44 
PRE-CAMBRIAN    GEOLOGY    OF    NORTH    AMERICA. 
Table  of  correlation  of  pre- Cambrian  rocks  of  North  America — Continued. 
Piedmont  Plateau  and  adjacent 
portions  of  the  southern  Ap- 
Pennsylvania. 
Maryland  and  adjacent  parts  of 
palachians  in  Alabama,  Geor- 
Virginia. 
gia,  Tennessee,  North  Carolina, 
South  Carolina,  and  southern 
Virginia. 
Algonkian  (?): 
Algonkian  (?): 
Cambro-Algonkian : 
Volcanics  of  South  Mountain. 
Volcanic     rocks.     Continu- 
Part of   Ocoee  representing 
Continuous  with  volcanics 
ous  with  volcanics  of  Pied- 
conformable downward  ex- 
of Piedmont. 
mont. 
tension    of   the   Cambrian 
Wissahickon  mica  gneiss. 
Wissahickon  mica  gneiss. 
beneath  now  known  Olen- 
Gneisses  of  Highland  region. 
Plutonic  igneous  rocks — age 
ellus.    Possibly  to  be  cor- 
in part  doubtful. 
related     with     Belt     and 
equivalent    series    of    the 
West. 
Unconformity. 
Algonkian  (?)  (Keith): 
Metarhyolite. 
Andesite. 
Flattop  schist. 
Catoctin  schist. 
Montezuma  schist. 
Linville  metadiabase. 
Fragmental   volcanics   of 
North  and  South  Carolina 
boundary. 
Archean  (?): 
Archean  (?) : 
Archean  (?)  (Keith): 
Baltimore   gneiss    (sedimen- 
Baltimore gneiss  (sedimen- 
tary).    (Corresponds    to 
Granites,    gneisses,    schists. 
tary)  of  Philadelphia  area. 
Largely  unclassified. 
(Corresponds    to    Carolina 
Carolina   gneiss    of    Pied- 
Discriminated    units     are 
gneiss  of  Piedmont.) 
mont.) 
(Keith)  — 
Max  Patch  granite. 
Beech  granite. 
Blowing  Rock  gneiss. 
Henderson  granite. 
Cranberry  granite. 
The  soapstone  group. 
Roan  gneiss. 
Carolina  gneiss  (sedimen- 
tary in  part) . 
Baraboo,  Waterloo,  Necedah, 
and  Sioux  areas  of  Wisconsin 
and  Minnesota. 
Missouri. 
Oklahoma. 
Algonkian: 
Quartzite.  In  the  Baraboo 
district  a  quartzite  is  over- 
lain conformably  by  slate 
and  ferruginous  dolomite. 
Intrusive  granite. 
Unconformity. 
Archean: 
Acidic  volcanics  and  granites 
of  the  Baraboo  district  and 
of  Fox  River  valley  (?). 
Algonkian  (?): 
Iron  formation  of  Pilot 
Knob  and  Iron  Mountain 
and  associated  granite  and 
porphyry. 
Unclassified  pre-Cambrian: 
Granites,  gneisses,  porphy- 
ries, and  gabbros  of  north- 
eastern Oklahoma,  in  Wich- 
ita and  Arbuckle  moun- 
tains of  south-central 
Oklahoma  and  in  Ouachita 
Mountains  of  southwestern 
Oklahoma. 
