﻿240 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  broken 
  by 
  low 
  hills 
  that 
  extend 
  on 
  the 
  north 
  to 
  the 
  Mohawk 
  river 
  

   and 
  on 
  the 
  east 
  to 
  the 
  Hudson. 
  The 
  physiography 
  and 
  stratig- 
  

   raphy 
  of 
  this 
  county 
  have 
  recently 
  been 
  quite 
  fully 
  described 
  by 
  

   Mr 
  N. 
  H. 
  Darton 
  in 
  his 
  paper 
  entitled 
  a 
  " 
  Preliminary 
  report 
  on 
  

   the 
  geology 
  of 
  Albany 
  county." 
  « 
  The 
  formations 
  of 
  the 
  Middle 
  

   and 
  Upper 
  Devonian 
  occur 
  only 
  on 
  the 
  Helderberg 
  plateau 
  in 
  the 
  

   southwestern 
  part 
  of 
  the 
  county. 
  On 
  the 
  eastern 
  slope 
  of 
  the 
  

   Catskills 
  in 
  the 
  southwestern 
  corner 
  of 
  the 
  county 
  are 
  the 
  latest 
  

   rocks, 
  probably 
  of 
  Catskill 
  age, 
  while 
  the 
  greater 
  part 
  of 
  the 
  three 
  

   southwestern 
  townships 
  of 
  Rensselaerville, 
  Westerlo 
  and 
  Berne 
  

   are 
  covered 
  by 
  rocks 
  belonging 
  in 
  the 
  Oneonta, 
  Sherburne 
  and 
  

   Hamilton 
  formations.- 
  To 
  the 
  north 
  and 
  east 
  of 
  these 
  townships 
  

   is 
  the 
  Helderberg 
  escarpment, 
  which 
  slopes 
  very 
  steeply 
  toward 
  

   the 
  plain. 
  It 
  enters 
  Knox 
  township 
  from 
  Schoharie 
  co. 
  with 
  

   a 
  nearly 
  east 
  and 
  west 
  trend 
  until 
  it 
  reaches 
  Guilderland 
  town- 
  

   ship 
  when 
  its 
  direction 
  changes 
  to 
  the 
  southeast 
  across 
  the 
  

   southern 
  part 
  of 
  the 
  county. 
  The 
  lower 
  part 
  of 
  the 
  escarpment 
  

   is 
  composed 
  generally 
  of 
  several 
  hundred 
  feet 
  of 
  Hudson 
  shales 
  

   and 
  sandstones 
  of 
  the 
  Lower 
  Silurian, 
  while 
  in 
  its 
  highest 
  part 
  

   on 
  the 
  eastern 
  side 
  the 
  crest 
  is 
  in 
  the 
  lower 
  half 
  of 
  the 
  Hamilton 
  

   formation. 
  

  

  Berne 
  

  

  In 
  describing 
  the 
  extent 
  of 
  the 
  Upper 
  Devonian 
  formations 
  of 
  

   Albany 
  co. 
  we 
  will 
  begin 
  with 
  the 
  northern 
  township 
  of 
  those 
  

   adjacent 
  to 
  Schoharie 
  co., 
  which 
  is 
  covered 
  by 
  these 
  forma- 
  

   tions. 
  Berne 
  township 
  lies 
  to 
  the 
  east 
  of 
  the 
  southern 
  part? 
  of 
  

   Wright, 
  Middleburg 
  and 
  the 
  northern 
  part 
  of 
  Broome 
  townships 
  

   of 
  Schoharie 
  co., 
  and 
  to 
  the 
  south 
  of 
  Knox 
  and' 
  north 
  of 
  Rens- 
  

   selaerville 
  and 
  Westerlo 
  townships 
  in 
  Albany 
  co. 
  ' 
  

  

  XXXVIII 
  B. 
  The 
  most 
  important 
  section 
  studied 
  in 
  this 
  town- 
  

   ship 
  is 
  one 
  near 
  ite 
  western 
  border 
  extending 
  from 
  the 
  Onondaga 
  

   limestone 
  in 
  the 
  valley 
  of 
  the 
  Foxkill 
  at 
  West 
  Berne 
  (Peoria) 
  in 
  the 
  

   northwestern 
  corner 
  to 
  near 
  the 
  base 
  of 
  the 
  lowe'st 
  reds 
  on 
  the 
  

   top 
  of 
  Bradt 
  hill 
  3.6 
  miles 
  SSW 
  of 
  West 
  Berne. 
  This 
  steep 
  hill 
  

   cut 
  by 
  a 
  deep 
  and 
  narrow 
  valley 
  known 
  as 
  Bradt 
  hollow 
  with 
  

  

  a 
  13th 
  an. 
  rep't 
  of 
  the 
  N. 
  Y. 
  state 
  geologist, 
  1894, 
  p. 
  229-61. 
  

  

  