DEVELOPMENTS IN PRE-CAMBRIAN STRATIGRAPHY 395 
considering the stratigraphical relations of greater importance than 
all the other criteria combined, the geologists who made the correla- 
tion ignored the possibility of overlap. 
The geological investigations carried on throughout the region 
north of Lake Superior have shown that the rocks classed as Lower- 
Middle Huronian occur here and there throughout the basal com- 
plex as trunkated synclinal remnants, and that relatively their 
areal extent is exceedingly small; and since the total area of the 
rocks which have been differentiated as Keewatin in the region 
south of Lake Superior is only 60 square miles in extent,’ it is 
possible that the stratigraphical relations observed are due to the 
fact that one of these synclinal remnants does not happen to occur 
in this limited area. If this were the case, then the pre-Huronian 
complex to the south of Lake Superior and the pre-Animikie complex 
to the north of the lake would be equivalent, although the strati- 
graphical relations of the Huronian to the south and Huronian 
to the north would be apparently the same. Consequently, 
although the stratigraphical relations of the so-called Lower- 
Middle Huronian of the Vermilion district are apparently similar 
to those of the Lower and Middle Huronian to the south of Lake 
Superior, yet from the consideration of the other facts—that the 
two groups of rocks are lithologically unlike, that those of the 
north are intruded by batholiths of granite and gneiss while those 
of the south are not so intruded, and that the deformation and 
folding in the south occurred long after that in the north—it must 
be concluded that the evidence in favor of their correlation is not 
sufficiently conclusive to preclude the possibility of an alternative 
hypothesis. 
CONCLUSION 
The evidence and the conclusions inferred from the evidence 
as stated in the preceding pages, may be summarized briefly as 
follows: (1) The paleoplains which underlie the original Huronian 
rocks on the north shore of Lake Huron and the Cobalt series in 
the Timiskaming region were originally continuous. (2) The 
complex which underlies the Cobalt series in the Timiskaming 
region and that which underlies the Animikie series in the region 
tU.S.G.S. Mon., Vol. LII, Plate I, 1912. 
