﻿80 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  their 
  headwaters 
  farther 
  southward, 
  but 
  only 
  along 
  belts 
  of 
  weak 
  

   rock 
  and 
  in 
  harmony 
  with 
  the 
  northeast-southwest 
  folded 
  structure 
  

   of 
  the 
  region. 
  

  

  In 
  a 
  similar 
  manner 
  the 
  great 
  Mohawk 
  valley 
  has 
  been 
  developed. 
  

   The 
  Mohawk 
  is 
  the 
  chief 
  tributary 
  of 
  the 
  Hudson, 
  and 
  whether 
  or 
  

   not 
  its 
  ancestor 
  flowed 
  in 
  about 
  the 
  same 
  position 
  upon 
  the 
  surface 
  

   of 
  the 
  peneplain, 
  we 
  do 
  know 
  that 
  the 
  present 
  Mohawk 
  valley 
  

   (below 
  Little 
  Falls) 
  has 
  been 
  carved 
  out 
  of 
  the 
  upraised 
  peneplain 
  

   by 
  the 
  Mohawk 
  river 
  and 
  its 
  tributaries 
  along 
  a 
  belt 
  of 
  weak 
  

   Ordovicic 
  shales. 
  The 
  valley 
  is 
  bounded 
  on 
  the 
  north 
  by 
  the 
  very 
  

   hard 
  Precambrie 
  rocks 
  and 
  on 
  the 
  south 
  by 
  the 
  fairly 
  resistant 
  

   limestones 
  of 
  the 
  Helderberg 
  escarpment. 
  Proof 
  will 
  be 
  given 
  

   on 
  a 
  later 
  page 
  for 
  the 
  statement 
  that 
  late 
  in 
  the 
  Tertiary 
  (that 
  

   is 
  just 
  prior 
  to 
  the 
  great 
  Ice 
  age) 
  the 
  Mohawk 
  river 
  had 
  its 
  

   source 
  near 
  Little 
  Falls, 
  and 
  that 
  at 
  the 
  same 
  time 
  another 
  stream 
  

   (Rome 
  river), 
  now 
  extinct, 
  flowed 
  westward 
  from 
  Little 
  Falls, 
  

   past 
  Utica 
  and 
  Rome 
  and 
  into 
  the 
  basin 
  now 
  occupied 
  by 
  Lake 
  

   Ontario. 
  West 
  Canada 
  creek 
  was 
  then 
  tributary 
  to 
  the 
  Rome 
  

   river, 
  while 
  the 
  Sacandaga 
  river 
  flowed 
  into 
  the 
  Mohawk 
  instead 
  

   of 
  the 
  Hudson 
  as 
  it 
  now 
  does. 
  

  

  However 
  uncertain 
  we 
  may 
  be 
  as 
  to 
  the 
  location 
  of 
  a 
  Precenozoic 
  

   Susquehanna 
  river, 
  we 
  are 
  very 
  certain 
  that 
  the 
  present 
  numerous 
  

   deep 
  channels 
  of 
  the 
  Susquehanna 
  drainage 
  system 
  have 
  been 
  cut 
  

   into 
  the 
  upraised 
  peneplain. 
  The 
  Susquehanna, 
  like 
  the 
  Hudson, 
  

   is 
  a 
  good 
  example 
  of 
  a 
  superimposed 
  stream 
  and 
  its 
  ancestor 
  may 
  

   have 
  flowed 
  along 
  the 
  same 
  general 
  course 
  over 
  the 
  low-lying 
  pene- 
  

   plain 
  before 
  its 
  uplift. 
  Immediately 
  after 
  the 
  uplift 
  some 
  of 
  the 
  

   more 
  easterly 
  headwaters 
  of 
  the 
  Susquehanna 
  came 
  out 
  of 
  the 
  

   southern 
  Adirondacks. 
  Evidences 
  of 
  this 
  are 
  as 
  follows: 
  (i) 
  The 
  

   present 
  Mohawk 
  valley 
  had 
  not 
  been 
  formed, 
  the 
  Mohawk 
  river 
  

   then 
  having 
  only 
  begun 
  the 
  westward 
  migration 
  of 
  its 
  headwaters 
  

   along 
  the 
  belt 
  of 
  soft 
  shales; 
  (2) 
  the 
  natural 
  slope 
  of 
  the 
  southern 
  

   Adirondack 
  region 
  was 
  then 
  southward 
  into 
  the 
  east 
  branches 
  of 
  

   the 
  upper 
  Susquehanna; 
  and 
  (3) 
  the 
  positions 
  of 
  the 
  present 
  

   sources 
  of 
  the 
  east 
  branches 
  of 
  the 
  Susquehanna 
  at 
  the 
  crest 
  of 
  

   the 
  high 
  Helderberg 
  escarpment, 
  and 
  in 
  some 
  cases 
  within 
  a 
  very 
  

   few 
  miles 
  of 
  the 
  present 
  Mohawk 
  river 
  (see 
  drainage 
  map, 
  figure 
  

   n) 
  strongly 
  argue 
  for 
  the 
  cutting 
  off 
  or 
  beheading 
  of 
  the 
  former 
  

   headwaters 
  of 
  the 
  east 
  branches. 
  This 
  beheading 
  was 
  accomplished 
  

   by 
  the 
  Mohawk 
  as 
  its 
  headwaters 
  migrated 
  slowly 
  westward 
  thus 
  

   tapping 
  one 
  by 
  one 
  of 
  the 
  upper 
  waters 
  of 
  the 
  east 
  branches 
  of 
  the 
  

   Susquehanna. 
  Even 
  today 
  the 
  Mohawk 
  continues 
  to 
  steal 
  drainage 
  

  

  