602  PRE-CAMBRTAN    GEOLOGY   OF    NORTH   AMERICA. 
character  of  the  gneissic  series,  containing  quartz  schist,  graphitic 
schist,  and  crystalline  limestone,  including  graphite,  it  is  regarded  as 
having  been  originally  clastic.  Its  present  crystalline  character  and 
quaquaversal  arrangement  are  doubtless  due  in  part  to  the  intrusion 
of  the  gabbro  and  the  consequent  dynamic  effects.  It  thus  appears 
that  there  is  in  this  region  a  great  bedded  succession  which  belongs 
to  the  Algonkian  system.  The  lowest  coarse-grained  gneiss  inferior 
to  the  limestone  perhaps  belongs  to  a  still  earlier  series,  but  this  is 
a  point  upon  which  closer  studies  are  needed. 
Smyth  (C.  H.),22  in  1893,  describes  the  rocks  near  Gouverneur, 
N.  Y.,  as  consisting  of  gneiss,  granite,  limestone,  and  sandstone,  with 
small  amounts  of  associated  schists.  The  gneiss  is  the  oldest  rock  of 
the  region,  underlying  the  other  formations.  It  sometimes  grades 
into  a  true  granite,  the  passage  being  gradual.  The  two  are  regarded 
as  different  phases  of  the  same  rock,  the  granite  being  either  an  un- 
changed remnant  of  a  plutonic  mass  from  which  the  gneiss  is  de- 
rived or  the  result  of  fusion  of  the  gneiss.  Evidence  of  unconform- 
ity between  the  beds  of  the  limestone  and  the  foliation  of  the  gneiss 
was  found  in  two  localities,  and  was  indicated  in  several  others ;  there 
is  no  evidence  of  irrupt ive  contacts  between  the  gneiss  and  the  lime- 
stone ;  the  gneiss  shows  no  evidence  of  sedimentary  origin ;  therefore 
the  simplest  hypothesis,  but  requiring  more  proof,  is  that  the  gneiss 
is  an  eroded  metamorphosed  plutonic  rock,  upon  which  the  limestone 
was  deposited.  The  marble  is  coarsely  crystalline,  and  in  age  is  next 
to  the  gneiss.  Near  the  base  of  the  limestone,  and  interbedded  with 
it,  are  peculiar  schistose  rocks,  which,  though  completely  crystalline 
and  resembling  igneous  rocks  in  composition,  their  field  relations  in- 
dicate to  be  of  sedimentary  origin.  Near  Gouverneur  an  outcrop  of 
limestone  contains  abundant  fragments  of  black  schist,  scattered 
through  the  limestone  in  a  most  irregular  manner,  and  making  up, 
perhaps,  one-third  of  the  rock.  This  and  other  outcrops  show  that 
the  schist  fragments  are  remains  of  once  continuous  schist  layers 
which  have  been  completely  shattered  in  the  course  of  metamorphism, 
since  between  the  continuous  belts  of  schist  and  the  Gouverneur  local- 
ity there  is  every  possible  gradation.  While  the  schists  show  the 
effects  of  foldings,  contortions,  stretchings,  and  shattering,  the  lime- 
stone shows  no  traces  of  them,  appearing  to  have  been  a  plastic  mass 
in  which  the  schists  moved  with  considerable  freedom.  The  con- 
spicuous result  of  metamorphism  in  the  limestone  is  crystallization. 
In  the  limestones  are  also  pegmatitic  veins,  which  have  been  much 
shattered  by  the  dynamic  action,  reducing  them  to  small  lumps  of 
quartz  and  feldspar,  scattered  through  the  limestone.  So  far  as 
observed  the  pegmatite  yields  to  strain  only  by  fracturing.,  not  show- 
ing preliminary  contortions,  so  general  in  the  schistose  layers. 
