﻿AT 
  SAINT 
  CROSS, 
  SOUTH 
  ELMHAM, 
  IN 
  SUFFOLK. 
  509 
  

  

  stratum 
  capable 
  of 
  preserving- 
  such 
  leaves, 
  but 
  which 
  does 
  not 
  con- 
  

   tain 
  them, 
  we 
  must 
  not 
  attach 
  too 
  much 
  significance 
  to 
  their 
  absence. 
  

   On 
  the 
  other 
  hand, 
  the 
  presence 
  of 
  a 
  large 
  tree 
  in 
  the 
  upper 
  por- 
  

   tion 
  of 
  bed 
  d 
  at 
  Saint 
  Cross, 
  considered 
  with 
  the 
  absence 
  of 
  

   northern 
  plants, 
  suggests 
  the 
  prevalence 
  of 
  a 
  much 
  less 
  rigorous 
  

   climate 
  than 
  that 
  under 
  which 
  the 
  leaf-bearing 
  beds 
  at 
  Hoxne 
  were 
  

   deposited. 
  Indeed, 
  some 
  of 
  the 
  plants 
  found 
  at 
  Saint 
  Cross 
  do 
  not 
  

   range 
  much 
  further 
  north 
  at 
  the 
  present 
  day, 
  and 
  with 
  two 
  or 
  three 
  

   exceptions 
  the 
  whole 
  of 
  them 
  are 
  now 
  living 
  in 
  the 
  immediate 
  

   vicinity. 
  It 
  is 
  possible, 
  therefore, 
  that 
  the 
  Saint-Cross 
  bed 
  d 
  may 
  

   be 
  synchronous 
  with 
  the 
  lowest 
  bed 
  (/) 
  of 
  the 
  Hoxne 
  section, 
  the 
  

   leaf-bearing 
  bed 
  above 
  marking 
  the 
  recurrence 
  of 
  another 
  cold 
  

   period, 
  corresponding 
  perhaps 
  with 
  the 
  advance 
  of 
  an 
  ice-sheet 
  over 
  

   the 
  northern 
  counties. 
  

  

  An 
  important 
  point 
  to 
  be 
  considered 
  with 
  reference 
  to 
  these 
  

   formations 
  is 
  their 
  connexion, 
  if 
  any, 
  with 
  the 
  present 
  drainage 
  

   system 
  of 
  the 
  country., 
  So 
  far 
  as 
  the 
  Saint-Cross 
  beds 
  are 
  concerned, 
  

   there 
  is 
  little 
  in 
  their 
  position 
  to 
  show 
  that 
  any 
  such 
  connexion 
  

   exists. 
  They 
  now 
  occupy 
  a 
  ridge 
  or 
  tongue 
  of 
  ]and 
  between 
  two 
  

   depressions, 
  from 
  both 
  of 
  which 
  they 
  may 
  have 
  been 
  in 
  part 
  denuded, 
  

   and 
  on 
  the 
  crest 
  of 
  this 
  ridge 
  they 
  appear 
  to 
  attain 
  their 
  greatest 
  

   depth. 
  Moreover, 
  the 
  deposits 
  terminate 
  on 
  the 
  very 
  verge 
  of 
  the 
  

   valley 
  of 
  the 
  South 
  Elmham 
  Beck, 
  high 
  above 
  the 
  present 
  level 
  of 
  the 
  

   stream, 
  the 
  sands 
  of 
  the 
  Middle 
  Glacial 
  Drift 
  being 
  exposed 
  below 
  

   the 
  brickyard 
  in 
  a 
  pit 
  at 
  the 
  base 
  of 
  the 
  valley 
  slope. 
  The 
  greater 
  

   part 
  of 
  the 
  valley 
  has 
  been 
  eroded 
  since 
  the 
  formation 
  of 
  the 
  lacus- 
  

   trine 
  beds, 
  and 
  it 
  is 
  at 
  least 
  doubtful 
  whether 
  during 
  that 
  period 
  

   the 
  stream 
  had 
  any 
  existence 
  at 
  all. 
  The 
  watercourse 
  which 
  now 
  

   drains 
  the 
  brickyard 
  may, 
  however, 
  indicate 
  the 
  direction 
  in 
  which 
  

   the 
  surplus 
  waters 
  of 
  the 
  old 
  lake 
  were 
  discharged. 
  

  

  It 
  appears 
  probable 
  that 
  on 
  the 
  final 
  retreat 
  of 
  the 
  last 
  ice-sheet 
  

   which 
  invaded 
  these 
  counties, 
  the 
  hollows 
  of 
  the 
  Boulder-clay 
  were 
  

   occupied 
  by 
  a 
  series 
  of 
  lakes 
  and 
  pools. 
  For 
  the 
  most 
  part 
  the 
  

   sedimentary 
  deposits 
  formed 
  in 
  these 
  hollows 
  have 
  been 
  entirely 
  

   swept 
  away. 
  But 
  at 
  Saint 
  Cross 
  the 
  mud 
  and 
  loam 
  of 
  one 
  such 
  

   lake, 
  the 
  position 
  of 
  which 
  has 
  protected 
  them 
  from 
  erosion, 
  have 
  

   resisted 
  the 
  agencies 
  which 
  have 
  completed 
  elsewhere 
  the 
  work 
  of 
  

   obliteration. 
  The 
  flora 
  of 
  the 
  bed 
  d 
  proves 
  that 
  Arctic 
  conditions 
  

   had 
  given 
  place 
  to 
  a 
  more 
  temperate 
  climate 
  when 
  that 
  deposit 
  was 
  

   thrown 
  down, 
  and 
  this 
  implies 
  the 
  lapse 
  of 
  a 
  considerable 
  interval 
  

   since 
  the 
  formation 
  of 
  the 
  Chalky 
  Boulder-clay. 
  A 
  long 
  period 
  of 
  

   time 
  must, 
  however, 
  have 
  been 
  required 
  for 
  the 
  accumulation 
  of 
  the 
  

   whole 
  series. 
  Bed 
  d 
  points 
  to 
  the 
  existence 
  of 
  a 
  shallow, 
  weed- 
  

   grown 
  pool 
  with 
  marshy 
  shores 
  and 
  islets, 
  filling 
  a 
  hollow 
  in 
  a 
  

   wooded 
  and 
  undulating 
  country. 
  After 
  this, 
  an 
  increasing 
  depth 
  

   of 
  water 
  checked 
  the 
  growth 
  of 
  vegetation, 
  and 
  the 
  clays 
  of 
  bed 
  c 
  

   were 
  deposited 
  by 
  the 
  waters 
  of 
  an 
  undisturbed 
  lake. 
  The 
  junction 
  

   of 
  beds 
  c 
  and 
  b 
  evidently 
  marks 
  a 
  change 
  of 
  conditions, 
  and, 
  if 
  the 
  

   root-fibres 
  in 
  the 
  clay 
  are 
  those 
  of 
  land-plants, 
  the 
  escape 
  or 
  

   evaporation 
  of 
  the 
  waters 
  of 
  the 
  lake 
  and 
  the 
  intervention 
  of 
  a 
  

  

  