﻿Report 
  of 
  tee 
  State 
  Geologist. 
  671 
  

  

  formations 
  with 
  great 
  accuracy. 
  In 
  Beekmantown, 
  Plattsburgh 
  

   and 
  Schuyler 
  Falls, 
  on 
  the 
  other 
  hand, 
  is 
  a 
  widespread 
  area 
  

   running 
  down 
  through 
  their 
  central 
  portions 
  in 
  which 
  all 
  under- 
  

   lying 
  rock 
  is 
  concealed 
  from 
  view 
  by 
  soil, 
  drift 
  and 
  extensive 
  

   plains 
  of 
  loose, 
  barren 
  sand, 
  through 
  which 
  the 
  roads 
  wander 
  

   at 
  random, 
  with 
  much 
  branching, 
  and 
  whose 
  flora 
  is 
  in 
  the 
  main 
  

   limited 
  to 
  huckleberries 
  and 
  stunted 
  pines, 
  just 
  as 
  is 
  the 
  case 
  on 
  

   the 
  so-called 
  Flat 
  Kocks 
  (Potsdam) 
  in 
  Alton 
  a 
  township. 
  

   This 
  extensive 
  area 
  is 
  underlaid 
  almost 
  wholly 
  by 
  Potsdam 
  and 
  

   Calciferous 
  strata 
  and 
  efficiently 
  conceals 
  their 
  contact 
  and 
  their 
  

   respective 
  extents 
  from 
  view. 
  Areas 
  of 
  such 
  character 
  and 
  

   extent 
  as 
  to 
  make 
  questionable 
  what 
  underlies 
  them 
  are 
  indicated 
  

   upon 
  the 
  map 
  as 
  such. 
  The 
  Potsdam 
  boundary 
  on 
  the 
  map 
  of 
  

   these 
  townships 
  shows 
  the 
  eastern 
  limit 
  of 
  Potsdam 
  outcrops. 
  

   The 
  formation 
  itself 
  certainly 
  extends 
  further 
  east. 
  

  

  Pre- 
  Cambrian 
  ?'ocks— 
  -Though 
  rocks 
  of 
  pre-Cambrian 
  age 
  were 
  

   approached 
  at 
  several 
  points, 
  they 
  were 
  met 
  with 
  but 
  twice. 
  In 
  

   the 
  extreme 
  southwestern 
  portion 
  of 
  Schuyler 
  Falls 
  township 
  the 
  

   edge 
  of 
  a 
  gneissic 
  ridge 
  of 
  considerable 
  dimensions 
  appears, 
  

   which 
  lies 
  mainly 
  in 
  Saranac 
  township, 
  west 
  of 
  Schuyler 
  Falls, 
  

   and 
  is 
  separated 
  from 
  a 
  like 
  gneissic 
  outcrop 
  in 
  Dannemora, 
  

   north 
  of 
  Saranac, 
  by 
  an 
  embayment 
  of 
  Potsdam 
  sandstone 
  lying 
  

   in 
  the 
  valley 
  of 
  the 
  Saranac 
  river. 
  Where 
  seen 
  in 
  Schuyler 
  

   Falls, 
  this 
  rock 
  differs 
  from 
  the 
  ordinary 
  acidic 
  gneiss 
  of 
  the 
  

   Adirondack 
  region 
  in 
  its 
  much 
  more 
  pronounced 
  red 
  color, 
  

   extremely 
  small 
  content 
  of 
  bisilicates 
  and 
  very 
  poor 
  exhibit 
  of 
  

   gneissic 
  structure. 
  

  

  In 
  northwest 
  Beekmantown 
  an 
  interesting 
  gabbro 
  (anorthosite) 
  

   outlier 
  is 
  found 
  occupying 
  an 
  area 
  about 
  three 
  miles 
  long 
  and 
  

   nearly 
  two 
  miles 
  broad, 
  the 
  northern 
  one- 
  third 
  lying 
  in 
  Altona 
  

   township. 
  On 
  the 
  east, 
  south 
  and 
  west 
  a 
  narrow 
  zone 
  of 
  gneiss 
  

   intervenes 
  between 
  it 
  and 
  the 
  Potsdam 
  ; 
  on 
  the 
  north, 
  however, 
  

   the 
  Potsdam 
  lies 
  directly 
  on 
  it. 
  With 
  the 
  exception 
  of 
  a 
  strip 
  

   two 
  miles 
  in 
  length 
  on 
  the 
  northwest, 
  the 
  outlier 
  was 
  completely 
  

   surveyed 
  and 
  found 
  to 
  be 
  entirely 
  surrounded 
  by 
  the 
  Potsdam, 
  

   so 
  that 
  it 
  is 
  practically 
  certain 
  that 
  this 
  is 
  true 
  of 
  the 
  whole, 
  

   though 
  the 
  topography 
  seems 
  to 
  indicate 
  a 
  greater 
  width 
  at 
  the 
  

   north 
  end. 
  This 
  gabbro 
  outlier 
  presents 
  many 
  interesting 
  

   foatures 
  and 
  merits 
  careful 
  study. 
  Contacts 
  between 
  gabbro 
  

  

  