﻿606 
  ME. 
  G. 
  W. 
  LAMPLTJGH 
  ON 
  THE 
  

  

  gestions 
  which 
  may 
  bear 
  fruit. 
  But 
  as 
  the 
  direct 
  object 
  of 
  my 
  work 
  

   has 
  been 
  to 
  describe 
  the 
  facts 
  of 
  the 
  Speeton 
  section 
  and 
  not 
  to 
  

   make 
  explanations 
  of 
  them, 
  I 
  have 
  not 
  sought 
  to 
  elaborate 
  this 
  part 
  

   of 
  my 
  paper. 
  

  

  My 
  study 
  of 
  the 
  Speeton 
  series 
  has 
  led 
  me 
  to 
  believe 
  that 
  in 
  this 
  

   area 
  there 
  has 
  been 
  an 
  almost 
  unbroken 
  period 
  of 
  gradual 
  deposition, 
  

   proceeding 
  at 
  all 
  times 
  slowly, 
  and 
  occasionally 
  all 
  but 
  ceasing, 
  but 
  

   nevertheless 
  continuing 
  from 
  the 
  Upper 
  Jurassic 
  stage 
  not 
  only 
  

   throughout 
  the 
  Lower 
  Cretaceous*, 
  but 
  possibly 
  throughout 
  the 
  

   Upper 
  Cretaceous 
  also. 
  

  

  To 
  support 
  the 
  latter 
  part 
  of 
  this 
  view, 
  the 
  great 
  unconformity 
  

   below 
  the 
  Red 
  Chalk 
  in 
  the 
  inland 
  sections 
  along 
  the 
  western 
  edge 
  

   of 
  the 
  "Wolds 
  needs 
  explanation. 
  But 
  I 
  see 
  no 
  difficulty 
  in 
  supposing 
  

   that 
  during 
  the 
  deposition 
  of 
  the 
  clays 
  in 
  the 
  Speeton 
  area 
  there 
  

   was 
  a 
  slow 
  elevation 
  going 
  on 
  in 
  the 
  sea-bottom 
  at 
  some 
  distance 
  

   to 
  the 
  westward 
  and 
  south-westward; 
  and 
  that 
  this 
  movement, 
  

   without 
  materially 
  altering 
  the 
  condition 
  of 
  affairs 
  at 
  Speeton, 
  

   resulted 
  in 
  the 
  appearance 
  in 
  the 
  south-west 
  of 
  a 
  ridge 
  of 
  low 
  land, 
  

   which 
  eventually 
  divided 
  the 
  once 
  continuous 
  seas 
  of 
  East 
  Yorkshire 
  

   and 
  Lincolnshire. 
  

  

  Rapid 
  denudation 
  of 
  this 
  ridge, 
  as 
  its 
  mudbanks 
  of 
  Kimeridge 
  Clay 
  

   emerged, 
  may 
  have 
  furnished, 
  among 
  other 
  material, 
  the 
  fragments 
  

   of 
  black 
  phosphatic 
  stone 
  which 
  occur 
  at 
  Speeton, 
  lying, 
  as 
  I 
  have 
  

   shown, 
  not 
  only 
  in 
  particular 
  bands, 
  but 
  also 
  scattered, 
  somewhat 
  

   sparsely 
  and 
  irregularly, 
  throughout 
  the 
  greater 
  part 
  of 
  the 
  clays. 
  

   These 
  fragments, 
  many 
  of 
  which 
  could 
  scarcely 
  have 
  been 
  carried 
  by 
  

   currents, 
  may, 
  I 
  think, 
  have 
  been 
  conveyed 
  from 
  the 
  shore-line 
  by 
  

   the 
  agency 
  of 
  some 
  drifting 
  body, 
  such 
  as 
  the 
  broad-fronded 
  sea- 
  

   weeds, 
  which 
  may 
  have 
  buoyed 
  them 
  up 
  and 
  dropped 
  them 
  on 
  a 
  

   quiet 
  muddy 
  bottom 
  as 
  it 
  floated 
  across. 
  

  

  The 
  elevation 
  and 
  denudation 
  of 
  this 
  ridge 
  may 
  have 
  commenced 
  

   about 
  the 
  close 
  of 
  the 
  Jurassic 
  period 
  : 
  and 
  it 
  went 
  on 
  throughout 
  

   the 
  Lower 
  Cretaceous, 
  by 
  which 
  time 
  the 
  crest 
  of 
  the 
  ridge 
  had 
  

   been 
  planed 
  down 
  to 
  the 
  level 
  of 
  the 
  Lower 
  Lias. 
  During 
  all 
  this 
  

   time 
  the 
  Speeton 
  area 
  seems 
  never 
  once 
  to 
  have 
  emerged, 
  but 
  the 
  

   proximity 
  of 
  timbered 
  land 
  is 
  shown 
  by 
  the 
  abundance 
  of 
  wood 
  

   preserved 
  at 
  various 
  horizons 
  in 
  the 
  clays. 
  

  

  But 
  at 
  the 
  close 
  of 
  the 
  Lower 
  Cretaceous 
  the 
  movement 
  in 
  the 
  

   west 
  seems 
  to 
  have 
  been 
  reversed 
  ; 
  elevation 
  ceased, 
  and 
  gave 
  place 
  

   to 
  a 
  gradual 
  sinking 
  of 
  the 
  whole 
  area, 
  during 
  which, 
  as 
  the 
  waves 
  

   once 
  more 
  passed 
  over 
  the 
  ridge, 
  the 
  conglomeratic 
  bed 
  at 
  the 
  base 
  

   of 
  the 
  Red 
  Chalk 
  of 
  the 
  western 
  Wolds 
  was 
  formed, 
  and 
  thus 
  

   this 
  rests 
  upon 
  the 
  edges 
  of 
  the 
  Jurassic 
  strata 
  on 
  the 
  anticline 
  with 
  

   a 
  strongly 
  marked 
  unconformit} 
  x 
  , 
  though, 
  could 
  we 
  trace 
  the 
  horizon 
  

   continuously 
  to 
  Speeton, 
  I 
  suspect 
  we 
  should 
  find 
  that 
  in 
  going 
  

   eastward 
  the 
  unconformity 
  would 
  give 
  place 
  to 
  overlap, 
  and 
  that 
  

   we 
  should 
  finally 
  run 
  into 
  the 
  marly 
  shales 
  below 
  the 
  Bed 
  Chalk 
  

   in 
  the 
  uninterrupted 
  succession 
  of 
  the 
  Speeton 
  section. 
  

  

  * 
  Professor 
  Phillips 
  seems 
  to 
  have 
  been 
  of 
  this 
  opinion 
  (Geol. 
  of 
  Yorksk. 
  

   3rd 
  ed. 
  pt. 
  i. 
  (p. 
  100). 
  

  

  