SOUTH EAS Ti  i;n    nkw  YORK.  631 
hornblende,  occur  in  subordinate  masses.  The  granites  are  probably 
igneous  and  of  great  age.  On  their  flanks  are  banded  gneisses  con- 
sisting chiefly  of  quartz  and  orthoclase,  with  biotite  and  hornblende, 
and  containing  numerous  beds  of  magnetic  iron  ore.  The  gneisses  on 
the  south  side  of  the  Highlands  extend  through  Westchester  County 
in  a  series  of  folds  with  southwesterly  trend,  and  on  the  northern 
slope  of  the  Highlands,  at  several  places  in  Dutchess  County,  are  over- 
lain unconformably  by  quartzites,  which  are  believed  to  be  of  Cam- 
brian age. 
Ries,ss  in  1898,  describes  the  geology  of  ( )range  County,  X.  Y.  Pre- 
Cambrian  rocks  form  the  Highland  region  in  the  eastern  part  of  the 
county,  the  northwestern  side  of  Bellvale  Mountain,  and  a  series  of 
rounded,  knoblike  hills  extending  from  Sugar  Loaf  village  to  New- 
burg.  They  comprise  gneiss,  at  times  massive  and  resembling  gran- 
ite and  limestone.  The  crystalline  rocks  are  folded  and  faulted,  the 
folds  plunging  frequently  to  the  northeast. 
In  the  south-central  part  of  the  county  is  found  an  area  of  white 
and  blue  limestone,  which  continues  southward  into  New  Jersey.  The 
white  limestone  in  New  Jersey  contains  fossils  of  Cambrian  age. 
About  1}  miles  west-southwest  of  Pine  Island  station,  east  of  the 
road,  are  exposures  which  show  the  passage  of  the  blue  into  the 
white  limestone.  Other  similar  areas  of  limestone  are  found  to  the 
northeast. 
Limestones  interbedded  with  the  gneisses  occur  at  Popolopen  Pond 
and  at  Fort  Montgomery. 
Van  Hise,S!)  in  1901,  visited  the  area  bordering  Long  Island  Sound 
and  other  localities  in  southeastern  New  York.  Just  as  in  western 
New  England,  there  is  here  present  below  the  undoubted  Cambrian 
and  later  sediments  a  basal  complex  of  pre-Cambrian  age.  In  the 
area  about  Long  Island  Sound  this  complex,  mapped  as  Fordham 
gneiss,  is  as  a  whole  a  very  evenly  banded  gray  gneiss.  In  places 
it  is  remarkably  like  the  pre-Cambrian  gneiss  of  western  New  Eng- 
land; that  is,  it  is  a  complex  of  white  banded  gneiss  and  black  biotitic 
amphibolitic  schist,  both  intricately  cut  by  pegmatite.  The  crystal- 
line Paleozoic  sediments  unconformably  above  this  are  also  very 
similar  to  those  of  western  New  England,  both  lithologically  and 
structurally.  At  the  base  is  quartzite,  above  this  limestone,  and 
above  this  schist  (the  Manhattan  schist),  into  which  the  limestone 
grades  with  interst rat iiication.  In  this  region  also  the  Manhattan 
schist  is  locally  found  resting  directly  on  the  pre-Cambrian,  due 
probably  to  overlap,  change  in  sedimentation,  or  overthrust  faulting, 
or  possibly  to  some  combination  of  these. 
Locally,  and  especially  in  the  area  about  Larchmont  and  New 
Rochelle,  the  Manhattan  schist  has  been  so  completely  metamor- 
phosed   and    so    intricately    injected    by    igneous    material    that    it    i- 
