﻿rY6 
  NEW 
  YOEK 
  STATE 
  MUSEUM 
  

  

  are 
  all 
  characteristic 
  delta 
  criteria. 
  They 
  have 
  level 
  tops, 
  steep 
  

   fronts 
  and 
  serrated 
  margins 
  ; 
  they 
  are 
  delta 
  shaped 
  and 
  built 
  of 
  

   thoroughly 
  water 
  worn 
  material 
  highly 
  stratified, 
  and 
  when 
  exposed 
  

   in 
  section 
  by 
  erosion 
  reveal 
  more 
  or 
  less 
  the 
  tripartite 
  structure 
  

   so 
  characteristic 
  of 
  all 
  delta 
  forms. 
  (Figures 
  10 
  and 
  11) 
  This 
  

   is 
  the 
  only 
  type 
  of 
  shore-line 
  phenomena 
  whicli, 
  when 
  considered 
  

   singly, 
  would 
  afford 
  confirmatory 
  evidence 
  of 
  a 
  past 
  lake. 
  No 
  

   beaches 
  of 
  even 
  fragile 
  formation 
  were 
  anywhere 
  found. 
  In 
  fact, 
  

   no 
  other 
  form 
  of 
  constructional 
  shore-line 
  has 
  been 
  seen, 
  save 
  in 
  one 
  

   or 
  two 
  instances 
  a 
  form 
  which 
  very 
  closely 
  simulates 
  the 
  bar, 
  and 
  

   has 
  been 
  classed 
  with 
  that 
  type. 
  These 
  terraces 
  will 
  be 
  further 
  

   considered 
  under 
  the 
  different 
  lake 
  stages. 
  

  

  Destructional 
  shorelines 
  of 
  wave-cut 
  origin. 
  This 
  type 
  of 
  

   shore-line 
  is 
  referred 
  to 
  with 
  considerable 
  doubt. 
  Only 
  where 
  

   correlation 
  with 
  the 
  constructional 
  forms 
  was 
  possible 
  were 
  the 
  ter- 
  

   races 
  in 
  the 
  till 
  deposits 
  considered 
  as 
  probablj'' 
  portion 
  of 
  a 
  wave-cut 
  

   shore-line. 
  In 
  areas 
  between* 
  many 
  of 
  the 
  streams 
  upon 
  which 
  deltas 
  

   are 
  to 
  be 
  found 
  and 
  where 
  the 
  drift 
  is 
  unusually 
  heavy, 
  benches 
  

   in 
  the 
  drift 
  and 
  at 
  corresponding 
  delta 
  levels, 
  were 
  traced 
  and 
  

   possibly 
  may 
  be 
  referred 
  to 
  wave 
  cutting 
  or, 
  some 
  modification 
  

   thereof. 
  The 
  forms 
  are 
  suggestive, 
  since 
  they 
  not 
  only 
  agree 
  in 
  

   correlation 
  with 
  the 
  other 
  shore 
  phenomena, 
  which 
  might 
  very 
  well 
  

   be 
  accidental 
  and 
  ascribed 
  to 
  other 
  causes, 
  but 
  in 
  many 
  instances 
  are 
  

   strewn 
  with 
  water-worn 
  material, 
  such 
  as 
  sand, 
  gravel 
  and 
  pebbles, 
  

   common 
  to 
  such 
  forms. 
  The 
  most 
  notable 
  ones 
  are 
  found 
  along 
  the 
  

   southwest 
  side 
  of 
  Six 
  Mile 
  creek 
  valley, 
  and 
  the 
  west 
  side 
  of 
  the 
  

   Inlet 
  valley 
  south 
  of 
  Ithaca. 
  They 
  are, 
  also, 
  found 
  on 
  a 
  smaller 
  

   scale 
  along 
  the 
  east 
  side 
  and 
  the 
  middle 
  southern 
  part 
  of 
  the 
  valley. 
  

  

  Terraces 
  of 
  differential 
  degradation. 
  Owing 
  to 
  differences 
  in 
  

   lithologic 
  and 
  physical 
  conditions 
  pertaining 
  in 
  the 
  majority 
  of 
  the 
  

   rock 
  masses 
  of 
  the 
  Finger-lake 
  region, 
  terraces 
  due 
  to 
  differential 
  

   atmospheric 
  erosion 
  are 
  of 
  frequent 
  occurrence, 
  and 
  in 
  some 
  places 
  

   are 
  conspicuous 
  topographic 
  forms. 
  These 
  special 
  forms 
  are 
  not 
  

   restricted 
  to 
  the 
  lake 
  area 
  of 
  the 
  plateau, 
  but, 
  in 
  some 
  places 
  are 
  

   found 
  in 
  abundance 
  to 
  the 
  south 
  of 
  the 
  divide. 
  At 
  all 
  times 
  they 
  

   are 
  here 
  characteristic 
  of 
  the 
  most 
  elevated 
  portions 
  of 
  the 
  valley 
  

   sides. 
  They 
  have 
  in 
  most 
  instances 
  reached 
  a 
  rather 
  advanced 
  stage 
  

   in 
  development, 
  being 
  continuous 
  for 
  some 
  distance. 
  In 
  several 
  

  

  