388  PRE-CAMBRIAN    ROCKS    OF    NORTH    AMERICA.  [bull.  86. 
Mather,38  in  1839,  describes  the  rocks  of  New  York,  Westchester 
and  Putnam  counties  as  comprising  granite,  gneiss,  mica-slate,  quartz 
rock,  talcose  slate,  limestone,  syenite,  serpentine,  steatite,  augite  rock, 
greenstone,  the  latter  traversing  the  other  rocks  like  veins  or  being 
interstratified  with  them.  The  gneiss  and  granitoid  rocks  are  distinctly 
stratified,  as  is  also  the  limestone. 
Horton,"  in  1839,  describes  the  Primitive  rocks  of  Orange  county 
as  less  regular  in  stratification  and  dip  along  the  banks  of  the  Hud- 
son and  at  their  western  margin  than  in  their  center.  The  strike  of 
the  primitive  gneiss  is  about  northeast  and  southwest,  with  a  dip  to 
the  southeast  from  45°  to  nearly  vertical.  Interstratified  among  the 
primitive  rocks  are  hornblende  rock  and  white  limestone.  Argillite  is 
placed  with  the  transition  formations. 
Gale,100  in  1839,  finds  that  the  rocks  of  New  York  county  are  chiefly  a 
gneiss,  associated  with  which  as  subordinate  rocks  are  serpentine,  horn- 
blende, primary  limestone  and  anthophyllite  rock.  On  the  western  side 
of  the  island  the  gneiss  so  abounds,  with  the  veins  of  granite  parallel  with 
the  strata,  that  in  many  places  they  constitute  the  chief  material.  At 
Kings  bridge  the  limestone  at  its  junction  with  the  gneiss  retains  the 
structure  of  that  rock  with  the  mineral  matter  of  limestone,  but  the 
pure  limestone  is  in  beds  without  stratification. 
Emmons  (E.),101  in  1839,  describes  Primitive  rocks  in  Hamilton,  Clin- 
ton and  Warren  counties.  The  primitive  rocks  are  gneiss,  hornblende, 
limestone  and  serpentine.  The  limestone  and  serpentine  occur  in  irreg- 
ular veins  or  beds,  which  are  sometimes  analogous  to  greenstone  dikes 
so  prevalent  in  the  hypersthene  rocks. 
Emmons  (E.),102  in  1840,  states  that  the  magnetic  iron  ore  occurs  asso- 
ciated with  granite,  gneiss  and  hypersthene  rock  in  veins  whicn  are 
regarded  as  of  igneous  origin.  The  specular  oxide  occurs  in  two  hori- 
zons, the  first  associated  with  the  primary  limestone,  the  second  with 
gneiss  or  some  other  primary  rock  beneath  it. 
Yanuxem,103  in  1840,  states  that  the  primary  rocks  which  are  defined 
as  earlier  than  any  which  bear  organic  bodies  in  Lewis  county  consist 
mostly  of  granite  and  gneiss,  but  are  associated  with  amphibolite  or 
hornblende,  forming  syenite  and  hornblende  rock.  The  Potsdam  sand- 
stone rests  unconformably  upon  the  primary  rocks.  There  is  a  great 
contrast  between  the  two  classes,  the  latter  presenting  a  disturbed 
appearance,  exhibiting  high  grades  of  inclination,  while  those  of  the 
transition  are  like  the  deposits  of  tranquil  waters. 
Mather,104  in  1841,  states  that  the  primitive  rocks  occupy  two-fifths 
of  Saratoga  and  one-fifth  of  Washington  county,  being  mostly  gneiss 
and  granite,  although  coarsely  crystalline  white  limestone  containing 
plumbago,  augite  and  hornblende  is  a  common  rock. 
Emmons  (E),105  in  1841,  mentions  primary  limestone  at  lake  Janet, 
gneiss  at  Long  lake,  and  on  Racket  river  hypersthene  rock. 
Emmons  (E.),106  in  1842,  gives  a  report  on  the  entire  Adirondack 
