﻿442 
  MR. 
  S. 
  S. 
  BTJCKMA.N 
  ON 
  THE 
  

  

  The 
  only 
  difference 
  was 
  that 
  the 
  upper 
  part 
  of 
  the 
  Procester-Hill 
  

   Cephalopoda-bed 
  was 
  placed 
  in 
  the 
  zone 
  of 
  A. 
  opalinus 
  ; 
  while 
  the 
  

   Sands 
  were 
  sometimes 
  spoken 
  of 
  as 
  part 
  of 
  the 
  zone 
  of 
  A. 
  bifrons, 
  at 
  

   other 
  times 
  as 
  the 
  zone 
  of 
  A. 
  jurensis 
  * 
  : 
  all 
  were 
  included 
  in 
  the 
  

   Upper 
  Lias. 
  

  

  The 
  chief 
  opposition 
  to 
  the 
  above 
  views 
  came 
  from 
  my 
  father 
  f 
  , 
  

   who 
  first 
  of 
  all 
  considered 
  the 
  Cotteswold 
  Sands 
  as 
  equivalent 
  to 
  the 
  

   Freestones 
  of 
  the 
  Cheltenham 
  district, 
  but 
  at 
  a 
  later 
  date 
  placed 
  the 
  

   Teovil 
  Sands 
  in 
  this 
  position, 
  the 
  Cotteswold 
  Sands 
  being 
  allowed 
  

   to 
  go 
  to 
  the 
  Upper 
  Lias 
  because 
  their 
  position 
  was 
  altogether 
  below 
  

   that 
  of 
  the 
  Yeovil 
  Sands. 
  This 
  view 
  of 
  the 
  different 
  positions 
  of 
  

   the 
  Cotteswold 
  and 
  Yeovil 
  Sands 
  is 
  noticeable, 
  for 
  it 
  coincides 
  

   closely 
  with 
  Opper's 
  ; 
  and 
  it 
  is 
  clearly 
  set 
  forth 
  in 
  a 
  diagram 
  of 
  the 
  

   Midford 
  Sands 
  compared 
  with 
  Haresfield 
  £. 
  

  

  To 
  the 
  sands 
  which 
  throughout 
  the 
  greater 
  part 
  of 
  England 
  lie 
  

   between 
  Liassic 
  clay 
  and 
  Oolitic 
  limestone, 
  Prof. 
  Phillips 
  § 
  ex- 
  

   tended 
  Smith's 
  name 
  and 
  applied 
  the 
  term 
  " 
  Midford 
  Sands 
  ; 
  " 
  

   -although 
  he 
  placed 
  them 
  in 
  the 
  Liassic 
  period, 
  he 
  considered 
  them 
  

   as 
  Transition 
  Strata. 
  H. 
  B. 
  Woodward, 
  in 
  the 
  first 
  edition 
  of 
  his 
  

   standard 
  work 
  |j, 
  restricted 
  the 
  term 
  "Midford 
  Sands" 
  to 
  the 
  

   counties 
  of 
  Dorset, 
  Somerset, 
  and 
  Gloucester, 
  and 
  attached 
  them 
  to 
  

   the 
  " 
  Oolitic." 
  Lately 
  (1887), 
  in 
  the 
  second 
  edition 
  (p. 
  285), 
  he 
  

   places 
  them 
  in 
  the 
  " 
  Inferior 
  Oolite 
  Series/' 
  considers 
  them 
  tran- 
  

   sitional, 
  and 
  defines 
  them 
  as 
  follows 
  : 
  — 
  

  

  " 
  Zones. 
  

   Midford 
  f 
  Ammonites 
  (Harpoceras) 
  opalinus. 
  

   Sand. 
  \ 
  „ 
  (Lytoceras) 
  Jurensis." 
  

  

  Such 
  is 
  the 
  position 
  of 
  affairs 
  at 
  present, 
  and 
  thus 
  the 
  name 
  

   " 
  Midford 
  Sands 
  " 
  is 
  in 
  common 
  use 
  for 
  the 
  Yellow 
  Sands 
  of 
  

   Gloucestershire 
  with 
  the 
  overlying 
  Cephalopoda-bed, 
  for 
  the 
  Yellow 
  

   Sands 
  of 
  North 
  Somerset, 
  and 
  for 
  the 
  Yellow 
  Sands 
  and 
  shelly 
  

   Sandstones 
  of 
  South 
  Somerset 
  and 
  Dorset 
  %. 
  Now 
  the 
  questions 
  

   arise, 
  Do 
  these 
  series 
  of 
  Sands 
  begin 
  on 
  the 
  same 
  horizon, 
  and, 
  

   including 
  the 
  Cephalopoda-bed, 
  do 
  they 
  end 
  on 
  the 
  same 
  horizon 
  ? 
  

   How 
  much 
  of 
  this 
  horizon 
  is 
  found 
  at 
  Midford 
  ? 
  Do 
  the 
  limits 
  of 
  

   the 
  Opalinum- 
  and 
  Jurense-zones 
  correspond 
  with 
  the 
  limits 
  of 
  the 
  

   Sands 
  ; 
  or 
  do 
  they 
  not 
  go 
  above 
  and 
  below 
  them 
  in 
  some 
  cases, 
  and 
  

   not 
  reach 
  the 
  bottom 
  in 
  others 
  ? 
  Are 
  the 
  sands 
  all 
  on 
  one 
  horizon, 
  

   as 
  stated 
  by 
  Wright 
  ; 
  or 
  are 
  they 
  on 
  two 
  different 
  horizons, 
  as 
  Oppel 
  

   and 
  my 
  father 
  thought 
  ? 
  

  

  We 
  must 
  appeal 
  to 
  the 
  Ammonite-fauna 
  ; 
  and 
  having 
  by 
  means 
  of 
  

   that 
  fauna 
  selected 
  a 
  definite 
  horizon 
  as 
  a 
  fixed 
  point, 
  it 
  will 
  be 
  

  

  * 
  "Lias 
  Ammonites," 
  Palaeont. 
  Soc. 
  p. 
  137 
  et. 
  seq. 
  (1879). 
  

  

  t 
  " 
  The 
  Oolites," 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  xiv. 
  p. 
  106 
  ; 
  also 
  "The 
  Cepha- 
  

   lopoda-bed," 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  xxxiii. 
  p. 
  3. 
  

  

  | 
  " 
  On 
  the 
  so-called 
  ' 
  Midford-Sands,' 
  " 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  xxxv. 
  

   p. 
  738 
  (1879). 
  

  

  § 
  Geology 
  of 
  Oxford 
  and 
  Valley 
  of 
  Thames, 
  p. 
  118 
  (1871). 
  

  

  || 
  The 
  Geology 
  of 
  England 
  and 
  Wales, 
  p. 
  166 
  (1876). 
  

  

  Tf 
  H. 
  B. 
  Woodward, 
  op. 
  cit. 
  2nd 
  ed. 
  p. 
  287. 
  

  

  