﻿172 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  were 
  swept 
  southward 
  by 
  the 
  earlier 
  glaciation. 
  Later 
  ice 
  work 
  

   with 
  more 
  abrasive 
  power 
  planed 
  the 
  harder 
  stratified 
  rocks, 
  grooved 
  

   the 
  limestones, 
  modified 
  the 
  topographic 
  forms 
  by 
  softening 
  the 
  

   scarps 
  and 
  rock 
  knobs 
  and 
  straightening 
  the 
  drainage 
  lines. 
  One 
  

   or 
  more 
  long 
  interglacial 
  epochs 
  partially 
  restored 
  the 
  character- 
  

   istic 
  atmospheric-erosion 
  forms 
  of 
  the 
  Theresa 
  and 
  Pamelia 
  scarps 
  

   and 
  cuesta 
  fronts; 
  reexcavated 
  the 
  valleys 
  and 
  basins; 
  and 
  de- 
  

   stroyed 
  the 
  surficial 
  glaciation 
  on 
  the 
  sandstones 
  and 
  limestones. 
  

   The 
  latest 
  ice 
  sheet 
  finding 
  the 
  northward 
  region 
  denuded 
  of 
  rock 
  

   debris 
  and 
  smoothed 
  by 
  the 
  earlier 
  glaciation 
  was 
  unable 
  to 
  arm 
  

   itself 
  for 
  effective 
  erosion 
  and 
  thus 
  handicapped 
  was 
  competent 
  only 
  

   to 
  weakly 
  abrade 
  in 
  places. 
  It 
  is 
  possible 
  that 
  while 
  the 
  deglacia- 
  

   tion 
  interval 
  in 
  our 
  district 
  produced 
  some 
  weathering 
  effects 
  the 
  

   northward 
  (Labrador) 
  region 
  was 
  continuously 
  snow-covered 
  and 
  

   the 
  ice 
  was 
  not 
  able 
  to 
  pluck 
  a 
  new 
  supply 
  of 
  granitic 
  tools. 
  

  

  Undoubtedly 
  there 
  were 
  important 
  differences 
  in 
  the 
  behavior 
  

   and 
  mechanical 
  effects 
  of 
  the 
  several 
  ice 
  sheets, 
  due 
  to 
  differences 
  

   in 
  rate 
  of 
  accumulation 
  and 
  velocity 
  of 
  flow 
  ; 
  of 
  depth 
  and 
  pressure 
  ; 
  

   of 
  temperature 
  and 
  rate 
  of 
  waning; 
  and 
  these 
  combined 
  with, 
  and 
  

   an 
  effect 
  of, 
  climatic 
  variations. 
  

  

  It 
  would 
  have 
  been 
  entirely 
  proper 
  in 
  this 
  writing 
  to 
  have 
  as 
  

   sumed 
  multiple 
  glaciation 
  and 
  confidently 
  to 
  have 
  explained 
  the 
  

   singular 
  features 
  of 
  the 
  area 
  on 
  that 
  basis. 
  Perhaps 
  the 
  method 
  

   of 
  argumentation 
  which 
  has 
  been 
  used 
  is 
  somewhat 
  confusing 
  to 
  

   the 
  reader, 
  but 
  he 
  will 
  better 
  appreciate 
  the 
  complexities 
  of 
  the 
  

   study 
  and 
  its 
  consequent 
  fascination. 
  

  

  ECONOMIC 
  GEOLOGY^ 
  

  

  While 
  the 
  district 
  under 
  consideration 
  is 
  bordered 
  on 
  the 
  east 
  

   by 
  an 
  area 
  in 
  which 
  hematite, 
  pyrite, 
  galena 
  and 
  talc 
  have 
  been, 
  

   or 
  are 
  being, 
  mined, 
  none 
  of 
  them 
  have 
  been 
  found 
  in 
  anything 
  

   like 
  workable 
  quantity 
  within 
  the 
  limits 
  of 
  the 
  map. 
  The 
  fer- 
  

   ruginous 
  quartz 
  schists 
  of 
  the 
  Grenville 
  are 
  present 
  in 
  quantity 
  but 
  

   are 
  very 
  lean 
  ores 
  indeed. 
  One 
  mile 
  north 
  of 
  Theresa 
  on 
  the 
  Red 
  

   lake 
  road 
  a 
  small 
  opening 
  has 
  been 
  made 
  on 
  a 
  hematite 
  mass 
  which 
  

   occurred 
  as 
  a 
  direct 
  replacement 
  of 
  Grenville 
  limestone. 
  The 
  ma- 
  

   terial 
  was 
  a 
  finely 
  crystalline, 
  scaly, 
  specular 
  iron, 
  and 
  was 
  of 
  great 
  

   purity, 
  but 
  there 
  were 
  only 
  a 
  few 
  tons 
  of 
  it. 
  While 
  therefore 
  the 
  

   deposit 
  was 
  of 
  interest 
  as 
  a 
  clear 
  and 
  pretty 
  example 
  of 
  replace- 
  

   ment 
  of 
  the 
  sort, 
  it 
  had, 
  no 
  economic 
  value. 
  

  

  iBy 
  H. 
  P. 
  Gushing. 
  

  

  