﻿rl50 
  

  

  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  Thirdly, 
  there 
  is 
  every 
  evidence 
  of 
  the 
  existence, 
  (probably 
  

   during 
  the 
  latter 
  part 
  of 
  the 
  glacial 
  epoch) 
  of 
  an 
  ice 
  tongue 
  extend- 
  

   ing 
  up 
  the 
  valley. 
  It 
  v^ould 
  be 
  reduced 
  by 
  melting, 
  but 
  the 
  hills, 
  

   would 
  concentrate 
  it 
  in 
  the 
  valley, 
  and 
  the 
  erosive 
  power 
  in 
  the 
  

   center 
  would 
  thus 
  be 
  increased. 
  Naturally 
  a 
  small 
  projection 
  like 
  

   this 
  from 
  the 
  front 
  of 
  the 
  ice 
  sheet 
  would 
  fluctuate 
  greatly, 
  thus 
  

   also 
  increasing 
  the 
  erosive 
  power 
  by 
  giving 
  an 
  alternating 
  motion. 
  

  

  There 
  are 
  considered 
  to 
  be 
  a 
  few 
  proofs 
  that 
  this 
  action 
  has 
  

   taken 
  place. 
  

  

  A 
  fair 
  sized 
  pebble 
  of 
  the 
  TuUy 
  limestone 
  can 
  be 
  recognized 
  by 
  

   any 
  one 
  familiar 
  with 
  the 
  Tully 
  strata 
  along 
  the 
  lake. 
  Immense 
  

   boulders 
  of 
  it 
  are 
  found 
  strewn 
  over 
  the 
  high 
  hills 
  south 
  of 
  the 
  

   lake, 
  often 
  10 
  miles 
  from 
  the 
  beginning 
  of 
  the 
  outcrop 
  along 
  the 
  

   lake, 
  and 
  several 
  hundred 
  feet 
  above 
  it. 
  They 
  can 
  be 
  accounted 
  

   for 
  only 
  by 
  ice 
  transportation, 
  and 
  the 
  lake 
  valley 
  is 
  the 
  only 
  place 
  

   they 
  can 
  have 
  come 
  from, 
  as 
  there 
  are 
  no 
  outcrops 
  of 
  it 
  elsewhere 
  

   in 
  the 
  neighborhood. 
  

  

  Glacial 
  striae 
  are 
  found 
  at 
  almost 
  any 
  point 
  along 
  the 
  slop 
  ^ 
  of 
  the 
  

   valley, 
  beneath 
  the 
  drift, 
  and 
  as 
  a 
  general 
  thing 
  they 
  run 
  in 
  several 
  

   directions, 
  showing 
  the 
  fluctuations 
  already 
  ascribed 
  to 
  the 
  ice 
  

   tongue. 
  Fig. 
  9 
  is 
  taken 
  exactly 
  from 
  a 
  slab 
  of 
  shale 
  from 
  the 
  north 
  

   side 
  of 
  Taughannock 
  ravine. 
  

  

  8°W.of 
  N. 
  

  

  Fig. 
  9 
  

  

  Shale 
  stKiated 
  in 
  four 
  

   di 
  Ke 
  ctions 
  

  

  