﻿Report 
  of 
  the 
  State 
  Geologist. 
  437 
  

  

  small 
  creek 
  a 
  few 
  rods 
  west 
  of 
  Peoria 
  (West 
  Berne), 
  the 
  upper 
  beds 
  

   are 
  seen 
  to 
  consist 
  of 
  a 
  very 
  dark, 
  coarse, 
  crystalline 
  limestone, 
  

   quite 
  closely 
  resembling 
  black 
  marble 
  in 
  appearance. 
  It 
  is 
  

   apparently 
  of 
  local 
  occurrence, 
  for 
  I 
  have 
  not 
  observed 
  it 
  else- 
  

   where. 
  The 
  occurrence 
  of 
  chert 
  in 
  the 
  formation 
  is 
  very 
  irregu- 
  

   lar, 
  but 
  it 
  is 
  in 
  largest 
  amount 
  in 
  the 
  lower 
  beds. 
  In 
  some 
  

   localities 
  it 
  is 
  almost 
  altogether 
  absent, 
  but 
  this 
  is 
  unusual. 
  

   Thin 
  intercalations 
  of 
  shale 
  occur 
  at 
  some 
  localities, 
  but 
  they, 
  

   also, 
  are 
  exceptional 
  features. 
  The 
  limestones 
  are 
  fossiliferous 
  to 
  

   a 
  variable 
  extent. 
  The 
  principal 
  fossils 
  are 
  comprised 
  in 
  beds 
  

   consisting 
  largely 
  of 
  corals 
  which 
  occur 
  in 
  some 
  places. 
  The 
  

   most 
  notable 
  outcrops 
  of 
  beds 
  of 
  this 
  character 
  are 
  along 
  the 
  

   road 
  a 
  half 
  mile 
  northwest 
  of 
  Thompson's 
  lake, 
  where 
  the 
  corals 
  

   are 
  so 
  numerous 
  that 
  the 
  bed 
  may 
  properly 
  be 
  designated 
  a 
  fossil 
  

   coral 
  reef. 
  In 
  the 
  bed 
  of 
  the 
  Foxkill, 
  at 
  Peoria, 
  corals 
  also 
  occur 
  

   in 
  abundance, 
  constituting 
  a 
  large 
  portion 
  of 
  the 
  beds 
  of 
  lime- 
  

   stone 
  here 
  exposed. 
  There 
  also 
  occur 
  other 
  fossils 
  than 
  corals, 
  

   and 
  these 
  are 
  present 
  in 
  greater 
  or 
  less 
  amount 
  at 
  almost 
  every 
  

   locality, 
  although 
  they 
  are 
  not 
  conspicuous. 
  One 
  of 
  the 
  finest 
  

   exposures 
  of 
  the 
  formation 
  in 
  the 
  county 
  is 
  in 
  the 
  cliffs 
  along 
  

   Oniskethau 
  creek, 
  at 
  Clarksville. 
  In 
  plate 
  2 
  there 
  is 
  given 
  a 
  

   view 
  of 
  the 
  general 
  appearance 
  of 
  a 
  portion 
  of 
  this 
  exposure. 
  

  

  The 
  occurrence 
  of 
  many 
  sinks 
  in 
  the 
  Onondaga 
  limestone 
  is 
  

   a 
  noteworthy 
  feature. 
  These 
  are 
  depressions 
  in 
  which 
  the 
  

   drainage 
  of 
  a 
  greater 
  or 
  less 
  area 
  disappears 
  into 
  fissures 
  or 
  

   caves 
  in 
  the 
  limestone. 
  Thompson's 
  lake 
  is 
  the 
  most 
  notable 
  

   of 
  these, 
  and 
  there 
  are 
  several 
  smaller 
  sinks 
  southeast 
  of 
  

   Thompson's 
  lake 
  and 
  another 
  at 
  a 
  point 
  two 
  miles 
  north-north- 
  

   east 
  of 
  Berne. 
  In 
  the 
  limestone 
  shelf 
  along 
  the 
  eastern 
  face 
  

   of 
  the 
  Helderberg 
  mountain, 
  Bennett, 
  Copeland 
  and 
  Blodgett 
  

   hills, 
  there 
  are 
  many 
  small 
  sinks 
  at 
  or 
  near 
  the 
  margin 
  of 
  the 
  

   Hamilton 
  shale, 
  which 
  are 
  a 
  conspicuous 
  and 
  characteristic 
  

   feature 
  of 
  this 
  formation. 
  

  

  Schoharie 
  grit. 
  — 
  This 
  formation 
  has 
  not 
  been 
  separately 
  repre- 
  

   sented 
  on 
  the 
  map 
  owing 
  to 
  its 
  restricted 
  occurrence. 
  It 
  is 
  well 
  

   characterized 
  at 
  Clarksville 
  and 
  for 
  several 
  miles 
  in 
  that 
  vicinity, 
  

   but 
  elsewhere 
  in 
  Albany 
  county 
  it 
  appears 
  to 
  be 
  absent. 
  It 
  

   is 
  a 
  very 
  impure 
  limestone, 
  which 
  weathers 
  at 
  the 
  surface 
  to 
  a 
  

  

  