﻿Rocks, 
  in 
  Littleton, 
  New 
  Hampshire. 
  235 
  

  

  The 
  series 
  as 
  a 
  whole 
  is 
  drab 
  or 
  greenish 
  gray 
  in 
  color. 
  Weath- 
  

   ered 
  surfaces 
  are 
  much 
  lighter, 
  sometimes 
  almost 
  white. 
  

  

  The 
  Fitch 
  Hill 
  granite 
  gneiss 
  : 
  Earlier 
  references. 
  — 
  "While 
  

   this 
  rock 
  has 
  been 
  mentioned 
  several 
  times 
  in 
  previous 
  writings 
  

   on 
  the 
  Littleton 
  district, 
  it 
  has 
  never 
  received 
  very 
  thorough 
  

   consideration, 
  nor 
  have 
  its 
  relations 
  to 
  the 
  adjoining 
  formations 
  

   been 
  described. 
  In 
  Hitchcock's 
  works 
  it 
  is 
  called 
  ' 
  chlorite,' 
  * 
  

   i 
  chlorite 
  rock,'f 
  ' 
  chloritic 
  foliated 
  granite,' 
  J 
  and 
  ' 
  protogene,'§ 
  

   a 
  name 
  given 
  to 
  it 
  by 
  Hawes. 
  Lambert 
  refers 
  to 
  it 
  as 
  a 
  

   " 
  stratum 
  of 
  igneous 
  rock,"|j 
  and 
  also 
  merely 
  as 
  "igneous 
  

   rock." 
  1 
  

  

  Distribution. 
  — 
  The 
  Fitch 
  Hill 
  granite 
  gneiss 
  outcrops 
  in 
  a 
  

   belt 
  which 
  trends 
  N.E.-S.W., 
  to 
  the 
  south 
  of 
  the 
  Lyman 
  schists, 
  

   It 
  is 
  widest 
  (3/-I 
  mile) 
  at 
  the 
  northeastern 
  edge 
  of 
  the 
  map, 
  and 
  

   can 
  be 
  traced 
  thence 
  for 
  two 
  miles 
  south 
  westward, 
  beyond 
  

   which 
  no 
  exposures 
  were 
  seen. 
  The 
  rock 
  is 
  essentially 
  a 
  valley- 
  

   maker, 
  although 
  it 
  rises 
  half-way 
  up 
  some 
  of 
  the 
  adjacent 
  hills, 
  

   Fitch 
  Hill 
  being 
  one 
  of 
  these 
  (Sec.'A, 
  fig. 
  3). 
  In 
  the 
  field 
  the 
  

   gneiss 
  can 
  be 
  followed 
  northeastward 
  for 
  more 
  than 
  a 
  mile 
  

   beyond 
  the 
  border 
  of 
  the 
  map. 
  

  

  In 
  passing 
  across 
  this 
  belt, 
  one 
  finds 
  that 
  the 
  rock 
  gradually 
  

   changes 
  from 
  a 
  dark, 
  hornblende-bearing, 
  northern 
  facies 
  to 
  a 
  

   lighter, 
  hornblende-free, 
  southern 
  facies. 
  The 
  petrology 
  of 
  

   these 
  two 
  phases 
  will 
  be 
  described 
  separately. 
  

  

  Northern 
  phase. 
  — 
  In 
  its 
  northern 
  outcrops 
  the 
  Fitch 
  Hill 
  

   granite 
  gneiss 
  is 
  a 
  fine-grained 
  (average 
  size 
  of 
  grain, 
  1/16 
  inch 
  

   or 
  less), 
  dark 
  gray 
  or 
  greenish 
  gray 
  rock, 
  composed 
  essentially 
  

   of 
  quartz, 
  feldspar, 
  and 
  hornblende. 
  The 
  hornblende 
  crystals 
  

   are 
  black, 
  are 
  more 
  than 
  twice 
  as 
  long 
  as 
  they 
  are 
  wide, 
  and 
  

   are 
  without 
  definite 
  orientation. 
  The 
  feldspar 
  is 
  of 
  a 
  dirty 
  

   pale 
  greenish 
  color. 
  Sometimes 
  a 
  few 
  A^ery 
  indistinct 
  pheno- 
  

   crysts 
  of 
  this 
  mineral 
  are 
  present, 
  and 
  rarely 
  these 
  are 
  pinkish. 
  

   The 
  quartz 
  is 
  inconspicuous 
  because 
  its 
  grains 
  are 
  small 
  and 
  

   transparent. 
  Fine 
  chlorite 
  and 
  sericite 
  may 
  be 
  observed, 
  partic- 
  

   ularly 
  in 
  those 
  outcrops 
  where 
  there 
  has 
  been 
  a 
  little 
  shearing. 
  

  

  In 
  thin 
  sections 
  the 
  microscope 
  reveals 
  evidence 
  of 
  crushing. 
  

   The 
  quartz, 
  which 
  is 
  more 
  or 
  less 
  granulated, 
  has 
  wavy 
  extinc- 
  

   tion. 
  Among 
  the 
  feldspars, 
  orthoclase, 
  microperthite, 
  micro- 
  

   cline, 
  and 
  plagioclase, 
  ranging 
  from 
  albite 
  to 
  oligoclase, 
  were 
  

  

  * 
  Geology 
  of 
  Northern 
  New 
  England, 
  p. 
  15. 
  Geology 
  of 
  New 
  Hampshire, 
  

   vol. 
  ii, 
  p. 
  327, 
  1877. 
  f 
  Ibid. 
  

  

  X 
  New 
  7 
  Studies 
  in 
  the 
  Ammonoosuc 
  District 
  of 
  New 
  Hampshire, 
  Bull. 
  Geol. 
  

   Soc. 
  Am., 
  xv, 
  p. 
  465, 
  1901. 
  

  

  § 
  Ibid., 
  p. 
  465. 
  Also, 
  by 
  the 
  same 
  author, 
  Geology 
  of 
  Littleton, 
  p. 
  13. 
  

  

  || 
  Lambert, 
  A. 
  E. 
  : 
  In 
  New 
  Studies 
  of 
  the 
  Ammonoosuc 
  District 
  of 
  New 
  

   Hampshire, 
  p. 
  480. 
  

  

  % 
  Geology 
  of 
  Littleton, 
  p. 
  34. 
  

  

  Am. 
  Jour. 
  Sci. 
  — 
  Fourth 
  Series, 
  Vol. 
  XXXVI, 
  No. 
  213. 
  — 
  September, 
  1913. 
  

   16 
  

  

  