﻿Geology 
  and 
  Mineralogy. 
  71 
  

  

  is 
  some 
  evidence 
  in 
  the 
  beaches 
  of 
  the 
  north 
  pointing 
  to 
  this 
  

   earlier 
  period 
  of 
  the 
  cataract. 
  But 
  this 
  episode 
  of 
  the 
  gorge 
  is 
  

   not 
  yet 
  so 
  strongly 
  established 
  as 
  the 
  other 
  two. 
  

  

  Fourth. 
  A 
  word 
  as 
  to 
  the 
  nature 
  of 
  the 
  changes 
  that 
  have 
  pro- 
  

   duced 
  these 
  great 
  alterations 
  of 
  land 
  altitude. 
  They 
  are 
  so 
  ex- 
  

   tensive, 
  so 
  great, 
  and 
  above 
  all 
  so 
  recent 
  as 
  to 
  be 
  almost 
  appalling 
  

   when 
  one 
  thinks 
  of 
  them. 
  

  

  Of 
  the 
  whole 
  amount 
  of 
  apparent 
  elevation 
  along 
  the 
  line 
  of 
  

   the 
  parallel 
  of 
  46° 
  30', 
  which 
  passes 
  close 
  to 
  Duluth, 
  Sault 
  Ste. 
  

   Marie 
  and 
  North 
  Bay, 
  I 
  think 
  I 
  can 
  make 
  out 
  fairly 
  well 
  that 
  

   between 
  600 
  and 
  800 
  feet 
  of 
  it 
  are 
  due 
  to 
  a 
  change 
  of 
  the 
  secular 
  

   kind, 
  while 
  the 
  rest 
  is 
  of 
  the 
  paroxysmal 
  sort, 
  I 
  have 
  always 
  em- 
  

   bodied 
  this 
  distinction 
  (which 
  is 
  derived 
  from 
  Dana's 
  Manual 
  of 
  

   Geology) 
  in 
  my 
  working 
  hypothesis, 
  and 
  with 
  good 
  effect. 
  I 
  am 
  

   quite 
  sure 
  that 
  it 
  was 
  the 
  secular 
  factor 
  that 
  changed 
  the 
  outlet 
  of 
  

   the 
  upper 
  lakes 
  this 
  last 
  time 
  and 
  brought 
  Niagara 
  into 
  its 
  pres- 
  

   ent 
  state 
  of 
  activity 
  — 
  in 
  consequence 
  of 
  a 
  secular 
  relative, 
  differ- 
  

   ential, 
  northward 
  elevation. 
  It 
  seems 
  probable 
  that 
  the 
  earlier 
  

   episode 
  of 
  Niagara 
  was 
  also 
  due 
  to 
  the 
  same 
  factor. 
  But 
  the 
  

   order 
  of 
  relative 
  change 
  was 
  probably 
  then 
  in 
  the 
  opposite 
  direc- 
  

   tion. 
  I 
  believe 
  that 
  maximum 
  northern 
  relative 
  elevation 
  coin- 
  

   cided 
  with 
  maximum 
  glaciation, 
  as 
  you 
  have 
  said. 
  But 
  I 
  believe, 
  

   further, 
  that 
  maximum 
  relative 
  northern 
  submergence 
  coincided 
  

   with 
  the 
  climax 
  of 
  the 
  postglacial 
  warm 
  epoch 
  now 
  passing 
  off. 
  

   Relative 
  northward 
  elevation 
  has 
  been 
  in 
  progress 
  for 
  some 
  time 
  

   past 
  and 
  we 
  are 
  now 
  advancing 
  again 
  toward 
  a 
  climax 
  of 
  cold." 
  

  

  3. 
  Introduction 
  to 
  Geology 
  as 
  historical 
  science. 
  Einleitung 
  in 
  

   die 
  Geologie 
  als 
  historische 
  Wissenschaft. 
  Beobachtungen 
  tiber 
  

   die 
  Bildung 
  der 
  Gesteine 
  und 
  ihren 
  organischen 
  Einschltisse. 
  

   I 
  Theil 
  : 
  Bionomie 
  des 
  Meeres. 
  II 
  Theil 
  : 
  Die 
  Lebensweise 
  der 
  

   Meeresthiere. 
  Ill 
  Theil 
  : 
  Lithogenesis 
  der 
  Gegenwart 
  (by 
  Jo- 
  

   hannes 
  Walther), 
  pp. 
  i-xxx 
  and 
  1055. 
  (Gustav 
  Fischer), 
  Jena, 
  

   1893-1894. 
  — 
  The 
  author 
  describes 
  the 
  method 
  employed 
  in 
  this 
  

   " 
  Introduction 
  to 
  Geology 
  " 
  as 
  the 
  ontological 
  method 
  of 
  investi- 
  

   gation, 
  which 
  consists 
  in 
  the 
  interpretation 
  of 
  the 
  events 
  of 
  the 
  

   past 
  by 
  the 
  phenomena 
  of 
  the 
  present. 
  The 
  aim 
  he 
  has 
  held 
  

   before 
  him 
  while 
  constructing 
  this 
  elaborate 
  work 
  has 
  been 
  to 
  

   bring 
  together 
  from 
  many 
  sources, 
  from 
  periodicals, 
  monographs 
  

   and 
  special 
  treatises, 
  all 
  the 
  facts 
  bearing 
  upon 
  the 
  general 
  ques- 
  

   tion 
  of 
  the 
  formation 
  of 
  rocks 
  and 
  upon 
  the 
  conditions 
  under 
  

   which 
  organisms 
  have 
  lived 
  and 
  died 
  and 
  been 
  fossilized. 
  

  

  The 
  work 
  is 
  divided 
  into 
  three 
  parts 
  : 
  The 
  first 
  (Bionomie 
  des 
  

   Meeres), 
  on 
  the 
  marine 
  conditions 
  of 
  life, 
  was 
  briefly 
  noted 
  when 
  

   it 
  first 
  appeared 
  in 
  1893.* 
  It 
  is 
  an 
  elaborate 
  description 
  and 
  

   classification 
  of 
  the 
  zones 
  of 
  life-habitat 
  of 
  the 
  ocean 
  following 
  the 
  

   system 
  of 
  classification 
  proposed 
  by 
  Haeckelf 
  and 
  gives 
  a 
  very 
  

   convenient 
  and 
  apparently 
  exhaustive 
  synopsis 
  of 
  the 
  facts 
  with 
  

   full 
  references 
  to 
  sources. 
  

  

  *This 
  Journal, 
  III, 
  vol. 
  xlvi, 
  p. 
  24 
  0. 
  

   f 
  Plank 
  ton 
  studien, 
  Jena, 
  1890. 
  

  

  