HIGHLANDS    OF    NEW    JERSEY.  637 
Trenton  are  much  more  like  a  true  gneiss  than  those  of  the  High- 
lands. The  Potsdam  sandstone,  the  base  of  the  Paleozoic,  is  found 
resting  imconformably  upon  the  A  zoic  gneiss  at  Franklin  Furnace 
and  at  Green  Pond  Mountain.  The  relations  of  the  two  rocks  are 
such  as  to  make  it  certain  that  the  sandstone  is  later  than  and  uncon- 
formably upon  the  gneiss.  The  Franklin  Furnace  sandstone  is  capped 
by  the  blue  magnesian  limestone,  which  is  equivalent  to  the  Calcifer- 
ous  sandstone  of  the  New  York  reports. 
Cook,"  in  1873,  gives  the  four  Azoic  belts  of  New  Jersey  the  names 
Ramapo,  Passaic,  Musconetcong,  and  Pequest.  In  the  first  and  last 
are  found  numerous  bands  of  interlaminated  limestones,  but  in  the 
others  these  are  not  known  to  occur.  Pathologically  the  greater  por- 
tion of  the  Azoic  rock  is  syenite  gneiss.  There  is  no  way  of  identify- 
ing it  with  the  Laurentian  or  Fluronian  of  Canada.  As  to  origin,  all 
are  agreed  that  these  Azoic  syenitic  gneisses  are  sedimentary.  The 
crystalline  limestone  of  the  Ramapo  belt  is  associated  with  the  ser- 
pentine, sometimes  in  large  quantity. 
Cook,100  in  1883,  states  that  the  rocks  of  the  Highlands  include 
granite,  syenite,  several  varieties  of  gneiss,  crystalline  limestone,  and 
magnetite,  with  rare  species  of  various  schists  and  some  serpentine. 
The  strata  dip  to  the  southeast  at  an  angle  of  45°  to  80°,  although  it 
is  often  difficult  to  determine  the  directions  of  strike  and  dip  posi- 
tively because  of  the  massive  character  of  the  rock.  The  ranges  are 
regarded  as  anticlinal  folds  in  general,  although  this  is  probably  not 
true  in  every  case,  and  the  valleys  are  s}rnclinal.  The  massive 
syenites,  granites,  and  traps  are  very  limited  in  quantity,  and  are  per- 
haps a  part  of  the  stratified  beds  in  which  stratification  has  been 
obliterated,  although  granite  and  syenite  dikes  are  found  traversing 
the  bedded  gneisses. 
Darton,1"1  in  1883,  states  that  at  Sparta  granite  cuts  across  the 
limestone  beds  and  may  be  in  true  veins. 
Cook,102  in  1884.  finds  that  besides  the  southeastern  dips  northwest 
dips  occur.  There  is  difficulty  in  separating  the  stratified  from  the 
unstratified  rocks,  as  nearly  all  the  glaciated  ledges  look  like  massive 
rocks.  The  relations  of  the  syenite  rocks  and  gneisses  are  not  made 
out  and  it  can  not  be  asserted  which  are  the  older,  but  these  grani- 
toid and  syenitic  rocks  are  surrounded  by  stratified  gneisses  and  oilier 
crystalline  rocks.  To  the  Highlands  the  term  Archean  is  applied 
because  it  does  not  necessitate  any  correlation  or  theory,  as  would  the 
use  of  Laurentian  or  Azoic. 
Britton.1o:{  in  1885,  states  that   few.  if  any.  of  the  ridges  are  simple 
anticlinal  folds,  the  southeast  dips  being  generally  as  prevalent  on  one 
side  of  the  mountain  as  on  the  other,  though  often  di  tiering  percept  i 
bly  in  degree.     The  crystalline  limestones  do  not  represent  the  blue 
magnesian  limestone  metamorphosed  by  granite  and   syenite.     The 
