﻿yO 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  not 
  before 
  noted 
  in 
  the 
  specimen. 
  The 
  outer 
  folds 
  of 
  the 
  hydro* 
  

   spires 
  were 
  seen 
  to 
  extend 
  under 
  the 
  interbrachials 
  to 
  the 
  edges 
  of 
  

   the 
  bibrachials. 
  The 
  position 
  of 
  the 
  stem 
  was 
  shown 
  to 
  be 
  not 
  

   normal, 
  as 
  Billings 
  supposed, 
  but 
  thrust 
  up 
  into 
  the 
  coelomic 
  cavity 
  

   and 
  separating 
  the 
  basals 
  from 
  the 
  radials. 
  There 
  were 
  no 
  features 
  

   to 
  show 
  a 
  specific 
  difference 
  between 
  the 
  Canadian 
  type 
  and 
  the 
  

   more 
  perfect 
  Valcour 
  island 
  specimen, 
  but 
  the 
  type 
  served 
  to 
  corrob- 
  

   orate 
  in 
  a 
  clear 
  manner 
  much 
  of 
  the 
  detail 
  worked 
  out 
  from 
  the 
  

   latter 
  and 
  published 
  in 
  Bulletin 
  107 
  of 
  the 
  New 
  York 
  State 
  Museum. 
  

   On 
  Monday, 
  July 
  8, 
  the 
  party 
  went 
  by 
  train 
  from 
  Plattsburg 
  to 
  

   Lyon 
  Mountain, 
  and 
  spent 
  the 
  day 
  studying 
  the 
  magnetite 
  mines 
  

   under 
  the 
  guidance 
  of 
  Mr 
  Newland. 
  After 
  lunch 
  the 
  section 
  lis- 
  

   tened 
  to 
  a 
  paper 
  by 
  D. 
  H. 
  Newland 
  on 
  

  

  The 
  iron 
  ores 
  of 
  the 
  Adirondack 
  region 
  

  

  Four 
  varieties 
  of 
  iron 
  ores 
  are 
  found 
  within 
  the 
  limits 
  of 
  the 
  

   Adirondack 
  region, 
  each 
  constituting 
  a 
  more 
  or 
  less 
  independent 
  

   class 
  of 
  deposits 
  as 
  regards 
  geological 
  associations 
  and 
  mode 
  of 
  

   origin. 
  The 
  varieties 
  are 
  as 
  follows 
  : 
  ( 
  1 
  ) 
  nontitaniferous 
  magnet- 
  

   ites, 
  (2) 
  titaniferous 
  magnetities, 
  (3) 
  hematites, 
  (4) 
  limonites. 
  In 
  

   respect 
  to 
  the 
  relative 
  age 
  or 
  period 
  of 
  formation, 
  it 
  is 
  probable 
  that 
  

   the 
  magnetites 
  of 
  class 
  1 
  are 
  the 
  oldest, 
  since 
  they 
  antedate 
  the 
  

   metamorphism 
  and 
  structural 
  disturbances 
  that 
  affected 
  the 
  region 
  

   during 
  Precambric 
  times. 
  The 
  titaniferous 
  ores 
  were 
  formed 
  before 
  

   the 
  oldest 
  of 
  the 
  fossiliferous 
  rocks 
  of 
  the 
  region 
  (the 
  Potsdam 
  

   sandstone) 
  was 
  deposited, 
  and 
  are 
  generally 
  regarded 
  to 
  be 
  con- 
  

   temporaneous 
  with 
  the 
  igneous 
  inclusions 
  in 
  which 
  they 
  occur. 
  The 
  

   hematite 
  ores 
  are 
  probably 
  later 
  than 
  the 
  Potsdam; 
  while 
  the 
  limo- 
  

   nites 
  have 
  the 
  character 
  of 
  bog 
  ores 
  and 
  are 
  relatively 
  recent 
  sur- 
  

   face 
  concentrations. 
  

  

  The 
  nontitaniferous 
  magnetites 
  are 
  the 
  most 
  widespread 
  of 
  all 
  

   the 
  ores 
  in 
  their 
  geographical 
  distribution, 
  and 
  have 
  been 
  in 
  the 
  

   past 
  and 
  still 
  are 
  the 
  main 
  source 
  of 
  supply 
  for 
  the 
  region. 
  In 
  a 
  

   strict 
  sense 
  they 
  are 
  hardly 
  deserving 
  of 
  the 
  name 
  that 
  has 
  been 
  

   applied 
  to 
  them 
  by 
  geologists, 
  since 
  they 
  nearly 
  always 
  carry 
  titan- 
  

   ium, 
  though 
  the 
  amount 
  is 
  small, 
  usually 
  but 
  a 
  fraction 
  of 
  one 
  per 
  

   cent. 
  These 
  ores 
  are 
  found 
  in 
  all 
  parts 
  of 
  the 
  Adirondacks, 
  except 
  

   the 
  central 
  which 
  is 
  occupied 
  by 
  the 
  great 
  gabbro-anorthosite 
  mass. 
  

   They 
  are 
  associated 
  with 
  different 
  members 
  of 
  the 
  Precambric 
  crys- 
  

   talline 
  series 
  including 
  gneisses 
  of 
  igneous 
  derivation 
  with 
  the 
  

   mineralogy 
  of 
  granites 
  and 
  syenites, 
  with 
  gneisses 
  of 
  doubtful 
  re- 
  

  

  