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  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  the 
  northwestern 
  and 
  southeastern 
  Adirondacks, 
  there 
  are 
  extensive 
  

   beds 
  of 
  crystalline 
  limestone, 
  such 
  as 
  the 
  Gouverneur 
  marble 
  of 
  St 
  

   Lawrence 
  county. 
  Such 
  rocks 
  could 
  not 
  have 
  been 
  of 
  igneous 
  

   origin. 
  In 
  many 
  places, 
  and 
  sometimes 
  in 
  sharp 
  contact 
  with 
  the 
  

   limestone, 
  are 
  beds 
  of 
  almost 
  pure 
  quartz 
  rock, 
  which 
  are 
  certainly 
  

   not 
  igneous 
  but 
  which 
  represent 
  original 
  sandstone 
  layers. 
  Again, 
  

   there 
  are 
  very 
  extensive 
  deposits 
  throughout 
  the 
  Adirondacks 
  of 
  

   generally 
  darker 
  colored 
  rocks 
  rich 
  in 
  such 
  minerals 
  as 
  quartz, 
  feld- 
  

   spar, 
  garnet, 
  mica, 
  pyroxene, 
  and 
  amphibole. 
  These 
  rocks, 
  because 
  

   of 
  their 
  constant 
  close 
  association 
  with 
  the 
  strata 
  just 
  described 
  as 
  

   well 
  as 
  their 
  banded 
  structure, 
  are 
  also 
  clearly 
  ancient 
  sediments. 
  

   The 
  composition 
  of 
  these 
  latter 
  rocks 
  shows 
  that 
  the 
  original 
  sedi- 
  

   ments 
  were 
  muds, 
  often 
  with 
  sand 
  or 
  lime. 
  Another 
  argument 
  in 
  

   support 
  of 
  the 
  sedimentary 
  character 
  of 
  the 
  Grenville 
  is 
  the 
  presence 
  

   of 
  flakes 
  of 
  graphite 
  (plumbago) 
  which 
  are 
  so 
  commonly 
  dis- 
  

   seminated 
  throughout 
  the 
  formation. 
  In 
  some 
  places 
  the 
  strata 
  are 
  

   so 
  filled 
  with 
  graphite 
  that 
  the 
  mineral 
  is 
  mined, 
  as 
  in 
  Essex 
  and 
  

   Saratoga 
  counties. 
  Carbon 
  existing 
  under 
  such 
  conditions 
  is 
  prob- 
  

   ably 
  of 
  organic 
  origin 
  and 
  represents 
  the 
  final 
  stage 
  in 
  the 
  decom- 
  

   position 
  of 
  organisms 
  which 
  lived 
  in 
  the 
  waters 
  while 
  the 
  Grenville 
  

   strata 
  were 
  Ibeing 
  deposited. 
  The 
  occurrence 
  of 
  so 
  much 
  garnet 
  is 
  

   also 
  at 
  least 
  highly 
  suggestive 
  because 
  this 
  mineral 
  is 
  especially 
  

   common 
  in 
  crystallized 
  sediments 
  in 
  many 
  parts 
  of 
  the 
  world. 
  

  

  Having 
  established 
  the 
  sedimentary 
  origin 
  of 
  the 
  oldest 
  known 
  

   formation 
  in 
  New 
  York 
  State, 
  we 
  are 
  led 
  to 
  the 
  interesting 
  and 
  

   important 
  conclusion 
  that 
  this 
  Grenville 
  formation 
  is 
  not 
  the 
  oldest 
  

   which 
  ever 
  existed 
  in 
  the 
  State. 
  The 
  Grenville 
  sediments 
  must 
  have 
  

   been 
  deposited, 
  layer 
  upon 
  layer, 
  upon 
  a 
  surface 
  of 
  still 
  older 
  rocks. 
  

   A 
  knowledge 
  of 
  the 
  character 
  and 
  composition 
  of 
  such 
  Pregrenville 
  

   rocks 
  would 
  be 
  of 
  very 
  great 
  interest, 
  but 
  thus 
  far 
  we 
  have 
  no 
  

   positive 
  evidence 
  that 
  such 
  rocks 
  are 
  visible 
  in 
  the 
  Adirondacks, 
  

   although 
  certain 
  rocks 
  still 
  of 
  somewhat 
  doubtful 
  age 
  and 
  origin 
  

   may 
  belong 
  to 
  that 
  very 
  ancient 
  rock 
  floor. 
  Again, 
  the 
  fact 
  that 
  

   Grenville 
  sediments 
  were 
  being 
  deposited 
  under 
  water 
  carries 
  with 
  

   it 
  the 
  corollary 
  that 
  there 
  must 
  have 
  been 
  land 
  somewhere 
  at 
  no 
  

   great 
  distance 
  from 
  the 
  area 
  of 
  deposition 
  because 
  then, 
  as 
  now, 
  

   such 
  sediments 
  as 
  muds 
  and 
  sands 
  could 
  have 
  been 
  derived 
  only 
  

   from 
  the 
  erosion 
  or 
  wearing 
  away 
  of 
  land 
  and 
  have 
  been 
  deposited 
  

   in 
  great 
  sheets 
  one 
  above 
  the 
  other, 
  under 
  water 
  adjacent 
  to 
  the 
  

   land 
  mass. 
  Here, 
  too, 
  we 
  are 
  as 
  yet 
  utterly 
  in 
  the 
  dark 
  so 
  far 
  as 
  

   any 
  knowledge 
  of 
  the 
  location 
  or 
  character 
  of 
  that 
  very 
  ancient 
  land 
  

   is 
  concerned, 
  

  

  