﻿REV. 
  W. 
  DOWNES 
  ON" 
  THE 
  BLACKDOWN 
  BEDS. 
  77 
  

  

  The 
  large 
  majority 
  of 
  the 
  above 
  writers 
  deal 
  prominently 
  with 
  

   the 
  question 
  of 
  the 
  age 
  of 
  the 
  Blackdown 
  and 
  Haldon 
  beds. 
  It 
  

   will 
  be 
  well 
  therefore, 
  before 
  proceeding 
  further, 
  to 
  sum 
  up 
  the 
  

   opinions 
  which 
  from 
  time 
  to 
  time 
  have 
  been 
  expressed. 
  

  

  The 
  Age 
  of 
  the 
  Beds. 
  

  

  It 
  appears 
  that 
  De 
  la 
  Beche 
  (Trans. 
  Geol. 
  Soc. 
  ser. 
  2. 
  vol. 
  ii. 
  

   1826) 
  and 
  (Ordn. 
  Survey 
  Beport, 
  p. 
  237, 
  1839) 
  classified 
  them 
  as 
  

   Upper 
  Greensand. 
  

  

  Fitton 
  (1836) 
  calls 
  them 
  Lower 
  Greensand. 
  

  

  Godwin- 
  Austen 
  (1842) 
  described 
  them 
  as 
  possibly 
  a 
  sandy 
  con- 
  

   dition 
  of 
  the 
  Gault. 
  

  

  Meyer 
  at 
  first 
  maintained 
  (1863, 
  1866) 
  that 
  they 
  were 
  Lower 
  

   Greensand, 
  but 
  subsequently 
  to 
  some 
  extent 
  changed 
  his 
  opinion 
  ; 
  

   and 
  I 
  gather 
  from 
  his 
  later 
  paper 
  (1874) 
  that 
  he 
  is 
  somewhat 
  dis- 
  

   posed 
  to 
  assent 
  to 
  an 
  opinion 
  which 
  had 
  been 
  expressed 
  by 
  Mr. 
  

   Etheridge. 
  who, 
  mainly 
  on 
  the 
  evidence 
  of 
  the 
  Black-Yen 
  section 
  

   near 
  Lyme 
  Kegis, 
  places 
  them 
  on 
  the 
  horizon 
  of 
  the 
  Gault 
  ; 
  but 
  

   he 
  still 
  thinks 
  that 
  some 
  part 
  may 
  be 
  of 
  Lower 
  Greensand 
  age. 
  A 
  

   quotation 
  may 
  make 
  this 
  more 
  clear. 
  He 
  says 
  : 
  — 
  " 
  True 
  Gault 
  is 
  to 
  

   be 
  seen 
  near 
  Punfield, 
  in 
  Swanage 
  Bay, 
  where 
  it 
  is 
  underlain 
  by 
  a 
  

   considerable 
  thickness 
  of 
  Lower 
  Greensand. 
  It 
  is 
  traceable 
  as 
  Gault 
  

   along 
  the 
  coast-line 
  as 
  far 
  westward 
  as 
  Mewps 
  Baj*-. 
  At 
  Lulworth 
  

   Cove 
  it 
  is 
  to 
  be 
  seen 
  no 
  longer 
  as 
  Grault, 
  which 
  in 
  its 
  argillaceous 
  

   condition 
  has 
  either 
  thinned 
  out 
  or 
  given 
  place 
  to 
  dark 
  greenish 
  

   sandy 
  strata 
  with 
  zones 
  of 
  large 
  concretionary 
  nodules. 
  

  

  " 
  These 
  beds 
  contain 
  Gault 
  fossils 
  in 
  abundance, 
  and 
  (what 
  is 
  

   well 
  worthy 
  of 
  notice) 
  pass 
  upwards 
  insensibly 
  into 
  Upper 
  Green- 
  

   sand, 
  and 
  downwards 
  into 
  ferruginous 
  sands 
  of 
  Lower 
  Greensand. 
  

  

  " 
  In 
  the 
  altered 
  condition 
  of 
  the 
  Gault, 
  as 
  present 
  at 
  Lulworth, 
  

   one 
  finds, 
  therefore, 
  an 
  approach 
  already 
  to 
  the 
  condition 
  of 
  the 
  so- 
  

   called 
  Gault 
  as 
  seen 
  at 
  Black 
  Yen. 
  And 
  there 
  is 
  no 
  doubt 
  whatever 
  

   that 
  Gault 
  in 
  such 
  condition 
  is 
  present 
  both 
  at 
  Black 
  Yen 
  and 
  in 
  

   the 
  sections 
  to 
  the 
  westward. 
  But 
  is 
  this 
  all 
  ? 
  I 
  think 
  it 
  possible 
  

   that 
  Lower 
  Greensand, 
  which, 
  as 
  we 
  have 
  seen 
  at 
  Lulworth, 
  actually 
  

   accompanies 
  the 
  Gault 
  to 
  its 
  extinction 
  as 
  a 
  clay-bed, 
  may 
  form 
  a 
  

   part 
  also 
  of 
  the 
  still 
  doubtful 
  strata 
  to 
  the 
  westward. 
  As 
  to 
  the 
  

   correctness 
  of 
  this 
  supposition, 
  it 
  is 
  only 
  fair 
  to 
  say 
  that 
  I 
  have 
  no 
  

   evidence 
  whatever"*. 
  

  

  I 
  have 
  reason 
  to 
  know 
  that 
  in 
  1879 
  Mr. 
  Meyer's 
  opinion 
  remained 
  

   unshaken; 
  for 
  he 
  says 
  then 
  "I 
  still 
  believe 
  the 
  Blackdown 
  Green- 
  

   sand 
  to 
  represent 
  a 
  littoral 
  deposit 
  of 
  more 
  than 
  one 
  age 
  or 
  period, 
  

   ranging 
  possibly 
  from 
  the 
  highest 
  beds 
  of 
  the 
  Lower 
  Greensand 
  to 
  

   the 
  lower 
  beds 
  of 
  the 
  Upper 
  Greensand 
  inclusive 
  "t. 
  

  

  Not 
  having 
  myself 
  as 
  yet 
  had 
  an 
  opportunity 
  of 
  visiting 
  the 
  Lul- 
  

   worth 
  section, 
  I 
  have 
  no 
  opinion 
  to 
  offer. 
  I 
  can 
  only 
  remark 
  that 
  

   it 
  appears 
  to 
  me 
  that 
  Meyer 
  and 
  Barrois 
  (to 
  whose 
  views 
  we 
  shall 
  

   next 
  come) 
  seem 
  to 
  differ 
  in 
  a 
  rather 
  important 
  point 
  in 
  their 
  de- 
  

  

  * 
  Meyer, 
  Quart, 
  Journ. 
  Geol. 
  Soc. 
  1874, 
  p. 
  382. 
  

   t 
  Extract 
  from 
  a 
  letter, 
  by 
  permission 
  of 
  the 
  writer. 
  

  

  