644  PRE-CAMBRIAN    GEOLOGY   OF    NORTH    AMERICA. 
which  are  shown  as  follows :  Pegmatites  are  found  cutting  all  of  the 
other  rocks  in  the  district;  the  white  gneiss  cuts  the  two  remaining 
gneisses ;  and  the  black  rock  cuts  the  gray  gneiss  and  the  limestone. ' 
The  age  relations  between  the  light-gray  and  the  dark-gray  gneisses 
have  not  been  determined,  and  only  the  former  has  been  found  cut- 
ting the  limestone.  So  far  as  observation  goes,  the  limestone  may  be 
infolded  with  the  dark-gray  gneiss.  An  intimate  association  between 
the  magnetic  iron  ores  and  the  pegmatites  leads  to  the  conclusion  that 
the  two  are  connected  in  origin. 
Bayley,118  in  1908,  maps  and  describes  the  pre-Cambrian  geology 
of  the  Passaic  quadrangle  of  New  Jersey  and  New  York,  which  in- 
cludes a  part  of  the  New  Jersey  Highlands  in  its  northwest  corner. 
Lithologically  the  rocks  of  the  Highlands  in  the  Passaic  quad- 
rangle, like  those  of  the  Highlands  elsewhere,  are  mainly  granitoid 
gneisses  and  pegmatites  with  subordinate  amounts  of  magnetite  and 
of  garnetiferous  graphite  schist.  In  one  locality,  on  Turkey  Moun- 
tain, north  of  Montville,  there  is  a  small  exposure  of  white  marble 
which  contains  nodules  of  serpentine;  and  on  Copperas  Mountain 
there  are  conglomerates  and  quartzites.  The  limestone  is  correlated 
with  the  Franklin  Furnace  limestone  because  of  similarity  in  lithology 
and  relations  to  gneisses.  It  is  certainly  pre-Cambrian,  but  whether 
Algonkian  or  pre-Algonkian  has  not  been  determined.  The  asso- 
ciated gneisses  are  grouped  into  three  lithological  types,  the  Losee 
gneiss,  the  Byram  gneiss,  and  the  Pochuck  gneiss.  Rarely  does  one 
type  alone  occupy  any  large  area,  but  each  occurs  variously  mixed 
with  others  in  long,  narrow  belts  wedging  out  at  their  ends.  The 
genetic  relations  of  the  three  are  largely  unknown,  though  part  of  the 
dark  Pochuck  gneiss  is  older  than  the  other  two  gneisses,  which  are 
acidic.  The  acidic  gneisses  and  a  part  of  the  Pochuck  gneiss  are 
intrusive  into  the  Franklin  limestone,  and  all  are  in  turn  intruded  by 
pegmatites.  No  evidence  has  been  discovered  in  the  Passaic  quad- 
rangle that  would  lead  to  a  decision  as  to  the  original  condition  of 
the  older  Pochuck  gneiss,  but  from  consideration  of  the  phenomena 
observed  in  the  Adirondacks  and  eastern  Canada,  where  the  geologic 
conditions  appear  to  be  nearly  identical  with  those  prevailing  in  the 
Highlands  of  New  Jersey  and  where  rocks  very  closely  resembling 
the  Pochuck  gneiss  appear  to  be  metamorphosed  sediments,  without 
doubt,  it  is  thought  possible  that  some  of  the  older  rocks  classified  as 
Pochuck  gneiss  in  New  Jersey  may  have  had  this  origin.  The  gen- 
eral structure  is  monoclinal  with  northeast-southwest  strike  and 
southeast  dip,  but  individual  layers  or  groups  of  layers  are  sharply 
corrugated. 
Spencer,119  in  1908,  maps  and  describes  the  pre-Cambrian  rocks  of 
the  Franklin  Furnace  quadrangle  of  the  Highlands  of  New  Jersey. 
These  rocks  are  similar  to  those  described  by  Bayley  for  the  Passaic 
quadrangle,  immediately  to  the  southeast.     The  pre-Cambrian  rocks 
