﻿COHOES 
  MASTODON. 
  

  

  Ill 
  

  

  vations, 
  and 
  in 
  a 
  few 
  instances, 
  sections 
  are 
  disclosed 
  in 
  the 
  progress 
  

   of 
  working. 
  

  

  The 
  accompanying 
  section 
  from 
  a 
  point 
  in 
  the 
  north 
  part 
  of 
  

   Albany, 
  will 
  serve 
  to 
  illustrate 
  the 
  superposition 
  of 
  these 
  beds. 
  

  

  a. 
  Stratified 
  clay. 
  

  

  b. 
  Gravel 
  and 
  sand. 
  

  

  c. 
  Grassy 
  slope 
  over 
  gravel 
  hill. 
  

  

  The 
  gravel 
  is 
  mainly 
  of 
  water- 
  worn 
  materials, 
  though 
  the 
  lower 
  

   beds 
  clo 
  not 
  exhibit 
  the 
  result 
  of 
  the 
  sorting 
  process 
  or 
  the 
  entire 
  

   smoothing 
  of 
  the 
  pebbles: 
  they 
  are 
  often 
  found 
  resting 
  upon 
  a 
  

   boulder-clay 
  or 
  a 
  mixture 
  of 
  clay 
  and 
  gravel, 
  the 
  whole 
  cover- 
  

   ing 
  an 
  extremely 
  uneven 
  surface 
  of 
  slate 
  rock, 
  which 
  has 
  pre- 
  

   viously 
  been 
  worn 
  into 
  great 
  inequalities 
  as 
  we 
  often 
  see 
  from 
  its 
  

   exposure 
  along 
  the 
  Hudson 
  and 
  Mohawk 
  rivers, 
  and 
  at 
  a 
  few 
  points 
  

   near 
  Schenectady 
  and 
  along 
  the 
  Normans 
  Kill. 
  The 
  pot-holes 
  in 
  

   the 
  slate 
  rock 
  have 
  been 
  formed 
  before 
  the 
  final 
  deposition 
  of 
  this 
  

   mass 
  of 
  gravel, 
  which 
  is 
  of 
  extremely 
  unequal 
  thickness, 
  in 
  some 
  

   places 
  acquiring 
  a 
  depth 
  of 
  two 
  hundred 
  feet 
  or 
  more, 
  and 
  again 
  

   thinning 
  down 
  so 
  as 
  almost 
  to 
  disappear. 
  Wherever 
  lines 
  of 
  bed- 
  

   ding 
  can 
  be 
  discovered, 
  the 
  strata 
  show 
  evidence 
  of 
  the 
  influence 
  

   of 
  violent 
  currents 
  in 
  the 
  discordant 
  stratification, 
  the 
  partial 
  

   wearing 
  away 
  of 
  the 
  finer 
  material, 
  and 
  the 
  substitution 
  of 
  coarser 
  

   beds, 
  or 
  the 
  deposition 
  of 
  very 
  coarse 
  pebbles 
  above 
  the 
  finer 
  

   beds 
  of 
  sand. 
  The 
  superimposed 
  beds 
  of 
  clay 
  and 
  loam 
  are 
  the 
  

   results 
  of 
  a 
  quiet 
  condition 
  of 
  the 
  water, 
  in 
  which 
  the 
  finer 
  sedi- 
  

   ments 
  were 
  deposited 
  without 
  interruption 
  for 
  a 
  long 
  time, 
  closing 
  

   with 
  the 
  fine 
  yellow 
  sand 
  of 
  the 
  plains. 
  These 
  clay 
  and 
  super- 
  

   incumbent 
  sand 
  deposits 
  are 
  of 
  essentially 
  uniform 
  character 
  

   throughout 
  much 
  of 
  the 
  Hudson 
  valley, 
  extending 
  northward 
  to 
  

   Saratoga, 
  Lake 
  Champlain 
  and 
  the 
  St. 
  Lawrence 
  valleys. 
  

  

  It 
  is 
  through 
  this 
  deposit 
  of 
  estuary 
  clay 
  and 
  sand 
  that 
  the 
  

   Mohawk 
  makes 
  its 
  way 
  in 
  the 
  neighborhood 
  of 
  Schenectady, 
  and 
  

   gradually 
  exposes 
  more 
  of 
  the 
  gravel 
  deposits 
  as 
  it 
  approaches 
  

   the 
  Hudson. 
  Soon 
  after 
  leaving 
  Schenectady, 
  the 
  shales 
  and 
  har- 
  

  

  