﻿692 
  Forty-seventh 
  Report 
  on 
  the 
  State 
  Museum. 
  

  

  might 
  well 
  result 
  from 
  folding 
  with 
  intense 
  metamorphism, 
  which 
  

   would 
  produce 
  parallelism 
  in 
  structure 
  and 
  give 
  a 
  transitional 
  

   character 
  to 
  the 
  rocks 
  along 
  the 
  contact 
  of 
  the 
  two 
  formations. 
  

   Instances 
  of 
  such 
  action 
  are 
  well 
  known 
  in 
  the 
  Appalachian 
  

   region 
  and 
  elsewhere. 
  Furthermore, 
  the 
  granitic 
  t 
  and 
  augen- 
  

   gneisses 
  differ 
  so 
  greatly 
  from 
  the 
  laminated 
  varieties 
  associated 
  

   with 
  the 
  limestone 
  that 
  they 
  suggest 
  an 
  entirely 
  different 
  origin, 
  

   and, 
  while 
  some 
  of 
  them 
  may 
  be 
  accounted 
  for 
  as 
  later 
  intrusions 
  

   in 
  the 
  surrounding 
  rock, 
  this 
  explanation 
  must 
  be 
  employed 
  with 
  

   caution, 
  as 
  the 
  establishment 
  of 
  the 
  intrusive 
  character 
  is 
  often 
  

   difficult 
  or 
  even 
  impossible. 
  Still, 
  if 
  the 
  explanation 
  of 
  structure 
  

   given 
  above 
  be 
  correct, 
  these 
  massive 
  gneisses 
  represent 
  the 
  lowest 
  

   rocks 
  of 
  the 
  series, 
  and 
  their 
  character 
  might 
  have 
  been 
  influ- 
  

   enced 
  by 
  the 
  depth 
  to 
  which 
  they 
  were 
  buried 
  and 
  by 
  the 
  intru- 
  

   sion 
  of 
  much 
  igneous 
  material. 
  

  

  Thus, 
  the 
  base 
  of 
  this 
  Oswegatchie 
  series 
  is 
  as 
  yet 
  undetermined, 
  

   and 
  its 
  position* 
  is 
  one 
  of 
  the 
  important 
  problems 
  to 
  be 
  solved. 
  

   With 
  the 
  evidence 
  at 
  hand 
  a 
  final 
  decision 
  of 
  these 
  points 
  is 
  out 
  

   of 
  the 
  question. 
  

  

  The 
  general 
  similarity 
  of 
  the 
  Oswegatchie 
  series 
  to 
  the 
  Gren- 
  

   ville 
  series 
  of 
  Canada 
  is 
  very 
  marked, 
  suggesting, 
  as 
  observed 
  by 
  

   Yan 
  Hise,* 
  a 
  possible 
  equivalency. 
  The 
  same 
  difficulty 
  exists 
  in 
  

   both 
  series, 
  in 
  determining 
  their 
  lower 
  limits 
  and 
  their 
  relation 
  

   to 
  the 
  underlying 
  rocks. 
  For 
  the 
  Oswegatchie 
  series, 
  it 
  is 
  hoped 
  

   that 
  the 
  problem 
  may 
  be 
  solved 
  by 
  extending 
  the 
  mapping 
  o*rer 
  

   a 
  larger 
  area 
  and 
  with 
  greater 
  detail 
  ; 
  by 
  accumulating 
  data 
  for 
  

   the 
  construction 
  of 
  sections 
  across 
  the 
  series 
  ; 
  and 
  by 
  ascertaining 
  

   the 
  true 
  nature 
  and 
  origin 
  of 
  rocks 
  whose 
  affinities 
  are 
  at 
  present 
  

   doubtful. 
  Nothing 
  can 
  so 
  greatly 
  aid 
  the 
  prosecution 
  of 
  this 
  

   work 
  as 
  good 
  topographical 
  maps, 
  and 
  the 
  sooner 
  these 
  are 
  avail- 
  

   able 
  the 
  sooner 
  the 
  task 
  will 
  be 
  accomplished. 
  

  

  ECONOMIC 
  GEOLOGY. 
  

   Iron 
  Ore. 
  

  

  This 
  portion 
  of 
  the 
  State 
  has 
  long 
  been 
  known 
  as 
  a 
  source 
  of 
  

   iron 
  ore, 
  the 
  Eossie 
  and 
  Antwerp 
  red 
  hematites 
  having 
  been 
  

   mined 
  for 
  many 
  years 
  in 
  some 
  quantity. 
  In 
  earlier 
  days 
  these 
  

   ores 
  were 
  smelted 
  on 
  the 
  ground 
  in 
  charcoal 
  furnaces, 
  but 
  later 
  

  

  *0. 
  R. 
  Van 
  Hise, 
  Bull. 
  86, 
  U. 
  S. 
  G. 
  S., 
  p. 
  508. 
  

  

  