﻿ECONOMIC 
  GEOLOGY 
  207 
  

  

  The 
  Hudson 
  River 
  Stone 
  Supply 
  Company 
  has 
  an 
  extensive 
  

   plant 
  for 
  quarrying 
  and 
  crushing 
  granite, 
  at 
  Breakneck 
  Mt, 
  

   north 
  of 
  Cold 
  Spring. 
  The 
  same 
  company 
  operates 
  a 
  second 
  

   plant 
  for 
  supplying 
  crushed 
  limestone 
  at 
  Stoneco, 
  north 
  of 
  New 
  

   Hamburg. 
  

  

  One 
  of 
  the 
  largest 
  quarries 
  in 
  the 
  state 
  is 
  that 
  of 
  P. 
  Callanan 
  

   at 
  South 
  Bethlehem, 
  Albany 
  county. 
  The 
  Lower 
  Helderberg 
  

   limestone 
  is 
  the 
  rock 
  used 
  and 
  it 
  makes 
  a 
  good 
  road. 
  

  

  The 
  Cauda 
  galli 
  grit 
  of 
  Albany 
  county 
  is 
  used 
  in 
  small 
  quanti- 
  

   ties 
  locally 
  and 
  makes 
  an 
  excellent 
  road, 
  though 
  it 
  is 
  not 
  durable. 
  

  

  At 
  Duanesburg, 
  near 
  Schenectady, 
  sandstone 
  of 
  the 
  Hudson 
  

   river 
  group 
  is 
  crushed 
  for 
  road 
  metal. 
  

  

  At 
  Port 
  Chester, 
  Westchester 
  county, 
  a 
  coarse-grained 
  granite 
  

   is 
  quarried 
  and 
  is 
  considerably 
  used 
  locally, 
  but 
  the 
  best 
  ma- 
  

   cadam 
  roads 
  of 
  that 
  district 
  are 
  of 
  limestone 
  from 
  Tomkins 
  Cove. 
  

  

  The 
  gray 
  gneiss 
  has 
  been 
  considerably 
  used 
  as 
  a 
  road 
  material 
  

   in 
  Westchester 
  county. 
  

  

  On 
  Staten 
  Island 
  the 
  yellow 
  gravel 
  is 
  much 
  used 
  for 
  road 
  

   making; 
  also 
  the 
  diabase 
  or 
  trap 
  from 
  the 
  Graniteville 
  quarries, 
  

   which 
  is 
  being 
  extensively 
  used 
  on 
  a 
  system 
  of 
  county 
  roads 
  

   with 
  the 
  most 
  satisfactory 
  results. 
  

  

  The 
  materials 
  used 
  for 
  making 
  roads 
  in 
  the 
  state 
  vary 
  with 
  the 
  

   locality. 
  If 
  the 
  traffic 
  on 
  the 
  road 
  is 
  moderate 
  it 
  is 
  generally 
  

   safe 
  to 
  use 
  the 
  local 
  material, 
  whatever 
  its 
  nature, 
  unless 
  it 
  be 
  

   shale, 
  but 
  if 
  there 
  is 
  a 
  heavy 
  traffic 
  it 
  will 
  pay 
  in 
  most 
  instancea 
  

   to 
  get 
  a 
  stone 
  of 
  superior 
  quality 
  from 
  elsewhere. 
  

  

  The 
  requisite 
  qualities 
  of 
  a 
  road 
  metal 
  are 
  hardness 
  and 
  tough- 
  

   ness. 
  Where 
  both 
  these 
  qualities 
  are 
  not 
  obtainable 
  in 
  the 
  same 
  

   stone 
  the 
  latter 
  is 
  perhaps 
  preferable. 
  

  

  Silicious 
  rocks, 
  though 
  often 
  hard, 
  do 
  not 
  consolidate 
  as 
  well 
  

   nor 
  so 
  quickly 
  as 
  limestone, 
  owing 
  to 
  the 
  sandy 
  detritus 
  formed 
  

   by 
  the 
  former 
  having 
  no 
  cohesion. 
  The 
  detritus 
  of 
  magnesian 
  

   limestone 
  acts 
  like 
  a 
  mortar. 
  

  

  Granite 
  and 
  gneiss, 
  especially 
  if 
  very 
  micaceous, 
  are 
  apt 
  to 
  dis- 
  

   integrate 
  rapidly 
  and 
  produce 
  dust 
  and 
  mud. 
  

  

  