﻿604 
  Forty-seventh 
  Report 
  on 
  the 
  State 
  Museum. 
  

  

  regard 
  to 
  distribution 
  and 
  the 
  features 
  of 
  notable 
  outcrops 
  which 
  

   have 
  not 
  before 
  been 
  as 
  fully 
  described. 
  

  

  Potsdam 
  sandstone. 
  — 
  This 
  formation 
  is 
  prominent 
  to 
  the 
  north 
  

   and 
  east 
  but 
  is 
  not 
  represented 
  on 
  the 
  Mohawk. 
  Vanuxem 
  has 
  

   expressed 
  the 
  opinion 
  that 
  it 
  merges 
  into 
  the 
  Calcif 
  erous 
  to 
  the 
  

   south 
  westward 
  and 
  I 
  believe 
  this 
  to 
  be 
  the 
  case. 
  The 
  lateral 
  

   merging 
  of 
  arenaceous 
  into 
  calcareous 
  deposits 
  is 
  quite 
  clearly 
  

   exhibited 
  in 
  several 
  districts, 
  and 
  the 
  vertical 
  gradation 
  is 
  nearly 
  

   everywhere 
  apparent. 
  

  

  The 
  Potsdam 
  formation, 
  in 
  the 
  region 
  to 
  which 
  the 
  paper 
  

   relates, 
  is 
  somewhat 
  variable 
  in 
  character. 
  In 
  larger 
  part 
  it 
  is 
  a 
  

   moderately 
  hard, 
  regularly-bedded, 
  light-colored, 
  fine-grained 
  

   sandstone. 
  In 
  places 
  it 
  is 
  quartzitic, 
  particularly 
  near 
  its 
  base, 
  

   or 
  where 
  its 
  thickness 
  is 
  slight. 
  Locally 
  its 
  basal 
  member 
  is 
  a 
  

   coarse 
  conglomerate 
  of 
  quartz 
  and 
  crystalline 
  rock 
  fragments, 
  

   but 
  generally 
  its 
  lower 
  member 
  is 
  a 
  dark 
  quartzite. 
  In 
  its 
  upper 
  

   portion 
  it 
  becomes 
  calcareous 
  and 
  merges 
  through 
  a 
  soft 
  calcare- 
  

   ous 
  sandstone 
  into 
  the 
  arenaceous 
  limestone 
  of 
  the 
  Calciferous. 
  

  

  In 
  Saratoga 
  county 
  it 
  is 
  conspicuous 
  west 
  of 
  Saratoga 
  Springs 
  

   and 
  through 
  Greenfield 
  township 
  to 
  Corinth, 
  or 
  Jessup's 
  Landing 
  ; 
  

   at 
  East 
  Gal 
  way, 
  West 
  and 
  North 
  Galway, 
  and 
  thence 
  at 
  intervals 
  

   to 
  and 
  through 
  Northampton 
  township 
  into 
  eastern 
  Mayfield. 
  

   It 
  outcrops 
  again 
  in 
  considerable 
  amount 
  on 
  the 
  uplifted 
  block 
  

   west 
  of 
  Johnstown. 
  In 
  the 
  western 
  part 
  of 
  Fulton 
  county 
  the 
  

   formation 
  probably 
  is 
  present, 
  but 
  the 
  drift 
  cover 
  is 
  wide 
  and 
  

   heavy 
  in 
  this 
  region 
  and 
  I 
  was 
  unable 
  to 
  discover 
  outcrops. 
  The 
  

   last 
  exposure 
  that 
  I 
  find 
  to 
  the 
  westward 
  was 
  on 
  Spruce 
  creek, 
  

   just 
  north 
  of 
  Diamond 
  hill. 
  To 
  the 
  eastward 
  it 
  is 
  supposed 
  that 
  

   Potsdam 
  underlies 
  the 
  Calciferous 
  extending 
  north 
  from 
  Saratoga 
  

   Springs 
  to 
  Lake 
  George, 
  but 
  it 
  is 
  thrust 
  down 
  against 
  the 
  fault 
  

   along 
  which 
  the 
  crystalline 
  rocks 
  rise 
  so 
  prominently 
  between 
  

   these 
  two 
  points. 
  

  

  Exposures 
  at 
  Jessup's 
  Landing. 
  — 
  In 
  the 
  south 
  bank 
  of 
  the 
  Hud- 
  

   son 
  in 
  the 
  vicinity 
  of 
  Corinth 
  or 
  Jessup's 
  Landing 
  there 
  are 
  the 
  

   finest 
  exposures 
  of 
  Potsdam 
  in 
  this 
  region. 
  They 
  extend 
  to 
  the 
  

   falls 
  about 
  half 
  a 
  mile 
  below 
  the 
  landing, 
  in 
  bluffs 
  averaging 
  

   forty 
  feet 
  in 
  height. 
  In 
  plate 
  1 
  a 
  portion 
  of 
  this 
  exposure 
  is 
  

   represented. 
  

  

  