326 M. E. WILSON 
Lake Superior, (2) the region south of Lake Superior, (3) the region 
extending northeastward from Lake Superior and Lake Huron to 
Lake Timiskaming and Lake Mistassini, and (4) eastern Ontario 
and the lower St. Lawrence, with which might be included the 
Adirondack region. With the possible exception of some of the late 
pre-Cambrian series occuring in the Lake Superior and the Timis- 
kaming subprovinces, the evidence upon which the rocks of these 
separate regions can be correlated is exceedingly meager, and for the 
present, at least, the only logical course would seem to be to build 
up a separate nomenclature in these various subprovinces by using 
those names already defined in these localities, supplemented by 
such local new names as become necessary from time to time as 
geological investigation is continued. 
OBJECTIONS TO AN INTER-SUBPROVINCIAL NOMENCLATURE 
The widespread correlations implied in the use of a common 
nomenclature throughout all the pre-Cambrian subprovinces of the 
St. Lawrence basin has been based on the assumption that the 
succession of formations within the various subprovinces has been 
worked out to practical completeness, and on the application of 
certain principles by which the correlation of the various formations 
in these widely separated areas is presumed to be established. The 
purpose of the following discussion is to point out that the assump- 
tion that our knowledge of the succession of formations in any of 
the subprovinces is complete is open to question and that the 
principles by which pre-Cambrian rocks are generally correlated 
are in part inapplicable and as a whole quite inadequate for the 
establishment of a pre-Cambrian nomenclature embracing all the 
territory in the St. Lawrence basin in which pre-Cambrian rocks 
occur. 
OUR KNOWLEDGE OF THE SUCCESSION OF FORMATIONS IN THE 
SUBPROVINCES INCOMPLETE 
The numerous regional classifications of the pre-Cambrian 
rocks of the St. Lawrence basin which have appeared from time to 
time in recent years, and the use of such terms as Keewatin, Lauren- 
tian, and Huronian nearly everywhere throughout this great pre- 
