﻿GEOLOGY 
  OF 
  WASHINGTON, 
  WARREN 
  COUNTIES, 
  ETC. 
  549 
  

  

  show 
  signs 
  of 
  having 
  been 
  subjected 
  to 
  pressure 
  but 
  they 
  exhibit 
  

   no 
  optical 
  anomalies. 
  

  

  The 
  wall 
  rock 
  of 
  the 
  garnetiferous 
  bed 
  is 
  a 
  gray 
  or 
  greenish 
  

   gneissoid 
  variety 
  that 
  consists 
  of 
  quartz, 
  microperthite, 
  plagio- 
  

   clase, 
  rarer 
  orthoclase, 
  orthorhombic 
  pyroxene, 
  augite, 
  zircon 
  

   and 
  pyrrhotite. 
  The 
  foliation 
  and 
  the 
  garnet 
  bed 
  dip 
  

   sharply 
  to 
  the 
  south. 
  A 
  little 
  over 
  a 
  mile 
  to 
  the 
  north 
  and 
  on 
  the 
  

   other 
  side 
  of 
  the 
  Blue 
  Mountain 
  highway 
  is 
  found 
  a 
  second 
  gar- 
  

   net 
  bed 
  high 
  up 
  in 
  a 
  steep 
  escarpment 
  north 
  of 
  the 
  road. 
  It 
  dips 
  

   to 
  the 
  northeast. 
  Between 
  the 
  two 
  lies 
  a 
  valley 
  with 
  limestone, 
  

   apparently 
  forming 
  the 
  eroded 
  core 
  of 
  an 
  anticline. 
  There 
  is 
  rea- 
  

   son 
  to 
  think 
  that 
  the 
  two 
  outcroppings 
  of 
  garnet 
  rock 
  belong 
  to 
  

   the 
  same 
  bed. 
  

  

  The 
  garnet 
  rock 
  is 
  mined 
  at 
  the 
  southern 
  exposure, 
  crushed, 
  

   washed 
  and 
  shipped 
  in 
  considerable 
  amount 
  each 
  year, 
  as 
  the 
  

   mineral 
  is 
  a 
  highly 
  prized 
  abrasive. 
  The 
  origin 
  of 
  this 
  peculiar 
  

   bed 
  presents 
  an 
  interesting 
  theme. 
  The 
  country 
  rock 
  is 
  probably 
  

   igneous. 
  Its 
  mineralogy 
  and 
  structure 
  favor 
  this 
  derivation. 
  

   The 
  garnet 
  rock 
  must 
  be 
  either 
  an 
  altered 
  form 
  of 
  a 
  very 
  impure 
  

   limestone, 
  or 
  else 
  a 
  very 
  basic 
  igneous 
  rock, 
  that 
  was 
  an 
  original 
  

   sheet 
  or 
  dike. 
  The 
  former 
  supposition 
  appeals 
  more 
  strongly 
  to 
  

   us. 
  

  

  Just 
  to 
  the 
  south 
  and 
  east 
  of 
  the 
  garnet 
  mine 
  and 
  between 
  it 
  

   and 
  North 
  River, 
  great 
  quantities 
  of 
  huge 
  boulders 
  of 
  Potsdam 
  

   sandstone 
  were 
  noted 
  in 
  the 
  fields. 
  Fragments 
  as 
  much 
  as 
  30 
  feet 
  

   by 
  15 
  feet 
  were 
  found 
  in 
  so 
  fresh 
  and 
  unweathered 
  a 
  condition 
  

   that 
  it 
  was 
  difficult 
  to 
  believe 
  that 
  they 
  were 
  not 
  in 
  place. 
  It 
  

   would 
  seem 
  as 
  if 
  there 
  must 
  have 
  been 
  in 
  this 
  valley 
  an 
  outlier 
  of 
  

   the 
  Potsdam, 
  similar 
  to 
  the 
  others 
  discovered 
  elsewhere 
  in 
  the 
  

   mountains, 
  and 
  that 
  it 
  has 
  been 
  but 
  slightly 
  broken 
  up 
  by 
  the 
  ice. 
  

   No 
  assured 
  examples 
  of 
  the 
  rock 
  in 
  place 
  were, 
  however, 
  found. 
  

   The 
  boulders 
  are 
  on 
  the 
  north 
  side 
  of 
  Thirteenth 
  brook 
  and 
  

   mostly 
  in 
  Warren 
  co. 
  a 
  

  

  Across 
  the 
  Hudson 
  from 
  North 
  River 
  an 
  interesting 
  section 
  

   is 
  afforded 
  of 
  pyroxenic 
  limestone 
  next 
  the 
  river, 
  striking 
  N30 
  

  

  a 
  The 
  Potsdam 
  was 
  found 
  In 
  place 
  in 
  1890 
  by 
  B. 
  F. 
  Hill. 
  

  

  