THE SUBPROVINCIAL LIMITATIONS OF PRE-CAMBRIAN 
NOMENCLATURE IN THE ST. LAWRENCE BASIN 
M. E. WILSON: 
Canadian Geological Survey, Ottawa, Canada 
INTRODUCTION 
The detailed geological work carried on in recent years through- 
out the southern part of the Canadian pre-Cambrian shield has 
shown that the geological succession in the ancient terranes of this 
territory is regionally less uniform and includes a greater number of 
rock series than was formerly supposed. Moreover, it has become 
evident that the widespread correlations implied by the use of the 
same nomenclature nearly everywhere throughout this great pre- 
Cambrian province assumes much more with regard to the regional 
succession in these ancient rocks than is actually known. 
Although it is not possible generally to demonstrate with 
mathematical conclusiveness that geological formations occurring 
in different localities are equivalent, nevertheless the premature 
use of the same name for formations, the correlation of which is 
open to question, or the continued use of the same name for forma- 
tions after it has become evident that their correlation is in doubt, 
is misleading, and is an obstacle rather than an aid in geologi- 
cal investigation. Hypothetical correlations of groups of rocks 
occurring in widely separated districts may serve for comparison 
or as a stimulus to investigation, but all the advantages of such 
tentative correlations may be attained by using a general ter- 
minology (Proterozoic, Archaeozoic, etc.) and thereby avoiding the 
definite correlations implied in the use of names of local origin. 
In the pre-Cambrian province which occupies the northern part 
of the St. Lawrence River basin there are four geographically and 
geologically separate subprovinces: (1) the region northwest of 
‘Published with the permission of the Director of the Geological Survey of 
Canada. 
