van  HisE.j  EASTERN    UNITED    STATES.  387 
Jessup,90  in  1821,  describes  in  Essex  county,  in  the  vicinity  of  lakes 
George  and  Champlain,  rocks  of  the  primitive  class,  including  trap, 
syenite  and  carbonate  of  lime. 
Eaton,91  in  1822,  describes  as  occurring  in  the  Highlands  of  the 
Hudson,  without  reference  to  order  of  time,  gneiss,  hornblende  rocks 
and  argillite.    The  gneiss  appears  to  be  the  center  or  oldest  formation. 
Eaton,92  in  1824,  describes  the  rocks  adjoining  the  Erie  canal. 
Among  the  primitive  rocks  are  placed  granite,  gneiss,  hornblende  rock, 
mica-slate,  talcose  rock,  granular  quartz,  granular  limerock,  sparry 
lime  rock  and  primitive  argillite,  which  are  described  as  occurring  at 
numerous  localities.  There  are  two  primitive  districts,  that  in  south- 
eastern New  York  and  that  west  of  lake  Champlain,  called  Macomb 
mountains. 
Emmons  (E.),93  in  1837,  describes  granite  and  gneiss  as  having  a  wide- 
spread occurrence  in  the  northeastern  part  of  the  state.  The  granitic 
nucleus  of  Essex  county  is  traversed  by  dikes  of  greenstone  of  igneous 
origin,  and  the  granite  is  considered  to  have  the  same  genesis.  Gneiss, 
hornblende  and  granular  limestone  are  classed  together  as  primitive 
rocks  and  regarded  as  absolutely  of  the  same  age.  Above  the  primi- 
tive rocks  is  a  transition  sandstone,  superimposed  upon  which  is  a 
transition  limestone.. 
Conrad,94  in  1837,  describes  at  the  base  of  the  Mohawk  valley  ridges 
of  gneiss  which  are  regarded  as  a  prolongation  of  the  northern  primary 
chain.     Upon  the  gneiss  is  found  calcareous  sandstone. 
Mather,95  in  1838,  mentions  gneiss  on  Long  island;  granite  and  ser- 
pentine on  Staten  island ;  and  granite,  gneiss  and  granular  quartz  in 
the  southeast  part  of  Dutchess  county.  In  the  serpentine  was  observed 
a  trap  rock. 
Emmons  (E.),96  in  1838,  states  that  in  St.  Lawrence  and  Essex  counties 
are  found  Primitive  rocks.  The  stratification  of  the  gneiss  is  often  ob- 
scure and  its  texture  confusedly  crystalline.  Subordinate  to  it  and 
mingled  with  it  is  granite,  which  occurs  in  beds  and  protruded  masses 
in  the  forms  of  veins  and  in  overlying  masses  analogous  to  lava  cur- 
rents and  greenstones.  In  St.  Lawrence  county  is  a  widespread  gran- 
ite composed  of  labradorite,  feldspar  and  hypersthene,  which  is  trav- 
ersed by  dikes  of  greenstone,  amphibolite,  syenite,  and  porphyry.  As- 
sociated with  the  gneiss  and  limestone  are  numerous  beds  of  magnetite 
and  hematite.  The  transition  rocks  of  Essex  county,  such  as  lime- 
stones and  shales,  are  cut  by  dikes  and  veins.  The  primitive  lime- 
stone is  always  coarse,  crystalline  and  friable.  It  occurs  in  most 
intricate  and  curious  relations  to  the  granite  and  hypersthene  rock, 
many  of  its  areas  being  in  vein-like  form.  This  fact,  combined  with 
the  presence  of  foliated  plumbago  and  the  induration  of  sandstone 
when  in  contact  with  the  limestone,  leads  to  the  conclusion  that  it  is 
of  igneous  origin. 
Vanuxem,97  in  1838,  finds  Primitive  rocks  in  Montgomery,  Herki- 
mer and  Oneida  counties. 
