﻿REPORT 
  OF 
  THE 
  DIRECTOR 
  39 
  

  

  Of 
  the 
  first 
  class 
  the 
  most 
  extensive 
  is 
  that 
  of 
  Staten 
  Island, 
  N. 
  Y., 
  

   next 
  in 
  size 
  are 
  those 
  of 
  Rye 
  and 
  New 
  Rochelle 
  in 
  Westchester 
  

   County, 
  N. 
  Y., 
  and 
  that 
  of 
  Castle 
  Point, 
  Hoboken, 
  N. 
  J. 
  A 
  fifth 
  area 
  

   is 
  to 
  be 
  found 
  in 
  New 
  York 
  City, 
  on 
  West 
  6oth 
  Street, 
  between 
  loth 
  

   and 
  nth 
  avenues.* 
  

  

  Of 
  the 
  second 
  class 
  the 
  most 
  prominent 
  examples 
  are 
  at 
  Montville 
  

   and 
  Mendharn 
  in 
  New 
  Jersey 
  and 
  others 
  are 
  found 
  in 
  the 
  continua- 
  

   tion 
  of 
  the 
  eastern 
  belt 
  of 
  crystalline 
  limestone 
  through 
  northeastern 
  

   New 
  Jersey 
  and 
  Orange 
  and 
  Putnam 
  Counties 
  in 
  New 
  York. 
  The 
  

   most 
  extensive 
  of 
  these, 
  on 
  the 
  east 
  bank 
  of 
  the 
  Hudson 
  River 
  near 
  

   West 
  Point, 
  was 
  described 
  by 
  Mather 
  under 
  the 
  local 
  name 
  of 
  "cot- 
  

   ton 
  rock."t 
  He 
  mentions 
  besides, 
  other 
  localities 
  in 
  Putnam 
  County, 
  

   notably 
  Huestis, 
  Quarry, 
  4J 
  miles 
  northeast 
  of 
  Cold 
  Spring. 
  In 
  

   Westchester 
  County 
  serpentine 
  occurs 
  in 
  small 
  masses 
  at 
  the 
  Snow- 
  

   flake 
  Marble 
  Quarry 
  at 
  Pleasantville. 
  

  

  A 
  third 
  class 
  might 
  be 
  constituted 
  of 
  the 
  serpentine 
  which 
  is 
  

   found 
  in 
  some 
  of 
  the 
  iron 
  mines 
  of 
  Putnam 
  County. 
  The 
  serpentine 
  

   pseudomorphs 
  of 
  the 
  Tilly 
  Foster 
  Mine 
  have 
  been 
  described 
  at 
  length 
  

   by 
  Prof. 
  J. 
  D. 
  Dana. 
  (Am. 
  Jour. 
  Sci. 
  III. 
  viii. 
  pp. 
  454, 
  455.) 
  

  

  THE 
  NEW 
  ROCHELLE 
  SERPENTINE. 
  

  

  The 
  serpentine 
  locality 
  of 
  Davenport's 
  Neck 
  at 
  New 
  Rochelle 
  has 
  

   long 
  been 
  known 
  to 
  geologists 
  and 
  mineralogists. 
  Its 
  position 
  and 
  

   stratigraphical 
  relations 
  are 
  shown 
  by 
  the 
  accompanying 
  map. 
  

   (PL 
  VI.) 
  

  

  Prof. 
  J. 
  D. 
  Dana 
  from 
  his 
  observations 
  on 
  this 
  serpentine 
  con- 
  

   cludes 
  that 
  it 
  is 
  associated 
  with 
  a 
  limestone 
  bed 
  which 
  is 
  not 
  now 
  visi- 
  

   ble, 
  having 
  been 
  removed 
  by 
  solution. 
  The 
  writers 
  study 
  of 
  the 
  local- 
  

   ity 
  suggests 
  that 
  the 
  serpentine 
  is 
  derived 
  from 
  magnesian 
  silicate 
  

   rocks 
  intruded 
  in 
  the 
  Manhattan 
  schist. 
  (Am. 
  Jour. 
  Sci. 
  III. 
  xxxix. 
  

   p. 
  391.) 
  

  

  The 
  only 
  exposures 
  now 
  visible 
  are 
  at 
  the 
  northeastern 
  and 
  south- 
  

   western 
  extremities 
  near 
  the 
  water's 
  edge, 
  and 
  the 
  outcrops 
  have 
  

   been 
  so 
  long 
  exposed 
  to 
  the 
  weather 
  that 
  the 
  process 
  of 
  serpentiniza- 
  

  

  * 
  This 
  locality 
  is 
  now 
  covered 
  with 
  buildings. 
  

  

  t 
  Cotton 
  rock 
  has 
  been 
  covered 
  by 
  the 
  railroad 
  embankment. 
  

  

  