NEW   ENGLAND.  583 
Dana,75  in  1872,  states  that  the  quartzite  of  Canaan  outcrops  in  six 
exposures,  is  unconformably  below  the  limestone,  and  its  jointing, 
uplifting,  and  consolidation  took  place  before  the  latter  was  de- 
posited. 
See  section  4  of  this  chapter  for  general  summary  of  the  geology  of 
western  Connecticut. 
SECTION  6.     RHODE!  ISLAND. 
SUMMARY  OF  LITERATURE. 
Jackson,70  in  1840,  describes  the  older  rocks  of  Rhode  Island  as 
Primary  and  Metamorphic.  The  Primary  rocks  are  generally  said  to 
be  rocks  produced  in  the  state  of  igneous  fusion.  Among  these  are 
placed  granite,  gneiss,  and  mica  slate,  although  it  is  doubtful  as  to  the 
manner  in  which  these  two  latter  rocks  were  formed.  At  Woonsocket 
a  conglomerate  passes  into  a  mica  slate.  In  general  the  contact  be- 
tween the  gneiss,  mica  slate,  and  graywacke  is  sharp. 
Cozzens,77  in  1843,  finds  that  the  section  on  the  island  of  Rhode 
Island  is,  from  the  base  up,  granite,  serpentine,  black  slate,  gray- 
wacke, black  slate,  Rhode  Island  coal,  and  diluvium. 
Jackson,78  in  1859,  maintains  that  the  pebbles  of  the  Newport  con- 
glomerates were  mechanically  formed  by  being  rolled  upon  beaches, 
many  of  the  distortions  and  indentations- being  accounted  for  in 
this  way. 
Hitchcock  (C.  H.),79  in  1861,  describes  the  lower  rocks  of  the 
island  of  Aquidneck  as,  in  ascending  order,  (1)  talcoid  schists,  and 
conglomerates  with  red  jasper  pebbles;  (-2)  Purgatory  conglomerate, 
the  pebbles  of  which  are  distorted;  (3)  mica  schists,  mica  slates,  con- 
glomerates, sandstones,  and  grits  west  of  Purgatory;  (4)  second  con- 
glomerate, and  (5)  coal  measures. 
Dale,80  in  1883,  gives. detailed  sections  of  many  localities  and  de- 
scriptions of  various  places.  The  conglomerates  are  found  in  some 
cases  to  be  highly  metamorphic,  the  pebbles  being  unmistakably 
elongated  and  cut  with  scales  of  mica.  The  cleavage  of  the  pebbles  is 
regarded  as  partly  due  to  their  adhesion  to  the  cement.  The  frac- 
tures with  which  they  are  cut  are  possibly  due  to  wave  motion  or  to  the 
contraction  of  the  conglomerate  in  cooling  from  a  heated  state.  The 
chronological  order  and  the  thickness  of  the  series  are  as  follows,  in 
ascending  order : 
Section  of  the  older  rocks  of  Rhode  Island. 
Feet. 
1.  Hornblende  schist  alternating  with  mien  schist 950 
2.  Ohloritic  schists  and  associated  argillaceous  and  micaceous  schists-      500-750 
.*!.  Greenish,  slaty  conglomerate,  with  argillaceous  and  siliceous  ser- 
pentine (conglomerate  I) •",l11 
4.  Quartz  and  clay,  aggregate 7~'(l 
