﻿14 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  able 
  character 
  that 
  their 
  relations 
  can 
  not 
  be 
  stated 
  definitely. 
  

   In 
  St 
  Lawrence 
  county 
  the 
  sedimentary 
  gneisses 
  are 
  widespread 
  

   in 
  the 
  vicinity 
  of 
  the 
  limestone 
  belts 
  above 
  mentioned. 
  They 
  have 
  

   also 
  been 
  traced 
  by 
  the 
  writer 
  to 
  the 
  east 
  toward 
  the 
  interior 
  as 
  

   far 
  as 
  Cranberry 
  lake. 
  They 
  are 
  the 
  country 
  rock 
  of 
  the 
  magnetite 
  

   deposits 
  in 
  this 
  section. 
  Professor 
  Kemp 
  has 
  described 
  gneisses 
  

   of 
  sedimentary 
  type 
  in 
  southern 
  Essex, 
  Warren 
  and 
  Washington 
  

   counties. 
  As 
  to 
  the 
  southern 
  border 
  of 
  the 
  Adirondack 
  region, 
  

   little 
  has 
  been 
  made 
  known 
  but 
  it 
  is 
  probable 
  that 
  the 
  sedimentary 
  

   gneisses 
  are 
  well 
  represented. 
  

  

  Amphibolite. 
  Involved 
  with 
  the 
  limestones 
  and 
  gneisses, 
  and 
  

   less 
  frequently 
  with 
  the 
  plutonic 
  igneous 
  rocks, 
  are 
  small 
  masses 
  

   of 
  amphibolite, 
  dark 
  colored 
  and 
  consisting 
  essentially 
  of 
  horn 
  

   blende 
  and 
  feldspar. 
  They 
  often 
  have 
  a 
  rusty 
  appearance 
  that 
  

   betrays 
  the 
  presence 
  of 
  pyrite. 
  Their 
  occurrence 
  in 
  tabular 
  bands; 
  

   which 
  may 
  be 
  persistent 
  for 
  considerable 
  distances, 
  is 
  suggestive 
  

   of 
  dikes 
  and 
  it 
  is 
  quite 
  likely 
  that 
  they 
  are 
  in 
  part 
  metamorphosed 
  

   diabases 
  or 
  gabbros. 
  This 
  view 
  is 
  particularly 
  applicable 
  to 
  

   examples 
  that 
  have 
  a 
  plagioclase 
  as 
  the 
  principal 
  feldspar 
  constitu- 
  

   ent, 
  but 
  can 
  hardly 
  be 
  accepted 
  for 
  occurrences 
  in 
  which 
  the 
  horn- 
  

   blende 
  is 
  associated 
  with 
  orthoclase, 
  as 
  is 
  not 
  infrequently 
  the 
  

   case. 
  For 
  these 
  the 
  derivation 
  from 
  a 
  magnesian 
  shale 
  seems 
  to 
  

   be 
  the 
  more 
  obvious 
  explanation. 
  

  

  Quartzite. 
  As 
  a 
  somewhat 
  uncommon 
  type 
  of 
  the 
  Precambric 
  

   sediments, 
  may 
  be 
  mentioned 
  the 
  occurrence 
  of 
  quartzite 
  which 
  

   has 
  been 
  made 
  known 
  on 
  both 
  the 
  eastern 
  and 
  western 
  borders 
  of 
  

   the 
  Adirondacks. 
  

  

  In 
  Essex 
  county, 
  Professor 
  Kemp 
  has 
  noted 
  several 
  localities 
  

   where 
  this 
  undoubted 
  fragmental 
  rock 
  occurs. 
  It 
  nearly 
  always 
  

   carries 
  graphite, 
  pyrite 
  and 
  sillimanite 
  and 
  sometimes 
  feldspar 
  

   and 
  mica. 
  At 
  Hague 
  on 
  Lake 
  George 
  and 
  at 
  the 
  village 
  of 
  Graph- 
  

   ite, 
  5 
  miles 
  west 
  from 
  Hague, 
  a 
  bed 
  up 
  to 
  15 
  feet 
  thick 
  is 
  included 
  

   between 
  a 
  garnetiferous 
  sillimanite 
  gneiss. 
  At 
  Rock 
  pond 
  between 
  

   Graphite 
  and 
  Hammond 
  ville, 
  - 
  there 
  is 
  another 
  area; 
  while 
  in 
  the 
  

   town 
  of 
  Lewis, 
  3 
  miles 
  south 
  of 
  Elizabethtown, 
  exposures 
  show 
  a 
  

   thickness 
  of 
  100 
  feet 
  of 
  quartzite 
  overlain 
  by 
  graphitic 
  gneiss. 
  

  

  Professor 
  Smyth 
  has 
  found 
  the 
  same 
  rock 
  in 
  St 
  Lawrence 
  county. 
  

   On 
  Wells 
  island 
  in 
  the 
  St 
  Lawrence 
  river 
  a 
  white 
  vitreous 
  quartzite 
  

   is 
  exposed 
  along 
  a 
  ridge 
  for 
  nearly 
  5 
  miles 
  with 
  an 
  estimated 
  thick- 
  

   ness 
  of 
  500 
  feet. 
  It 
  is 
  associated 
  with 
  schist 
  and 
  both 
  are 
  cut 
  out 
  

   by 
  granite 
  gneiss 
  which 
  forms 
  the 
  southern 
  part 
  of 
  the 
  island. 
  

   A 
  second 
  belt 
  occurs 
  between 
  Redwood 
  and 
  Rossie, 
  the 
  quartzite 
  

  

  