﻿GEOLOGY 
  OF 
  THE 
  PORT 
  LEYDEN 
  QUADRANGLE 
  45 
  

  

  even 
  the 
  hardest 
  rocks, 
  exposed 
  during 
  all 
  of 
  postglacial 
  time, 
  

   have 
  been 
  weathered 
  enough 
  to 
  cause 
  an 
  obliteration 
  of 
  the 
  glacial 
  

   marks. 
  

  

  Striae 
  pointing 
  from 
  s. 
  25° 
  to 
  40° 
  e. 
  have 
  been 
  located 
  as 
  follows: 
  

   On 
  Trenton 
  limestone 
  i 
  mile 
  south 
  of 
  Martinsburg 
  and 
  also 
  Yz 
  

   mile 
  to 
  the 
  east 
  of 
  that 
  village 
  (s. 
  25° 
  e.) 
  ; 
  on 
  Black 
  River 
  lime- 
  

   stone 
  just 
  west 
  of 
  Lyons 
  Falls 
  ; 
  on 
  Precambric 
  near 
  the 
  

   mouth 
  of 
  Roaring 
  brook, 
  i^/^ 
  miles 
  northeast-north 
  of 
  Glenfield 
  and 
  

   also 
  Yz 
  mile 
  southwest 
  and 
  ^ 
  mile 
  southeast-south 
  of 
  the 
  same 
  vil- 
  

   lage; 
  on 
  Precambric 
  i 
  mile 
  northeast 
  of 
  Denley 
  and 
  ^ 
  mile 
  north- 
  

   east 
  of 
  Hawkinsville. 
  Striae 
  bearing 
  nearly 
  south 
  occur 
  on 
  the 
  Pre- 
  

   cambric 
  I 
  mile 
  east 
  of 
  Port 
  Leyden. 
  The 
  southeasterly 
  movement, 
  

   shown 
  by 
  these 
  marks, 
  changed 
  to 
  a 
  more 
  nearly 
  easterly 
  move- 
  

   ment 
  in 
  the 
  Mohawk 
  valley 
  region, 
  and 
  this 
  is 
  just 
  what 
  would 
  be 
  

   expected 
  according 
  to 
  the 
  statement 
  of 
  Chamberlin. 
  It 
  should 
  be 
  

   noted 
  that 
  the 
  Black 
  river 
  valley, 
  which 
  is 
  the 
  chief 
  topographic 
  

   feature 
  on 
  the 
  western 
  side 
  of 
  the 
  Adirondacks, 
  had 
  much 
  to 
  do 
  

   with 
  determining 
  the 
  direction 
  of 
  flow 
  of 
  the 
  ice. 
  This 
  valley 
  

   existed 
  in 
  preglacial 
  time 
  and 
  the 
  close 
  parallelism 
  between 
  the 
  

   directions 
  of 
  the 
  striae 
  and 
  the 
  direction 
  of 
  the 
  valley 
  shows 
  the 
  

   influence 
  of 
  the 
  latter 
  in 
  determining 
  the 
  ice 
  movement. 
  Along 
  the 
  

   northwestern 
  border 
  of 
  the 
  Adirondacks 
  the 
  ice 
  undoubtedly 
  moved 
  

   southwestwardly. 
  Along 
  the 
  eastern 
  border 
  of 
  the 
  Adirondacks 
  

   the 
  general 
  southerly 
  movement 
  of 
  the 
  ice 
  has 
  been 
  well 
  established, 
  

   as 
  has 
  also 
  the 
  westerly 
  movement 
  up 
  the 
  ]\Iohawk 
  valley 
  toward 
  

   Little 
  Falls. 
  Thus 
  the 
  statement 
  of 
  Chamberlin, 
  regarding 
  ice 
  flow 
  

   around 
  the 
  Adirondacks, 
  harmonizes 
  almost 
  perfectly 
  with 
  the 
  

   observed 
  striae. 
  

  

  But 
  the 
  question 
  still 
  arises, 
  what 
  was 
  the 
  direction 
  of 
  the 
  current 
  

   during 
  the 
  hight 
  of 
  glaciation? 
  \\^e 
  have 
  abundant 
  evidence 
  to 
  

   prove 
  that, 
  during 
  the 
  hight 
  of 
  glaciation, 
  the 
  main 
  current 
  was 
  a 
  

   southeasterly 
  one. 
  On 
  the 
  Long 
  Lake 
  quadrangle 
  in 
  the 
  midst 
  of 
  

   the 
  Adirondacks 
  Professor 
  Gushing 
  has 
  recorded 
  a 
  number 
  of 
  striae 
  

   all 
  of 
  which 
  point 
  toward 
  the 
  southwest.^ 
  Over 
  the 
  region 
  south 
  of 
  

   the 
  Adirondacks 
  and 
  the 
  Mohawk 
  valley 
  the 
  observations 
  of 
  both 
  

   Brigham^ 
  and 
  Chamberlin-'^ 
  show 
  that 
  the 
  ice 
  moved 
  in 
  a 
  general 
  

   southwesterly 
  direction. 
  Another 
  strong 
  evidence 
  favoring 
  the 
  

   southwesterly 
  current 
  is 
  the 
  distribution 
  of 
  glacial 
  boulders 
  over 
  the 
  

  

  ' 
  N. 
  Y. 
  State 
  Mus. 
  Bui. 
  115. 
  1906. 
  p. 
  495. 
  

   ^Amer. 
  Jour. 
  Sci. 
  1895. 
  49:216. 
  

   ^loc. 
  cit. 
  p. 
  365. 
  

  

  