vanhisr.]  EASTERN    UNITED    STATES.  395 
Leeds,114  in  1878,  describes  the  rocks  of  the  Adirorfdacks.  They  arc 
found  to  be  stratified  rocks  which  belong  in  the  Norhin  system,  are 
composed  of  hypersthene  and  diallage,  and  labradorite  with  menac- 
canite. 
Dana,115  in  1880  and  1881,  considers  the  geological  relations  of  the 
limestone  belts  of  Westchester  comity.  The  rocks  here  found  are 
divided  into  metamorphic  rocks,  not  calcareous ;  calcareous  rocks  or 
limestones;  serpentines  and  other  hydrous  minerals;  augitic  and 
hornblendic  rocks  not  above  included.  Of  metamorphic  rocks  the 
prevalent  kinds  are  micaceous  gneiss,  mica-schist,  ordinary  gneiss,  and 
granitoid  gneiss.  The  calcareous  rocks  are  white  and  coarsely  crystal- 
line, although  locally  they  are  feebly  crystalline.  The  hornblendic  and 
augitic  rocks  constituting  the  Oortlandt  series  include  soda  granite, 
norite,  augite-norite,  diorite,  hornblendite,  pyroxenite,  and  chrysolitic 
kinds.  These  rocks  are  held  to  be  conformable  with  a  part  of  the  ad- 
joining schists  and  limestone,  which  are  of  metamorphic  origin,  although 
they  may  have  been  in  a  former  state  of  fusion  or  plasticity.  The  lime- 
stones and  adjoining  schists  are  found  to  be  one  in  series  and  system 
of  disturbance,  are  considered  a  part  of  the  Green  mountain  system, 
younger  than  the  Highland  Archean,  and  probably  Lower  Silurian. 
At  Annsville  there  is  evidence  of  unconformity  between  the  Archean 
and  this  series.  The  limestone  here  lies  unconformably  against  the 
hornblendic  contorted  Archean  gneiss.  A  similar  unconformity  exists 
half  a  mile  northeast,  although  the  upturning  of  the  limestone  and  its 
associated  schist  has  usually  placed  them  in  near  conformity  to  the 
strike  of  the  Archean  rocks. 
Dana,116  in  1882,  ascertained  that  a  large  part  of  the  rocks  referred 
to  the  Taconic  range  are  shown  by  their  fossiliferous  contents  to  be 
Silurian  and  the  equivalent  of  the  Hudson  river  group,  although  it  is 
not  asserted  that  all  of  the  hydromica-schists  do  belong  here.  A  part 
are  Primordial. 
Newberry,117  in  1882,  states  that  the  mottled  serpentine  of  New 
York  island  is  like  the  Moriah  marble  of  the  Adirondack  region,  which 
affords  strong  indication  of  a  Laurentian  age  of  the  New  York  and 
Staten  Island  rocks. 
Hunt,118  in  1883,  describes  near  port  Henry  coarsely  crystalline  lime- 
stones in  the  highly  inclined  Laurentian  gneisses,  in  which  are  inclosed 
irregular  masses  and  layers  of  the  adjacent  gneiss.  Although  re- 
garded by  Emmons  and  Mather  as  eruptive  and  by  another  eminent 
geologist  as  evidence  that  the  crystalline  limestone  unconformably 
overlies  the  gneiss,  it  is  believed  to  be  a  great  calcareous  vein  stone. 
The  Norian,  massive,  bedded,  labradoritic  rocks  are  well  displayed  be- 
tween Westport  and  port  Kent. 
Dana,119  in  1884,  finds  that  the  hornblendic  and  augitic  rocks  of  the 
Cortlandt  series  have  such  relations  to  the  schists  as  to  show  that  they 
are  of  igneous  origin,  the  eruptions  taking  place  subsequent  to  the  era 
of  the  limestone,  mica-schist,  and  soda-granite. 
