﻿BEYKICH 
  OLIGOCENE. 
  11 
  

  

  Nummulitic 
  formation 
  of 
  the 
  Western 
  Alps 
  is 
  contemporaneous 
  with 
  

   the 
  Fontainebleau 
  Sands. 
  

  

  As 
  regards 
  the 
  Fluvio 
  -marine 
  series 
  of 
  the 
  Isle 
  of 
  Wight, 
  Professor 
  

   Beyrich 
  gives 
  a 
  general 
  sketch 
  of 
  the 
  relative 
  position 
  of 
  its 
  various 
  

   parts, 
  and 
  notices 
  the 
  conclusion 
  of 
  Prof. 
  Forbes 
  *, 
  that 
  they 
  form 
  

   one 
  natural 
  series, 
  and 
  that 
  it 
  is 
  quite 
  artificial 
  to 
  consider 
  one 
  por- 
  

   tion 
  as 
  Miocene 
  and 
  the 
  rest 
  as 
  Eocene. 
  He 
  then 
  remarks 
  that 
  the 
  

   Hempstead 
  beds 
  correspond 
  to 
  the 
  Middle 
  Limburg 
  beds 
  of 
  Belgium, 
  

   and 
  that, 
  like 
  the 
  marine 
  and 
  brackish 
  -water 
  beds 
  of 
  the 
  Mayence 
  

   Basin, 
  they 
  cannot 
  be 
  placed 
  in 
  parallelism 
  with 
  the 
  Lower 
  Limburg, 
  

   or 
  Lower 
  Tongrian, 
  beds. 
  In 
  the 
  underlying 
  Bembridge 
  beds 
  have 
  

   been 
  found 
  species 
  of 
  Mammalia 
  which 
  occur 
  in 
  the 
  Paris 
  Gypsum, 
  

   and, 
  on 
  this 
  account, 
  the 
  two 
  formations 
  have 
  been 
  considered 
  con- 
  

   temporaneous 
  ; 
  but 
  the 
  few 
  marine 
  Shells 
  hitherto 
  found 
  permit 
  no 
  

   more 
  rigorous 
  comparison 
  of 
  the 
  marine 
  fauna 
  of 
  this 
  formation 
  with 
  

   that 
  of 
  other 
  marine 
  equivalents 
  of 
  the 
  Paris 
  freshwater 
  strata. 
  The 
  

   Osborne 
  beds 
  contain 
  only 
  fresh- 
  and 
  brackish-water 
  Shells 
  ; 
  by 
  

   Prof. 
  Forbes 
  they 
  were 
  closely 
  connected 
  with 
  the 
  Headon 
  Beds, 
  

   which, 
  on 
  account 
  of 
  their 
  including 
  a 
  middle 
  stratum 
  containing 
  

   marine 
  Shells, 
  are 
  of 
  the 
  highest 
  importance 
  to 
  the 
  classification 
  

   of 
  the 
  freshwater 
  formations 
  of 
  the 
  Isle 
  of 
  Wight. 
  In 
  this 
  bed 
  

   occur 
  two 
  species, 
  whose 
  association 
  in 
  every 
  other 
  marine 
  fauna 
  

   has 
  alone 
  been 
  considered 
  sufficient 
  proof 
  of 
  its 
  Oligocene 
  rela- 
  

   tion. 
  The 
  first 
  of 
  these 
  is 
  the 
  Cytherea 
  incrassata, 
  which 
  is 
  quite 
  

   foreign 
  to 
  the 
  Barton 
  Clay, 
  but 
  which 
  first 
  appears 
  in 
  the 
  Headon 
  

   beds, 
  and, 
  in 
  its 
  many 
  forms, 
  occurs 
  in 
  all 
  succeeding 
  Oligocene 
  

   faunas 
  ; 
  with 
  it 
  is 
  associated 
  the 
  second 
  species, 
  Cerithium 
  plica- 
  

   turn. 
  And 
  it 
  is 
  remarkable 
  that 
  the 
  accompanying 
  Eocene 
  species 
  

   of 
  the 
  Barton 
  Clay 
  are 
  such 
  as 
  are 
  also 
  found, 
  in 
  Belgium 
  or 
  near 
  

   Egeln, 
  associated 
  with 
  Cytherea 
  incrassata 
  in 
  the 
  Lower 
  Tongrian 
  

   marine 
  fauna. 
  Amongst 
  the 
  peculiar 
  marine 
  forms 
  of 
  the 
  Headon 
  

   beds 
  the 
  occurrence 
  of 
  the 
  genus 
  Borsonia 
  is 
  noteworthy, 
  as 
  it 
  is 
  

   present 
  in 
  all 
  German 
  Oligocene 
  faunas. 
  Of 
  freshwater 
  species, 
  

   Melania 
  muricata 
  is 
  very 
  important, 
  as 
  it 
  occurs 
  in 
  all 
  the 
  fresh- 
  

   water 
  beds 
  of 
  the 
  Isle 
  of 
  Wight, 
  and 
  is 
  also 
  found 
  in 
  the 
  Middle 
  

   Oligocene 
  freshwater 
  strata 
  of 
  Hesse, 
  from 
  which 
  it 
  was 
  described 
  

   by 
  Dunkerf, 
  in 
  1853, 
  as 
  Melania 
  horrida. 
  All 
  these 
  facts 
  lead 
  

   to 
  the 
  conclusion 
  that 
  the 
  Headon 
  beds 
  and 
  the 
  succeeding 
  fresh- 
  

   water 
  strata 
  all 
  belong 
  to 
  the 
  Oligocene 
  period. 
  If 
  the 
  Barton 
  

   Clay 
  be 
  the 
  equivalent 
  of 
  the 
  Beauchamp 
  Sands, 
  as 
  considered 
  by 
  

   Sir 
  Charles 
  Lyell 
  and 
  M. 
  Hebert, 
  then 
  the 
  Headon, 
  Osborne, 
  and 
  

   Bembridge 
  beds 
  must 
  together 
  be 
  considered 
  the 
  equivalents 
  of 
  the 
  

   undivided 
  French 
  freshwater 
  formation, 
  which 
  is 
  of 
  Lower 
  Oligocene 
  

   age, 
  and 
  which 
  separates 
  the 
  youngest 
  Eocene 
  beds 
  from 
  the 
  Middle 
  

   Oligocene 
  Fontainebleau 
  Sands 
  — 
  the 
  equivalent 
  of 
  the 
  Hempstead 
  

   beds. 
  This 
  classification 
  is 
  quite 
  in 
  accordance 
  with 
  the 
  conclusions 
  

   arrived 
  at 
  by 
  Prof. 
  Forbes, 
  and 
  also 
  with 
  Sir 
  Charles 
  Lyell's 
  original 
  

  

  * 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  ix. 
  1859, 
  p. 
  259. 
  

  

  f 
  Programm 
  der 
  hoheren 
  Gewerbschule 
  in 
  Cassel 
  zu 
  Michaelis, 
  1853, 
  p. 
  17. 
  

  

  