﻿8 
  GEOLOGICAL 
  MEMOIRS. 
  

  

  tels 
  que 
  nous 
  les 
  concevons, 
  nous 
  admittrions 
  pour 
  les 
  sables 
  de 
  Fon- 
  

   tainebleau 
  un 
  quatrieme 
  membre 
  parmi 
  les 
  terrains 
  tertiaires 
  aussi 
  

   independant 
  de 
  l'etage 
  moyen 
  que 
  de 
  l'etage 
  inferieur." 
  

  

  Again, 
  in 
  1857, 
  Herr 
  Karl 
  Mayer, 
  of 
  Zurich, 
  published 
  a 
  tabular 
  

   view 
  of 
  the 
  European 
  Tertiaries, 
  in 
  which 
  he 
  divided 
  them 
  into 
  three 
  

   groups, 
  the 
  middle 
  corresponding 
  to 
  the 
  Oligocene, 
  and 
  the 
  upper 
  to 
  

   the 
  " 
  Neogene 
  " 
  of 
  Homes, 
  including 
  the 
  Miocene 
  and 
  the 
  Pliocene. 
  

  

  Recently 
  Sir 
  Charles 
  Lyell* 
  has 
  altered 
  his 
  view 
  of 
  the 
  boundary- 
  

   line 
  between 
  Eocene 
  and 
  Miocene, 
  so 
  as 
  to 
  bring 
  it 
  in 
  accord 
  with 
  

   that 
  of 
  M. 
  Elie 
  de 
  Beaumont, 
  and 
  he 
  now 
  calls 
  " 
  Upper 
  Miocene 
  " 
  

   what 
  was 
  formerly 
  his 
  " 
  Miocene," 
  and 
  " 
  Lower 
  Miocene 
  " 
  what 
  

   used 
  to 
  be 
  called 
  " 
  Upper 
  Eocene." 
  Professor 
  Beyrich 
  believes 
  that 
  

   this 
  change 
  entails 
  certain 
  consequences, 
  the 
  knowledge 
  of 
  which 
  had 
  

   probably 
  withheld 
  Sir 
  Charles 
  Lyell 
  from 
  adopting 
  this 
  view 
  before, 
  

   and 
  which 
  are 
  connected 
  with 
  the 
  question, 
  Where 
  is 
  naturally 
  the 
  

   boundary 
  between 
  the 
  Oligocene 
  and 
  the 
  Eocene 
  ? 
  

  

  As 
  regards 
  the 
  Paris 
  Basin, 
  it 
  is 
  well 
  known 
  that 
  the 
  Fontaine- 
  

   bleau 
  Sands 
  are 
  separated, 
  on 
  the 
  one 
  hand, 
  from 
  the 
  Calcaire 
  gros- 
  

   sier 
  by 
  the 
  freshwater 
  Paris 
  Gypsum, 
  and, 
  on 
  the 
  other 
  hand, 
  from 
  

   the 
  younger 
  beds 
  of 
  Touraine 
  by 
  the 
  freshwater 
  limestone 
  known 
  

   as 
  the 
  " 
  Calcaire 
  de 
  la 
  Beauce." 
  The 
  occurrence 
  of 
  these 
  freshwater 
  

   formations 
  is 
  alone 
  sufficient 
  to 
  prove 
  that 
  considerable 
  local 
  changes 
  

   in 
  the 
  relations 
  of 
  land 
  and 
  sea 
  occurred 
  at 
  the 
  beginning 
  and 
  at 
  the 
  

   end 
  of 
  the 
  deposition 
  of 
  the 
  Fontainebleau 
  Sands 
  ; 
  but 
  it 
  leaves 
  open 
  

   the 
  question 
  whether 
  those 
  changes 
  were 
  contemporaneous 
  with 
  the 
  

   general 
  alterations 
  in 
  the 
  configuration 
  of 
  the 
  continent, 
  through 
  

   which 
  the 
  dissimilar 
  distribution 
  of 
  the 
  three 
  principal 
  Tertiary 
  

   groups 
  resulted. 
  As 
  regards 
  the 
  Paris 
  Basin, 
  the 
  question 
  also 
  

   stands 
  thus 
  : 
  — 
  If 
  the 
  Fontainebleau 
  Sands 
  be 
  termed 
  Oligocene, 
  is 
  

   the 
  freshwater 
  formation 
  with 
  the 
  Gypsum 
  of 
  Montmartre 
  to 
  be 
  

   called 
  Eocene 
  or 
  Oligocene 
  ? 
  — 
  and 
  is 
  the^Calcaire 
  de 
  la 
  Beauce 
  to 
  be 
  

   considered 
  Oligocene 
  or 
  Miocene 
  ? 
  The 
  answer 
  cannot 
  be 
  obtained 
  

   by 
  a 
  study 
  of 
  the 
  relations 
  of 
  the 
  Paris 
  beds 
  alone, 
  but 
  naturally 
  only 
  

   by 
  a 
  comparison 
  of 
  them 
  with 
  the 
  strata 
  of 
  other 
  districts, 
  where 
  

   the 
  French 
  freshwater 
  beds 
  are 
  represented 
  partly 
  by 
  brackish 
  -water 
  

   and 
  partly 
  by 
  marine 
  formations. 
  Such 
  formations 
  occur 
  in 
  Belgium, 
  

   the 
  North 
  of 
  Germany, 
  and 
  the 
  South 
  of 
  England. 
  

  

  In 
  Belgium, 
  the 
  beds 
  considered 
  to 
  belong 
  to 
  the 
  Oligocene 
  period 
  

   form 
  so 
  closely 
  connected 
  a 
  series, 
  that 
  Sir 
  Charles 
  Lyell 
  substituted 
  

   for 
  Dumont's 
  terms 
  "Tongrien" 
  and 
  "Rupelien" 
  a 
  single 
  designation, 
  

   calling 
  them 
  the 
  " 
  Limburg 
  Beds 
  ; 
  " 
  but 
  a 
  freshwater 
  formation 
  

   similar 
  to 
  the 
  Paris 
  Gypsum 
  does 
  not 
  exist. 
  Professor 
  Beyrich 
  then 
  

   observes 
  that 
  the 
  uppermost 
  formation 
  — 
  the 
  Bolderberg 
  deposit 
  — 
  ■ 
  

   belongs 
  to 
  the 
  Miocene 
  period, 
  and 
  the 
  lowermost 
  strata 
  — 
  the 
  Laeken 
  

   Beds 
  — 
  are 
  doubtfully 
  Eocene, 
  so 
  that 
  it 
  is 
  very 
  probable 
  that 
  the 
  

   Belgian 
  beds 
  not 
  only 
  include 
  the 
  period 
  of 
  the 
  Fontainebleau 
  Sands, 
  

   but 
  also 
  that 
  of 
  the 
  freshwater 
  Paris 
  Gypsum 
  and 
  that 
  of 
  the 
  Calcaire 
  

   de 
  la 
  Beauce 
  ; 
  but 
  he 
  remarks 
  that 
  the 
  different 
  distribution 
  of 
  the 
  

  

  * 
  Supplement 
  to 
  the 
  Fifth 
  Edition 
  of 
  a 
  Manual 
  of 
  Elementary 
  Geology, 
  1857, 
  

   pp. 
  5 
  et 
  scq. 
  

  

  