﻿BEER 
  HEAD 
  AND 
  THE 
  ADJACENT 
  CLTEE-SECTIONS. 
  383 
  

  

  a 
  feature 
  in 
  the 
  Beer-Head 
  and 
  other 
  sections, 
  are 
  in 
  great 
  measure 
  

   local. 
  The 
  recurrence 
  of 
  these 
  shingle-beds 
  throughout 
  the 
  several 
  

   sections 
  in 
  the 
  district, 
  and 
  their 
  limitation 
  to 
  distinct 
  and 
  definite 
  

   horizons, 
  would 
  seem, 
  however, 
  to 
  indicate 
  some 
  special 
  periods 
  of 
  

   disturbance. 
  It 
  is 
  at 
  least 
  worth 
  notice 
  that 
  the 
  horizon 
  of 
  one 
  of 
  

   them 
  is 
  marked 
  as 
  far 
  eastward 
  as 
  Lulworth 
  by 
  a 
  layer 
  of 
  phos- 
  

   phatic 
  nodules. 
  These 
  pebbles, 
  in 
  the 
  Devon 
  sections, 
  are 
  formed 
  

   entirely 
  of 
  sandstone, 
  and, 
  as 
  long 
  since 
  also 
  suggested 
  by 
  Mr. 
  

   Godwin-Austen 
  *, 
  would 
  seem 
  to 
  have 
  resulted 
  from 
  the 
  destruction 
  

   of 
  Portland 
  strata. 
  

  

  The 
  sand-beds 
  6 
  and 
  8 
  of 
  the 
  Branscombe 
  and 
  Weston 
  sections 
  

   are 
  also 
  in 
  so 
  far 
  peculiar 
  to 
  the 
  Devon 
  Upper 
  Greensand, 
  that 
  

   they 
  are 
  scarcely 
  represented 
  either 
  at 
  Lulworth 
  or 
  in 
  the 
  Isle 
  of 
  

   Wight. 
  It 
  would 
  appear, 
  however, 
  that 
  both 
  these 
  beds 
  exist 
  to 
  the 
  

   westward, 
  Orbitolina 
  concava, 
  Lam., 
  and 
  Exogyra 
  digitata, 
  Sow., 
  

   their 
  characteristic 
  and 
  common 
  fossils, 
  being 
  present 
  in 
  the 
  Haldon 
  

   Hills 
  f, 
  in 
  the 
  Irish 
  Greensand 
  %, 
  and, 
  I 
  believe, 
  also 
  in 
  the 
  greensand 
  

   of 
  Normandy. 
  

  

  The 
  Chert-beds 
  of 
  the 
  Devon 
  " 
  Upper 
  Greensand," 
  although 
  

   greatly 
  varying 
  in 
  thickness, 
  are 
  traceable 
  continuously 
  from 
  the 
  

   Dunscombe 
  Cliffs 
  to 
  the 
  Isle 
  of 
  Wight. 
  From 
  the 
  Blackdown 
  Hills 
  

   they 
  have 
  been 
  in 
  great 
  part 
  denuded. 
  

  

  The 
  Chloride 
  Marl 
  of 
  the 
  Beer-Head 
  section 
  is 
  remarkable 
  (as 
  

   already 
  stated) 
  on 
  account 
  of 
  its 
  unusual 
  development, 
  the 
  beds 
  

   10 
  to 
  12 
  of 
  Table 
  II., 
  which 
  from 
  their 
  fauna 
  and 
  mineral 
  character 
  

   certainly 
  represent 
  the 
  chloritic 
  marl, 
  having 
  in 
  the 
  Beer-Head 
  under- 
  

   cliff 
  a 
  thickness 
  collectively 
  of 
  not 
  less 
  than 
  20 
  feet. 
  It 
  is 
  true 
  that 
  

   this 
  thickness 
  is 
  exceptional, 
  and 
  that 
  the 
  beds 
  diminish 
  rapidly 
  to 
  the 
  

   east 
  and 
  west 
  of 
  the 
  Beer 
  basin. 
  Yet 
  their 
  presence 
  in 
  such 
  local 
  force 
  

   is 
  worth 
  notice 
  as 
  illustrating 
  the 
  variable 
  character 
  of 
  this 
  division. 
  

  

  Judging 
  from 
  appearances, 
  the 
  Chloritic 
  Marl 
  of 
  many 
  of 
  our 
  coast- 
  

   sections 
  would 
  seem 
  to 
  have 
  been 
  a 
  deposit 
  of 
  slow 
  accumulation. 
  

   Indeed 
  one 
  may 
  observe 
  in 
  it, 
  in 
  places, 
  an 
  almost 
  entire 
  change 
  

   of 
  fossils 
  within 
  the 
  thickness 
  of 
  only 
  a 
  few 
  inches. 
  Such 
  being 
  

   the 
  case, 
  an 
  occasional 
  thickening 
  of 
  the 
  strata, 
  as 
  at 
  Beer 
  Head, 
  

   and 
  possibly 
  at 
  Warminster, 
  is 
  far 
  from 
  unlikely. 
  

  

  In 
  tracing 
  these 
  beds 
  eastward, 
  the 
  threefold 
  subdivision 
  of 
  the 
  

   strata, 
  as 
  seen 
  between 
  Beer 
  Head 
  and 
  Branscombe, 
  becomes 
  less 
  

   and 
  less 
  apparent. 
  It 
  may 
  be 
  seen, 
  however, 
  although 
  somewhat 
  

   obscurely, 
  in 
  Pinhay 
  Cliffs 
  near 
  Lyme 
  Begis, 
  at 
  White 
  Nore 
  in 
  the 
  

   Isle 
  of 
  Purbeck, 
  and 
  more 
  clearly 
  in 
  cliffs 
  just 
  east 
  of 
  Punfield 
  

   Cove. 
  At 
  Chard 
  and 
  Chardstock 
  the 
  threefold 
  subdivision 
  of 
  the 
  

   strata 
  has 
  been 
  well 
  described 
  by 
  Mr. 
  Davidson 
  (Mon. 
  Pal. 
  Soc. 
  

   vol. 
  viii. 
  p. 
  114), 
  the 
  beds 
  IT., 
  V., 
  and 
  VI. 
  of 
  the 
  section 
  therein 
  

   given 
  answering 
  extremely 
  well 
  to 
  beds 
  10, 
  11, 
  12 
  of 
  the 
  Beer-Head 
  

   strata. 
  Curiously 
  enough, 
  this 
  section 
  of 
  Mr. 
  Davidson's 
  appears 
  to 
  

   have 
  been 
  taken 
  by 
  many 
  continental 
  geologists 
  as 
  a 
  measure 
  of 
  

   the 
  whole 
  of 
  the 
  English 
  Upper 
  Greensand. 
  

  

  * 
  Proc. 
  Geol. 
  Soc. 
  vol. 
  iv. 
  p. 
  197. 
  t 
  Trans. 
  Geol. 
  Soc. 
  ser. 
  2. 
  vol. 
  vi. 
  p. 
  452. 
  

   % 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  xxi. 
  p. 
  35. 
  

  

  