﻿180 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  and 
  extensively; 
  and 
  since 
  they 
  were 
  uplifted 
  to 
  their 
  present 
  

   elevation, 
  the 
  elements 
  have 
  unremittingly 
  acted 
  upon 
  them. 
  

  

  As 
  the 
  rocks, 
  newer 
  than 
  the 
  Carboniferous, 
  occur 
  in 
  but 
  small 
  

   areas 
  within 
  our 
  state, 
  it 
  may 
  be 
  concluded 
  that 
  the 
  greater 
  part 
  

   of 
  this 
  region 
  has 
  been 
  above 
  water 
  since 
  the 
  Carboniferous 
  

   period, 
  during 
  the 
  countless 
  ages 
  while 
  the 
  Triassic, 
  Jurassic, 
  

   Cretaceous 
  and) 
  Tertiary 
  rocks 
  were 
  formed 
  and 
  during 
  the 
  depo- 
  

   sition 
  of 
  which 
  the 
  animated 
  population 
  of 
  the 
  earth 
  has 
  been 
  

   changed 
  many 
  times. 
  All 
  of 
  these 
  formations 
  were 
  made 
  of 
  sedi- 
  

   ments 
  worn 
  from 
  pre-existing 
  land. 
  It 
  is 
  to 
  be 
  expected, 
  there- 
  

   fore, 
  that 
  this 
  ancient 
  land 
  should 
  show 
  the 
  marks 
  of 
  vast 
  erosion 
  

   and 
  wear. 
  Some 
  marks 
  of 
  this 
  are 
  found 
  in 
  the 
  long 
  and 
  deep 
  

   valleys 
  which 
  traverse 
  the 
  state, 
  all 
  lof 
  which 
  have 
  been 
  worn 
  

   out 
  of 
  the 
  solid 
  strata, 
  the 
  remaining 
  portions 
  of 
  which 
  form 
  the 
  

   adjacent 
  hills. 
  These 
  valleys 
  are 
  being 
  worn 
  deeper 
  where 
  the 
  

   rivers 
  are 
  strong 
  and 
  their 
  cutting 
  action 
  continues, 
  and 
  every- 
  

   where 
  they 
  are 
  being 
  widened 
  and 
  the 
  mountains 
  and 
  hills 
  re- 
  

   duced 
  in 
  height 
  by 
  rains 
  and 
  frost. 
  Some 
  valleys 
  have 
  been 
  

   excavated 
  much 
  below 
  the 
  level 
  of 
  their 
  present 
  outlets, 
  so 
  that 
  

   they 
  retain 
  the 
  drainage 
  and 
  form 
  the 
  remarkable 
  series 
  of 
  finger 
  

   lakes 
  previously 
  mentioned. 
  

  

  Vast 
  as 
  the 
  work 
  may 
  seem, 
  the 
  fact 
  is 
  plain 
  that 
  not 
  only 
  

   have 
  these 
  valleys 
  been 
  formed 
  by 
  erosion, 
  but 
  hundreds 
  of 
  feet 
  

   of 
  rocky 
  strata 
  have 
  been 
  removed 
  from 
  the 
  summits 
  of 
  the 
  hills 
  

   themselves 
  and 
  from 
  large 
  tracts 
  of 
  plain 
  country. 
  The 
  whole 
  

   vast 
  basin 
  of 
  Lake 
  Ontario 
  is 
  an 
  excavation 
  in 
  rocks 
  which 
  still 
  

   lie 
  nearly 
  as 
  level 
  as 
  when 
  first 
  deposited; 
  and 
  there 
  seems 
  no 
  

   reason 
  to 
  doubt 
  that 
  the 
  northern 
  edges 
  of 
  the 
  enormous 
  thick- 
  

   ness 
  of 
  formations 
  above 
  the 
  Helderberg 
  limestones 
  once 
  over- 
  

   spread 
  the 
  present 
  lowlands 
  of 
  the 
  counties 
  bordering 
  that 
  great 
  

   body 
  of 
  water. 
  

  

  Such 
  long 
  lines 
  of 
  bluffs 
  as 
  the 
  Niagara 
  ' 
  mountain 
  ridge,^ 
  and 
  

   the 
  steep 
  escarpments 
  of 
  the 
  Helderberg 
  limestones, 
  are 
  evidences 
  

   of 
  the 
  great 
  work 
  of 
  erosion. 
  The 
  existence 
  of 
  old 
  beaches, 
  such 
  

   as 
  the 
  Lake 
  Ridge 
  near 
  Rochester, 
  proves 
  that 
  the 
  waters 
  of 
  the 
  

   lake 
  once 
  stood 
  far 
  higher 
  than 
  now. 
  

  

  