﻿128 
  PROCEEDINGS 
  OF 
  THE 
  GEOLOGICAL 
  SOCIETY. 
  

  

  The 
  plate 
  of 
  comparative 
  sections 
  given 
  by 
  Mr. 
  Blake, 
  on 
  the 
  scale 
  

   of 
  48 
  feet 
  to 
  an 
  inch, 
  admirably 
  shows 
  the 
  proportional 
  thickness 
  

   and 
  development 
  of 
  the 
  different 
  horizons 
  through 
  the 
  country, 
  and 
  

   also 
  explains 
  the 
  table 
  of 
  fossils 
  prepared 
  by 
  Mr. 
  Blake, 
  and 
  my 
  

   numerical 
  analysis 
  reconstructed 
  to 
  show 
  the 
  generic 
  and 
  specific 
  

   values 
  in 
  one 
  table. 
  The 
  generalized 
  theoretical 
  section 
  on 
  the 
  same 
  

   sheet 
  will 
  bear 
  close 
  attention 
  and 
  scrutiny. 
  The 
  intermittent 
  

   thickening 
  and 
  thinning 
  of 
  the 
  series 
  from 
  Portland 
  and 
  St. 
  Alban's 
  

   Head 
  on 
  the 
  coast 
  to 
  Buckinghamshire, 
  diagrammatically 
  explains 
  

   the 
  vertical 
  columns 
  above. 
  

  

  The 
  next 
  communication 
  naturally 
  follows 
  on 
  the 
  two 
  previous 
  

   papers 
  by 
  Mr. 
  Blake, 
  viz. 
  the 
  Portland 
  Rocks 
  and 
  the 
  Kimmeridge 
  

   Clay, 
  and 
  the 
  third 
  by 
  Messrs. 
  Blake 
  and 
  Hudleston, 
  on 
  the 
  Corallian 
  

   rocks. 
  These 
  papers 
  referred 
  to 
  the 
  development 
  of 
  these 
  forma- 
  

   tions 
  in 
  Britain 
  only. 
  The 
  one 
  I 
  have 
  now 
  to 
  notice 
  is 
  " 
  On 
  the 
  

   Correlation 
  of 
  the 
  Upper 
  Jurassic 
  rocks 
  of 
  England 
  with 
  those 
  of 
  

   the 
  Continent. 
  — 
  Part. 
  I. 
  The 
  Paris 
  Basin, 
  by 
  the 
  Rev. 
  J. 
  F. 
  Blake, 
  

   M.A." 
  The 
  author 
  shows 
  that 
  while 
  the 
  normal 
  deposits 
  of 
  the 
  

   period 
  commencing 
  with 
  the 
  Oxford 
  Clay 
  and 
  continuing 
  to 
  the 
  

   close 
  of 
  the 
  Jurassic 
  era 
  were 
  essentially 
  argillaceous, 
  the 
  uniformity 
  

   was 
  broken 
  by 
  the 
  deposition 
  of 
  the 
  calcareous 
  Corallian 
  rocks 
  — 
  but 
  

   that, 
  in 
  spite 
  of 
  episodes, 
  there 
  is 
  a 
  continuity 
  both 
  in 
  the 
  physical 
  

   and 
  biological 
  features, 
  uniting 
  the 
  whole 
  into 
  one 
  great 
  group 
  to 
  

   which 
  the 
  term 
  Upper 
  Jurassic 
  is 
  appropriately 
  given 
  (p. 
  497). 
  The 
  

   rocks 
  hitherto 
  called 
  Corallian 
  in 
  England 
  comprise 
  much 
  that 
  is 
  

   classed 
  with 
  the 
  Oxfordian 
  by 
  the 
  French 
  geologists. 
  

  

  The 
  Upper 
  Jurassic 
  rocks 
  of 
  France 
  occur 
  in 
  two 
  distinct 
  areas. 
  

   The 
  Seine 
  and 
  the 
  Loire 
  and 
  smaller 
  rivers 
  drain 
  the 
  more 
  northern 
  ; 
  

   the 
  more 
  southern 
  is 
  a 
  continuation 
  of 
  the 
  Swiss 
  Jura, 
  and 
  lies 
  to 
  

   the 
  south 
  of 
  the 
  central 
  plateau 
  of 
  Auvergne. 
  

  

  The 
  former 
  (Seine 
  and 
  Loire) 
  constitutes 
  the 
  basin 
  of 
  Paris, 
  and 
  

   is 
  the 
  subject 
  of 
  Mr. 
  Blake's 
  paper. 
  Within 
  the 
  Paris-basin 
  area 
  

   there 
  are 
  five 
  ranges, 
  of 
  unequal 
  size 
  and 
  importance, 
  separated 
  

   from 
  each 
  other 
  by 
  intervals 
  in 
  which 
  either 
  older 
  or 
  newer 
  rocks 
  

   occupy 
  the 
  surface 
  of 
  the 
  ground. 
  These 
  are 
  : 
  — 
  

  

  1. 
  From 
  the 
  Ardennes 
  to 
  the 
  Cher. 
  

  

  2. 
  The 
  two 
  Charentes. 
  

  

  3. 
  Normandy 
  with 
  Orne 
  and 
  Sarthe. 
  

  

  4. 
  The 
  Pays 
  de 
  Bray. 
  

  

  5. 
  The 
  Boulonnais. 
  

  

  The 
  physical 
  features 
  and 
  palaeontology 
  of 
  these 
  five 
  areas 
  are 
  cor- 
  

   related 
  by 
  Mr. 
  Blake 
  with 
  the 
  Upper 
  Jurassic 
  rocks 
  of 
  Britain. 
  

  

  I. 
  From 
  the 
  Ardennes 
  to 
  the 
  Cher. 
  

  

  The 
  classification 
  of 
  the 
  rocks 
  of 
  this 
  area 
  has 
  been 
  completed 
  by 
  

   MM. 
  Sauvage 
  and 
  Buvignier*. 
  The 
  3 
  divisions 
  are 
  : 
  — 
  I. 
  The 
  

  

  * 
  Sauvage 
  and 
  Buvignier, 
  ' 
  Statistique 
  Mineralogique 
  et 
  Greologique 
  du 
  dept. 
  

   des 
  Ardennes.' 
  

  

  