vanhise.]  EASTERN    UNITED    STATES.  389 
region.  The  older  rocks  are  classified  under  primary  and  transition. 
There  are  few  transitions  from  the  primary  into  the  sedimentary  rocks. 
There  are,  however,  many  transitions  among  the  primary  masses  them- 
selves, and  often  intermediate  series  are  found  which  are  with  difficulty 
placed  under  appropriate  names.  The  primary  rocks  are  divided  into 
unstratified,  stratified  and  subordinate.  Among  the  unstratified  rocks 
are  included  granite,  hypersthene  rock,  primitive  limestone,  serpentine 
and  rensselaerite.  The  stratified  rocks  include  gneiss,  hornblende, 
syenite,  talc  or  steatite ;  the  subordinate  rocks  include  porphyry,  trap, 
magnetic  and  specular  oxides  of  iron. 
The  granites  occupy  a  comparatively  small  extent  in  the  region, 
being  in  limited  patches  of  irregular  appearance.  One  of  the  largest 
beds  of  granite  is  about  G  miles  long.  In  one  place  granite  and  lime- 
stone are  somewhat  intermingled.  The  hypersthene  rock  occupies  a 
triangular  area  to  which  it  is  almost  wholly  confined,  but  it  constitutes 
almost  the  entire  county  of  Essex,  with  the  exception  of  a  belt  a  few 
miles  in  width  along  the  shore  of  the  lake.  Under  primitive  limestone 
is  included  a  coarse,  crystalline  mass,  readily  recognized  as  a  minera- 
logical  species,  but  as  a  rock  not  holding  a  definite  place  in  the  pri- 
mary series.  This  rock  is  believed  to  be  unstratified  and  of  igneous 
origin,  as  is  shown  by  its  occurrence  in  dike-like  forms  and  its  asso- 
ciation with  eruptive  rocks,  the  imbedded  minerals  being  of  such  a 
character  as  would  be  produced  by  metamorphism.  Also  limestone 
produces  a  metamorphosing  effect  upon  the  minerals  imbedded  in  it, 
is  always  without  stratification,  often  underlies  granite,  and  is  so  inti- 
mately associated  with  it  as  to  make  it  probable  that  the  two  have  a 
common  origin.  Serpentine  intimately  associated  with  the  limestone 
has 'an  origin  common  with  it. 
The  stratified  rocks  have  a  much  wider  occurrence  than  the  massive 
ones.  Of  these  gneiss  is  by  far  the  most  important.  Syenite  is  ap- 
plied to  a  stratified  rock  composed  of  feldspar  and  hornblende.  It 
often  occurs  injected  in  the  form  of  dikes  and  associated  with  beds  of 
iron  ore  and  is  in  part  an  igneous  rock.  Trap  includes  dark-colored 
igneous  rocks,  which  cut  the  various  other  primitive  formations.  These 
are  compared  with  mineral  veins,  and  because  the  former  is  eruptive 
the  latter  is  concluded  to  have  a  probably  similar  origin.  Porphyry  is 
also  found  in  igneous  forms.  Magnetic  and  specular  oxides  of  iron  oc- 
cur as  masses  and  as  veins.  They  are  sometimes  apparently  inter- 
stratified  with  rocks  with  which  they  are  associated,  but  often  also 
break  across  the  strata.  In  their  mode  of  occurrence  they  resemble 
trap,  greenstone,  and  porphyry,  and  are  therefore  regarded  as  of 
igneous  origin.  Between  the  primary  and  transition  systems  is  the 
Taconic  system. 
Vanuxem,107  in  1842,  describes  the  primary  system  as  occurring  in 
the  northern  parts  of  Montgomery  and  Herkimer  counties,  the  north- 
east corner  of  Oneida,  and  the  whole  of  Lewis  county  east  of  Black 
