﻿132 
  proceedings 
  of 
  the 
  geological 
  society. 
  

  

  Department 
  oe 
  the 
  Chek. 
  — 
  As 
  far 
  back 
  as 
  1838 
  this 
  department 
  

   was 
  described 
  by 
  Fabre 
  ; 
  followed 
  by 
  Boulanger 
  and 
  Bertera 
  in 
  1850 
  

   (Texte 
  explicatif 
  de 
  la 
  carte 
  geologique 
  du 
  Cher) 
  ; 
  but 
  Douville 
  and 
  

   Jourdy 
  in 
  1875 
  (Bull. 
  Soc. 
  Geol. 
  France, 
  ser. 
  8, 
  vol. 
  iii. 
  p. 
  93) 
  have 
  

   most 
  recently 
  described 
  the 
  area. 
  Their 
  classification 
  is 
  as 
  follows 
  : 
  — 
  

  

  KlMMERIDGIAN. 
  

  

  1. 
  Limestone 
  of 
  Barrois. 
  

  

  2. 
  Virgulian 
  Marls. 
  

  

  3. 
  Astartian 
  Limestone. 
  

  

  A. 
  Mavis 
  and 
  Nodular 
  Limestones. 
  

  

  B. 
  Nerinsean 
  Oolite. 
  

  

  C. 
  Fucoidal 
  Marls 
  and 
  Limestones. 
  

  

  Corallian. 
  

  

  4. 
  Upper 
  Lithographic 
  Limestones 
  with 
  Aram, 
  achilles. 
  

  

  D. 
  Limestone 
  with 
  Pinna. 
  

  

  E. 
  Compact 
  Limestone. 
  

  

  5. 
  Chalky 
  Limestone 
  of 
  Bourges. 
  

  

  6. 
  Lithographic 
  Limestones. 
  

  

  7. 
  Sponge-limestones 
  with 
  Aon. 
  maraoitiaoins, 
  Am. 
  bi- 
  

  

  mammatus, 
  and 
  Am. 
  plicatilis. 
  

  

  II. 
  The 
  two 
  Charentes. 
  

  

  The 
  main 
  question 
  to 
  be 
  solved 
  in 
  this 
  district 
  of 
  the 
  Charentes 
  

   was 
  the 
  age 
  of 
  the 
  so-called 
  " 
  Portland 
  n 
  and 
  even 
  " 
  Purbeck 
  ,: 
  

   beds, 
  to 
  ascertain 
  Avhether 
  there 
  arc 
  any 
  rocks 
  corresponding 
  to 
  

   those 
  that 
  we 
  know 
  as 
  such 
  in 
  England. 
  Coquand 
  in 
  ]858 
  

   (' 
  Statistique 
  de 
  la 
  Charente 
  ') 
  proposed 
  a 
  classification 
  for 
  the 
  Jurassic- 
  

   rocks 
  of 
  the 
  Upper 
  Charente, 
  dividing 
  the 
  upper 
  portion 
  of 
  the 
  Juras- 
  

   sic 
  rocks 
  as 
  follows 
  : 
  — 
  

  

  Upper 
  Jurassic. 
  

   Purheckian. 
  

   Portlandian. 
  

  

  Carious 
  Limestone. 
  

   Limestone 
  with 
  Nncula 
  inflexa. 
  

   Oolitic 
  Limestone. 
  

   Limestone 
  with 
  Cardium 
  dissimile. 
  

   Sands. 
  

   Kimmeridgian. 
  

   Virgulian 
  Marls. 
  

   Pterocerian 
  Limestones. 
  

   Astartian 
  Limestones. 
  

  

  Middle 
  Jurassic. 
  

   Corallian. 
  

  

  Oolite 
  with 
  Nerincea. 
  

  

  Coral 
  Limestone. 
  

  

  Solid 
  Limestone. 
  

   Oxfordian. 
  

   Callovian. 
  

  

  Prof. 
  Blake 
  closely 
  examined 
  the 
  distribution 
  of 
  the 
  fossils 
  and 
  

   other 
  characters 
  in 
  the 
  beds 
  of 
  this 
  and 
  the 
  following 
  department, 
  

   the 
  Lower 
  Charente, 
  and 
  satisfied 
  himself 
  of 
  the 
  presence 
  of 
  the 
  

   Lower 
  Portland 
  and 
  of 
  beds 
  representing 
  the 
  Purbeck. 
  

  

  