﻿06 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  the 
  retreat 
  of 
  the 
  great 
  ice 
  sheet 
  the 
  valleys 
  were 
  partially 
  filled 
  

   with 
  drift 
  deposits. 
  Decomposed 
  rock 
  material 
  of 
  preglacial 
  age 
  

   can 
  now 
  be 
  seen 
  at 
  very 
  few 
  localities 
  and 
  those 
  in 
  specially 
  shel- 
  

   tered 
  places 
  on 
  steep 
  south 
  slopes 
  where 
  ice 
  erosion 
  was 
  very 
  

   ineffective. 
  One 
  such 
  place 
  is 
  along 
  the 
  road 
  I 
  mile 
  east-northeast 
  

   of 
  Wevertown 
  at 
  the 
  south 
  base 
  of 
  the 
  mountain 
  where 
  the 
  granite 
  

   is 
  decomposed, 
  and 
  another 
  is 
  just 
  west 
  of 
  Crane 
  mountain 
  where 
  

   the 
  south 
  side 
  of 
  a 
  ridge 
  of 
  hornblende 
  gneiss 
  is 
  badly 
  decomposed 
  

   to 
  a 
  reddish 
  brown 
  color. 
  

  

  Where 
  favorably 
  situated 
  with 
  reference 
  to 
  the 
  direction 
  of 
  

   ice 
  flow, 
  the 
  fault 
  scarps 
  were 
  freshened 
  up 
  chiefly 
  by 
  the 
  removal 
  

   of 
  the 
  heavy 
  talus 
  slopes. 
  An 
  especially 
  noteworthy 
  example 
  is 
  

   the 
  steep 
  scarp 
  i 
  J 
  / 
  3 
  miles 
  north 
  of 
  Valentine 
  pond 
  where, 
  on 
  the 
  

   nearly 
  vertical 
  wall 
  of 
  rock, 
  good 
  glacial 
  striae 
  may 
  be 
  seen. 
  Heavy 
  

   talus 
  deposits 
  which 
  were 
  not 
  favorably 
  situated 
  for 
  removal 
  by 
  

   ice 
  erosion 
  occur 
  at 
  the 
  base 
  of 
  the 
  Loon 
  lake 
  mountain 
  scarp 
  on 
  

   the 
  south 
  side, 
  and 
  also 
  at 
  the 
  base 
  of 
  the 
  scarp 
  next 
  to 
  the 
  south. 
  

  

  There 
  is 
  good 
  evidence 
  for 
  vigorous 
  ice 
  erosion 
  in 
  the 
  valleys 
  

   in 
  the 
  southeastern 
  portion 
  of 
  the 
  quadrangle, 
  some 
  of 
  the 
  facts 
  

   favoring 
  this 
  view 
  being: 
  (i) 
  the 
  abundance 
  of 
  scratched, 
  polished, 
  

   and 
  rounded 
  rock 
  surfaces; 
  (2) 
  the 
  comparative 
  freshness 
  of 
  the 
  

   rocks, 
  even 
  in 
  the 
  case 
  of 
  the 
  weak 
  Grenville 
  ; 
  (3) 
  the 
  unusual 
  

   weakness 
  of 
  much 
  of 
  the 
  rock, 
  especially 
  limestone, 
  which 
  occupies 
  

   the 
  valleys 
  ; 
  (4) 
  the 
  fact 
  that 
  these 
  belts 
  of 
  weak 
  rock 
  must 
  have 
  

   been 
  deeply 
  decomposed 
  during 
  the 
  long 
  preglacial 
  time, 
  thus 
  favor- 
  

   ing 
  extensive 
  removal 
  of 
  material; 
  and 
  (5) 
  the 
  north-south 
  move- 
  

   ment 
  of 
  the 
  ice 
  being 
  parallel 
  to 
  the 
  Grenville 
  valleys 
  and 
  hence 
  

   being 
  favorable 
  for 
  ice 
  erosion 
  because 
  of 
  easy 
  flowage 
  of 
  the 
  deep 
  

   ice 
  through 
  the 
  valleys. 
  Other 
  Grenville 
  valleys 
  were 
  doubtlessly 
  

   also 
  similarly 
  lowered 
  by 
  ice 
  erosion. 
  

  

  GLACIAL 
  DEPOSITS 
  

  

  Glacial 
  boulders 
  or 
  erratics 
  are 
  very 
  common 
  over 
  the 
  entire 
  

   area 
  and, 
  as 
  usual, 
  most 
  of 
  them 
  are 
  of 
  local 
  origin. 
  This 
  fact 
  

   of 
  local 
  origin 
  was 
  successfully 
  employed 
  to 
  locate 
  certain 
  import- 
  

   ant 
  outcrops, 
  especially 
  of 
  gabbro 
  or 
  diabase, 
  by 
  tracing 
  the 
  line 
  

   of 
  boulders 
  to 
  the 
  parent 
  ledge. 
  All 
  sorts 
  of 
  Precambric 
  rocks 
  of 
  

   the 
  region 
  are 
  represented 
  among 
  the 
  boulders, 
  the 
  granite 
  and 
  

   syenite 
  naturally 
  being 
  the 
  most 
  common. 
  A 
  type 
  of 
  boulder 
  

  

  