﻿698 
  SEAEXES 
  Y. 
  WOOD. 
  ON 
  THE 
  NEWER 
  

  

  having 
  obtained, 
  from 
  the 
  bed 
  over 
  the 
  Coralline 
  Crag 
  which 
  yielded 
  

   him 
  the 
  Cijrena 
  in 
  association 
  with 
  marine 
  shells, 
  specimens 
  of 
  

   Uydrobia 
  ulvce 
  in 
  this 
  imperfectly 
  fossilized 
  condition, 
  so 
  that 
  I 
  can 
  

   hardly 
  doubt 
  that 
  the 
  sea 
  entered 
  the 
  Butley-Creek 
  valley 
  during 
  

   the 
  stage 
  under 
  consideration, 
  and 
  from 
  the 
  elevation 
  at 
  which 
  this 
  

   bed 
  occurs, 
  up 
  to 
  the 
  height 
  at 
  least 
  of 
  40 
  feet 
  above 
  its 
  present 
  

   level, 
  j^orth 
  of 
  this, 
  along 
  the 
  eastern 
  side 
  of 
  East 
  Anglia, 
  no 
  

   further 
  trace 
  of 
  this 
  shell 
  (save 
  in 
  the 
  Crag 
  and 
  in 
  the 
  sand 
  hi) 
  has 
  

   yet 
  been 
  detected 
  ; 
  and 
  but 
  for 
  what 
  seems 
  to 
  occur 
  in 
  the 
  Butlev 
  

   valley, 
  I 
  should 
  have 
  inferred 
  that 
  the 
  sea 
  at 
  this 
  time 
  did 
  not 
  enter 
  

   the 
  valleys 
  of 
  the 
  Suffolk 
  and 
  Norfolk 
  coast 
  : 
  but 
  at 
  Barnwell 
  on 
  

   the 
  Cam 
  (slightly 
  to 
  the 
  south-west 
  of 
  the 
  centre 
  of 
  Sheet 
  51) 
  it 
  

   occurs 
  in 
  a 
  bed, 
  the 
  top 
  of 
  which 
  is 
  about 
  45 
  feet 
  above 
  0. 
  D., 
  

   associated 
  with 
  land 
  and 
  freshwater 
  mollusca 
  only. 
  To 
  the 
  north 
  

   of 
  this 
  bed, 
  and 
  distributed 
  over 
  the 
  north 
  centre 
  of 
  Sheet 
  51, 
  the 
  

   centre 
  and 
  west 
  of 
  Sheet 
  65, 
  and 
  the 
  east 
  of 
  Sheet 
  64*, 
  there 
  occur 
  

   patches 
  of 
  gravel 
  rising 
  as 
  very 
  low 
  eminences 
  out 
  of 
  the 
  level 
  of 
  

   the 
  Fen, 
  in 
  some 
  of 
  which 
  marine 
  molluscan 
  remains 
  occur 
  nu- 
  

   merously 
  ; 
  and 
  on 
  the 
  east 
  side 
  of 
  the 
  Wash, 
  in 
  Sheet 
  69, 
  the 
  same 
  

   formation 
  is 
  continued 
  by 
  a 
  brick-clay 
  in 
  the 
  valley 
  of 
  the 
  Nar, 
  

   and 
  a 
  gravel 
  at 
  Hunstanton, 
  all 
  yielding 
  numerous 
  remains 
  of 
  

   marine 
  mollusca, 
  all 
  of 
  living 
  species. 
  This 
  formation, 
  in 
  its 
  marine 
  

   condition 
  in 
  Sheets 
  51, 
  65, 
  and 
  the 
  Nar 
  valley, 
  seems 
  not 
  to 
  reach 
  

   elevations 
  of 
  more 
  than 
  30 
  feet 
  above 
  0. 
  D., 
  thus 
  corresponding 
  with 
  

   the 
  freshwater 
  part 
  at 
  Barnwell 
  at 
  about 
  45 
  ; 
  and 
  though 
  the 
  Cyrena 
  

   has 
  not 
  been 
  found 
  in 
  it 
  at 
  Hunstanton 
  or 
  in 
  the 
  War 
  valley, 
  my 
  

   friend 
  Mr. 
  Harmer 
  found 
  many 
  specimens 
  of 
  that 
  shell 
  (some 
  of 
  

   which 
  I 
  have) 
  in 
  association 
  with 
  the 
  marine 
  shells 
  in 
  this 
  gravel 
  

   at 
  March, 
  in 
  Sheet 
  65, 
  just 
  as 
  they 
  are 
  in 
  the 
  Yorkshire 
  part 
  of 
  the 
  

   formation 
  at 
  Kelsea 
  Hill, 
  in 
  Sheet 
  86. 
  

  

  At 
  Overton 
  (or 
  Orton) 
  on 
  the 
  Nen, 
  in 
  Sheet 
  64, 
  where 
  this 
  gravel 
  

   appears 
  to 
  be 
  at 
  an 
  elevation 
  of 
  about 
  20 
  feet 
  above 
  the 
  jSTen, 
  and 
  

   40 
  above 
  0. 
  D., 
  Mr. 
  Trimmer 
  f 
  found 
  Ostrea 
  edulis 
  and 
  Cardimn 
  

   edide 
  in 
  it, 
  in 
  association 
  with 
  freshwater 
  shells 
  ; 
  but 
  Prof. 
  Seeley 
  J 
  

   states 
  that 
  the 
  nuvio-marine 
  gravel 
  here 
  is 
  underlain 
  by 
  clay 
  con- 
  

   taining 
  freshwater 
  shells 
  only, 
  thus 
  x^resenting 
  the 
  same 
  evidence 
  

   of 
  change 
  from 
  fresh 
  to 
  salt 
  water 
  by 
  depression 
  as 
  is 
  furnished 
  

   by 
  Clacton. 
  The 
  strong 
  broken 
  line 
  on 
  Map 
  5, 
  indicating 
  the 
  

  

  * 
  For 
  the 
  distribution 
  of 
  this 
  gravel 
  in 
  Sheets 
  51, 
  65, 
  and 
  69, 
  see 
  Seeley 
  

   in 
  vol. 
  xxii. 
  of 
  the 
  Journal, 
  p. 
  470. 
  For 
  Nar 
  brickearth, 
  see 
  Rose 
  in 
  Phil. 
  Mag. 
  

   for 
  1836, 
  and 
  Geol. 
  Mag. 
  for 
  1865, 
  p. 
  8. 
  For 
  the 
  Mollusca 
  of 
  both, 
  see 
  Tabular 
  

   list 
  in 
  1st 
  Supplement 
  to 
  ' 
  Crag 
  Mollusca,' 
  Palasontographical 
  Society 
  volume 
  

   for 
  1873, 
  the 
  Fen 
  gravel 
  being 
  under 
  the 
  heading 
  of 
  " 
  March 
  gravel," 
  and 
  in 
  

   same 
  table 
  is 
  a 
  column 
  with 
  the 
  Mollusca 
  from 
  the 
  Yorkshire 
  part 
  of 
  the 
  forma- 
  

   tion 
  (" 
  Kelsea 
  Hill 
  ") 
  and 
  from 
  Hunstanton. 
  

  

  t 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  x. 
  p. 
  345. 
  

  

  t 
  Ibid. 
  vol. 
  xxii. 
  p. 
  474. 
  Mr. 
  Trimmer's 
  section 
  shows 
  the 
  freshwater 
  bed 
  as 
  

   underlain 
  by 
  gravel 
  with 
  marine 
  shells 
  ; 
  but 
  as 
  he 
  states 
  that 
  this 
  rested 
  on 
  the 
  

   authority 
  of 
  the 
  workmen, 
  and 
  he 
  himself 
  found 
  the 
  marine 
  shells 
  at 
  7 
  feet 
  

   from 
  the 
  surface, 
  which, 
  on 
  the 
  scale 
  of 
  his 
  figure, 
  would 
  be 
  above 
  the 
  part 
  with 
  

   freshwater 
  shells, 
  and 
  the 
  mammalian 
  remains 
  were 
  in 
  the 
  lower 
  part, 
  it 
  is 
  

   likely 
  that 
  this 
  was 
  a 
  mistake, 
  and 
  that 
  Prof. 
  Seeley's 
  statement 
  is 
  correct. 
  

  

  