  of 
  the 
  Tertiary 
  formations 
  

   of 
  the 
  Mayence 
  Basin, 
  Belgium, 
  and 
  Northern 
  Germary. 
  

  

  Swiss 
  geologists 
  had 
  for 
  some 
  time 
  been 
  well 
  aware 
  * 
  that 
  certain 
  

   of 
  the 
  beds 
  in 
  the 
  valleys 
  of 
  the 
  Northern 
  Jura 
  and 
  in 
  the 
  neigh- 
  

   bourhood 
  of 
  Basel 
  corresponded 
  with 
  the 
  deposits 
  of 
  the 
  Mayence 
  

   Basin 
  ; 
  and 
  this 
  fact 
  was, 
  in 
  1855, 
  rendered 
  still 
  more 
  certain 
  by 
  M. 
  

   Hebert, 
  who 
  published 
  a 
  catalogue 
  of 
  the 
  Shells 
  of 
  the 
  Delsberg 
  dis- 
  

   trictf 
  , 
  comparing 
  them 
  with 
  those 
  of 
  France, 
  Germany, 
  and 
  Belgium. 
  

  

  As 
  a 
  general 
  result 
  of 
  these 
  various 
  researches, 
  besides 
  different 
  

   views 
  on 
  special 
  points, 
  there 
  are 
  two 
  general 
  conclusions 
  of 
  the 
  

   greatest 
  importance, 
  and 
  the 
  truth 
  of 
  which 
  can 
  no 
  longer 
  remain 
  

   in 
  doubt 
  : 
  namely, 
  (1) 
  that 
  during 
  the 
  deposition 
  of 
  the 
  Fontaine- 
  

   bleau 
  Sands 
  the 
  sea 
  was 
  inhabited 
  by 
  a 
  peculiar 
  and 
  rich 
  fauna, 
  

   equally 
  distinct 
  from 
  that 
  which 
  existed 
  before 
  it 
  and 
  that 
  which 
  

   succeeded 
  it 
  ; 
  (2) 
  that 
  the 
  beds 
  contemporaneous 
  with 
  the 
  Fontaine- 
  

   bleau 
  Sands, 
  and 
  those 
  which 
  most 
  nearly 
  approximate 
  in 
  age 
  to 
  

   them, 
  occur 
  in 
  particular 
  areas, 
  which 
  do 
  not 
  correspond 
  with 
  the 
  

   areas 
  of 
  occurrence 
  of 
  the 
  older 
  deposits, 
  or 
  with 
  those 
  of 
  the 
  newer. 
  

   Professor 
  Beyrich 
  then 
  observes 
  that, 
  in 
  his 
  opinion, 
  these 
  two 
  facts 
  

   not 
  only 
  justify, 
  but 
  also 
  render 
  necessary 
  the 
  establishment 
  of 
  a 
  great 
  

   division 
  of 
  the 
  Tertiary 
  period 
  for 
  the 
  reception 
  of 
  these 
  strata, 
  — 
  that 
  

   is, 
  if 
  the 
  general 
  classification 
  of 
  the 
  Tertiary 
  formations 
  is 
  to 
  remain 
  

   in 
  accordance 
  with 
  our 
  knowledge 
  both 
  of 
  the 
  changes 
  in 
  the 
  organic 
  

   contents 
  of 
  the 
  strata 
  and 
  the 
  alterations 
  in 
  the 
  physical 
  features 
  of 
  

   the 
  earth's 
  crust 
  during 
  their 
  deposition 
  ; 
  and 
  he, 
  therefore, 
  felt 
  him- 
  

   self 
  justified 
  in 
  establishing 
  an 
  " 
  Oligocene 
  " 
  period 
  as 
  already 
  noticed. 
  

  

  In 
  support 
  of 
  his 
  view, 
  and 
  to 
  show 
  that 
  the 
  necessity 
  of 
  such 
  a 
  

   subdivision 
  had 
  been 
  recognized 
  before 
  the 
  reading 
  of 
  his 
  paper 
  in 
  

   which 
  he 
  first 
  used 
  the 
  term, 
  he 
  cites 
  the 
  memoir 
  on 
  the 
  Tertiaries 
  

   of 
  Northern 
  Europe 
  by 
  M. 
  Hebert 
  i, 
  already 
  noticed, 
  who 
  considered 
  

   the 
  evidence 
  so 
  strong 
  in 
  favour 
  of 
  M. 
  Elie 
  de 
  Beaumont's 
  earlier 
  

   view 
  of 
  the 
  age 
  of 
  the 
  Fontainebleau 
  Sands, 
  that 
  he 
  observed 
  that, 
  if 
  

   Sir 
  Charles 
  Lyell 
  considered 
  that 
  formation 
  an 
  essential 
  part 
  of 
  his 
  

   " 
  Eocene," 
  the 
  terms 
  " 
  Eocene," 
  " 
  Miocene," 
  and 
  " 
  Pliocene 
  " 
  must 
  

   be 
  abolished. 
  At 
  the 
  same 
  time 
  he 
  remarked 
  that 
  it 
  would 
  probably 
  

   be 
  better 
  to 
  divide 
  the 
  Tertiary 
  formations 
  into 
  four 
  great 
  groups 
  

   instead 
  of 
  three, 
  if 
  it 
  could 
  be 
  shown 
  that 
  the 
  extension 
  of 
  the 
  sea 
  

   at 
  the 
  time 
  of 
  the 
  deposition 
  of 
  the 
  Faluns 
  of 
  Touraine 
  differed 
  as 
  

   much 
  from 
  that 
  during 
  the 
  deposition 
  of 
  the 
  Fontainebleau 
  Sands 
  as 
  

   during 
  that 
  of 
  the 
  Calcaire 
  grossier. 
  

  

  On 
  other 
  grounds, 
  Deshayes 
  arrived§, 
  in 
  1857, 
  at 
  a 
  very 
  similar 
  

   conclusion; 
  for, 
  while 
  he 
  admitted 
  that 
  the 
  very 
  peculiar 
  fauna 
  of 
  the 
  

   Fontainebleau 
  Sands 
  contained 
  but 
  few 
  species 
  in 
  common 
  with 
  the 
  

   Calcaire 
  grossier, 
  yet 
  he 
  considered 
  that 
  it 
  presented 
  a 
  still 
  greater 
  

   contrast 
  to 
  that 
  of 
  the 
  Faluns 
  of 
  Touraine, 
  and 
  he 
  added, 
  " 
  si 
  no 
  as 
  

   avions 
  a 
  nous 
  prononcer 
  et 
  a 
  formuler 
  une 
  opinion 
  conforme 
  aux 
  faits 
  

  

  * 
  Studer's 
  Geologie 
  der 
  Schweitz, 
  vol. 
  ii. 
  1853, 
  p. 
  403. 
  

  

  t 
  " 
  Note 
  sur 
  le 
  terrain 
  tertiaire 
  moyen 
  du 
  nord 
  de 
  l'Europe," 
  Bull. 
  Soc. 
  Geol. 
  

   de 
  France, 
  deuxieme 
  serie, 
  1855, 
  vol. 
  xii. 
  p. 
  762. 
  J 
  Ibid. 
  p. 
  771. 
  

  

  § 
  Animaux 
  sans 
  vertebres 
  du 
  Bassin 
  de 
  Paris, 
  Introduction, 
  p. 
  17. 
  

  

  c2 
  

  

  