﻿22 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  county, 
  reaches 
  an 
  altitude 
  of 
  nearly 
  2100 
  feet, 
  while 
  the 
  central 
  

   portion 
  of 
  the 
  province, 
  covering 
  many 
  square 
  miles, 
  is 
  remarkably 
  

   flat 
  and 
  swampy 
  with 
  the 
  general 
  level 
  above 
  1800 
  feet 
  of 
  elevation. 
  

   On 
  a 
  smaller 
  scale, 
  this 
  is 
  as 
  truly 
  a 
  plateau 
  as 
  the 
  great 
  South- 
  

   western 
  plateau 
  already 
  described 
  and, 
  interesting 
  to 
  note, 
  this 
  

   Tug 
  Hill 
  plateau 
  is 
  merely 
  an 
  erosion 
  remnant 
  of 
  the 
  great 
  up- 
  

   raised 
  Cretacic 
  peneplain 
  (see 
  chapter 
  5) 
  which 
  formerly 
  included 
  

   all 
  of 
  New 
  York 
  State. 
  

  

  On 
  the 
  south 
  and 
  west 
  this 
  province 
  slopes 
  rapidly 
  downward 
  

   to 
  the 
  lowlands 
  of 
  the 
  Mohawk 
  valley 
  and 
  Ontario 
  plain 
  provinces, 
  

   while 
  on 
  the 
  east 
  and 
  north 
  the 
  Black 
  river 
  valley 
  sharply 
  separates 
  

   this 
  province 
  from 
  the 
  Adirondack 
  and 
  St 
  Lawrence 
  Valley 
  prov- 
  

   inces. 
  The 
  rapid 
  descent 
  into 
  the 
  Black 
  river 
  valley 
  bottom 
  is 
  

   everywhere 
  1000 
  feet 
  or 
  more 
  over 
  a 
  series 
  of 
  high, 
  steep 
  terrace 
  

   fronts 
  (see 
  plate 
  8). 
  In 
  passing, 
  it 
  should 
  be 
  stated 
  that, 
  though 
  

   seldom 
  recognized, 
  this 
  Black 
  river 
  depression 
  takes 
  rank 
  as 
  one 
  

   of 
  the 
  few 
  greatest 
  valleys 
  within 
  the 
  borders 
  of 
  the 
  State. 
  

  

  Near 
  Boonville, 
  and 
  at 
  an 
  elevation 
  of 
  about 
  1100 
  feet, 
  occurs 
  

   the 
  division 
  of 
  drainage 
  between 
  the 
  Mohawk 
  and 
  Black 
  rivers, 
  

   and 
  this 
  divide 
  forms 
  the 
  highest 
  land 
  connecting 
  the 
  Tug 
  Hill 
  and 
  

   Adirondack 
  provinces. 
  But 
  in 
  spite 
  of 
  this 
  partial 
  connection 
  and 
  

   the 
  close 
  proximity 
  of 
  the 
  province 
  to 
  the 
  Adirondacks, 
  the 
  rock 
  

   formations 
  and 
  structure 
  are 
  wholly 
  different 
  from 
  those 
  of 
  the 
  

   Adirondacks 
  while 
  they 
  greatly 
  resemble 
  those 
  of 
  the 
  Southwestern 
  

   plateau. 
  The 
  rocks 
  are 
  all 
  of 
  lower 
  Paleozoic 
  (chiefly 
  Ordovicic) 
  

   age, 
  with 
  several 
  hundred 
  feet 
  of 
  limestone 
  at 
  the 
  base 
  followed 
  by 
  

   about 
  a 
  thousand 
  feet 
  of 
  shales, 
  the 
  whole 
  being 
  capped 
  by 
  a 
  

   resistant 
  sandstone 
  of 
  Siluric 
  age. 
  These 
  strata 
  tilt 
  slightly 
  west- 
  

   ward 
  but 
  they 
  have 
  never 
  been 
  disturbed 
  by 
  folding, 
  faulting 
  or 
  

   igneous 
  activity 
  (see 
  figure 
  35). 
  

  

  ST 
  LAWRENCE 
  VALLEY 
  PROVINCE 
  

  

  The 
  St 
  Lawrence 
  valley, 
  lying 
  along 
  the 
  northern 
  boundary 
  of 
  

   the 
  State, 
  is 
  a 
  great, 
  open 
  depression 
  of 
  comparatively 
  simple 
  struc- 
  

   ture 
  and 
  near 
  sea 
  level. 
  Where 
  the 
  river 
  leaves 
  Lake 
  Ontario, 
  the 
  

   elevation 
  is 
  only 
  247 
  feet, 
  while 
  points 
  with 
  elevations 
  more 
  than 
  

   a 
  few 
  hundred 
  feet 
  seldom 
  occur 
  within 
  the 
  province. 
  As 
  shown 
  

   on 
  the 
  accompanying 
  map 
  (plate 
  9), 
  low 
  hills 
  are 
  common 
  over 
  

   the 
  valley 
  floor. 
  The 
  Thousand 
  Islands 
  form 
  a 
  remarkable 
  physio- 
  

   graphic 
  feature 
  of 
  the 
  province, 
  where 
  the 
  wide, 
  slow-moving 
  St 
  

   Lawrence 
  river 
  does 
  not 
  occupy 
  any 
  very 
  distinct 
  channel, 
  but 
  

  

  