﻿234 
  T. 
  M. 
  EEADE 
  ON 
  THE 
  CHALK-MASSES 
  

  

  dimensions*. 
  That 
  ice 
  can 
  accumulate 
  on 
  land 
  in 
  an 
  enormous 
  mass, 
  

   not 
  as 
  a 
  glacier, 
  is 
  well 
  shown 
  by 
  W. 
  H. 
  Dall, 
  in 
  the 
  description 
  of 
  

   what 
  he 
  saw 
  in 
  Alaska 
  in 
  the 
  vicinity 
  of 
  Bering 
  Straits 
  f. 
  After 
  

   describing 
  ice-cliffs 
  with 
  interstratified 
  beds 
  of 
  clay 
  and 
  vegetable 
  

   matter, 
  rising 
  in 
  two 
  faces 
  about 
  30 
  feet 
  high 
  each, 
  he 
  proceeds 
  to 
  

   explain 
  that 
  about 
  a 
  mile 
  from 
  the 
  sea 
  the 
  ice 
  formed 
  a 
  ridge 
  about 
  

   250 
  feet 
  above 
  high 
  water, 
  and 
  observes 
  : 
  — 
  " 
  That 
  is 
  to 
  say, 
  it 
  appeared 
  

   that 
  the 
  ridge 
  itself, 
  two 
  miles 
  wide, 
  and 
  250 
  feet 
  high, 
  was 
  chiefly 
  

   composed 
  of 
  solid 
  ice 
  overlaid 
  with 
  clay 
  and 
  vegetable 
  mould." 
  In 
  con- 
  

   clusion, 
  Mr. 
  Dall 
  says 
  " 
  the 
  formation 
  of 
  the 
  surrounding 
  country 
  

   shows 
  no 
  high 
  land 
  or 
  rocky 
  hills 
  from 
  which 
  a 
  glacier 
  might 
  have 
  

   been 
  derived 
  and 
  then 
  covered 
  with 
  debris 
  from 
  their 
  sides. 
  The 
  con- 
  

   tinuity 
  of 
  the 
  mossy 
  surface 
  showed 
  that 
  the 
  ice 
  must 
  be 
  quite 
  desti- 
  

   tute 
  of 
  motion; 
  and 
  the 
  circumstances 
  appeared 
  to 
  point 
  to 
  one 
  conclu- 
  

   sion, 
  that 
  there 
  is 
  here 
  a 
  ridge 
  of 
  solid 
  ice, 
  rising 
  several 
  hundred 
  feet 
  

   above 
  the 
  sea 
  and 
  higher 
  than 
  any 
  of 
  the 
  land 
  about 
  it, 
  and 
  older 
  

   than 
  the 
  mammoth 
  and 
  fossil 
  horse, 
  this 
  ice 
  taking 
  upon 
  itself 
  the 
  

   functions 
  of 
  a 
  regular 
  stratified 
  rock. 
  The 
  formation, 
  though 
  visited 
  

   before, 
  has 
  not 
  hitherto 
  been 
  intelligibly 
  described 
  from 
  a 
  geological 
  

   standpoint. 
  Though 
  many 
  facts 
  may 
  remain 
  to 
  be 
  investigated, 
  and 
  

   whatever 
  be 
  the 
  conclusions 
  as 
  to 
  its 
  origin 
  and 
  mode 
  of 
  preservation, 
  

   it 
  certainly 
  remains 
  one 
  of 
  the 
  most 
  wonderful 
  and 
  puzzling 
  geolo- 
  

   logical 
  phenomena 
  in 
  existence." 
  

  

  * 
  April 
  28, 
  1882. 
  — 
  Since 
  this 
  paper 
  was 
  written, 
  Mr. 
  H. 
  B. 
  Woodward, 
  

   F.G.S., 
  has 
  kindly 
  allowed 
  me 
  to 
  read 
  the 
  proof 
  of 
  his 
  forthcoming 
  Survey 
  

   Memoir 
  on 
  the 
  Geology 
  of 
  the 
  country 
  about 
  Norwich. 
  In 
  this 
  he 
  gives 
  sections 
  

   and 
  a 
  detailed 
  description 
  of 
  the 
  " 
  disturbed 
  chalk 
  at 
  Trowse." 
  The 
  pit 
  in 
  

   which 
  the 
  sections 
  occurred 
  is 
  on 
  a 
  range 
  of 
  low 
  hills 
  bordering 
  the 
  river 
  Yare. 
  

   Two 
  sections 
  are 
  given 
  in 
  parallel 
  planes 
  twenty 
  yards 
  apart. 
  One 
  (fig. 
  24) 
  shows 
  

   disturbed 
  chalk 
  with 
  lines 
  of 
  flints 
  bent 
  upwards 
  in 
  a 
  south-easterly 
  direction, 
  

   at 
  an 
  angle 
  of 
  from 
  35° 
  to 
  40°, 
  having 
  a 
  vertical 
  south-easterly 
  face, 
  against 
  

   which 
  is 
  banked 
  up 
  a 
  mass 
  of 
  reconstructed 
  chalk 
  containing 
  drift-pebbles. 
  The 
  

   other 
  shows 
  a 
  disturbed 
  mass 
  of 
  chalk 
  containing 
  sandy 
  pockets, 
  and 
  having 
  an 
  

   irregular 
  vertical 
  overhanging 
  face, 
  against 
  which 
  the 
  reconstructed 
  material, 
  

   consisting 
  of 
  contorted 
  laminated 
  loam 
  and 
  marl, 
  rubbly 
  chalk 
  and 
  sand, 
  recon- 
  

   structed 
  chalk, 
  &c, 
  abuts, 
  and 
  is 
  apparently 
  forced 
  underneath 
  the 
  ovei'hang 
  in 
  

   a 
  tongue-like 
  form. 
  Mr. 
  Woodward 
  satisfactorily 
  shows 
  that 
  the 
  disturbance 
  

   is 
  not 
  of 
  preglacial 
  origin. 
  He 
  also 
  says, 
  " 
  In 
  the 
  neighbourhood 
  of 
  Norwich 
  

   the 
  disturbed 
  or 
  glaciated 
  chalk 
  is 
  seen 
  in 
  the 
  pits 
  bordering 
  the 
  rivers." 
  It 
  

   appears 
  that 
  these 
  disturbances 
  are 
  of 
  frequent 
  occurrence 
  in 
  such 
  situations. 
  

   Mr. 
  Woodward 
  points 
  out 
  that 
  mammalian 
  remains 
  are 
  frequently 
  found 
  in 
  the 
  

   disturbed 
  chalk 
  ; 
  they 
  include 
  the 
  mammoth, 
  the 
  red 
  deer, 
  and 
  a 
  species 
  like 
  

   the 
  roe-deer. 
  All 
  these 
  facts 
  point 
  to 
  a 
  subaerial 
  origin 
  ; 
  and 
  the 
  position 
  of 
  

   most 
  frequent 
  occurrence 
  being 
  the 
  banks 
  of 
  river-valleys 
  is 
  very 
  suggestive. 
  

   It 
  is 
  here, 
  by 
  drainage 
  through 
  the 
  strata, 
  that 
  the 
  intrusive 
  subaerial 
  ice 
  would 
  

   be 
  capable 
  of 
  splitting, 
  wedging 
  off, 
  and 
  disturbing 
  portions 
  of 
  the 
  chalk 
  ; 
  and 
  

   during 
  this 
  time 
  it 
  is 
  quite 
  possible 
  the 
  mammalian 
  remains 
  may 
  have 
  been 
  

   introduced. 
  As 
  the 
  land 
  became 
  submerged 
  some 
  of 
  these 
  detached 
  masses 
  

   might 
  be 
  rafted 
  off 
  in 
  the 
  manner 
  I 
  have 
  described, 
  while 
  some 
  few 
  might 
  

   remain 
  at 
  their 
  place 
  of 
  origin. 
  Mr. 
  Woodward 
  says 
  (p. 
  137), 
  "It 
  has 
  been 
  

   hinted 
  that 
  the 
  disturbance 
  at 
  Trowse 
  might 
  have 
  been 
  due 
  to 
  the 
  ice 
  having 
  

   acted 
  on 
  some 
  irregularity 
  in 
  the 
  ground, 
  impinging 
  perhaps 
  on 
  an 
  old 
  cliff 
  

   which 
  formed 
  a 
  local 
  bar." 
  

  

  t 
  " 
  Notes 
  in 
  Alaska 
  and 
  the 
  vicinity 
  of 
  Bering 
  Straits," 
  American 
  Journ. 
  of 
  

   Science, 
  February 
  1881, 
  p. 
  107. 
  

  

  