﻿I30 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  we 
  owe 
  most 
  of 
  our 
  knowledge 
  concerning 
  the 
  subject. 
  1 
  Professor 
  

   Smyth 
  has 
  worked 
  mainly 
  in 
  the 
  outlying 
  sections, 
  including 
  cen- 
  

   tral 
  and 
  western 
  St 
  Lawrence 
  county 
  and 
  eastern 
  Lewis 
  and 
  

   Jefferson 
  counties, 
  but 
  the 
  salient 
  facts 
  of 
  structure 
  and 
  strati- 
  

   graphy 
  he 
  has 
  brought 
  to 
  light 
  apply 
  as 
  well 
  to 
  the 
  region 
  under 
  

   discussion. 
  

  

  The 
  rocks 
  which 
  have 
  widespread 
  development 
  comprise 
  crystal- 
  

   line 
  limestones, 
  schists, 
  gneisses 
  and 
  a 
  series 
  of 
  intrusives 
  ranging 
  

   from 
  granite 
  to 
  basic 
  varieties 
  represented 
  by 
  the 
  gabbros. 
  They 
  

   are 
  lithologically 
  analogous 
  to 
  the 
  prevailing 
  rock 
  types 
  that 
  are 
  

   described 
  in 
  connection 
  with 
  the 
  mining 
  districts 
  of 
  Clinton 
  and 
  

   Essex 
  counties 
  and 
  in 
  some 
  cases 
  no 
  doubt 
  can 
  be 
  correlated 
  as 
  

   parts 
  of 
  the 
  same 
  geologic 
  formations, 
  though 
  it 
  is 
  not 
  to 
  be 
  inferred 
  

   that 
  they 
  are 
  strictly 
  equivalent 
  as 
  to 
  time. 
  All 
  are 
  older 
  than 
  

   the 
  most 
  ancient 
  of 
  the 
  fossiliferous 
  strata 
  in 
  the 
  region, 
  the 
  Pots- 
  

   dam 
  sandstone, 
  and 
  underlie 
  the 
  latter 
  unconformably. 
  

  

  The 
  Grenville 
  limestones 
  and 
  their 
  associated 
  schists 
  (called 
  

   the 
  Oswegatchie 
  series 
  by 
  Professor 
  Smyth) 
  are 
  relatively 
  less 
  

   important 
  in 
  the 
  interior 
  than 
  in 
  the 
  western 
  part 
  of 
  St 
  Lawrence 
  

   county. 
  A 
  belt 
  of 
  these 
  rocks 
  traverses 
  the 
  town 
  of 
  Pitcairn 
  and 
  

   extends 
  across 
  the 
  line 
  into 
  Jefferson 
  county, 
  with 
  a 
  length 
  of 
  15 
  

   miles 
  from 
  northeast 
  to 
  southwest. 
  There 
  are 
  good 
  exposures 
  of 
  

   the 
  limestone 
  at 
  Harrisville 
  and 
  on 
  the 
  east 
  side 
  of 
  Bonaparte 
  

   lake, 
  in 
  the 
  middle 
  portion 
  of 
  the 
  belt. 
  This 
  is 
  the 
  most 
  easterly 
  

   of 
  the 
  larger 
  areas, 
  as 
  elsewhere 
  in 
  the 
  interior 
  the 
  rocks 
  occur 
  in 
  

   isolated 
  patches 
  of 
  no 
  great 
  size. 
  The 
  limestone 
  is 
  always 
  thor- 
  

   oughly 
  crystalline; 
  the 
  schists 
  belong 
  to 
  the 
  hornblendic, 
  micaceous, 
  

   pyroxenic 
  or 
  quartzose 
  types 
  so 
  characteristic 
  of 
  the 
  Grenville 
  

   series 
  throughout 
  the 
  Adirondacks. 
  

  

  Among 
  the 
  gneisses 
  which 
  occupy 
  most 
  of 
  the 
  area 
  in 
  the 
  vicinity 
  

   of 
  the 
  mines, 
  there 
  is 
  great 
  variety. 
  Some 
  are 
  closely 
  related 
  to 
  the 
  

   igneous 
  rocks 
  and 
  have 
  been 
  demonstrated 
  to 
  be 
  in 
  part 
  simply 
  

   gneissoid 
  phases 
  of 
  the 
  latter. 
  On 
  the 
  south 
  side 
  of 
  the 
  limestone 
  

   belt 
  referred 
  to 
  above, 
  syenitic 
  gneiss 
  grading 
  into 
  massive 
  syenite 
  

   is 
  exposed 
  in 
  force 
  underlying 
  an 
  area 
  estimated 
  at 
  75 
  square 
  miles. 
  

   It 
  is 
  clearly 
  igneous 
  and 
  later 
  than 
  the 
  limestone. 
  In 
  association 
  

   with 
  it 
  occurs 
  a 
  more 
  acid 
  hornblende 
  gneiss 
  which 
  seems 
  to 
  belong 
  

   to 
  the 
  same 
  intrusive 
  mass, 
  since 
  there 
  is 
  a 
  gradual 
  transition 
  

   across 
  the 
  contact. 
  On 
  the 
  north 
  side 
  of 
  the 
  limestone 
  belt, 
  

  

  x 
  For 
  the 
  results 
  of 
  Professor 
  Smyth's 
  work, 
  consult 
  the 
  annual 
  reports 
  of 
  

   the 
  New 
  York 
  State 
  Museum 
  for 
  1893, 
  1895, 
  1897, 
  1898 
  and 
  1899. 
  

  

  