﻿ANNIVERSARY 
  ADDRESS 
  OF 
  THE 
  PRESIDENT. 
  I 
  23 
  

  

  be 
  seen. 
  It 
  has 
  also 
  been 
  my 
  good 
  fortune 
  to 
  spend 
  an 
  entire 
  day 
  

   in 
  these 
  quarries 
  ; 
  and 
  I 
  fully 
  indorse 
  his 
  reading 
  of 
  the 
  succession. 
  

   (Vide 
  Mr. 
  Blake's 
  minute 
  description, 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  

   xxxvi. 
  pp. 
  203-213.) 
  

  

  The 
  general 
  succession 
  and 
  contents 
  I 
  give, 
  as 
  in 
  previous 
  cases. 
  

  

  Bed 
  No. 
  1. 
  Portland 
  Eock. 
  

  

  n 
  ri 
  1 
  j 
  /t. 
  i 
  f 
  Triqonia 
  qibbosa, 
  Ostrea 
  solitaria, 
  Lima 
  

  

  „ 
  2. 
  Calcareous 
  sands 
  (basal 
  I 
  ^J, 
  Myt 
  \ 
  lus 
  unguiculat 
  ^ 
  Cy- 
  

  

  sancls) 
  - 
  the 
  lisbury 
  < 
  ^^ 
  pulckell(lf 
  C 
  orbula 
  dammari- 
  

  

  [ 
  ensis, 
  an 
  d 
  Pleuromya 
  tellina. 
  

  

  „ 
  3. 
  Rubbly 
  and 
  glauconite 
  Trigonia 
  gibbosa; 
  20 
  species 
  occur 
  in 
  this 
  

   beds 
  ( 
  Trigonia-beds). 
  and 
  the 
  same 
  beds 
  at 
  Coate. 
  

  

  These 
  beds, 
  Mr. 
  Blake 
  believes, 
  succeed 
  those 
  of 
  the 
  Great 
  

   Swindon 
  Quarry 
  in 
  a 
  downward 
  direction. 
  The 
  Trigonia-beds 
  in 
  

   the 
  Coate 
  section 
  have 
  yielded 
  to 
  Mr. 
  Blake 
  22 
  species, 
  17 
  of 
  which 
  

   are 
  bivalves. 
  

  

  The 
  Bourton 
  outlier 
  is 
  a 
  marked 
  feature 
  in 
  the 
  history 
  of 
  the 
  

   Swindon 
  Portland 
  rocks. 
  Palaeontologically 
  the 
  Bourton 
  beds 
  are 
  

   peculiar. 
  Echinobrissus 
  Brodiei, 
  so 
  rare 
  elsewhere 
  in 
  the 
  Port- 
  

   landian 
  series, 
  is 
  here 
  abundant 
  ; 
  the 
  true 
  Cardium 
  dissimile 
  is 
  re- 
  

   placed 
  by 
  C. 
  Morinicum, 
  a 
  shell 
  characteristic 
  of 
  the 
  lowest 
  true 
  

   Portland 
  beds 
  of 
  Boulogne 
  ; 
  downwards, 
  a 
  thick 
  bed 
  of 
  limestone 
  

   contains 
  Perna 
  Bouchardi, 
  and 
  its 
  base 
  is 
  full 
  of 
  various 
  dark- 
  

   coloured 
  stones 
  or 
  pebbles. 
  " 
  Among 
  them 
  are 
  Lydian 
  stones, 
  light- 
  

   coloured 
  quartz, 
  also 
  hardened 
  phosphate 
  nodules 
  derived 
  from 
  

   previous 
  formations 
  " 
  (Kimmeridge 
  Clay). 
  The 
  inference 
  drawn 
  by 
  

   Mr. 
  Blake 
  relative 
  to 
  these 
  facts 
  is 
  one 
  of 
  considerable 
  physical 
  

   importance. 
  These 
  pebble-beds 
  do 
  not 
  occur 
  in 
  the 
  Portland 
  area 
  ; 
  

   hence 
  Mr. 
  Blake 
  assumes 
  that 
  " 
  these 
  more 
  northern 
  districts 
  were 
  

   more 
  rapidly 
  upheaved 
  than 
  those 
  to 
  the 
  south, 
  and 
  brought 
  earlier 
  

   into 
  the 
  conditions 
  necessary 
  for 
  calcareous 
  deposits 
  " 
  (loc. 
  cit. 
  

   p. 
  210). 
  

  

  Again, 
  the 
  author 
  gives 
  reasons 
  for 
  believing 
  that 
  the 
  Purbecks 
  

   of 
  Swindon 
  differ 
  from 
  those 
  of 
  the 
  southern 
  districts 
  through 
  dif- 
  

   ference 
  of 
  character. 
  In 
  the 
  Swindon 
  Purbecks 
  we 
  have 
  uniform 
  

   deposits 
  over 
  considerable 
  distances, 
  lying 
  on 
  unevenly 
  but 
  not 
  

   deeply 
  eroded 
  Portland 
  rocks. 
  In 
  the 
  southern 
  Purbecks 
  there 
  are 
  

   carvings 
  of 
  rivers, 
  transported 
  blocks, 
  and 
  the 
  rapid 
  dying-out 
  of 
  

   deposits 
  — 
  all 
  features 
  characteristic 
  of 
  subaerial 
  action. 
  Seeing, 
  

   then, 
  that 
  we 
  have 
  reason 
  to 
  believe 
  that 
  the 
  earliest 
  Swindon 
  Port- 
  

   land 
  Stone 
  antedated 
  that 
  at 
  Portland, 
  we 
  are 
  justified 
  in 
  concluding 
  

   that 
  the 
  land 
  here 
  emerged 
  sooner 
  and 
  more 
  rapidly 
  from 
  the 
  ocean 
  ; 
  

   hence 
  the 
  regular 
  deposits 
  reached 
  only 
  the 
  " 
  basal 
  sands." 
  Finally, 
  

   Mr. 
  Blake 
  believes 
  that 
  the 
  " 
  newly-risen 
  Portland 
  was 
  carved 
  out 
  by 
  

   the 
  river 
  whose 
  course 
  is 
  still 
  marked 
  in 
  the 
  quarry, 
  and 
  that 
  the 
  more 
  

   gradual 
  elevation 
  of 
  the 
  south 
  left 
  time 
  for 
  the 
  deposition 
  of 
  the 
  

   "Whit 
  bed" 
  and 
  "the 
  Boach," 
  and 
  that 
  when 
  the 
  sea 
  was 
  finally 
  

   expelled 
  its 
  place 
  was 
  taken 
  by 
  a 
  large 
  shallow 
  lake, 
  ofttimes 
  dried 
  

   up, 
  and 
  during 
  minor 
  oscillations 
  supporting 
  forests 
  of 
  Cycads 
  and 
  

   Conifers, 
  the 
  growth 
  of 
  which 
  on 
  the 
  spot, 
  well 
  known 
  there, 
  is 
  

  

  