PRECAMBRIAN STRATIGRAPHY 
57 
mentation. They are now so widely known, so well determined, 
and so numerous that they become prime values in the sys- 
tematic arrangement of the strata. For purposes of wide and 
exact stratigraphic correlation they far surpass any service that 
fossils might perform. 
That the primary subdivisions, here designated as Proterozoic 
and Archeozoic, each have eral rank in the general scheme of 
terranal classification rather than periodic or serial position 
as they are often assigned, is amply supported by many con- 
siderations. Laying down of a few miles’ thickness of strata 
which each of these divisions represents is surely a time equiva- 
lent of that of any known Paleozoic section in the world. The 
transcontinental unconformity which marks the base of both 
of these divisions certainly represents diastrophic revolution 
of the first magnitude, and movement greater than that which 
characterizes any other recognized eral division. In the rela- 
tive degree of metamorphism which the several divisions dis- 
play in the same vertical section is indicated also something 
of a time measure. Of less taxonomic importance is the com- 
parative amount of deformation exhibited. 
The lesser subdivisions 1 which have been recognized in various 
regions under geographic designations as formations hold only 
a transitory taxonomic tank. In place of tens or hundreds of 
feet their thicknesses are often measured in thousands of feet. 
In the majority of cases doubtless these terranes will be found 
actually to possess the rank of provincial series, and to permit 
of further subdivisions into formations, that are comparable 
to those commonly defined among the Paleozoics. 
For classificatory purposes the fossils of the Pre-Cambrian 
rocks, no matter how plentiful they may occur, are not likely 
ever to prove so important as they have in connection with 
the Post-Cambrian strata. Notwithstanding the facts that or- 
ganic remains have been discovered in both great sections of 
Pre-Cambrian elastics and that they will be doubtless disclosed 
in more or less abundance throughout the entire succession, the 
W'arennesic, as a periodic title, was' proposed (Proc. Iowa Acad. Sci., XXI, 
201, 1914) to take the place of A. C. Lawson’s name Ontario, which was 
preoccupied. It is the old French designation of Ontario Province. It is 
probably not co-extensive with the term Loganian Series, which a few 
months after Varennesic was proposed, was- adapted for the same purpose 
by Miller and Knight (Rept. Ontario Bureau of Mines, XXII, pt. II, 127, 
1914). 
