S0UTHEAS1  i  i:.\    NEW    rOKK.  627 
conformable  to  one  another  and  arranged  in  uninterrupted  succession. 
although  their  lithological  characters  are  very  diverse.  The  Taconic 
system  comprises  the  Taconic  slate,  bearing  fossils,  the  Sparry  lime- 
stone, the  Stockbridge  limestone,  and  the  brown  sandstone  or  granu- 
lar quartz.  The  Primary  limestone  carries  graphite,  and  on  this 
account  can  always  be  distinguished  from  Stockbridge  limestone; 
also  other  minerals,  such  as  spinel,  sapphire,  idocrase,  hornblende, 
pyroxene,  chondrodite,  and  mica,  are  found  plentifully  in  the  Pri- 
mary, but  do  not  occur  in  the  Stockbridge.  The  rocks  of  the  Taconic 
system  are  inverted  and  greatly  disturbed,  and  their  relations  with  the 
underlying  and  overlying  rocks  are  obscure,  so  that  the  true  structure 
can  be  ascertained  only  by  the  most  careful  examination. 
Ceedner,72  in  1865,  states  that  the  island  of  New  York  and  the 
eastern  part  of  Long  Island  consist  of  gneiss,  which,  toward  the 
north,  contains  hornblende  gneiss,  hornblende  schist,  syenite,  and 
hypersthenite,  and  in  the  last  two  are  magnetite.  The  northern,  hilly 
part  of  Staten  Island  consists  of  dioritic  rocks  and  serpentine  with 
layers  of  soapstone. 
Stevens,73  in  1867,  describes  New  York  Island  as  consisting  in  the 
main  of  gneiss,  in  which  lie  veins  and  beds  of  granite,  anthophvllite, 
and  hornblende.  The  granite  occurs  in  veins  generally  coincident 
with  the  gneiss,  but  also  in  massive  beds  which  lie  across  the  strata. 
In  places  it  is  distinctly  separated,  but  in  other  places  it  insensibly 
blends  into  the  gneiss.  The  hornblende  and  anthophvllite  occur  Like 
the  granite.  Limestone  occurs  at  several  points  and  is  interlaminated 
and  folded  with  the  gneiss.  This  New  York  group  of  rocks  is  like 
and  regarded  as  equivalent  to  Emmons's  Taconic.  For  it  is  proposed 
the  name  Manhattan  group. 
Dana,74  in  1872,  describes  the  mica  schist  of  Poughquag  as  under- 
lying conformably  the  Stockbridge  limestone.  The  mica  schist  is 
underlain  conformably  by  the  gneiss  of  the  Taconic  series.  Besides 
the  Limestones  and  Taconic  schists  and  gneiss,  there  is  near  Pough- 
quag, in  still  more  intimate  connection  with  the  quartzite  rock's  of 
Azoic  age,  a  continuation  of  the  Highlands  of  New  Jersey,  which  are 
probably  Laurentian.  Bui  as  this  point  is  not  definitely  settled,  and 
since  the  term  Azoic  has  been  ruled  out  by  facts  proving  that  the  era 
was  not  throughout  destitute  of  life,  it  is  proposed  to  use  for  the 
Azoic  area  and  its  rock-  the  general  term  Archaean  (or  Archean). 
Tliese  Archean  rocks,  coarsely  crystalline  gneisses,  arc  exposed  in  a 
deep  cut  on  the  Hartford  and  Fishkill  Railroad.  The  quartzite 
formation  of  this  region  shows  no  conformity  to  the  Archean  gneiss, 
and  none  to  the  gneiss,  mica  schist,  or  Limestone  of  the  Taconic  series. 
The  nearly  horizontal  beds  of  quartzite  lie  on  the  nearly  vertical 
Archean.  and  both  occur  within  a  i'cw  hundred  yard-  <»1*  the  steeply 
inclined  Taconic  beds. 
