370  PRE-CAMBRIAN    ROCKS    OF    NORTH    AMERICA.  [bull. 86. 
erous  mica-schist.     Granite  and  syenite  are  placed  as  eruptive  rocks  of 
the  older  series. 
Crosby,61  in  1888,  maintains  that  there  are  no  Carboniferous  beds  in 
the  Boston  basin;  that  it  contains  essentially  one  formation  of  conglom- 
erate and  one  formation  of  slate;  that  these  sediments  include  the 
Paradoxides  bed  at  Braintree,  are  conformable,  and  therefore  are  Pri- 
mordial or  at  least  of  Cambrian  age;  that  the  conglomerate  underlies 
the  slate.  The  pebbles  of  the  conglomerates  are  made  up  of  crystalline 
rocks  of  the  regions  adjacent.  The  contacts  of  the  conglomerate  and 
felsite  are  always  well  defined,  and  fragments  of  the  latter  are  always 
contained  abundantly  in  the  former.  The  same  relations  hold  between 
the  granites  and  conglomerates.  The  conglomerates  and  slates  have 
often  a  well  developed  cleavage,  which  frequently  cuts  across  the  bed- 
ding, although  in  places  where  the  folding  has  been  intense  the  two 
correspond.  The  discordance  is  shown  by  bands  of  the  conglomerate 
cutting  across  the  cleavage. 
Shaler,62  in  1889,  describes  cape  Ann  as  consisting  mainly  of  gran- 
ite1, which  is  cut  by  very  numerous  dikes  of  diabase  and  quite  abun- 
dant ones  of  quartz  porphyry.  Squam  river  is  an  area  of  diorite.  The 
relative  age  of  the  granite  and  diorite  has  not  been  determined. 
Emerson,63  in  1890,  describes  the  Bernardston  series  of  rocks.  The 
succession  is  here  found  to  consist  of  fourteen  members.  From  above 
downward  the  upper  seven  consist  of  alternations  of  mica-schist  and 
hornblende-schist,  after  which  follow  quartzite,  hornblende-schist,  and 
magnetite,  limestone,  hornblende-schist,  quartzite-conglomerate,  argil- 
lite,  and  ealciferous  mica  schist.  The  whole  series  is  very  crystalline, 
some  parts  so  thoroughly  so  as  to  have  been  compared  by  Hitchcock 
with  the  Bethlehem  gneiss,  his  ba seinent  Lauren  ti  an.  In  the  limestones 
fossils  are  found  of  such  a  character  as  to  prove  that  the  whole  series 
is  Upper  Devonian. 
Emerson,64  in  1890,  describes  the  rocks  of  central  Massachusetts, 
between  the  Berkshire  limestone  and  the  Boston  basin,  as  consisting  of 
a  series  of  mica-schists,  quartz  schists,  and  hornblende-schists,  pre- 
sumably Paleozoic,  and  eight  bands  of  granite  and  granitoid  gneiss, 
in  small  part  Archean,  in  larger  part  Cambrian,  and  in  largest  part 
intrusive.  In  the  western  part  is  a  small  row  of  Archean  ovals,  about 
which  are  the  Cambrian  conglomerates  and  conglomerate-gneisses,  the 
latter  rocks  having  a  quaquaversal  arrangement.  Here  are  included  1 
the  Princeton  and  Athol  granites,  often  well  foliated,  which  have  a  great 
extent  north  and  south.  To  the  great  intrusive  masses  of  granite  is 
applied  Suess's  name  batliolites.  These  have  melted  their  way  through 
a  great  thickness  of  folded  strata  and  absorbed  much  of  the  latter  in 
their  own  mass.  At  times  the  central  masses  of  granite  are  cut  by 
dikes  of  coarse  rauscovite-granite  which  seem  to  be  later  intrusions. 
About  the  batliolites  are  broad  areas  in  which  contact  metamorphism 
has  altered  the  rocks,  changing  the  argillites  to  mica-schists,  etc.     The 
