42 
PRE-CAMBRIAN    GEOLOGY    OF    NORTH    AMERICA. 
Table  of  correlation  of  pre- Cambrian  rocks  of  North  America. 
Lake  Superior  region.     (For  de- 
tailed correlation  see  pp.  328- 
329.) 
Lake  Huron  region.     (For  de- 
tailed correlation  see  p.  443.) 
Rainy  Lake,  Lake  of  the  Woods, 
and  adjacent  territory. 
Algonkian: 
Algonkian: 
Algonkian: 
Keweena  wan     series .     Sedi- 
Huronian series. 
Huronianseries.     Sediments, 
ments  and  intrusives  and 
Upper  Hii- 
mainly   slates    and    mica 
extrusives. 
ro  n  i  a  n 
schists,  with  intrusives  and 
Unconformity. 
(Animi- 
extrusives,  probably  lower 
Huronian  series. 
kie)    of 
11  u  fonian  .       Previously 
Upper  Hu- 
Sudbury 
mapped  in  part  as  "  Cou- 
tchiching"  series. 
ronian 
district". 
Sediments, 
(Animi- 
Uncon- 
with intru- 
kie). 
formity. 
sives    and 
U  n  c  o  n  - 
Sediments, 
Middle  Hu- 
extrusives. 
formity. 
with  intru- 
ronian. 
Middle  Hu- 
sives    and 
U  n  c  o  n  - 
* 
ronian. 
extrusives. 
formity. 
U  n  c  o  n  - 
Lower  Hu- 
formity. 
ronian. 
Lower  Hu- 
ronian. 
TT                 f              •  + 
TTr>f»nnf  (irmitr 
TT                 f               •  + 
U nconiormi i\ . 
\J  I.H_<*J111U1  1111  L  \   . 
u  ncontormit^ . 
Archean: 
Archean: 
Archean: 
Laurentian  series.     Granites 
Laurentian  series.   Granites 
Laurentian  series.    Granites 
and  gneisses,  intrusive  into 
and     gneisses,     intrusive 
and     gneisses,    intrusive 
Keewatin. 
into  Keewatin. 
into  Keewatin. 
Keewatin     series     (formerly 
Keewatin  series.    Thessalon 
Keewatin    series.     Green- 
"Mareniscan").     Green- 
group   (greenstones     and 
stones,  green  schists,  with 
stones,  green  schists,  with 
green  schists,  mapped  by 
some  slate  and  iron.     Pre- 
some slate  and  iron  forma- 
Logan   and    Murray    as 
viously  mapped   in  small 
tion. 
"Huronian' 
slate). 
part  as  "  Coutchiching." 
Northern  interior  of  Canada. 
Original  Laurentian  district. 
Hastings  district. 
Algonkian: 
{Copper  Mine 
River  trap. 
Copper- bear- 
ing series  of 
Hudson  Bay. 
Huronian.  Sediments,  with 
intrusives  and  extrusives, 
as  yet  largely  undifferen- 
tiated from  greenstones 
and  green  schists  of  Ar- 
chean age. 
Unclassified: 
Grenville  series,  consisting 
of  limestones  with  associ- 
ated conglomerates  and 
gneisses  of  sedimentary 
origin;  also  granites, 
gneisses,  and  greenstones 
of  igneous  origin,  at  least 
partly  intrusive  into  the 
Grenville  series.  Prob- 
ably to  be  correlated  with 
Grenville  of  Hastings  dis- 
trict, Adirondacks,  south- 
eastern New  York,  and 
New  Jersey.  Position  too 
doubtful  to  warrant  cor- 
relation with  Archean  or 
Algonkian. 
Unconformity. — 
Archean: 
Laurentian.  Granites  and 
gneisses,  intrusive  into 
Keewatin. 
Keewatin.  Greenstones, 
green  schists,  and  iron  for- 
mation, largely  mapped  as 
Huronian. 
Unclassified : 
Two  unconformable  series, 
the  upper  of  which  (Hast- 
ings), according  to  Miller, 
carries  limestone  and  is 
probably  to  be  correlated 
with  the  Huronian.  The 
lower  series,  also  carrying 
limestone,  is  associated  with 
gneisses  of  sedimentary 
origin  and  granites  and 
gneisses  of  igneous  origin, 
at  least  partly  intrusive 
into  the  sediments.  The 
lower  sedimentary  series 
rests  on  a  basement  of  basic 
igneous  flows  similar  to  the 
Keewatin  of  the  Lake  Su- 
perior region.  This  series 
is  to  be  correlated  with  the 
Grenville  of  the  original 
Laurentian  district.  Mil- 
ler therefore  correlates  this 
series  with  the  Lake  Supe- 
rior Keewatin. 
