﻿220 
  GRANITE-BOULDERS 
  FROM 
  THE 
  MIDDLE 
  CHALK!. 
  [May 
  1 
  897, 
  

  

  out 
  to 
  sea 
  entangled 
  in 
  the 
  roots 
  of 
  trees. 
  On 
  the 
  other 
  hand, 
  the 
  

   theoiy 
  of 
  glacial 
  transport 
  needed 
  confirmafcuy 
  evidence. 
  

  

  Dr. 
  Heme 
  thought 
  that 
  the 
  presence 
  of 
  these 
  boulders 
  in 
  the 
  

   Chalk 
  could 
  not 
  be 
  taken 
  as 
  evidence 
  of 
  the 
  existence 
  of 
  a 
  Cretaceous 
  

   glacial 
  period. 
  There 
  is 
  a 
  total 
  absence 
  of 
  the 
  traces 
  of 
  a 
  glacial 
  

   current, 
  and 
  the 
  fauna 
  observed 
  points 
  rather 
  to 
  the 
  conclusion 
  

   that, 
  if 
  a 
  current 
  existed, 
  it 
  would 
  more 
  probably 
  have 
  come 
  from 
  

   the 
  south. 
  The 
  large 
  size 
  of 
  the 
  Purley 
  boulder 
  makes 
  it 
  difficult 
  

   to 
  assume 
  the 
  transport 
  by 
  seaweed, 
  trees, 
  and 
  especially 
  fishes, 
  so 
  

   that 
  at 
  present 
  the 
  action 
  of 
  ice 
  as 
  an 
  agent 
  cannot 
  be 
  absolutely 
  

   dismissed. 
  

  

  Prof. 
  Jtjdd 
  maintained 
  that 
  the 
  size 
  of 
  the 
  boulders 
  from 
  Croydon 
  

   was 
  such 
  that 
  it 
  was 
  impossible 
  to 
  account 
  for 
  their 
  transport 
  by 
  

   floating 
  trees 
  or 
  floating 
  seaweeds 
  over 
  great 
  areas 
  of 
  the 
  ocean. 
  

   He 
  considered 
  that 
  the 
  larger 
  blocks 
  could 
  only 
  have 
  been 
  carried 
  by 
  

   ice 
  — 
  though 
  the 
  paucity 
  of 
  blocks 
  pointed 
  to 
  the 
  conclusion 
  that, 
  

   while 
  the 
  Cretaceous 
  sea 
  was 
  occasionally 
  traversed 
  by 
  stray 
  ice- 
  

   bergs, 
  there 
  could 
  have 
  been 
  nothing 
  like 
  a 
  glacial 
  period. 
  

  

  Mr. 
  A. 
  E. 
  Salter 
  thought 
  that 
  the 
  smaller 
  pebbles 
  found 
  in 
  the 
  

   Chalk 
  were 
  deserving 
  of 
  attention 
  and 
  study. 
  They 
  were 
  more 
  

   numerous 
  and 
  of 
  greater 
  variety 
  than 
  the 
  large 
  boulders, 
  and 
  

   might, 
  on 
  careful 
  microscopical 
  examination, 
  yield 
  valuable 
  evidence 
  

   as 
  to 
  the 
  source 
  of 
  origin 
  of 
  these 
  erratic 
  bodies. 
  Mr. 
  Dibley 
  had 
  

   recently 
  obtained 
  more 
  than 
  a 
  dozen 
  pebbles 
  of 
  various 
  rocks 
  from 
  

   the 
  same 
  pit 
  near 
  Croydon 
  as 
  that 
  whence 
  the 
  large, 
  so-called 
  'Purley 
  

   boulder 
  ' 
  came. 
  He 
  had 
  also 
  obtained 
  several 
  from 
  JSTorthfleet. 
  A 
  

   now 
  disused 
  portion 
  of 
  the 
  great 
  chalk-pit 
  at 
  Burham 
  had 
  yielded 
  

   several 
  some 
  years 
  ago, 
  and 
  Prof. 
  Wiltshire 
  also 
  obtained 
  a 
  large 
  

   number 
  from 
  Northfleet 
  which 
  are 
  now 
  in 
  the 
  Woodwardian 
  

   Museum. 
  

  

  Mr. 
  Whitaker 
  also 
  spoke. 
  

  

  The 
  Author, 
  in 
  reply, 
  explained 
  that 
  he 
  had 
  never 
  supposed 
  

   a 
  glacial 
  period 
  to 
  be 
  a 
  condition 
  of 
  the 
  migration 
  of 
  these 
  boulders, 
  

   since 
  any 
  winter 
  would 
  have 
  sufficed. 
  On 
  behalf 
  of 
  the 
  hypothesis 
  

   of 
  coast-ice 
  which 
  had 
  been 
  criticized, 
  he 
  reminded 
  the 
  Society 
  of 
  

   the 
  presence 
  of 
  beach-sand 
  with 
  the. 
  Purley 
  boulder. 
  The 
  question 
  

   of 
  small 
  pebbles 
  had 
  been 
  left 
  untouched 
  by 
  him 
  as 
  being 
  outside 
  

   the 
  sphere 
  of 
  the 
  present 
  paper, 
  which 
  was 
  concerned 
  only 
  with 
  the 
  

   larger 
  specimens. 
  

  

  