﻿6 
  GEOLOGICAL 
  MEMOIRS. 
  

  

  Upper 
  Eocene 
  or 
  as 
  Lower 
  Miocene, 
  and 
  at 
  last 
  to 
  that 
  of 
  the 
  desira- 
  

   bility 
  of 
  instituting 
  a 
  fourth 
  principal 
  division 
  of 
  the 
  Tertiary 
  period 
  

   for 
  their 
  reception. 
  

  

  The 
  only 
  reason 
  why 
  the 
  equivalents 
  of 
  the 
  Fontainebleau 
  Sands 
  had 
  

   not 
  been 
  made 
  known 
  before 
  was 
  the 
  incomplete 
  knowledge 
  which 
  

   formerly 
  existed 
  of 
  the 
  organic 
  contents 
  of 
  that 
  formation 
  ; 
  but 
  this 
  

   want 
  has 
  since 
  been 
  removed 
  by 
  the 
  publication 
  of 
  Deshayes's 
  great 
  

   work 
  on 
  the 
  Tertiary 
  Shells 
  of 
  the 
  Environs 
  of 
  Paris. 
  It 
  should 
  not, 
  

   however, 
  be 
  forgotten 
  that, 
  in 
  the 
  gereral 
  remarks 
  at 
  the 
  conclusion 
  

   of 
  that 
  work, 
  M. 
  Deshayes 
  does 
  not 
  express 
  any 
  decided 
  opinion 
  of 
  

   the 
  age 
  of 
  the 
  Mayence 
  Basin, 
  which 
  is 
  contemporaneous 
  with 
  the 
  

   Fontainebleau 
  Sands, 
  but 
  merely 
  observes 
  that 
  the 
  former 
  probably 
  

   belongs 
  to 
  the 
  Middle-Tertiary 
  period, 
  from 
  which, 
  however, 
  he 
  ex- 
  

   cludes 
  the 
  latter. 
  So 
  also 
  Bronn*, 
  after 
  an 
  examination 
  of 
  a 
  great 
  

   number 
  of 
  Shells 
  from 
  the 
  Mayence 
  Basin, 
  came 
  to 
  the 
  conclusion 
  

   that 
  they 
  indicated 
  a 
  high 
  Miocene 
  horizon. 
  

  

  In 
  the 
  introduction 
  of 
  the 
  later 
  work 
  of 
  M. 
  Deshayes 
  f, 
  that 
  

   author 
  describes 
  how 
  the 
  railway-works 
  near 
  Etampes 
  have 
  contri- 
  

   buted 
  to 
  our 
  knowledge 
  of 
  the 
  fauna 
  of 
  the 
  Fontainebleau 
  Sands, 
  

   chiefly 
  through 
  the 
  exertions 
  of 
  MM. 
  Raulin 
  and 
  Hebert, 
  and 
  thus 
  

   to 
  the 
  determination 
  of 
  the 
  parallelism 
  of 
  that 
  formation 
  with 
  Ter- 
  

   tiary 
  beds 
  of 
  other 
  districts, 
  more 
  especially 
  its 
  correlation, 
  as 
  deter- 
  

   mined 
  by 
  Hebert 
  i, 
  with 
  a 
  part 
  of 
  the 
  Belgian 
  Tertiary 
  formation, 
  

   the 
  Shells 
  from 
  which 
  had 
  been 
  already 
  described 
  by 
  M. 
  Nyst. 
  Thus 
  

   Sir 
  Charles 
  Lyell 
  was 
  enabled 
  § 
  to 
  draw 
  up 
  a 
  scheme 
  of 
  a 
  classifica- 
  

   tion 
  of 
  the 
  Tertiaries 
  of 
  Belgium 
  and 
  French 
  Flanders, 
  in 
  which 
  the 
  

   Fontainebleau 
  Sands 
  were 
  referred 
  to 
  the 
  middle 
  portion 
  of 
  the 
  Upper 
  

   Eocene 
  period 
  ; 
  and 
  this 
  memoir 
  was 
  the 
  foundation 
  of 
  the 
  rapid 
  pro- 
  

   gress 
  made 
  so 
  soon 
  afterwards 
  towards 
  a 
  better 
  understanding 
  of 
  the 
  

   German 
  Tertiaries. 
  

  

  Shortly 
  afterwards, 
  in 
  1853, 
  Dr. 
  Fridolin 
  Sandberger 
  showed 
  || 
  the 
  

   close 
  relationship 
  of 
  the 
  Mayence 
  beds 
  to 
  those 
  of 
  Belgium, 
  which 
  

   were 
  considered 
  Upper 
  Eocene 
  by 
  Sir 
  Charles 
  Lyell. 
  Previously 
  to 
  

   this, 
  it 
  had 
  been 
  shown 
  that 
  the 
  Hermsdorf 
  Clay 
  was 
  of 
  the 
  same 
  

   age 
  as 
  that 
  of 
  Boom 
  and 
  Basele 
  in 
  Belgium, 
  and 
  that 
  the 
  interpreta- 
  

   tion 
  of 
  the 
  remaining 
  beds 
  of 
  Northern 
  Germany 
  must 
  be 
  arrived 
  at 
  

   through 
  the 
  study 
  of 
  the 
  Belgian 
  Tertiaries. 
  In 
  1853, 
  in 
  the 
  intro- 
  

   duction 
  to 
  his 
  work 
  on 
  the 
  Tertiary 
  Shells 
  of 
  Northern 
  Germany, 
  

   Professor 
  Beyrich 
  was 
  the 
  first 
  to 
  show 
  the 
  connexion 
  of 
  the 
  German 
  

   Tertiaries, 
  according 
  to 
  their 
  received 
  relations, 
  with 
  those 
  of 
  Belgium 
  

   accoiding 
  to 
  the 
  new 
  classification 
  of 
  Sir 
  Charles 
  Lyell 
  ; 
  but 
  it 
  was 
  

   only 
  in 
  1854 
  that 
  he 
  was 
  enabled, 
  through 
  the 
  investigation 
  of 
  the 
  

   clay 
  which 
  occurs 
  south 
  of 
  Antwerp 
  and 
  near 
  Berlin, 
  as 
  well 
  as 
  at 
  

   Cassel, 
  where 
  it 
  overlies 
  freshwater 
  beds 
  containing 
  layers 
  of 
  brown 
  

   coal, 
  which 
  are 
  connected 
  with 
  the 
  younger 
  beds 
  of 
  the 
  Mayence 
  

  

  * 
  Leonhard 
  und 
  Bronn's 
  Neues 
  Jahrbuch, 
  1837, 
  pp. 
  153 
  et 
  seq. 
  

   t 
  Descr. 
  des 
  Animaux 
  sans 
  vertebres 
  decouverts 
  dans 
  le 
  Bassin 
  de 
  Paris, 
  1857, 
  

   p. 
  16. 
  | 
  Bull. 
  Soc. 
  G-eol. 
  de 
  France, 
  deuxieme 
  serie, 
  vol. 
  vi. 
  pp. 
  459 
  et 
  seq. 
  

  

  § 
  Quart. 
  Journ. 
  G-eol. 
  Soc. 
  vol. 
  viii. 
  pp. 
  277 
  et 
  seq. 
  

   || 
  TJntersuchungen 
  liber 
  das 
  Mainzer 
  Tertiarbecken. 
  

  

  