﻿so 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  BelP 
  has 
  noted 
  similar 
  conditions 
  in 
  Canada 
  and 
  he 
  says 
  that 
  when 
  

   the 
  ice 
  sheet 
  moved 
  from 
  the 
  crystallines 
  against 
  the 
  edges 
  of 
  the 
  

   unaltered 
  sedimentaries 
  " 
  great 
  erosion 
  has 
  always 
  taken 
  place 
  and 
  

   valleys 
  and 
  basins 
  are 
  formed 
  whose 
  width 
  depends 
  upon 
  the 
  angle 
  

   of 
  dip 
  and 
  the 
  softness 
  of 
  the 
  strata 
  which 
  have 
  been 
  scooped 
  out. 
  

   The 
  strata 
  are 
  presented 
  in 
  the 
  most 
  favorable 
  attitude 
  for 
  abrasion. 
  

   The 
  wearing 
  down 
  would 
  go 
  on 
  till 
  the 
  resisting 
  rock 
  front 
  had 
  

   attained 
  a 
  hight 
  and 
  weight 
  sufficient 
  to 
  counterbalance 
  those 
  of 
  the 
  

   glacier." 
  In 
  the 
  Black 
  river 
  valley 
  the 
  ice 
  moved 
  from 
  the 
  crystal- 
  

   lines 
  against 
  the 
  slightly 
  upturned 
  edges 
  of 
  the 
  sediments. 
  

  

  In 
  much 
  the 
  same 
  way 
  the 
  soft 
  shales 
  were 
  stripped 
  off 
  the 
  sur- 
  

   face 
  of 
  the 
  hard 
  limestones 
  to 
  form 
  the 
  broad 
  terrace 
  and 
  the 
  steep 
  

   front 
  of 
  Tug 
  hill. 
  Such 
  a 
  stripping 
  off 
  of 
  the 
  shales 
  occurred, 
  but 
  

   to 
  a 
  less 
  extent, 
  over 
  the 
  southern 
  part 
  of 
  the 
  Port 
  Leyden 
  quad- 
  

   rangle 
  and 
  the 
  western 
  part 
  of 
  the 
  Remsen 
  quadrangle. 
  The 
  maxi- 
  

   mum 
  thickness 
  of 
  shale 
  thus 
  removed 
  was 
  probably 
  several 
  hun- 
  

   dred 
  feet, 
  but 
  not 
  over 
  a 
  wide 
  area. 
  The 
  total 
  amount 
  of 
  shale 
  re- 
  

   moved 
  was 
  not 
  nearly 
  as 
  much 
  as 
  may 
  at 
  first 
  sight 
  be 
  supposed. 
  

   Then 
  too 
  the 
  shales 
  were 
  soft 
  and 
  highly 
  jointed 
  even 
  to 
  a 
  consider- 
  

   able 
  depth 
  as 
  may 
  now 
  be 
  seen 
  in 
  the 
  Whetstone 
  gulf 
  section. 
  

  

  Two 
  other 
  factors 
  which 
  greatly 
  aided 
  the 
  work 
  of 
  the 
  ice 
  in 
  the 
  

   Tug 
  hill 
  region 
  must 
  not 
  be 
  overlooked. 
  One 
  of 
  these 
  is 
  the 
  fact 
  

   that 
  the 
  ice 
  moved 
  up 
  hill 
  as 
  it 
  advanced 
  southward 
  along 
  the 
  valley 
  

   and 
  so 
  had 
  its 
  cutting 
  power 
  increased. 
  On 
  reaching 
  the 
  divide 
  be- 
  

   tween 
  Black 
  river 
  and 
  West 
  Canada 
  creek 
  the 
  cutting 
  power 
  was 
  

   lessened 
  and 
  till 
  and 
  other 
  drift 
  materials 
  were 
  deposited 
  in 
  great 
  

   quantities 
  as 
  the 
  ice 
  moved 
  down 
  hill 
  toward 
  the 
  Mohawk 
  river. 
  

   Another 
  factor 
  which 
  the 
  writer 
  regards 
  as 
  important 
  in 
  this 
  con- 
  

   nection 
  is 
  the 
  angle 
  at 
  which 
  the 
  ice 
  current 
  entered 
  the 
  Black 
  river 
  

   valley 
  in 
  its 
  sweep 
  around 
  the 
  Adirondacks. 
  The 
  greatest 
  amount 
  

   of 
  erosion 
  was 
  along 
  the 
  eastern 
  side 
  of 
  Tug 
  hill, 
  and 
  it 
  is 
  just 
  here 
  

   where 
  the 
  ice 
  current 
  must 
  have 
  struck 
  with 
  greatest 
  force 
  as 
  it 
  

   crowded 
  into 
  the 
  valley. 
  In 
  harmony 
  with 
  this 
  idea 
  is 
  the 
  fact 
  that 
  

   the 
  glacial 
  striae 
  near 
  Martinsburg 
  bear 
  more 
  toward 
  the 
  south 
  than 
  

   does 
  the 
  steep 
  front 
  of 
  Tug 
  hill. 
  

  

  It 
  may 
  be 
  fairly 
  asked, 
  what 
  became 
  of 
  the 
  materials 
  thus 
  re- 
  

   moved? 
  The 
  very 
  resistent 
  Precambrics 
  ought 
  to 
  be 
  present 
  in 
  

   considerable 
  force 
  somewhere 
  in 
  the 
  region 
  as 
  erratics 
  and 
  this 
  

   is 
  the 
  case 
  southward 
  especially 
  in 
  the 
  townships 
  of 
  Boonville 
  and 
  

   Remsen 
  where 
  vast 
  numbers 
  of 
  such 
  erratics 
  may 
  be 
  seen. 
  Shale 
  

  

  ' 
  Geol. 
  Soc. 
  Am. 
  Bui. 
  1890. 
  i 
  :2g6. 
  

  

  