﻿460 
  Forty- 
  seventh 
  Report 
  on 
  the 
  State 
  Museum, 
  

  

  The 
  Gravels, 
  Sands 
  and 
  Clays. 
  

  

  The 
  gravels, 
  sands 
  and 
  clays 
  of 
  Albany 
  county 
  belong, 
  as 
  has 
  

   already 
  been 
  stated, 
  to 
  the 
  Quaternary 
  age. 
  They 
  are 
  a 
  part 
  of 
  

   a 
  more 
  or 
  less 
  connected 
  whole, 
  extending 
  from 
  the 
  Highlands 
  

   of 
  the 
  Hudson 
  to 
  the 
  St. 
  Lawrence 
  river. 
  

  

  Their 
  boundary 
  lines 
  in 
  Albany 
  county 
  may 
  thus 
  be 
  roughly 
  

   outlined. 
  Beginning 
  at 
  Coeymans 
  Landing 
  on 
  the 
  Hudson 
  they 
  

   are 
  bounded 
  on 
  the 
  southwest 
  by 
  the 
  Helderberg 
  mountains, 
  on 
  

   the 
  north 
  by 
  the 
  Mohawk, 
  and 
  on 
  the 
  east 
  by 
  the 
  Hudson. 
  The 
  

   deposits 
  do 
  not 
  stop 
  at 
  the 
  county 
  lines, 
  but 
  extend 
  through 
  the 
  

   northwest 
  part 
  of 
  the 
  county 
  reaching 
  to 
  the 
  Mohawk 
  river 
  in 
  

   Schenectady 
  county. 
  

  

  Inclosed 
  within 
  this 
  triangular 
  area 
  are 
  numerous 
  high 
  rocky 
  

   points 
  which 
  were 
  probably 
  islands 
  during 
  the 
  period 
  of 
  time 
  in 
  

   which 
  the 
  laminated 
  clays 
  and 
  molding 
  sands 
  were 
  deposited. 
  

  

  Along 
  the 
  southwestern 
  flank 
  of 
  the 
  Quaternary 
  shore 
  line 
  

   the 
  coarse 
  delta 
  sands, 
  cross-bedded 
  and 
  of 
  irregular 
  texture, 
  lie 
  

   against 
  the 
  rocks 
  of 
  the 
  Helderberg 
  mountain 
  series, 
  while 
  along 
  

   the 
  Mohawk 
  and 
  Hudson 
  rivers 
  the 
  same 
  deposits 
  lie 
  upon 
  the 
  

   uneven 
  surface 
  of 
  the 
  Hudson 
  river 
  group 
  of 
  sandstones 
  and 
  

   slates, 
  a 
  deposit 
  of 
  glacial 
  clay 
  with 
  striated 
  pebbles 
  usually 
  inter- 
  

   vening. 
  The 
  relation 
  of 
  these 
  deposits 
  to 
  the 
  rocks 
  is 
  clearly 
  

   shown 
  at 
  many 
  points. 
  At 
  Coeymans 
  Landing 
  the 
  Coeyman 
  s 
  creek 
  

   falls 
  over 
  a 
  precipice 
  of 
  these 
  rocks 
  ; 
  at 
  Yan 
  Wie's 
  Point 
  they 
  reach 
  

   to 
  a 
  considerable 
  height 
  above 
  the 
  river 
  level 
  ; 
  at 
  South 
  Albany, 
  

   at 
  Kenwood 
  and 
  in 
  the 
  city 
  proper 
  the 
  slates 
  appear 
  at 
  varying 
  

   levels. 
  At 
  North 
  Albany 
  a 
  cutting 
  in 
  the 
  New 
  York 
  Central 
  rail- 
  

   road 
  shows 
  the 
  crushed 
  and 
  polished 
  slates 
  not 
  fifty 
  i 
  eet 
  above 
  the 
  

   river 
  level. 
  Westward 
  is 
  a 
  depression, 
  partly 
  filled 
  with 
  laminated 
  

   clay, 
  but 
  near 
  the 
  railroad 
  shops 
  at 
  West 
  Albany 
  the 
  slates 
  again 
  

   appear. 
  Thence 
  following 
  a 
  line 
  nearly 
  due 
  north, 
  which 
  swings 
  

   out 
  and 
  in 
  toward 
  the 
  Hudson 
  river, 
  through 
  Menands 
  and 
  

   West 
  Troy, 
  the 
  slates 
  reach 
  the 
  Mohawk 
  at 
  Cohoes, 
  over 
  200 
  feet 
  

   above 
  the 
  level 
  of 
  the 
  Hudson. 
  From 
  the 
  foot 
  of 
  the 
  falls 
  in 
  

   the 
  Mohawk, 
  at 
  Cohoes, 
  the 
  river 
  flows 
  over 
  slate 
  rocks, 
  while 
  in 
  

   its 
  bed 
  are 
  numerous 
  small 
  rocky 
  islets 
  with 
  precipitous 
  sides 
  and 
  

   of 
  varying 
  altitudes, 
  none 
  over 
  seventy-five 
  feet 
  in 
  height, 
  which 
  

   remain 
  to 
  point 
  out 
  conclusively 
  the 
  work 
  of 
  the 
  river 
  in 
  the 
  past. 
  

  

  