﻿l6o 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  recently 
  exposed 
  with 
  perfectly 
  preserved 
  polish. 
  While 
  it 
  is 
  

   possible 
  that 
  this 
  difference 
  in 
  surface 
  characters 
  may 
  be 
  the 
  eft'ect 
  

   of 
  differences 
  in 
  present 
  conditions 
  of 
  drainage 
  and 
  solution, 
  though 
  

   improbable, 
  it 
  seems 
  more 
  likely 
  that 
  we 
  have 
  here 
  another 
  illustra- 
  

   tion 
  of 
  multiple 
  ice 
  work. 
  

  

  In 
  the 
  Potsdam 
  areas 
  the 
  impression 
  is 
  given 
  of 
  general 
  ice 
  

   abrasion 
  by 
  the 
  frequent 
  patches 
  of 
  polish 
  and 
  striae; 
  but 
  the 
  un- 
  

   scored 
  surfaces 
  far 
  outnumber 
  the 
  striated. 
  Here, 
  again, 
  we 
  have 
  

   the 
  uncertainty 
  as 
  to 
  the 
  degree 
  of 
  weathering 
  and 
  destruction 
  of 
  the 
  

   latest 
  glacial 
  records, 
  because 
  exposed 
  surfaces, 
  apparently 
  of 
  iden- 
  

   tical 
  quality 
  of 
  rock 
  and 
  equality 
  in 
  exposure 
  exhibit 
  partly 
  highly 
  

   polished 
  and 
  partly 
  unscratched 
  surfaces. 
  The 
  fact 
  of 
  a 
  general 
  

   grinding- 
  and 
  smoothing 
  of 
  the 
  rock 
  is 
  clear, 
  but 
  quite 
  certainly 
  not 
  

   by 
  the 
  latest 
  ice 
  sheet. 
  

  

  Direction 
  [see 
  pi. 
  44-47]. 
  Near 
  the 
  St 
  Lawrence 
  the 
  average 
  

   direction 
  of 
  striae 
  is 
  about 
  parallel 
  witli 
  the 
  river. 
  Leaving 
  out 
  the 
  

   extreme 
  and 
  aberrant 
  marks 
  they 
  may 
  be 
  generalized 
  as 
  follows 
  : 
  

   at 
  Chippewa 
  Bay, 
  s. 
  25° 
  w. 
  ; 
  Alexandria 
  Bay, 
  s. 
  25-40° 
  w. 
  ; 
  Clayton, 
  

   s. 
  40-50° 
  w. 
  ; 
  eastward 
  from 
  the 
  river 
  and 
  from 
  the 
  axis 
  of 
  the 
  val- 
  

   ley 
  the 
  striae 
  are 
  more 
  variable 
  and 
  swing 
  more 
  southerly. 
  About 
  

   Redw^ood 
  some 
  striae 
  are 
  s. 
  40° 
  w., 
  probably 
  representing 
  the 
  

   stronger 
  flow 
  of 
  the 
  deeper 
  ice, 
  but 
  a 
  great 
  number 
  range 
  within 
  

   s. 
  10-20° 
  w. 
  About 
  Theresa 
  the 
  greater 
  number 
  lie 
  within 
  s, 
  10° 
  w. 
  

   and 
  s. 
  10° 
  e. 
  East 
  of 
  Chaumont 
  the 
  striae 
  are 
  s. 
  35° 
  e. 
  ; 
  at 
  Evans 
  

   Mills, 
  10-20° 
  east 
  of 
  south 
  and 
  at 
  Sanfords 
  Corners, 
  30° 
  east 
  of 
  

   south. 
  The 
  Leraysville 
  moraine 
  [pi. 
  44] 
  clearly 
  shows 
  the 
  south- 
  

   easterly 
  push 
  of 
  the 
  latest 
  ice 
  in 
  the 
  district. 
  This 
  easterly 
  swing 
  of 
  

   the 
  ice 
  in 
  the 
  eastern 
  part 
  of 
  our 
  area 
  was 
  due 
  to 
  the 
  well 
  known 
  

   spreading 
  or 
  radial 
  flow 
  of 
  a 
  lobation 
  in 
  the 
  ice 
  front. 
  As 
  the 
  ice 
  

   sheet 
  waned 
  the 
  last 
  portion 
  resting 
  over 
  the 
  area 
  was 
  a 
  broad 
  lobe 
  

   occupying 
  the 
  St 
  Lawrence 
  depression 
  and 
  having 
  spreading 
  flow 
  

   toward 
  the 
  east 
  side 
  of 
  the 
  valley. 
  Along 
  the 
  east 
  side 
  of 
  our 
  maps 
  

   the 
  most 
  westward 
  striae 
  represent 
  the 
  general 
  direction 
  of 
  the 
  maxi- 
  

   mum 
  flow 
  while 
  the 
  eastward 
  striae 
  are 
  later 
  scratches 
  by 
  the 
  ice 
  

   margin. 
  

  

  Curved 
  scorings. 
  A 
  remarkable 
  example 
  of 
  curved 
  scorings 
  

   may 
  be 
  seen 
  on 
  a 
  broad, 
  flat, 
  smoothed 
  surface 
  of 
  Potsdam 
  sand- 
  

   stone 
  2j4 
  miles 
  east-southeast 
  of 
  Alexandria 
  Bay, 
  about 
  ^2 
  mile 
  

   west 
  of 
  three 
  corners. 
  The 
  bare 
  area 
  lies 
  in 
  the 
  track 
  and 
  on 
  the 
  

   north 
  side 
  of 
  an 
  abandoned 
  highway, 
  on 
  land 
  of 
  John 
  Bogert. 
  The 
  

   locality 
  is 
  indicated 
  by 
  three 
  converging 
  arrows 
  on 
  plate 
  47, 
  and 
  one 
  

   photograph 
  is 
  given 
  in 
  plate 
  59. 
  

  

  