﻿lO 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  the 
  more 
  basic 
  rocks 
  which 
  appear 
  in 
  large 
  quantity 
  further 
  east 
  

   are 
  but 
  sparingly 
  present. 
  But 
  granitic 
  intrusion 
  took 
  place 
  on 
  a 
  

   large 
  scale 
  at 
  least 
  twice, 
  probably 
  three 
  times, 
  and 
  possibly 
  sev- 
  

   eral 
  times. 
  This 
  it 
  was 
  which 
  was 
  so 
  effective 
  in 
  breaking 
  up, 
  al- 
  

   tering 
  and 
  destroying 
  wholesale 
  the 
  Grenville 
  sediments 
  and 
  their 
  

   floor. 
  

  

  Laurentian 
  granite 
  gneiss. 
  The 
  oldest 
  of 
  these 
  igneous 
  rocks 
  

   is 
  a 
  granite 
  which 
  has, 
  since 
  its 
  intrusion, 
  been 
  sufficiently 
  sub- 
  

   jected 
  to 
  compression 
  to 
  have 
  become 
  pretty 
  thoroughly 
  crushed, 
  

   or 
  granulated, 
  with 
  the 
  development 
  of 
  a 
  rude 
  foliated, 
  or 
  gneis- 
  

   soid, 
  structure. 
  It 
  is 
  a 
  reddish 
  to 
  gray 
  granite 
  gneiss 
  which 
  con- 
  

   tains 
  nearly 
  everywhere 
  inclusions 
  of 
  the 
  Grenville 
  rocks 
  in 
  vary- 
  

   ing 
  abundance, 
  but 
  always 
  most 
  abundant 
  near 
  the 
  contacts 
  with 
  

   the 
  Grenville, 
  into 
  which 
  it 
  always 
  sends 
  a 
  multitude 
  of 
  dikes. 
  

   The 
  inclusions 
  are 
  usually 
  of 
  amphibolite 
  and 
  all 
  stages 
  of 
  their 
  

   assimilation 
  by 
  the 
  granite 
  are 
  found, 
  giving 
  rise 
  to 
  a 
  group 
  of 
  

   intermediate 
  rocks 
  which 
  seem 
  unquestionably 
  to 
  have 
  been 
  de- 
  

   rived 
  from 
  the 
  digestion 
  of 
  the 
  one 
  rock 
  by 
  the 
  other. 
  It 
  is 
  pos- 
  

   sible 
  that 
  some 
  of 
  these 
  amphibolite 
  inclusions 
  may 
  actually 
  repre- 
  

   sent 
  fragments 
  of 
  the 
  old 
  Grenville 
  floor, 
  and 
  furnish 
  the 
  sole 
  re- 
  

   maining 
  traces 
  of 
  that 
  floor, 
  but 
  as 
  yet 
  this 
  is 
  mere 
  conjecture. 
  

   This 
  granite 
  gneiss 
  occurs 
  in 
  both 
  large 
  and 
  small 
  masses, 
  so 
  called 
  

   bathyliths 
  and 
  stocks, 
  which 
  invaded 
  the 
  Grenville 
  rocks 
  from 
  be- 
  

   neath 
  at 
  an 
  exceedingly 
  early 
  period.^ 
  In 
  addition 
  to 
  forming 
  a 
  

   large 
  portion 
  of 
  the 
  present 
  surface 
  occupied 
  by 
  the 
  Precambric 
  

   rocks 
  it 
  likely 
  also 
  underlies 
  the 
  Grenville 
  rocks 
  over 
  the 
  entire 
  

   district, 
  except 
  where 
  they 
  have 
  been 
  cut 
  away 
  by 
  succeeding 
  

   igneous 
  rocks. 
  Since 
  the 
  rock 
  solidified 
  it 
  has 
  been 
  subjected 
  to 
  

   compression, 
  together 
  with 
  the 
  Grenville 
  rocks, 
  giving 
  to 
  each 
  a 
  

   foliation 
  parallel 
  to 
  that 
  of 
  the 
  other, 
  and 
  elongating 
  the 
  bathyliths 
  

   in 
  a 
  northeast-southwest 
  direction 
  with 
  corresponding 
  shortening 
  

   at 
  right 
  angles 
  to 
  this, 
  the 
  shortening 
  being 
  of 
  course 
  in 
  the 
  di- 
  

   rection 
  of 
  the 
  pressure 
  and 
  the 
  elongation- 
  at 
  right 
  angles 
  to 
  it. 
  

  

  Alexandria 
  syenite. 
  On 
  the 
  Alexandria 
  quadrangle, 
  some 
  3 
  

   miles 
  a 
  little 
  west 
  of 
  north 
  of 
  Redwood, 
  is 
  a 
  mass 
  of 
  rather 
  coarse 
  

   grained 
  igneous 
  rock 
  which 
  shows 
  little 
  sign 
  of 
  crushing 
  and 
  is 
  un- 
  

   questionably 
  younger 
  than 
  the 
  Laurentian 
  granite 
  gneiss. 
  In 
  as- 
  

   sociation 
  with 
  it 
  is 
  a 
  much 
  greater 
  amount 
  of 
  a 
  coarse, 
  but 
  crushed, 
  

   porphyritic 
  igneous 
  rock, 
  now 
  converted 
  into 
  an 
  " 
  augen 
  " 
  gneiss. 
  

  

  1 
  Bathylith 
  is 
  a 
  term 
  applied 
  to 
  large 
  masses 
  of 
  igneous 
  rock, 
  which 
  masses 
  

   are 
  believed 
  to 
  continue 
  to 
  great 
  depths 
  with 
  generally 
  increasing 
  size 
  

   downward. 
  A 
  stock 
  is 
  a 
  smaller 
  mass 
  of 
  the 
  sort. 
  

  

  