fAN   HISE.] 
EASTERN    UNITED    STATES.  363 
laceous  slate,  limestone,  quartz  rock,  mica-slate,  talcose  slate,  serpen- 
tine, hornblende- slate,  gneiss,  greenstone,  porphyry,  syenite,  and  granite. 
Prom  the  graywacke  to  the  gneiss,  this  is  the  order  of  occurrence, 
rhc  greenstone,  porphyry,  syenite,  and  granite  are  regarded  as  erup 
tive.  At  Bellingham  is  a  remarkable  metamorphie  rock,  which  is  a 
listinct  mica-slate  and  a  no  less  distinct  conglomerate.  In  this  for- 
mation is  also  placed  aggregates  of  porphyry,  which  is  a  coarse 
breccia  or  conglomerate,  chiefly  made  up  of  fragments  of  porphyry 
reunited  by  a  cement  of  the  same  material,  and  sometimes  almost 
reconverted  into  a  compact  porphyry.  Flinty  slate,  chert,  and  jasper 
ire  simply  the  ordinary  slate  which  have  been  changed  to  their  unusual 
condition  by  the  proximity  of  granite,  porphyry,  or  trap.  The  clay- 
Sate  is  entirely  destitute  of  organic  remains,  as  is  also  the  graywacke. 
rhe  limestones  are  water- deposited  stratified  rocks  metamorphosed 
by  heat.  The  mica-slate  is  generally  associated  with  gneiss,  but  also 
occurs  associated  with  all  other  rocks  at  least  as  high  as  the  argillaceous 
date.  Hornblende-schist  and  greenstone-slate,  a  single  formation,  are 
tentatively  regarded  as  metamorphosed  from  ordinary  argillaceous  rock 
by  the  action  of  heat.  Gneiss  is  often  much  folded  and  curved,  is  cut 
by  veins  of  other  rocks,  but  is  regarded  as  generally  regularly  stratified. 
At  Whately  occurs  a  peculiar  conglomeratic  syenite.  The  syenite  is 
|eherally  found  between  the  granite  and  metamorphie  rocks  and  may 
be  due  to  the  conversion  of  the  granite  into  syenite  or  else  to  the  erup- 
tion of  the  syenite  at  a  different  epoch.  The  pseudo- stratification  of 
o-ranite  is  regarded  as  due  to  concretionary  action  on  a  gigantic  scale. 
The  granite  cuts  and  is  interstratined  with  all  the  stratified  rocks  and 
pertain  of  the  other  eruptives  in  the  most  intricate  fashion. 
In  Massachusetts  are  six  systems  which  are  unconformable  and  suc- 
ceed each  other  in  age.  These  are  as  follows:  The  Oldest  Meridional 
system,  the  Northeast  and  Southwest  system,  the  East  and  West  sys- 
tem, Hoosac  mountain  system,  the  Red  Sandstone  system,  the  North- 
west and  Southeast  system.  In  western  Massachusetts,  from  Hoosac 
mountain  to  the  Taconic  range,  a  powerful  force  has  folded  the  strata 
so  that  in  many  cases  they  have  actually  been  reversed. 
Lyell,38  in  1844,  describes  the  plumbago  and  anthracite  in  the 
mica-schist  near  Worcester.  This  is  in  the  immediate  neighborhood  of 
masses  of  granite  and  syenite,  the  character  of  the  plumbago  and 
anthracite  being  due  to  this  local  metamorphosing  effect  and  to  more 
general  chemical  or  plutonic  action.  The  difference  in  dip  of  these  rocks 
from  the  nearest  Carboniferous  of  Rhode  Island  and  Massachusetts 
is  no  evidence  that  they  are  not  equivalent  and  the  graphite  meta- 
morphosed organic  material. 
Rogers,39  in  1857,  describes  Trilobites  belonging  to  the  Paradoxides 
as  occuring  in  the  metamorphie  beds  of  eastern  Massachusetts  at  Brain- 
tree,  which  shows  that  these  ancient  and  highly  altered  sediments  are 
the  base  of  the  Paleozoic  column. 
