﻿BEYKICH 
  — 
  0LIG0CENE. 
  9 
  

  

  organic 
  remains 
  in 
  the 
  members 
  of 
  the 
  Belgian 
  Oligocene 
  furnishes 
  

   evidence 
  that 
  in 
  them 
  is 
  developed 
  a 
  palasontological 
  division 
  into 
  

   parts, 
  which 
  does 
  not 
  exist 
  in 
  the 
  Fontainebleau 
  Sands, 
  and 
  that 
  

   they 
  decide 
  only 
  in 
  part 
  the 
  question 
  of 
  the 
  time- 
  equivalent 
  of 
  this 
  

   French 
  marine 
  formation. 
  

  

  M. 
  Hebert's 
  Catalogue 
  of 
  Shells 
  common 
  to 
  the 
  Fontainebleau 
  

   Sands 
  and 
  the 
  Belgian 
  Tertiaries 
  comprises 
  24 
  species 
  which, 
  as 
  

   already 
  noticed 
  by 
  Sir 
  Charles 
  Lyell, 
  occur 
  jointly 
  in 
  the 
  Upper 
  and 
  

   Middle 
  Limburg 
  beds, 
  and 
  15 
  of 
  which 
  are 
  confined 
  to 
  beds 
  of 
  that 
  

   age 
  ; 
  but 
  none 
  of 
  these 
  24 
  species 
  are 
  peculiar 
  to 
  the 
  Lower 
  Limburg 
  

   beds 
  — 
  Dumont's 
  " 
  Tongrien 
  inferieur," 
  — 
  so 
  that 
  it 
  is 
  extremely 
  pro- 
  

   bable 
  that 
  the 
  latter 
  formation 
  is 
  unrepresented 
  in 
  the 
  Fontainebleau 
  

   Sands 
  ; 
  and 
  the 
  more 
  the 
  relations 
  of 
  the 
  Paris 
  freshwater 
  beds 
  to 
  

   the 
  overlying 
  marine 
  formations 
  of 
  neighbouring 
  districts 
  are 
  studied, 
  

   the 
  less 
  probable 
  does 
  it 
  appear 
  that, 
  between 
  the 
  Gypsum 
  of 
  Mont- 
  

   martre 
  and 
  the 
  first 
  appearance 
  of 
  species 
  belonging 
  to 
  the 
  succeed- 
  

   ing 
  marine 
  fauna, 
  there 
  should 
  exist 
  a 
  gap, 
  represented 
  in 
  Belgium 
  

   by 
  the 
  Lower 
  Limburg 
  beds. 
  The 
  conclusion, 
  therefore, 
  seems 
  in- 
  

   evitable 
  that 
  the 
  last-named 
  formation 
  is 
  partly 
  contemporaneous 
  

   with 
  the 
  French 
  freshwater 
  strata. 
  In 
  fact, 
  a 
  similar 
  conclusion 
  

   has 
  already 
  been 
  drawn 
  by 
  Dumont*, 
  who 
  considered 
  the 
  Lower 
  

   Tongrian 
  (sable 
  glauconifere 
  de 
  Lethen) 
  equivalent 
  to 
  the 
  Paris 
  

   freshwater 
  formation, 
  and 
  the 
  succeeding 
  beds 
  (Middle 
  Limburg 
  of 
  

   Sir 
  Charles 
  Lyell) 
  to 
  correspond 
  to 
  the 
  Fontainebleau 
  Sands. 
  

  

  The 
  results 
  of 
  the 
  researches 
  of 
  Dr. 
  Fridolin 
  Sandberger 
  on 
  the 
  

   Mayence 
  Basin 
  are 
  also 
  quite 
  in 
  harmony 
  with 
  the 
  above 
  conclusion, 
  

   for 
  he 
  finds 
  that 
  the 
  oldest 
  bed 
  of 
  that 
  series 
  — 
  the 
  marine 
  sand 
  of 
  

   Alzey, 
  — 
  about 
  the 
  contemporaneity 
  of 
  which 
  with 
  the 
  Fontainebleau 
  

   Sands 
  there 
  is 
  no 
  doubt, 
  — 
  corresponds, 
  not 
  with 
  the 
  Lower 
  Limburg 
  

   beds, 
  but 
  with 
  the 
  Middle. 
  The 
  Alzey 
  Sand 
  is, 
  however, 
  of 
  the 
  

   same 
  age 
  as 
  the 
  marine 
  beds 
  of 
  Basel 
  and 
  the 
  Northern 
  Jura, 
  which, 
  

   near 
  Delsberg, 
  repose 
  on 
  a 
  freshwater 
  formation 
  equivalent 
  to 
  the 
  

   Gypsum 
  of 
  Montmartre, 
  so 
  that 
  here 
  also 
  there 
  is 
  no 
  marine 
  equi- 
  

   valent 
  of 
  the 
  Lower 
  Tongrian 
  beds 
  of 
  Belgium. 
  

  

  It 
  is, 
  therefore, 
  apparent 
  that 
  it 
  is 
  necessary 
  to 
  include 
  Dumont's 
  

   " 
  Systeme 
  Tongrien 
  inferieur" 
  in 
  the 
  Eocene 
  period 
  if, 
  in 
  the 
  French 
  

   series, 
  the 
  boundary-line 
  be 
  drawn 
  between 
  the 
  Gypsum 
  of 
  Mont- 
  

   martre 
  and 
  the 
  Fontainebleau 
  Sands, 
  that 
  is 
  to 
  say, 
  where 
  M. 
  Elie 
  

   de 
  Beaumont 
  originally 
  drew 
  the 
  line 
  between 
  Older 
  and 
  Middle 
  

   Tertiary. 
  Sir 
  Charles 
  Lyell 
  could 
  not 
  but 
  consider 
  the 
  Limburg 
  

   beds 
  as 
  a 
  natural 
  whole, 
  while, 
  in 
  his 
  earlier 
  classification, 
  he 
  ter- 
  

   minated 
  his 
  Middle 
  Eocene 
  with 
  the 
  equivalents 
  of 
  the 
  Sandstones 
  

   of 
  Beauchamp, 
  and 
  called 
  all 
  above 
  them, 
  and 
  below 
  the 
  Faluns, 
  

   Upper 
  Eocene 
  ; 
  but 
  it 
  is 
  not 
  admissible, 
  as 
  in 
  his 
  newer 
  classifi- 
  

   cation, 
  to 
  place 
  all 
  the 
  Limburg 
  beds 
  together 
  above 
  the 
  Gypsum 
  of 
  

   Montmartre 
  and 
  call 
  them 
  Miocene, 
  while 
  the 
  Gypsum 
  itself 
  remains 
  

   Eocene. 
  Against 
  the 
  adoption 
  of 
  this 
  classification 
  are, 
  moreover, 
  

   the 
  stratigraphical 
  relations 
  of 
  the 
  Limburg 
  Beds, 
  as 
  well 
  as 
  their 
  

   geographical 
  and 
  organic 
  connexion 
  ; 
  and 
  still 
  more 
  strongly 
  against 
  

  

  * 
  Bull. 
  Acad. 
  Koy. 
  de 
  Belg. 
  vol. 
  xviii., 
  No. 
  8. 
  

  

  