﻿GEOLOGY 
  OF 
  THOUSAND 
  ISLANDS 
  REGION 
  1 
  75 
  

  

  for 
  paving 
  blocks. 
  It 
  is 
  fairly 
  evenly 
  and 
  thinly 
  bedded 
  here, 
  mostly 
  

   of 
  red 
  color, 
  well 
  indurate'd, 
  and 
  quite 
  well 
  adapted 
  to 
  the 
  pur- 
  

   pose. 
  The 
  same 
  would 
  be 
  tiaie 
  of 
  much 
  of 
  the 
  Potsdam 
  of 
  the 
  

   adjacent 
  portion 
  of 
  the 
  Alexandria 
  sheet, 
  were 
  it 
  as 
  conveniently 
  

   situated 
  as 
  regards 
  transportation. 
  

  

  Limestone 
  quarries 
  

  

  There 
  are 
  many 
  of 
  these 
  in 
  the 
  district, 
  quarrying 
  the 
  Pamelia, 
  

   Lowville 
  and 
  Black 
  River 
  limestones, 
  both 
  for 
  structural 
  purposes^ 
  

   and 
  for 
  burning 
  for 
  lime. 
  The 
  massive 
  7 
  foot 
  tier 
  of 
  the 
  Black 
  

   River 
  is 
  largely 
  quarried, 
  the 
  large 
  solid 
  blocks 
  obtainable 
  render- 
  

   ing 
  it 
  an 
  exceedingly 
  serviceable 
  material 
  for 
  heavy 
  masonry 
  con- 
  

   struction, 
  much 
  more 
  so 
  than 
  the 
  thinner 
  bedded 
  Lowville 
  and 
  

   Pamelia 
  limestones. 
  Some 
  of 
  the 
  beds 
  of 
  the 
  upper 
  Lowville 
  are 
  

   also 
  fairly 
  thick, 
  make 
  very 
  serviceable 
  stone 
  where 
  construction 
  is 
  

   less 
  massive, 
  and 
  hence 
  are 
  quarried 
  in 
  many 
  places. 
  Most 
  of 
  the 
  

   Pamelia 
  is 
  much 
  thinner 
  bedded, 
  and 
  the 
  thicker 
  beds 
  are 
  mostly 
  

   separated 
  from 
  one 
  another 
  by 
  much 
  thin 
  bedded 
  material. 
  Never- 
  

   theless 
  the 
  formation 
  contains 
  some 
  good 
  stone, 
  ' 
  and 
  there 
  are 
  

   numerous 
  quarries 
  in 
  it 
  all 
  the 
  way 
  from 
  Leraysville 
  to 
  west 
  of 
  

   Clayton, 
  which, 
  however, 
  chiefly 
  serve 
  a 
  local 
  use 
  in 
  the 
  northern 
  

   part 
  of 
  the 
  mapped 
  area. 
  It 
  is 
  not 
  so 
  largely 
  quarried 
  and 
  used 
  

   as 
  the 
  upper 
  Lowville. 
  The 
  dove 
  limestones 
  of 
  the 
  upper 
  part 
  of 
  

   the 
  formation 
  should, 
  it 
  would 
  seem, 
  make 
  an 
  excellent 
  cement 
  rock. 
  

  

  A 
  single 
  quarry 
  has 
  been 
  opened 
  in 
  the 
  impure, 
  thin 
  beds 
  of 
  the 
  

   upper 
  division, 
  a 
  few 
  miles 
  south 
  of 
  Clayton, 
  and 
  the 
  stone 
  used 
  

   for 
  flagging 
  in 
  Clayton. 
  Owing 
  to 
  the 
  joints 
  only 
  medium 
  sized 
  

   slabs 
  can 
  be 
  obtained, 
  but 
  otherwise 
  the 
  rock 
  is 
  fairly 
  smooth 
  sur- 
  

   faced 
  and 
  makes 
  a 
  very 
  respectable 
  flagstone. 
  

  

  The 
  quantity 
  of 
  limestone 
  in 
  the 
  district 
  available 
  for 
  these 
  vari- 
  

   ous 
  uses 
  is 
  enormous, 
  and 
  the 
  nearness 
  of 
  water 
  transportation 
  

   bespeaks 
  a 
  considerable 
  future 
  for 
  the 
  industry. 
  

  

  PETROGRAPHY 
  OF 
  SOME 
  PRECAMBRIC 
  ROCKSi 
  

  

  It 
  is 
  proposed 
  here 
  to 
  treat, 
  in 
  somewhat 
  more 
  detail 
  than 
  seemed 
  

   suitable 
  in 
  the 
  general 
  account, 
  of 
  certain 
  of 
  the 
  Precambric 
  rocks 
  

   with 
  discussion 
  of 
  chemical 
  analyses. 
  While 
  some 
  of 
  the 
  igneous 
  

   rocks 
  of 
  northern 
  New 
  York 
  have 
  already 
  received 
  detailed 
  study, 
  

   more 
  especially 
  the 
  syenites 
  and 
  certain 
  gabbros, 
  others 
  have 
  been 
  

   comparatively 
  neglected, 
  notably 
  the 
  granites. 
  For 
  the 
  purpose 
  of 
  

  

  iBy 
  H. 
  P. 
  Gushing. 
  - 
  

  

  