﻿108 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  tures 
  of 
  the 
  topography 
  about 
  Lyon 
  Mountain 
  and 
  the 
  distribution 
  

   of 
  the 
  magnetite 
  deposits. 
  The 
  deposits 
  indicated 
  by 
  the 
  numbers 
  

   on 
  the 
  map 
  are 
  as 
  follows: 
  i, 
  Stan 
  dish 
  or 
  81 
  mine; 
  2, 
  Phillips 
  vein; 
  

   3, 
  Main 
  group; 
  4, 
  Parkhurst. 
  

  

  General 
  geology 
  

  

  The 
  several 
  prominences, 
  which 
  include 
  Lyon 
  mountain 
  in 
  the 
  

   middle, 
  Averill 
  peak 
  and 
  Morton's 
  peak 
  on 
  the 
  western 
  flank 
  and 
  

   the 
  Dannemora 
  mountain 
  on 
  the 
  east, 
  constitute 
  the 
  main 
  axis 
  of 
  

   elevation 
  in 
  this 
  section 
  of 
  the 
  Adirondacks. 
  Towards 
  the 
  east 
  the 
  

   ridge 
  is 
  succeeded 
  by 
  the 
  narrow 
  abruptly 
  sloping 
  plain 
  of 
  Lake 
  

   Champlain, 
  while 
  on 
  the 
  north 
  the 
  elevations 
  gradually 
  die 
  out 
  

   beneath 
  the 
  broad 
  plain 
  of 
  the 
  St 
  Lawrence. 
  Lyon 
  mountain, 
  the 
  

   culminating 
  point, 
  rises 
  to 
  an 
  altitude 
  of 
  3,800 
  feet, 
  and 
  is 
  the 
  most 
  

   conspicuous 
  landmark 
  in 
  the 
  northern 
  Adirondacks. 
  The 
  ridge 
  is 
  

   separated 
  from 
  the 
  parallel 
  one 
  to 
  the 
  north, 
  known 
  as 
  Ellenburgh 
  

   mountain, 
  by 
  a 
  valley 
  5 
  or 
  6 
  miles 
  wide, 
  the 
  floor 
  of 
  which 
  lies 
  at 
  

   an 
  elevation 
  ranging 
  from 
  1500 
  to 
  1700 
  feet. 
  On 
  the 
  west 
  the 
  

   valley 
  contracts 
  owing 
  to 
  a 
  line 
  of 
  spurs 
  which 
  offshoot 
  from 
  Averill 
  

   peak 
  in 
  a 
  northwesterly 
  direction. 
  Upper 
  Chateaugay 
  lake 
  which 
  

   receives 
  the 
  drainage 
  of 
  the 
  valley 
  lies 
  in 
  the 
  western 
  part 
  while 
  

   Chazy 
  lake 
  is 
  on 
  the 
  eastern 
  side 
  of 
  a 
  low 
  ridge 
  that 
  extends 
  

   northeast 
  from 
  Lyon 
  mountain. 
  

  

  The 
  higher 
  ridges 
  mentioned 
  above 
  mark 
  the 
  limits 
  of 
  the 
  gneisses 
  

   and 
  associated 
  crystalline 
  rocks 
  in 
  the 
  northeastern 
  Adirondacks. 
  

   As 
  they 
  fade 
  out 
  into 
  the 
  bordering 
  plains, 
  the 
  crystallines 
  are 
  suc- 
  

   ceeded 
  unconformably 
  by 
  Paleozoic 
  sediments 
  which 
  extend 
  over 
  

   the 
  remaining 
  area 
  as 
  far 
  as 
  the 
  shores 
  of 
  Lake 
  Champlain 
  and 
  the 
  

   St 
  Lawrence 
  river. 
  The 
  present 
  line 
  of 
  contact 
  between 
  the 
  two 
  

   series 
  is 
  well 
  up 
  on 
  the 
  outer 
  slopes 
  of 
  the 
  ridges 
  but 
  follows 
  the 
  

   main 
  valleys 
  for 
  considerable 
  distances 
  into 
  the 
  interior. 
  

  

  Paleozoic 
  rocks. 
  Within 
  the 
  area 
  under 
  discussion 
  the 
  Paleozoic 
  

   strata 
  are 
  of 
  little 
  areal 
  importance. 
  A 
  narrow 
  belt 
  of 
  Potsdam 
  

   sandstone 
  occupies 
  the 
  lower 
  part 
  of 
  the 
  depression 
  between 
  Ellen- 
  

   burgh 
  and 
  Dannemora 
  mountains 
  extending 
  as 
  far 
  as 
  Chazy 
  lake 
  

   and 
  to 
  an 
  elevation 
  of 
  about 
  1500 
  feet. 
  Another 
  Potsdam 
  area 
  

   occurs 
  on 
  the 
  northeastern 
  border 
  of 
  Dannemora 
  township 
  where 
  

   it 
  is 
  found 
  as 
  high 
  as 
  1700 
  feet. 
  According 
  to 
  H. 
  P. 
  Cushing, 
  1 
  who 
  

   has 
  mapped 
  the 
  areas, 
  the 
  rock 
  is 
  a 
  reddish 
  arkose 
  quite 
  different 
  

   from 
  the 
  coarse 
  phase 
  usually 
  occurring 
  at 
  the 
  base 
  of 
  the 
  formation. 
  

  

  1 
  Geology 
  of 
  Clinton 
  County. 
  N. 
  Y. 
  State 
  Mus. 
  49th 
  An. 
  Rep't. 
  1898. 
  

   2:537. 
  Also 
  Geology 
  of 
  Rand 
  Hill, 
  53d 
  Mus. 
  Rep't. 
  1901. 
  1:63. 
  

  

  