﻿338 
  T. 
  F, 
  JAMIE80N 
  ON 
  THE 
  GLACIAL 
  PERIOD 
  IN 
  NORTH 
  BRITAIN. 
  

  

  cata, 
  a 
  species 
  which 
  lives 
  in 
  very 
  shallow 
  water, 
  has 
  been 
  found 
  in 
  

   much 
  deeper 
  water 
  in 
  a 
  semifossil 
  state. 
  At 
  Fort 
  "William 
  there 
  is 
  

   a 
  bed 
  containing 
  Arctic 
  species 
  of 
  shells 
  7 
  or 
  8 
  feet 
  above 
  the 
  level 
  

   of 
  the 
  sea. 
  Arctic 
  shells 
  of 
  deep-water 
  species 
  have 
  occurred 
  200 
  

   feet 
  above 
  the 
  sea. 
  Different 
  conditions 
  have 
  existed 
  at 
  different 
  

   parts 
  of 
  the 
  same 
  seas, 
  altering 
  the 
  character 
  of 
  the 
  Mollusca. 
  The 
  

   raising 
  of 
  the 
  sea-beds 
  above 
  the 
  level 
  proper 
  to 
  enable 
  certain 
  Mol- 
  

   lusca 
  to 
  nourish, 
  would 
  cause 
  them 
  to 
  become 
  extinct. 
  

  

  Dr. 
  Carpenter 
  mentioned 
  that 
  cold 
  water 
  may 
  be 
  thrown 
  up 
  into 
  

   very 
  small 
  depths 
  under 
  certain 
  circumstances. 
  Near 
  Halifax, 
  N. 
  S., 
  

   the 
  surface-water 
  is 
  tolerably 
  warm, 
  but 
  at 
  no 
  great 
  depth 
  the 
  tem- 
  

   perature 
  falls 
  to 
  35° 
  P. 
  In 
  this 
  case 
  the 
  rotation 
  of 
  the 
  earth 
  causes 
  

   the 
  cold 
  water 
  from 
  the 
  north 
  to 
  surge 
  up 
  on 
  its 
  western 
  coast. 
  The 
  

   North 
  Sea 
  is 
  a 
  shallow 
  sea, 
  with 
  a 
  shoal 
  in 
  the 
  middle, 
  and 
  having 
  

   off 
  the 
  coast 
  of 
  Norway 
  a 
  deep 
  channel 
  which 
  conveys 
  the 
  cold 
  

   Arctic 
  undercurrent; 
  hence 
  the 
  east 
  side 
  is 
  10° 
  P. 
  colder 
  than 
  the 
  

   west 
  side. 
  Local 
  peculiarities 
  of 
  disturbance 
  of 
  temperature 
  may 
  

   thus 
  occur 
  within 
  short 
  distances. 
  

  

  Prof. 
  Ramsay 
  remarked 
  that 
  the 
  author 
  was 
  not 
  dealing 
  with 
  wide 
  

   ocean- 
  deposits, 
  but 
  with 
  ice 
  coming 
  down 
  to 
  the 
  sea 
  from 
  the 
  land. 
  

   He 
  had 
  described 
  certain 
  changes 
  — 
  a 
  great 
  Glacial 
  period, 
  a 
  period 
  

   of 
  submergence, 
  and 
  a 
  second 
  minor 
  Glacial 
  period. 
  

  

  Mr. 
  Prestwich 
  maintained 
  that 
  temperature 
  was 
  a 
  most 
  im- 
  

   portant 
  question 
  in 
  connexion 
  with 
  the 
  subject 
  of 
  Mr. 
  Jamieson's 
  

   paper. 
  The 
  shells 
  of 
  the 
  Glacial 
  deposits, 
  however, 
  were 
  mostly 
  

   littoral, 
  and 
  therefore 
  dependent 
  upon 
  the 
  local 
  temperature. 
  The 
  

   subject 
  was 
  one 
  of 
  much 
  interest 
  ; 
  but 
  the 
  paper 
  was 
  somewhat 
  

   speculative, 
  and 
  he 
  should 
  like 
  to 
  see 
  all 
  the 
  evidence 
  upon 
  which 
  

   the 
  opinions 
  expressed 
  were 
  founded. 
  

  

  