﻿GEOLOGICAL 
  SURVEY 
  OF 
  THE 
  STATE 
  OF 
  NEW 
  YORK. 
  

  

  (GEOLOGICAL 
  MAP.) 
  

  

  Preliminary 
  Report 
  on 
  the 
  Geology 
  of 
  Albany 
  

  

  County, 
  

  

  By 
  N. 
  H. 
  DARTON. 
  

  

  Contents.— 
  Physiography. 
  General 
  relations; 
  The 
  great 
  plain. 
  The 
  

   Helderberg 
  escarpment. 
  The 
  Southwestern 
  townships. 
  General 
  structural 
  

   relations. 
  Stratigraphy; 
  Oneonta 
  formation. 
  Hamilton 
  flags 
  and 
  

   shales. 
  Hamilton 
  black 
  shales. 
  Onondaga 
  limestone. 
  Schoharie 
  grit, 
  

   Esopus 
  shales. 
  Orishany 
  sandstone. 
  Beer 
  aft 
  limestone. 
  Shaly 
  limestone. 
  

   Pentamerus 
  limestone. 
  Tentaculite 
  limestone. 
  Salina 
  waterlime. 
  The 
  

   unconformity. 
  Hudson 
  river 
  formation. 
  Structure. 
  Pleistocene 
  

  

  GEOLOGY. 
  

  

  Physiography. 
  

   James 
  Hall, 
  State 
  Geologist: 
  

  

  Sir. 
  — 
  Albany 
  county, 
  in 
  central 
  eastern 
  New 
  York, 
  has 
  an 
  

   area 
  of 
  approximately 
  550 
  square 
  miles. 
  It 
  has 
  a 
  frontage 
  of 
  

   about 
  twenty-four 
  miles 
  on 
  the 
  Hudson 
  river 
  from 
  north 
  of 
  the 
  

   Mohawk 
  river 
  to 
  below 
  Coeymans 
  Landing, 
  and 
  extends 
  about 
  

   twenty-five 
  miles 
  westward. 
  It 
  is 
  bounded 
  on 
  the 
  south 
  by 
  

   Greene 
  county, 
  on 
  the 
  west 
  by 
  Schoharie 
  county, 
  on 
  the 
  north 
  

   by 
  Schenectady 
  and 
  Saratoga 
  counties, 
  and 
  on 
  the 
  east 
  by 
  the 
  

   Hudson 
  river 
  which 
  separates 
  it 
  from 
  Eensselaer 
  county. 
  It 
  is 
  

   separated 
  from 
  Saratoga 
  county 
  by 
  the 
  Mohawk 
  river. 
  

  

  Topographically 
  the 
  country 
  comprises 
  three 
  principal 
  prov- 
  

   inces 
  ranging 
  in 
  altitude 
  from 
  tide 
  water 
  along 
  the 
  Hudson 
  river 
  

   to 
  2200 
  feet 
  to 
  the 
  south 
  west 
  ward. 
  They 
  are, 
  first, 
  the 
  elevated 
  

   plain 
  extending 
  from 
  the 
  banks 
  of 
  the 
  Hudson 
  and 
  Mohawk 
  

   rivers 
  over 
  the 
  eastern 
  and 
  northeastern 
  townships, 
  to 
  a 
  line 
  

   passing 
  from 
  near 
  Coeymans 
  Junction 
  through 
  Altamont, 
  with 
  

   an 
  area 
  approximately 
  of 
  200 
  miles 
  ; 
  second, 
  the 
  Helderberg 
  escarp- 
  

   ment, 
  a 
  line 
  of 
  high 
  cliffs 
  arising 
  abruptly 
  from 
  the 
  plain, 
  along 
  

   54 
  

  

  