vanhise.]  EASTERN    UNITED    STATES.  351 
Jackson,12  in  1848,  maintains  that  in  the  White  mountains  are  numer- 
ous localities  where  fragments  of  slate  are  included  in  the  granite 
which  are  not  altered  by  heat  beyond  mere  induration.  In  New  Hamp- 
shire numerous  masses  of  older  Silurian  strata  occur  intercalated  with 
the  Primary  rocks. 
Hitchcock  (0.  H.)  and  Huntington,13  in  1877,  give  a  full  account  of 
the  geology  of  New  Hampshire.  Hitchcock  divides  the  pre-Paleozoic 
rocks  of  the  northeastern  United  States  into  two  divisions :  first,  the  more 
ancient  gneisses  and  granites;  second,  the  area  of  hydromicaeeous and 
micaceous  schists,  which  are  termed  Huronian.  In  the  Paleozoic  are 
placed  great  expanses  of  clay-slates.  The  first  division  is  divided  into 
four  parts :  first  and  oldest,  the  Laurentian ;  second,  the  porphyritic 
gneiss  and  the  various  undetermined  granites ;  third,  the  Atlantic ;  and 
fourth,  the  Labradorian.  Among  the  Huronian  is  placed  the  Quebec 
group  of  Logan. 
Huntington  gives  the  geology  of  the  Coos  and  Essex  district.  The 
Coos  rocks,  consisting  of  argillaceous  schists,  clay-slates,  and  micaceous 
sandstones,  are  supposed  to  belong  to  the  fossiliferous  series.  The  Hu- 
ronian rocks  are  found  east  of  the  line  limiting  the  Coos  group.  They 
consist  of  green  chloritic  rocks,  in  which  the  lines  of  stratification  are 
obscure.  Contained  are  greenish  feldspathic  sandstones,  with  inter- 
calated bands  of  siliceous  limestones.  There  are  also  here  contained 
stratified  diorites,  diabases,  and  hornblende-rocks.  The  porphyry  which 
occurs  connected  with  the  Coos  and  Huronian  penetrates  the  rocks 
with  which  it  comes  in  contact,  and  the  intrusive  character  can  not  be 
doubted.  Outcrops  of  granites  and  granitoid  gneisses  have  a  wide  ex- 
tent, a  part  of  them  being  regarded  as  genuine  eruptive  granites  since 
they  intersect  the  schists  in  numerous  veins  and  beds.  The  basic  dikes 
are  the  latest  of  all,  cutting  the  granites  and  intersecting  the  schists 
at  many  places. 
Hitchcock  gives  the  formations  of  the  White  mountain  district  in 
ascending  order,  as  follows:  (1)  Porphyritic  gneiss;  (2)  Bethlehem 
gneiss;  (3)  Berlin  or  Lake  gneiss;  (4)  Montalban  group;  (5)  Franconia 
breccia;  (6)  Labrador  system  or  Pemigewasset  series  of  granites,  ossi- 
pytes,  compact  feldspars,  etc.;  (7)  syenite;  (8)  andalusite  slates;  (9) 
Pequawket  or  mount  Mote  granite.  The  three  first  are  regarded  as 
metamorphic,  although  the  stratification  is  destroyed.  The  Montalban 
group  includes  granitic  gneiss,  mica- schist,  and  quartzite.  The  gran- 
itic gneiss  sometimes  shows  no  visible  mark  of  stratification,  as  in 
the  Concord  granite,  although  the  whole  is  regarded  as  metamor- 
phic. An  unconformity  is  inferred  between  the  Montalban  schists 
and  the  porphyritic  gneiss  on  account  of  the  divergence  in  the  strike 
of  the  two  groups.  Eruptive  granite  is  found  in  the  Montalban  schists. 
The  Franconia  breccia  is  placed  later  in  the  chronological  scale  than 
the  Montalban  group,  because  it  is  the  impression  of  the  author  that 
he  has  seen  Montalban  fragments  in  this  rock.    The  Labrador  system 
