﻿146 
  GLACIAL 
  PHENOMENA. 
  OF 
  PALAEOZOIC 
  AGE. 
  [May 
  1897, 
  

  

  same 
  time. 
  It 
  follows 
  that 
  the 
  quartzite 
  was 
  not 
  hardened 
  by 
  the 
  

   deposition 
  of 
  the 
  silica 
  until 
  after 
  the 
  deposition 
  of 
  the 
  boulder-rock. 
  

   For 
  this 
  observation 
  I 
  am 
  indebted 
  to 
  Mr. 
  G. 
  Barrow. 
  

  

  One 
  of 
  the 
  slices 
  referred 
  to 
  traverses 
  the 
  junction 
  of 
  the 
  boulder- 
  

   rock 
  and 
  quartzite, 
  and 
  shows 
  that 
  the 
  grains 
  composing 
  the 
  

   quartzite 
  project 
  into 
  the 
  overlying 
  boulder-bed 
  and 
  have 
  not 
  been 
  

   cut 
  or 
  broken 
  through 
  ; 
  such 
  as 
  were 
  removed 
  in 
  the 
  process 
  of 
  

   glaciation 
  were 
  torn 
  away 
  bodily 
  and 
  incorporated 
  in 
  the 
  boulder- 
  

   rock. 
  On 
  the 
  other 
  hand, 
  when 
  the 
  quartzite 
  in 
  its 
  present 
  condi- 
  

   tion 
  of 
  induration 
  is 
  broken, 
  many 
  of 
  the 
  grains 
  seem 
  to 
  be 
  broken 
  

   across 
  — 
  owing 
  to 
  the 
  firmness 
  with 
  which 
  they 
  are 
  held 
  in 
  the 
  

   matrix. 
  This 
  observation, 
  which 
  is 
  due 
  to 
  Mr. 
  Teall, 
  proves 
  that 
  

   the 
  quartzite 
  is 
  harder 
  now 
  than 
  at 
  the 
  time 
  of 
  its 
  glaciation. 
  In 
  

   one 
  of 
  my 
  specimens, 
  moreover, 
  a 
  small 
  chip 
  of 
  a 
  granitic 
  rock 
  lies 
  

   embedded 
  in 
  the 
  surface 
  of 
  the 
  quartzite, 
  as 
  though 
  it 
  had 
  been 
  

   forced 
  in 
  before 
  that 
  rock 
  was 
  hard. 
  

  

  It 
  seems 
  that 
  even 
  an 
  incoherent 
  sand 
  is 
  capable 
  of 
  retaining 
  

   glacial 
  groovings, 
  for 
  I 
  am 
  informed 
  by 
  Mr. 
  Clement 
  Reid 
  that 
  the 
  

   base 
  of 
  a 
  boulder-clay 
  resting 
  on 
  soft 
  sand 
  on 
  the 
  Norfolk 
  coast 
  

   showed 
  ridges 
  which 
  were 
  obviously 
  casts 
  of 
  furrows 
  in 
  the 
  surface 
  

   of 
  the 
  sand 
  below. 
  A 
  suggestive 
  observation 
  has 
  been 
  made 
  also 
  

   in 
  Alaska 
  by 
  Mr. 
  Harry 
  Fielding 
  Reid, 
  1 
  who 
  states 
  that 
  ' 
  the 
  

   alpine 
  end 
  of 
  the 
  Charpentier 
  Glacier 
  rests 
  on 
  gravels. 
  In 
  the 
  

   hundred 
  feet 
  or 
  more 
  between 
  the 
  glacier 
  and 
  Hugh 
  Miller 
  Inlet 
  

   the 
  gravels 
  are 
  streaked 
  with 
  uniform, 
  straight, 
  parallel 
  grooves, 
  a 
  

   foot 
  or 
  two 
  apart, 
  which 
  looked 
  as 
  if 
  they 
  had 
  been 
  ploughed 
  out.' 
  A 
  

   further 
  suggestion, 
  made 
  by 
  Mr. 
  Belinfante, 
  that 
  the 
  sand 
  may 
  have 
  

   been 
  frozen 
  when 
  the 
  ice 
  passed 
  over 
  it, 
  is 
  deserving 
  of 
  considera- 
  

   tion.— 
  January 
  29th, 
  1897.] 
  

  

  1 
  Sixteenth 
  Annual 
  Eeport 
  U. 
  S. 
  Geol. 
  Surv. 
  (1891-95) 
  p. 
  452. 
  

  

  PLATES 
  VIII-X. 
  

  

  Views 
  of 
  cliff 
  near 
  Bigganjargga, 
  showing 
  the 
  contemporaneous 
  Boulder 
  Clay 
  

   interbedded 
  with 
  the 
  Quartz-grits. 
  

  

  [For 
  the 
  Discussion, 
  see 
  p. 
  153.] 
  

  

  