ADIRONDACK    MOUNTAINS.  599 
beds  of  granite  is  about  6  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  con- 
stitutes almost  the  entire  county  of  Essex,  with  the  exception  of  a 
belt  a  few  miles  in  width  along  the  shore  of  the  lake.  Under  Primi- 
tive limestone  is  included  a  coarse,  crystalline  mass,  readily  recog- 
nizee! as  a  mineralogical  species,  but  as  a  rock  not  holding  a  definite 
place  in  the  Prifnary  series.  This  rock  is  believed  to  be  unstratified 
and  of  igneous  origin,  as  is  shown  by  its  occurrence  in  dikelike  forms 
and  its  association  with  eruptive  rocks,  the  embedded  minerals  being 
of  such  a  character  as  would  be  produced  by  metamorphism.  Also 
limestone  produces  a  metamorphosing  effect  upon  the  minerals  em- 
bedded in  it,  is  always  without  stratification,  often  underlies  granite, 
and  is  so  intimately  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  it  is  concluded  that  the  latter  probably  have  a  similar  origin. 
Porphyry  is  also  found  in  igneous  forms.  Magnetic  and  specular 
oxides  of  iron  occur  as  masses  and  as  veins.  They  are  sometimes 
apparently  interstratified  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,13  in  184*2,  describes  the  Primary  system  as  occurring  in 
the  northern  parts  of  Montgomery  and  Herkimer  counties,  the  north- 
east corner  of  Oneida  County,  and  the  whole  of  Lewis  County  east 
of  Black  River.  This  system  consists  wholly  of  granite  and  gneiss, 
with  which  is  associated  a  small  quantity  of  limestone  and  iron  ore. 
Primary  rocks  occur  isolated  in  the  New  York  system — at  the  Noses  on 
the  Mohawk,  at  the  little  falls  of  the  Mohawk,  and  at  Middleville. 
With  the  Taconic  system  are  placed  a  lamellar  white  crystalline  lime- 
stone, with  specular  iron  ore  and  compact  red  iron  ore  and  plumba- 
ceous  rocks  in  Lewis  County 
Macfarlane,14  in  L865,  describes  the  rocks  in  the  neighborhood  of 
Kossie  as  belonging  almosl  exclusively  to  the  Laurent  ian  formation, 
which  is  here  and  there  unconformably  overlain  by  patches  of  Pots- 
dam sandstone.     The  rocks  here  found  comprise  micaceous  and  horn 
