﻿140 
  TWENTY-FIRST 
  REPORT 
  ON 
  THE 
  STATE 
  CABINET. 
  

  

  the 
  Hudson, 
  and 
  some 
  distance 
  up 
  that 
  river.* 
  In 
  one 
  place 
  a 
  

   narrow 
  cutting 
  through 
  it 
  and 
  its 
  foundation 
  of 
  drift 
  connects 
  the 
  

   area 
  described 
  above 
  with 
  a 
  stream 
  flowing 
  toward 
  the 
  Hudson. 
  

   The 
  drift 
  hills 
  frequently 
  rise 
  above 
  the 
  level 
  of 
  the 
  terrace. 
  Mr. 
  

   Johnston's 
  house 
  is 
  on 
  a 
  hill 
  of 
  drift 
  a 
  trifle 
  higher 
  than 
  the 
  clay 
  

   of 
  the 
  terrace. 
  I 
  think 
  the 
  layer 
  of 
  sand, 
  where 
  unblown, 
  is 
  not 
  

   very 
  thick 
  ; 
  one 
  section 
  in 
  the 
  road 
  between 
  Middletown 
  and 
  

   Waterford 
  shows 
  about 
  five 
  feet. 
  

  

  Chronology. 
  — 
  1. 
  The 
  ancient 
  pot-holes, 
  whether 
  formed 
  by 
  

   glacial 
  or 
  fluvial 
  action, 
  are 
  as 
  old 
  as 
  the 
  present 
  conformation 
  of 
  

   the 
  surface 
  of 
  the 
  rock. 
  No 
  agency 
  that 
  would 
  permit 
  the 
  exist- 
  

   ence 
  of 
  the 
  present 
  yielding 
  shores 
  of 
  the 
  Mohawk 
  valley 
  could 
  

   drill 
  them. 
  If 
  they 
  are 
  not 
  glacial, 
  they 
  are 
  pre-glacial. 
  The 
  

   surface 
  of 
  the 
  rock 
  was 
  shaped 
  by 
  a 
  force 
  acting 
  due 
  south, 
  and 
  

   was 
  anterior 
  to 
  the 
  deposition 
  of 
  gravel 
  and 
  clay. 
  2. 
  The 
  gravel 
  

   hills 
  are 
  older 
  than 
  the 
  clay. 
  3. 
  The 
  clay 
  was 
  quietly 
  deposited, 
  

   and 
  was 
  continued 
  across 
  the 
  Mohawk 
  and 
  Hudson 
  valleys. 
  

   4. 
  The 
  absence 
  of 
  lower 
  terraces 
  indicates 
  that 
  in 
  the 
  rising 
  of 
  

   the 
  land 
  there 
  were 
  no 
  considerable 
  rests. 
  During 
  or 
  after 
  the 
  

   elevation, 
  the 
  Mohawk 
  cleared 
  its 
  present 
  valley, 
  and 
  chose 
  its 
  

   bed. 
  

  

  Levels. 
  — 
  The 
  rock 
  plateau 
  below 
  Cohoes 
  Falls 
  is 
  the 
  base 
  line 
  

   for 
  sections 
  near 
  the 
  Falls; 
  it 
  is 
  61 
  feet 
  above 
  tide-water. 
  

  

  Above 
  Above 
  

   plateau. 
  tide. 
  

  

  The 
  elevation 
  of 
  the 
  Erie 
  canal 
  above 
  lock 
  18 
  is 
  127 
  188 
  

  

  Upper 
  level 
  of 
  Cohoes 
  Company's 
  race 
  94 
  155 
  

  

  Cliff 
  near 
  falls 
  _ 
  115 
  

  

  Top 
  of 
  clay 
  between 
  Cohoes 
  and 
  Crescent, 
  ._ 
  207 
  268 
  

  

  Top 
  of 
  clay 
  in 
  Greenbush 
  194 
  

  

  Top 
  of 
  sand 
  in 
  Greenbush 
  212 
  

  

  Plateau 
  west 
  of 
  Albany 
  225 
  

  

  Top 
  of 
  gravel 
  hill 
  near 
  " 
  Patroon's," 
  about 
  -„. 
  240 
  

  

  Top 
  of 
  gravel 
  hill 
  near 
  Shakers' 
  road, 
  about 
  .. 
  325 
  

  

  Eochester 
  Pot-holes. 
  — 
  The 
  pot-holes 
  in 
  the 
  Niagara 
  limestone 
  

   at 
  Rochester 
  are 
  generally 
  not 
  so 
  deep 
  as 
  broad, 
  and 
  range 
  from 
  

  

  * 
  See 
  p. 
  141. 
  

  

  