﻿l6o 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  in 
  succession 
  and 
  the 
  lower 
  foot 
  or 
  two 
  may 
  be 
  free 
  from 
  the 
  

   action 
  of 
  water 
  only 
  in 
  exceptional 
  seasons. 
  

  

  Plate 
  I 
  presents 
  a 
  view 
  taken 
  November 
  7, 
  1908. 
  The 
  fore- 
  

   ground 
  is 
  near 
  the 
  water 
  level 
  and 
  the 
  little 
  potholes 
  have 
  been 
  

   filled 
  by 
  the 
  waves 
  of 
  a 
  moderate 
  sea 
  which 
  was 
  running 
  at 
  the 
  

   time. 
  The 
  upper 
  portions 
  of 
  this 
  exposed 
  rock 
  area 
  are 
  prac- 
  

   tically 
  as 
  they 
  were 
  left 
  by 
  the 
  Wisconsin 
  ice 
  sheet. 
  These 
  are 
  

   the 
  portions 
  rarely 
  covered 
  or 
  covered 
  but 
  a 
  month 
  or 
  two 
  in 
  

   the 
  year. 
  In 
  the 
  immediate 
  foreground 
  the 
  potholes 
  have 
  become 
  

   confluent 
  and 
  this 
  represents 
  that 
  portion 
  of 
  the 
  rock 
  surface 
  

   which 
  is 
  rarely 
  uncovered 
  and 
  which 
  has 
  thus 
  been 
  acted 
  upon 
  

   more 
  persistently 
  by 
  water, 
  wave 
  and 
  undertow. 
  Plate 
  2 
  is 
  a 
  

   view 
  of 
  a 
  portion 
  of 
  this 
  region 
  near 
  the 
  water 
  level 
  of 
  September 
  

   2y, 
  1908. 
  The 
  character 
  of 
  the 
  little 
  potholes 
  on 
  the 
  glaciated 
  

   surface 
  is 
  here 
  better 
  seen 
  as 
  is 
  also 
  their 
  increasing 
  number 
  per 
  

   unit 
  area, 
  as 
  we 
  reach 
  near 
  the 
  water 
  level 
  of 
  the 
  right-hand 
  lower 
  

   corner. 
  

  

  In 
  the 
  bay 
  back 
  of 
  the 
  lighthouse 
  is 
  a 
  very 
  perfect 
  and 
  interest- 
  

   ing 
  roche 
  moutoneee 
  bearing 
  a 
  record 
  which 
  alsO' 
  testifies 
  to 
  present 
  

   stability 
  of 
  the 
  water 
  level 
  of 
  Lake 
  Champlain. 
  The 
  position 
  is 
  

   here 
  much 
  more 
  sheltered 
  and 
  the 
  little 
  potholes 
  \see 
  pi. 
  3] 
  do 
  

   not 
  appear 
  to 
  descend 
  to 
  so 
  great 
  a 
  depth 
  as 
  in 
  the 
  former 
  locality. 
  

   To 
  the 
  left 
  they 
  occur 
  at 
  a 
  lower 
  level 
  and 
  have 
  become 
  confluent. 
  

   These 
  little 
  potholes 
  were 
  not 
  cut 
  by 
  pebbles. 
  Not 
  one 
  in 
  

   several 
  hundreds 
  has 
  a 
  pebble 
  in 
  it 
  and 
  no 
  pebble 
  could 
  

   have 
  found 
  a 
  lodging 
  on 
  the 
  steep 
  and 
  smooth 
  glaciated 
  sides 
  

   of 
  these 
  '' 
  sheepbacks." 
  They 
  all 
  contain 
  sand 
  however 
  and 
  

   were 
  cut 
  by 
  water 
  vortexes 
  carrying 
  sand 
  and 
  finer 
  silt. 
  They 
  

   rarely 
  exceed 
  12 
  centimeters 
  in 
  diameter, 
  unless 
  confluent, 
  and 
  

   many 
  are 
  very 
  much 
  smaller. 
  They 
  are 
  cut 
  also 
  in 
  very 
  steep 
  

   sides 
  as 
  shown 
  in 
  plate 
  4, 
  where 
  they 
  appear 
  as 
  glacial 
  sections 
  

   of 
  small 
  potholes. 
  The 
  maintenance 
  of 
  a 
  water 
  vortex 
  carrying 
  

   material 
  which 
  ever 
  cuts 
  back 
  and 
  widens 
  the 
  rock 
  at 
  one 
  side, 
  

   while 
  the 
  other 
  side 
  of 
  the 
  vortex 
  is 
  not 
  inclosed, 
  and 
  which 
  thus 
  

   continues 
  to 
  develop 
  the 
  vertical 
  and 
  conical 
  character 
  of 
  the 
  ex- 
  

   cavation, 
  is 
  of 
  special 
  interest. 
  

  

  Potholes 
  are 
  said 
  to 
  '' 
  often 
  point 
  to 
  the 
  former 
  existence 
  of 
  

   rapids 
  or 
  falls 
  " 
  and 
  the 
  term 
  usually 
  carries 
  with 
  it 
  the 
  idea 
  of 
  

   much 
  larger 
  excavations 
  than 
  those 
  found 
  on 
  the 
  shores 
  of 
  Val- 
  

   cour 
  island. 
  The 
  potholes 
  of 
  rivers 
  and 
  glacial 
  streams 
  are 
  not 
  

   due 
  to 
  wind 
  action 
  on 
  water 
  and 
  are 
  not 
  confined 
  to 
  one 
  level 
  

  

  