﻿Report 
  of 
  the 
  State 
  Geologist. 
  611 
  

  

  although 
  an 
  increased 
  amount 
  of 
  arenaceous 
  material 
  is 
  usually 
  

   apparent 
  for 
  the 
  first 
  few 
  inches 
  above 
  the 
  crystalline 
  rocks. 
  

   Walcott 
  refers 
  to 
  the 
  discovery 
  by 
  Professors 
  Shaler 
  and 
  Williams 
  

   of 
  a 
  thin 
  layer 
  of 
  shale 
  containing 
  a 
  Potsdam 
  fossil, 
  Lingulepis 
  

   acuminata, 
  at 
  this 
  locality. 
  The 
  layer 
  is 
  said 
  to 
  lie 
  on 
  a 
  basal 
  bed 
  

   of 
  sandstone, 
  on 
  the 
  north 
  side 
  of 
  the 
  Mohawk. 
  Walcott, 
  in 
  

   commenting 
  on 
  the 
  value 
  of 
  this 
  evidence, 
  states, 
  "as 
  this 
  

   species 
  ranges 
  up 
  into 
  the 
  Calcif 
  erous 
  at 
  Whitehall, 
  New 
  York, 
  

   and 
  on 
  the 
  north 
  side 
  of 
  the 
  Adirondacks 
  it 
  is 
  doubtful 
  if 
  we 
  can 
  

   claim 
  the 
  presence 
  of 
  the 
  Potsdam 
  at 
  any 
  point 
  in 
  the 
  Mohawk 
  

   valley." 
  

  

  Along 
  the 
  southern 
  edge 
  of 
  the 
  crystalline 
  area 
  north 
  of 
  Little 
  

   Falls 
  there 
  is 
  heavy 
  drift 
  cover 
  and 
  I 
  found 
  but 
  one 
  exposure 
  of 
  

   the 
  Potsdam 
  horizon. 
  It 
  is 
  a 
  locality 
  referred 
  to 
  by 
  Yanuxem. 
  * 
  

   at 
  the 
  paper 
  mill 
  on 
  Spruce 
  creek 
  a 
  short 
  distance 
  north 
  of 
  

   Diamond 
  hill. 
  Here 
  there 
  is 
  a 
  " 
  coarse 
  gray 
  rock, 
  resembling 
  

   in 
  parts, 
  at 
  first 
  sight, 
  a 
  decomposed 
  granite 
  ; 
  that 
  is, 
  a 
  granite 
  

   whose 
  mineral 
  constituents 
  had 
  been 
  separated 
  and 
  reunited 
  

   again, 
  without 
  much, 
  if 
  any, 
  change 
  of 
  place. 
  The 
  first 
  layer 
  is 
  

   about 
  six 
  inches 
  thick 
  and 
  contains 
  fragments 
  of 
  vitreous 
  quartz, 
  

   which 
  are 
  likewise 
  found 
  in 
  some 
  of 
  the 
  layers 
  " 
  of 
  Calcif 
  erous 
  

   " 
  a 
  few 
  feet 
  above." 
  

  

  From 
  this 
  locality 
  for 
  many 
  miles 
  northwestward 
  the 
  base 
  of 
  

   the 
  Calcif 
  erous 
  was 
  not 
  observed, 
  and 
  in 
  the 
  eastern 
  part 
  of 
  

   Oneida 
  county 
  the 
  Black 
  River 
  limestone 
  lies 
  upon 
  or 
  against 
  the 
  

   crystallines, 
  so 
  that 
  the 
  Potsdam 
  horizon 
  is 
  not 
  near 
  the 
  surface. 
  

  

  Calcif 
  erous 
  sandroch. 
  — 
  This 
  f 
  ormation 
  covers 
  a 
  wide 
  area 
  in 
  

   the 
  region 
  to 
  which 
  this 
  paper 
  relates. 
  It 
  is 
  brought 
  up 
  along 
  

   the 
  Mohawk 
  by 
  each 
  of 
  the 
  principal 
  faults 
  and 
  extends 
  north- 
  

   ward 
  more 
  or 
  less 
  widely 
  to 
  the 
  crystalline 
  rocks. 
  Except 
  where 
  

   covered 
  by 
  drift 
  it 
  outcrops 
  conspicuously 
  in 
  cliffs 
  along 
  the 
  

   river 
  and 
  creeks 
  and 
  has 
  more 
  or 
  less 
  bare 
  surfaces 
  over 
  the 
  inter- 
  

   mediate 
  regions. 
  Its 
  typical 
  character 
  is 
  uniform 
  throughout 
  ; 
  a 
  

   light 
  bluish-gray, 
  fine-grained, 
  massively-bedded 
  arenaceous 
  

   limestone, 
  with 
  a 
  characteristic 
  glimmering 
  surface 
  on 
  fresh 
  

   fracture. 
  On 
  exposure 
  it 
  becomes 
  lighter, 
  usually 
  of 
  a 
  dirty 
  buff 
  

   tint. 
  There 
  are 
  certain 
  beds 
  presenting 
  more 
  or 
  less 
  persistent 
  

  

  * 
  Loc. 
  cit, 
  page 
  28. 
  

  

  