﻿70 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  There 
  is 
  certainly 
  a 
  great 
  fault 
  between 
  the 
  limestone 
  and 
  the 
  

   eastern 
  edge 
  of 
  the 
  ore, 
  since 
  north 
  along 
  the 
  railway 
  the 
  limestone 
  

   gives 
  way 
  to 
  greatly 
  brecciated 
  gneisses. 
  Farther 
  north 
  again 
  

   gabbro 
  appears, 
  but 
  in 
  irregular 
  exposures 
  mingled 
  with 
  horn- 
  

   blendic 
  gneisses 
  and 
  quite 
  difficult 
  to 
  understand. 
  The 
  ore 
  itself, 
  

   however, 
  outcrops 
  as 
  a 
  marked 
  band 
  or 
  bed 
  in 
  green 
  syenitic 
  

   gneisses, 
  and 
  runs 
  to 
  the 
  north 
  for 
  nearly 
  a 
  mile, 
  with 
  occasional 
  

   pits. 
  The 
  Cheever 
  at 
  the 
  southern 
  end 
  is, 
  however, 
  the 
  chief 
  one. 
  

   These 
  workings, 
  now 
  being 
  revived 
  after 
  years 
  of 
  idleness, 
  dip 
  

   down 
  steeply, 
  at 
  50 
  or 
  6o°, 
  then 
  flatten 
  at 
  somewhat 
  over 
  200 
  feet 
  

   vertically 
  from 
  the 
  surface 
  and 
  run 
  westward 
  until 
  cut 
  off 
  by 
  a 
  

   fault. 
  Their 
  relations 
  are 
  shown 
  on 
  the 
  accompanying 
  section 
  

   [fig. 
  5] 
  reproduced 
  and 
  reduced 
  from 
  the 
  bulletin 
  of 
  the 
  New 
  

   York 
  State 
  Museum 
  14, 
  page 
  346. 
  The 
  only 
  point 
  of 
  revision 
  

   lies 
  in 
  the 
  fact 
  that 
  our 
  recent 
  fuller 
  knowledge 
  of 
  the 
  basic 
  syenite 
  

   gneisses, 
  makes 
  the 
  occurrence 
  of 
  unbroken 
  gabbro 
  on 
  the 
  east 
  

   doubtful. 
  Field 
  observations 
  the 
  past 
  summer 
  led 
  to 
  the 
  con- 
  

  

  r^r^^^^^^^^^s 
  

  

  

  * 
  * 
  ^ 
  — 
  : 
  — 
  

  

  Il|S§sllji§ 
  " 
  */'* 
  « 
  " 
  * 
  * 
  Gabbro 
  k 
  x 
  » 
  * 
  *^-- 
  

  

  St-.-t 
  -^=^^S^^y/*. 
  *««»* 
  >• 
  x 
  X 
  Xxicj, 
  >e* 
  , 
  N___ 
  

   ^^ 
  « 
  ■ 
  » 
  « 
  « 
  x 
  * 
  * 
  x 
  XX.,, 
  K^p 
  

  

  M 
  U>-JOC 
  

  

  

  Fig. 
  s 
  Cross-section 
  of 
  the 
  Cheever 
  mine 
  

  

  elusion 
  that 
  much 
  of 
  the 
  black 
  hornblendic 
  gneiss, 
  formerly 
  taken 
  

   for 
  gabbro, 
  is 
  basic 
  syenite 
  gneiss, 
  but 
  massive 
  gabbro 
  does 
  occur 
  

   mingled 
  with 
  it. 
  The 
  ore 
  is 
  a 
  band 
  in 
  the 
  syenitic 
  gneiss, 
  here 
  

   quite 
  quartzose, 
  and 
  about 
  150 
  feet 
  from 
  the 
  undoubted 
  Grenville. 
  

   Below 
  the 
  ore 
  50 
  feet 
  of 
  similar 
  gneiss 
  appears 
  before 
  the 
  basic 
  

   rocks 
  take 
  its 
  place. 
  As 
  the 
  ore 
  bed 
  is 
  followed 
  north 
  the 
  dip 
  

   appears 
  to 
  flatten 
  and 
  in 
  an 
  old 
  working 
  about 
  half 
  a 
  mile 
  from 
  

   the 
  Cheever 
  slopes, 
  the 
  strike 
  is 
  north 
  and 
  south 
  and 
  the 
  dip 
  20 
  w. 
  

   The 
  same 
  wall 
  rocks, 
  however, 
  appear. 
  

  

  Another 
  outcrop 
  of 
  ore 
  appears 
  along 
  the 
  present 
  highway 
  a 
  

   quarter 
  of 
  a 
  mile 
  north 
  of 
  the 
  old 
  Cheever 
  engine 
  house. 
  It 
  strikes 
  

   northeast 
  and 
  dips 
  southeast. 
  It 
  has 
  limestone 
  not 
  over 
  15 
  feet 
  

   above 
  it 
  and 
  while 
  thus 
  apparently 
  stratigraphically 
  higher 
  or 
  

   nearer 
  the 
  limestone 
  than 
  the 
  position 
  of 
  the 
  western 
  end 
  of 
  the 
  

   Cheever, 
  if 
  we 
  consider 
  it 
  the 
  same 
  bed, 
  it 
  suggests 
  a 
  synclinal 
  

   basin 
  for 
  the 
  ore, 
  with 
  a 
  pitch 
  of 
  the 
  fold 
  to 
  the 
  south. 
  There 
  can 
  

   be 
  no 
  doubt 
  that 
  a 
  north 
  and 
  south 
  fault 
  on 
  the 
  west 
  beneath 
  a 
  

   meadow 
  cuts 
  off 
  both 
  the 
  ore 
  and 
  the 
  Grenville 
  series 
  in 
  this 
  

   direction. 
  

  

  