NEW   ENGLAND.  577 
coarse  gneisses  similar  to  the  basement  gneiss,  through  finer  grained 
banded  gneisses,  gneisses  with  but  a  small  amount  of  mica,  meta- 
morphic  gneiss  conglomerate,  and  ordinary  quartzite  conglomerate,  to 
quartzites.  These  phases  pass  into  one  another  along  the  strike.  In 
the  metamorphic  conglomerate  it  is  difficult  or  impossible  to  separate 
the  old  quartz  and  feldspar  from  that  formed  in  situ.  The  rock  is 
considered  metamorphic  because  of  the  shape  of  the  pebbles  and  their 
distribution  in  alternations  of  coarse  and  fine  materials,  because  of 
the  diverse  nature  of  the  pebbles,  including  blue  quartz,  white  quartz, 
granulite  rock,  and  granite,  and  because  of  frequent  transitions  into 
quartzite  and  quartzite  conglomerate. 
At  the  Hoosac  Tunnel  the  main  facts  brought  out  are  that  there  is 
a  large  central  mass  of  coarse  granitoid  gneiss  (Stamford  gneiss) 
forming  the  core  of  Hoosac  Mountain;  that  this  is  flanked  on  both 
sides  by  the  white  gneiss  conglomerate  (Vermont  conglomerate),  the 
eastern  band  having  a  steady  dip  east  and  being  overlain  by  the  albite 
schist  series,  the  western  band  broader,  with  varying  dips,  passing  by 
gradual  transitions  into  the  coarse  gneiss,  and  bounded  on  the  west 
by  a  narrow  band  of  the  albite  schist  (Hoosac  schist),  the  contact  be- 
ing conformable  and  transitional.  This  schist  is  succeeded  on  the 
west  by  another  band  of  fine-grained  white  gneiss  (Vermont),  and 
this  in  turn  by  the  limestone  (Stockbridge),  no  contacts  being  ob- 
served.    The  structure  is  anticlinal. 
This  succession  and  these  relations  are  found  to  correspond  with 
the  distribution  in  the  central  district  of  Hoosac  Mountain.  It  is 
also  found  that  the  anticline  of  Hoosac,  consisting  of  the  Stamford 
gneiss,  Vermont  formation,  and  Hoosac  schist,  has  a  pitch  to  the 
north  of  10°  to  15°,  while  the  western  side  has  been  overturned,  which 
makes  the  beds  in  inverted  order  on  the  west  side. 
At  Clarksburg  Mountain  the  granitoid  gneiss  (Stamford  gneiss)  is 
overlain  by  Clarksburg  quartzite  (Vermont  formation),  in  which 
Walcott  has  found  remains  of  trilobites,  showing  it  to  be  Lower  Cam- 
brian. 
Emerson,63  in  1890,  describes  the  Bernardston  series  of  rocks. 
The  succession  is  here  found  to  comprise  fourteen  members.  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,  argillite,  and 
calciferous  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  basement  Laurentian.  In  the  limestones 
fossils  are  found  such  a  character  as  to  prove  that  the  whole  series 
is  Upper  Devonian. 
55721— Bull.  360—09 37 
