NEW   ENGLAND.  557 
gneiss;  (4)  ferruginous  concretionary  schist;  (5)  fibrolite  schist, 
sometimes  gneissic  and  passing  into  common  mica  schist;  (6)  quartz- 
ites  and  quartz  conglomerates;  (7)  intrusive  rocks  and  veinstones. 
Hitchcock  gives  the  order  in  the  eastern  part  of  the  district  thus: 
(1)  Porphyritic  gneiss;  (2)  Lake  gneiss;  (3)  Montalban  series,  in- 
cluding the  Concord  granite;  (4)  ferruginous  schist;  (5)  andalusite 
mica  schists,  with  coarse  granite  veins;  (6)  Rockingham  mica  schists; 
(7)  Kearsarge  andalusite  group;  (8)  Merrimac  group,  including  a 
little  clay  slate.  There  are  no  eruptive  rocks  in  this  area  of  sufficient 
importance  to  find  a  place  on  the  map. 
Hitchcock  gives  the  succession  in  the  Lake  district,  embracing  the 
Winnipiseogee  Lake  and  the  flat  country  to  the  north,  as  follows : 
(1)  Porphyritic  gneiss;  (2)  Lake  gneiss;  (3)  Montalban.  The 
eruptive  rocks  are  more  plentiful  and  varied,  consisting  of  (1)  Con- 
way; (2)  Albany;  (3)  Chocorua  granites;  (4)  porphyry;  (5) 
Pequawket  breccia;  (0)  labradorite  diorite;  (7)  syenite;  (8)  gran- 
ite, not  allied  to  any  of  the  foregoing. 
The  succession  in  the  coast  district,  including  the  southeast  corner 
of  the  State,  is  as  follows:  (1)  Porphyritic  gneiss;  (2)  Lake  gneiss 
(including  the  Laurentian  of  Massachusetts);  (3)  Montalban;  (4:) 
Rockingham  group;  (5)  Merrimac  group;  (6)  Kearsarge  group: 
(7)  Huronian  and  Cambrian  of  Massachusetts.  The  unstratified 
rocks  are  the  syenites  of  Exeter  and  Pawruckaway,  inferior  granites, 
and  the  well-developed  granites  and  porphyries  of  York  County,  be- 
sides a  great  many  trap  dikes  along  the  coast. 
In  considering  the  principles  of  classification,  as  guiding  principles 
it  is  premised  that  in  this  field  are  inverted  flexures  and  dislocations 
of  the  strata  ;  also  that  formations  of  the  same  mineral  composition  in 
one  part  of  the  field  may  be  identified  with  those  of  like  composition 
in  another  part  of  the  field.  For  instance,  the  porphyritic  gneiss  in 
thirty  areas  has  feldspar  crystals  very  conspicuous  for  their  size;  all 
these  areas  are  assumed  to  be  identical  in  age,  and  in  placing  the  rela- 
tive positions  of  the  intervening  groups  this  is  relied  upon  for  a  start- 
ing point.  The  general  order  of  succession  for  New  Hampshire  is, 
from  the  base  upward :  Porphyritic  gneiss ;  Bethlehem  gneiss ;  Lake 
and  Montalban  series;  argillaceous,  talcose,  hydromicaceous,  and 
calcareous  series;  Labrador  series  (present  in  New  Hampshire,  limited 
in  amount)  ;  various  types  of  mica  schists.  Andalusite  slate  in  this 
mica  schist  formation  lies  unconformably  upon  the  Montalban  at 
Mounts  Monadnock  and  Kearsarge.  The  principal  eruptive  masses 
are  the  Conway,  Albany,  Chocorua  granites,  s}Tenites,  other  granites, 
and  labradorite,  diorites,  and  dolerites.  The  granite-  cut  rocks  as 
high  as  the  Coos  group.  The  porphyritic  gneiss  and  the  Bethlehem 
group  are  referred  to  the  Laurentian.  The  Lake  gneiss  can  not 
easily  be  assigned.     The  Montalban  certainly  is  not  characteristic  of 
