﻿REPORT 
  OF 
  THE 
  DIRECTOR 
  23 
  

  

  Putnam 
  county 
  to 
  the 
  subjacent 
  gneiss, 
  and 
  from 
  the 
  nearly 
  complete 
  

   stratigraphic 
  continuity, 
  it 
  is 
  inferred 
  that 
  the 
  crystalline 
  limestone 
  

   of 
  Westchester 
  county 
  is 
  equivalent 
  to 
  that 
  of 
  southeastern 
  

   Dutchess 
  county, 
  the 
  age 
  of 
  which 
  has 
  been 
  satisfactorily 
  established 
  

   by 
  the 
  work 
  of 
  Dwight, 
  Dana, 
  and 
  others 
  to 
  be 
  Calciferous-Trenton, 
  

   and 
  the 
  schist 
  and 
  micaceous 
  gneiss 
  overlying 
  the 
  limestone 
  by 
  like 
  

   analogy 
  is 
  considered 
  to 
  be 
  of 
  Hudson 
  river 
  age. 
  

  

  Besides 
  the 
  older 
  granites 
  just 
  mentioned, 
  there 
  are 
  in 
  West- 
  

   chester 
  and 
  New 
  York 
  counties 
  many 
  later 
  eruptive 
  rocks 
  of 
  con- 
  

   siderable 
  areal 
  importance. 
  

  

  Prominent 
  among 
  them 
  is 
  a 
  red 
  granite 
  consisting 
  chiefly 
  of 
  quart*, 
  

   orthoclase 
  and 
  biotite 
  which 
  is 
  injected 
  into 
  and 
  through 
  the 
  gneiss 
  

   at 
  many 
  points, 
  and 
  at 
  Sing 
  Sing, 
  ,through 
  the 
  overlying 
  limestone. 
  

   In 
  Yonkers 
  township 
  is 
  a 
  large 
  area 
  of 
  reddish 
  granite 
  quite 
  gneissoid 
  

   in 
  texture, 
  which 
  is 
  intrusive 
  in 
  the 
  Fordham 
  gneiss. 
  

  

  The 
  mica 
  schist 
  has 
  been 
  specially 
  subject 
  to 
  igneous 
  intrusions. 
  

   Within 
  its 
  areas 
  occur 
  the 
  Cortland 
  series 
  of 
  diorites 
  and 
  norites 
  

   described 
  by 
  J. 
  D. 
  Dana* 
  and 
  Geo. 
  H. 
  Williams, 
  f 
  the 
  Harrison 
  

   diorite 
  described 
  in 
  detail 
  by 
  H. 
  Ries,| 
  the 
  serpentines 
  which 
  are 
  

   altered 
  eruptives 
  and 
  certain 
  gray 
  granites 
  which 
  occur 
  in 
  domes, 
  

   bosses 
  and 
  lenses 
  in 
  the 
  southernmost 
  part 
  of 
  Westchester 
  county. 
  

   Near 
  the 
  shores 
  of 
  Long 
  Island 
  Sound 
  the 
  Manhattan 
  schist 
  is 
  

   everywhere 
  injected 
  with 
  bands, 
  lenses 
  and 
  dykes 
  of 
  pegmatite, 
  

   granite, 
  amphibolite 
  and 
  pyroxenite. 
  

  

  All 
  the 
  stratified 
  crystalline 
  rocks 
  above 
  described, 
  with 
  the 
  pos- 
  

   sible 
  exception 
  of 
  the 
  Fordham 
  gneiss, 
  were 
  originally 
  sediments 
  laid 
  

   down 
  in 
  horizontal 
  strata, 
  the 
  quartzite 
  representing 
  a 
  beach 
  deposit, 
  

   the 
  limestone, 
  a 
  deposit 
  in 
  water 
  unaffected 
  by 
  wash 
  from 
  the 
  land 
  

   and 
  probably 
  of 
  warmer 
  temperature, 
  and 
  the 
  schist 
  a 
  deposit 
  of 
  

   sandy 
  mud 
  in 
  shoaler 
  water. 
  These 
  three 
  rocks 
  form 
  a 
  reliable 
  

   record 
  of 
  a 
  period 
  of 
  subsidence 
  of 
  the 
  land 
  and 
  transgression 
  of 
  the 
  

   sea 
  with 
  subsequent 
  recession 
  and 
  emergence. 
  

  

  *Am. 
  Jour. 
  Sci. 
  Ill, 
  Vol. 
  xxii 
  1881 
  pp. 
  103-iig. 
  

   t 
  " 
  " 
  " 
  xxxi 
  1886 
  pp. 
  26-41. 
  

  

  xxxiii 
  1887 
  pp. 
  135-144; 
  191-199. 
  

   t 
  Trans. 
  N. 
  Y. 
  Acad. 
  Sci., 
  Vol. 
  xiv., 
  1895 
  pp. 
  80-86. 
  

  

  