van  Hiss.]  EASTERN    UNITED    STATES.  419 
their  structure,  consisting  of  gneiss,  slate,  and  schist,  with  some  granite, 
while  those  of  the  western  division  are  almost  exclusively  granife. 
The  transition  argillite  is  widespread,  and  in  it  occurs  most  of  the  gold 
mines. 
Mitchell,189  in  1842,  describes  as  primitive  formations  the  granites, 
gneiss,  mica-slate,  chlorite-slate,  hornblende-slate,  and  talcose-slate, 
quartz-rock,  serpentine,  and  limestone.  A  vast  body  of  granite  trav- 
erses the  state  in  a  northeast  and  southwest  direction,  comprising  a 
large  part  of  Person,  Caswell,  Orange,  Guilford,  Randolph,  Davidson, 
Rowan,  Cabarrus,  and  Mecklenburg  counties;  also  some  of  Lincoln, 
Iredell,  Davie,  Stokes,  and  Rockingham  counties.  Within  this  belt  is  no 
well  denned  gneiss,  micaceous  primitive  slate,  serpentine,  or  limestone. 
West  of  this  formation  are  the  most  ancient  primitive  rocks,  on  the 
upper  waters  of  the  Dan,  Yadkin,  Catawba,  and  French  Broad.  Here 
are  a  great  variety  of  granites.  Gneiss  and  slate  also  occur.  All  of 
these  are  interstratified.  Limestones  are  found  at  three  points  in 
Stokes  county.  In  Anson  and  Richmond  counties  is  a  beautiful  por- 
phyritic  granite.  East  of  the  red  sandstone  in  the  counties  of  Cumber- 
land, Wake,  Granville,  Warren,  Franklin,  Nash,  Johnston,  Halifax, 
and  Northampton,  is  another  body  of  ancient  primitive  rock  in  which 
granite  prevails. 
Emmons  (E.),190  in  1856,  gives  a  systematic  account  of  the  crystal- 
line rocks  of  North  Carolina.  Rocks  of  igneous  origin  are  often  massive, 
but  also  frequently  are  laminated,  and  laminated  rocks  are  frequently 
called  stratified,  but  this  latter  term  should  be  restricted  to  the  sedi- 
mentary  rocks.  The  inetainorphic  rocks  are  excluded  from  the  sedi- 
mentary classification  because  all  rocks  may  become  metamorphic,  and 
a  stratum  metamorphic  in  one  locality  may  not  be  metamorphic  fai 
another.  The  highest  proof  of  the  age  of  rocks  is  the  order  of  super- 
position. When  this  method  can  be  applied  it  is  paramount,  but  pale: 
ontology  may  be  used  subject  to  proper  principles.  At  the  base  of  the 
Paleozoic,  under  the  Silurian,  is  placed  the  Taconic. 
The  granitic  formations  are  regarded  as  eruptive  or  pyrocry  stall  inc. 
They  form  two  continuous  belts,  which  cross  the  state  in  a  northeast 
and  southwest  direction.  The  eastern  one  is  the  Raleigh  belt,  and  the 
western  one  the  Salisbury  and  Greensboro  belt.  Granite  is  generally 
the  underlying  rock,  but  there  are  cases  on  record  in  which  it  is  shown 
that  it  is  an  overlying  one.  At  Warrenton,  in  Warren  county,  of  the 
Raleigh  belt,  it  is  found  to  overlie  gneiss,  mica-slate,  and  hornblende, 
where  it  is  considered  to  have  been  projected  through  fissures  in  these 
rocks.  This  eastern  belt  contains  no  metallic  veins,  nor  is  it  cut  by  trap 
or  other  instrusive  rocks.     Its  breadth  is  from  20  to  25  miles. 
The  Salisbury  granite  is  frequently  syenitic,  that  is,  hornblende  takes 
the  place  of  mica.  This  belt  is  cut  by  numerous  peculiar  dike  rocks  in 
which,  when  they  decompose,  the  hornblende  trap  appears  in  dark- 
green  stripes,  and  many,  when  carefully  examined,  have  assumed  the 
