﻿IN 
  THE 
  CONTOETED 
  DEIFT 
  OE 
  CEOMEE. 
  229 
  

  

  in 
  a 
  section 
  illustrating 
  a 
  paper 
  "On 
  the 
  Sequence 
  of 
  Glacial 
  Beds 
  " 
  

   (Geol. 
  Mag. 
  Sept. 
  1871, 
  p. 
  4 
  of 
  reprint) 
  ; 
  but 
  I 
  agree 
  with 
  Mr. 
  Jukes- 
  

   Browne, 
  and 
  others 
  of 
  the 
  Survey, 
  in 
  thinking 
  that 
  they 
  do 
  not 
  lie 
  

   in 
  valleys 
  of 
  erosion. 
  Mr. 
  Wood 
  calls 
  these 
  gravels 
  " 
  middle 
  

   glacial," 
  a 
  term 
  that 
  has 
  been 
  very 
  generally 
  adopted; 
  but 
  Mr. 
  

   Penning 
  says* 
  " 
  If 
  these 
  views 
  be 
  correct, 
  there 
  is, 
  between 
  the 
  Lower 
  

   and 
  Middle 
  Glacial, 
  no 
  definite 
  line 
  of 
  demarcation." 
  As 
  the 
  object 
  

   of 
  this 
  paper 
  is 
  not 
  to 
  discuss 
  the 
  nomenclature 
  of 
  the 
  drift 
  beds, 
  I 
  

   will 
  pass 
  on 
  to 
  a 
  description 
  of 
  the 
  chalk 
  inclusions. 
  

  

  Included 
  Chalk 
  Masses. 
  

  

  The 
  simplest 
  form 
  of 
  chalk 
  inclusion 
  is 
  an* 
  irregularly 
  shaped, 
  

   partially 
  rounded, 
  isolated 
  mass, 
  as 
  fig. 
  8, 
  A 
  and 
  B 
  ; 
  a 
  still 
  more 
  

   irregular 
  and 
  angular 
  form 
  is 
  shown 
  in 
  fig. 
  8, 
  C, 
  an 
  instructive 
  ex- 
  

   ample 
  of 
  what 
  happens 
  to 
  these 
  masses 
  when 
  the 
  base 
  of 
  the 
  drift 
  

   gets 
  swept 
  away 
  by 
  the 
  sea. 
  At 
  first 
  sight 
  this 
  looks 
  like 
  an 
  isolated 
  

   pinnacle, 
  the 
  part 
  c 
  standing 
  out 
  in 
  relief 
  from 
  the 
  cliff 
  with 
  

   talus 
  at 
  the 
  base, 
  a 
  ; 
  further 
  examination 
  shows, 
  however, 
  that 
  it 
  

   is 
  part 
  of 
  a 
  mass 
  1, 
  2, 
  3, 
  4, 
  5, 
  6, 
  7, 
  of 
  which 
  5, 
  6, 
  7, 
  1, 
  constitute 
  a 
  

   surface 
  flush 
  with 
  the 
  natural 
  face 
  of 
  drift, 
  this 
  portion 
  of 
  the 
  boulder 
  

   evidently 
  having 
  split 
  off 
  through 
  the 
  removal 
  of 
  the 
  drift 
  from 
  below. 
  

   Fracture 
  of 
  the 
  masses 
  in 
  this 
  way 
  is 
  a 
  frequent 
  occurrence, 
  arising 
  

   from 
  the 
  incapacity 
  of 
  the 
  chalk 
  to 
  support 
  the 
  weight 
  of 
  the 
  super- 
  

   incumbent 
  drift 
  when 
  partially 
  undermined. 
  This 
  fact 
  was 
  well 
  

   illustrated 
  by 
  a 
  landslip 
  I 
  observed 
  between 
  Cromer 
  and 
  Sherring- 
  

   ham, 
  where 
  a 
  portion 
  of 
  a 
  horizontal 
  chalk-mass 
  of 
  considerable 
  

   proportions 
  had 
  slipped 
  down 
  bodily 
  onto 
  the 
  shore, 
  and, 
  though 
  

   shattered, 
  retained 
  generally 
  its 
  relative 
  position 
  and 
  form. 
  

  

  The 
  next 
  form 
  of 
  inclusion 
  is 
  an 
  apparent 
  aggregation 
  of 
  irregular 
  

   masses, 
  as 
  shown 
  in 
  fig. 
  8, 
  D, 
  but 
  which 
  have 
  really 
  originally 
  been 
  

   one 
  mass, 
  afterwards 
  separated, 
  as 
  shown 
  in 
  the 
  sketch, 
  the 
  cavities 
  

   being 
  infilled 
  with 
  drift 
  apparently 
  folding 
  round 
  the 
  masses 
  and 
  

   penetrating 
  them 
  in 
  a 
  very 
  remarkable 
  manner. 
  Fig. 
  8, 
  E, 
  is 
  an 
  in- 
  

   structive 
  example 
  of 
  how 
  this 
  separation 
  develops 
  and 
  comes 
  about. 
  

   The 
  larger 
  masses 
  of 
  chalk, 
  however, 
  are 
  distinctly 
  characterized 
  by 
  

   length 
  and 
  horizontality, 
  as 
  shown 
  in 
  fig. 
  8, 
  F, 
  G, 
  and 
  in 
  fig. 
  9. 
  

  

  How 
  horizontal 
  masses 
  of 
  such 
  longitudinal 
  dimensions 
  could 
  be 
  

   conveyed 
  and 
  imbedded 
  in 
  mud 
  and 
  sand 
  with 
  so 
  little 
  fracture 
  is 
  

   one 
  of 
  the 
  suggestive 
  problems 
  presented 
  for 
  our 
  solution. 
  From 
  

   the 
  position 
  of 
  the 
  boulders 
  and 
  the 
  nature 
  of 
  the 
  cliff 
  it 
  is 
  no 
  easy 
  

   matter, 
  nay, 
  often 
  impossible, 
  to 
  examine 
  them 
  closely 
  ; 
  but 
  it 
  is 
  plain 
  

   to 
  see 
  that, 
  as 
  a 
  rule, 
  the 
  junction 
  of 
  the 
  external 
  surface 
  of 
  the 
  chalk 
  

   with 
  the 
  drift 
  in 
  which 
  it 
  is 
  imbedded 
  is 
  marked 
  by 
  laminated 
  beds 
  

   of 
  the 
  drift 
  a 
  few 
  inches 
  in 
  thickness 
  enwrapping 
  the 
  mass 
  or 
  boulder, 
  as 
  

   shown 
  in 
  the 
  numerous 
  examples 
  figured. 
  The 
  most 
  surprising 
  feature 
  

   about 
  the 
  boulders 
  is 
  perhaps 
  the 
  length 
  and 
  extreme 
  tenuity 
  some 
  

  

  * 
  "On 
  the 
  Physical 
  Geology 
  of 
  East 
  Anglia 
  during 
  the 
  Glacial 
  Period," 
  

   Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  xsxii. 
  p. 
  195. 
  

  

  