﻿120 
  PROCEEDINGS 
  OF 
  THE 
  GEOLOGICAL 
  SOCIETY. 
  

  

  Succeeding 
  the 
  paper 
  on 
  the 
  Corallian 
  Rocks 
  of 
  England, 
  by 
  the 
  

   Rev. 
  J. 
  E. 
  Blake, 
  M.A., 
  and 
  W. 
  H. 
  Hudleston, 
  M.A., 
  and 
  more 
  or 
  

   less 
  a 
  companion 
  to 
  or 
  continuation 
  of 
  the 
  same 
  important 
  subject, 
  I 
  

   have 
  now 
  to 
  notice 
  the 
  exhaustive 
  paper 
  " 
  On 
  the 
  Portland 
  Rocks 
  

   of 
  England," 
  by 
  the 
  Rev. 
  J. 
  E. 
  Blake, 
  who 
  alone 
  undertook 
  this 
  

   important 
  investigation. 
  Like 
  the 
  previous 
  paper 
  by 
  himself 
  and 
  

   Mr. 
  Hudleston, 
  this 
  interpretation 
  of 
  the 
  distribution 
  of 
  the 
  

   Portland 
  Rocks 
  has 
  had 
  no 
  equal 
  since 
  the 
  memorable 
  and 
  masterly 
  

   memoir 
  by 
  Dr. 
  Eitton 
  " 
  On 
  the 
  Strata 
  between 
  the 
  Chalk 
  and 
  

   Kimmeridge 
  Clay 
  in 
  the 
  South-east 
  of 
  England 
  " 
  (Transactions 
  of 
  

   the 
  Geological 
  Soc. 
  ser. 
  2, 
  vol. 
  iv. 
  pp. 
  103-388). 
  I 
  shall 
  have 
  to 
  

   notice 
  a 
  subsequent 
  paper 
  by 
  Mr. 
  Blake 
  " 
  On 
  the 
  Correlation 
  of 
  the 
  

   Upper 
  Jurassic 
  Rocks 
  with 
  those 
  of 
  the 
  Continent 
  — 
  Part 
  I. 
  the 
  

   Paris 
  basin," 
  which 
  unites 
  the 
  labours 
  of 
  Hudleston 
  and 
  himself 
  

   with 
  those 
  of 
  the 
  Erench 
  geologists 
  in 
  a 
  more 
  correct 
  reading 
  of 
  the 
  

   Anglo-Erench 
  Jurassic 
  rocks, 
  especially 
  those 
  of 
  the 
  Anglo-Parisian 
  

   basin, 
  to 
  which 
  his 
  first 
  paper 
  is 
  devoted. 
  Mr. 
  Blake 
  and 
  Mr. 
  

   Hudleston, 
  in 
  the 
  introduction 
  to 
  their 
  paper 
  upon 
  " 
  the 
  Corallian 
  

   Rocks 
  of 
  England," 
  regarded 
  the 
  Portlandian 
  as 
  a 
  local 
  development 
  

   in 
  a 
  great 
  "Pelolithic" 
  formation, 
  determining 
  not 
  to 
  extend 
  the 
  

   term 
  " 
  Corallian 
  " 
  to 
  beds 
  of 
  probably 
  various 
  ages 
  which 
  agreed 
  

   " 
  only 
  with 
  our 
  own 
  in 
  occurring 
  in 
  the 
  Oxford-Kimmeridge 
  seas, 
  

   and 
  in 
  containing 
  corals." 
  Doubtless 
  in 
  England 
  we 
  had 
  two 
  " 
  epi- 
  

   sodes," 
  the 
  " 
  Corallian 
  and 
  Portlandian." 
  How 
  far 
  the 
  continental 
  

   " 
  episodes 
  " 
  may 
  be 
  correlated 
  with 
  ours, 
  has 
  yet 
  to 
  be 
  determined. 
  

   It 
  is 
  the 
  endeavour 
  of 
  Mr. 
  Blake, 
  in 
  his 
  paper, 
  to 
  show 
  that 
  the 
  

   rocks 
  which 
  have 
  been 
  called 
  Middle 
  and 
  Lower 
  Portlandian 
  at 
  

   Boulogne 
  have 
  their 
  representatives 
  in 
  tbe 
  Kimmeridge 
  Clay. 
  He 
  

   describes 
  the 
  relations 
  of 
  the 
  various 
  parts 
  of 
  the 
  Portlandian 
  episode 
  

   with 
  each 
  other, 
  thus 
  endeavouring 
  to 
  obtain 
  some 
  "insight 
  into 
  

   those 
  final 
  oscillations 
  which 
  converted 
  the 
  open 
  argillaceous 
  ocean 
  

   into 
  the 
  lake-bearing 
  and 
  cycad-growing 
  continent 
  of 
  the 
  Purbecks." 
  

  

  Mr. 
  Blake 
  divides 
  the 
  subject 
  of 
  his 
  paper 
  into 
  six 
  geographical 
  

   areas 
  : 
  — 
  

  

  1. 
  The 
  Island 
  of 
  Portland. 
  

  

  2. 
  St. 
  Alban's 
  Head 
  and 
  Kimmeridge. 
  

  

  3. 
  Upway. 
  

  

  4. 
  The 
  Vale 
  of 
  Wardour. 
  

  

  5. 
  Devizes. 
  

  

  6. 
  Swindon. 
  

  

  The 
  Portland 
  Oolite 
  of 
  Portland 
  he 
  divides 
  into 
  9 
  beds, 
  the 
  sandy 
  

   series 
  below 
  into 
  5, 
  making 
  all 
  together 
  14 
  divisions. 
  Each 
  of 
  the 
  

   9 
  limestone 
  beds 
  possesses 
  distinctive 
  species; 
  and 
  such 
  being 
  the 
  

   case, 
  I 
  name 
  these 
  and 
  the 
  forms 
  illustrating 
  them 
  : 
  — 
  

  

  