﻿14i 
  NEW 
  YOEK 
  STATE 
  MUSEUM 
  

  

  is 
  quarried 
  at 
  Middle 
  Granville 
  and 
  vicinity, 
  and 
  broadening 
  

   out 
  soutliward, 
  extends 
  nearly 
  across 
  the 
  southern 
  part 
  of 
  

   Rensselaer 
  county. 
  

  

  Acadian 
  

  

  The 
  Middle 
  Cambrian, 
  or 
  Acadian, 
  group 
  is 
  not 
  so 
  well 
  de- 
  

   veloped 
  in 
  New 
  York. 
  

  

  Marble 
  and 
  limestone 
  of 
  this 
  age 
  are 
  found 
  resting 
  conform- 
  

   ably 
  upon 
  the 
  Lower 
  Cambrian 
  rocks 
  about 
  Stissing 
  mountain, 
  

   shown 
  in 
  the 
  cut 
  for 
  the 
  N. 
  Y. 
  & 
  Mass. 
  R. 
  R. 
  near 
  Stissing, 
  and 
  

   extending 
  into 
  Massachusetts, 
  where 
  the 
  development 
  is 
  greater. 
  

   A 
  portion 
  of 
  the 
  Stockbridge 
  limestone 
  may 
  belong 
  to 
  this 
  group, 
  

   though 
  most 
  of 
  it 
  is 
  Lower 
  Silurian. 
  

  

  Potsdam 
  

  

  The 
  Upper 
  Cambrian, 
  or 
  Potsdam, 
  group 
  is 
  exposed 
  over 
  a 
  

   larger 
  area 
  in 
  New 
  York 
  than 
  the 
  two 
  lower 
  divisions 
  an(^ 
  is 
  

   typically 
  represented 
  by 
  the 
  Potsdam 
  sandstone, 
  which 
  is 
  seen 
  

   in 
  many 
  places 
  to 
  rest 
  directly 
  upon 
  the 
  Archaean. 
  It 
  is 
  a 
  hard 
  

   siiicious 
  sandstone 
  and 
  an 
  excellent 
  building 
  material, 
  often 
  

   thinly 
  bedded 
  and 
  usually 
  reddish-brown 
  in 
  color, 
  though 
  some- 
  

   times 
  gray 
  or 
  buff. 
  On 
  many 
  of 
  its 
  layers, 
  are 
  waved 
  surfaces, 
  

   precisely 
  resembling 
  the 
  ripple-marks 
  seen 
  on 
  sandy 
  bottoms 
  

   over 
  which 
  waters 
  are 
  agitated 
  by 
  waves 
  or 
  currents. 
  They 
  were 
  

   formed 
  in 
  the 
  same 
  way, 
  by 
  movements 
  of 
  the 
  waters 
  in 
  which 
  

   were 
  deposited 
  the 
  sands 
  which 
  were 
  finally 
  hardened 
  into 
  the 
  

   Potsdam 
  sandstone. 
  Similar 
  markings 
  are 
  frequent 
  on 
  almost 
  

   all 
  sandstones. 
  The 
  edge 
  of 
  this 
  formation 
  can 
  be 
  traced 
  nearly 
  

   all 
  around 
  the 
  region 
  of 
  the 
  Adirondacks, 
  except 
  between 
  Cana- 
  

   joharie 
  and 
  Carthage, 
  and 
  is 
  especially 
  well 
  seen 
  near 
  Keese- 
  

   ville 
  in 
  Clinton 
  county, 
  where 
  the 
  deep 
  chasm 
  of 
  the 
  Ausable 
  

   river 
  is 
  cut 
  through 
  it, 
  showing 
  333 
  ft. 
  of 
  horizontal 
  strata, 
  at 
  

   Chateaugay 
  chasm, 
  where 
  the 
  section 
  exposes 
  a 
  thickness 
  of 
  

   250 
  ft., 
  and 
  at 
  Potsdam, 
  St 
  Lawrence 
  county, 
  from 
  which 
  place 
  

   it 
  received 
  its 
  name, 
  and 
  where, 
  in 
  the 
  valley 
  of 
  the 
  Raquette 
  

   river 
  a 
  thickness 
  of 
  70 
  ft. 
  is 
  shown. 
  

  

  