U.S.  GEOLOGICAL    SURVEY. 
iOUerl     ~  )\      ^— -"A 
Archean 
Algonkia 
HURONIAN 
a  |        |  Gray  Quartzite 
b  I |  Green  Chlorite  Slate 
c  i        I  Lower  White  Quartzite 
d  I        I  Lower  Slate  Conglomerate 
e  I        1  Limestone 
f  I       I  Upper  Slate  Conglomerate 
MAP  OF  THE  ORIGINAL 
(After  Loj 
Scale   50^ 
