﻿150 
  - 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  area 
  the 
  front 
  was 
  faced 
  by 
  about 
  400 
  feet 
  of 
  water 
  in 
  the 
  Red- 
  

   wood 
  district. 
  Just 
  what 
  that 
  condition 
  impHes 
  in 
  its 
  effects 
  on 
  

   the 
  ice 
  and 
  the 
  drift 
  is 
  uncertain. 
  We 
  do 
  not 
  know 
  whether 
  the 
  ice 
  

   melted 
  back 
  as 
  a 
  steep, 
  high 
  front 
  under 
  the 
  dissolving 
  influence 
  

   of 
  the 
  water, 
  or 
  whether 
  it 
  melted 
  as 
  a 
  thinning 
  sheet, 
  partially 
  pro- 
  

   tected 
  by 
  its 
  scanty 
  drift, 
  until 
  it 
  was 
  lifted 
  by 
  the 
  water 
  and 
  rafted 
  

   away. 
  

  

  - 
  To 
  epitomize 
  : 
  We 
  conclude 
  that 
  the 
  basins 
  and 
  stronger 
  valleys 
  

   were 
  excavated 
  by 
  weathering 
  and 
  stream 
  erosion 
  in 
  preglacial 
  or 
  

   interglacial 
  time, 
  with 
  perhaps 
  some 
  help 
  from 
  early 
  ice 
  erosion 
  ; 
  

   and 
  that 
  the 
  latest 
  ice 
  sheet 
  had 
  little 
  effect 
  beyond 
  clearing 
  out 
  

   the 
  debris 
  which 
  it 
  found. 
  

  

  Glacial 
  deposits 
  

  

  Introduction. 
  General 
  features. 
  Compared 
  with 
  areas 
  to 
  the 
  

   southward 
  the 
  area 
  under 
  description 
  has 
  very 
  scanty 
  drift, 
  and 
  

   has 
  suffered 
  little 
  recent 
  ice 
  erosion. 
  The 
  area 
  did 
  not 
  lie 
  in 
  the 
  

   zone 
  either 
  of 
  dominant 
  deposition 
  or 
  dominant 
  erosion 
  of 
  the 
  

   latest 
  ice 
  sheet. 
  Over 
  large 
  portions 
  of 
  the 
  area 
  the 
  rocks 
  are 
  

   nearly 
  bare, 
  and 
  even 
  in 
  the 
  districts 
  where 
  the 
  drift 
  cover 
  pre- 
  

   vails 
  the 
  rock 
  appears 
  frequently 
  and 
  unexpectedly. 
  The 
  amount 
  

   or 
  depth 
  of 
  drift 
  increases 
  southward 
  but 
  the 
  only 
  heavy 
  moraine 
  

   lies 
  in 
  the 
  southeast 
  corner 
  of 
  the 
  area 
  [pi. 
  44]'. 
  

  

  In 
  considering 
  the 
  character 
  and 
  distribution 
  of 
  the 
  drift 
  it 
  is 
  

   necessary 
  to 
  emphasize 
  again 
  the 
  fact 
  that 
  during 
  the 
  ice 
  recession 
  

   the 
  whole 
  area 
  was 
  submerged 
  in 
  the 
  waters 
  of 
  Lake 
  Iroquois, 
  and 
  

   this 
  was 
  followed 
  by 
  the 
  sea-level 
  waters 
  of 
  Gilbert 
  gulf. 
  The 
  

   marginal 
  drift 
  was 
  all 
  deposited 
  under 
  subaqueous 
  conditions, 
  and 
  

   wholly 
  subjected 
  to 
  the 
  distributive 
  action 
  of 
  the 
  shallowing 
  waters. 
  

  

  Over 
  the 
  northern 
  part 
  of 
  the 
  area, 
  where 
  the 
  rock 
  foundation 
  

   is 
  either 
  Potsdam 
  or 
  Precambric 
  and 
  the 
  land 
  surface 
  irregular, 
  the 
  

   scanty 
  drift 
  is 
  largely 
  in 
  the 
  depressions, 
  due 
  specially 
  to 
  the 
  work 
  

   of 
  the 
  shallow 
  waters. 
  Over 
  the 
  southern 
  districts, 
  where 
  the 
  lime- 
  

   stones 
  form 
  wide 
  plains 
  or 
  plateaus, 
  the 
  drift 
  is 
  usually 
  a 
  veneer 
  

   giving 
  the 
  broad 
  stretches 
  flat 
  or 
  gently 
  rolling 
  surfaces. 
  Because 
  

   of 
  the 
  lack 
  of 
  drift 
  the 
  preglacial 
  valleys 
  are 
  still 
  open, 
  and 
  one 
  of 
  

   the 
  characters 
  of 
  the 
  region 
  is 
  the 
  valleys 
  and 
  basins 
  with 
  steep 
  

   rock 
  walls 
  and 
  silt-plain 
  bo-ttoms. 
  The 
  valleys 
  of 
  French 
  creek 
  

   and 
  Chaumont 
  river 
  are 
  open 
  down 
  to 
  Ontario 
  level 
  ; 
  and 
  the 
  Perch 
  

   lake 
  valley 
  is 
  filled 
  to 
  only 
  70 
  feet 
  over 
  Ontario. 
  The 
  open 
  char- 
  

   acter 
  of 
  these 
  southern 
  valleys 
  is 
  to 
  be 
  only 
  partly 
  explained 
  by 
  the 
  

  

  