THE 
IuURNAL OF GEOLOGY 
EDO) A Ke = VAR GE 1909 
PRINCIPLES OF CLASSIFICATION AND CORRELATION 
OF THE PRE-CAMBRIAN ROCKS?’ 
i 
CHARLES RICHARD VAN HISE 
A half-hour summary of the principles of classification and correla- 
tion of the pre-Cambrian rocks can give no more than the barest 
outline of the subject. 
In the classification and correlation of the pre-Cambrian forma- 
tions we lack the guide of fossils. While life existed in pre-Cambrian 
times, and a few fossils are found in several areas, they are not suffi- 
ciently abundant to serve either for the purposes of classification 
or correlation. How far-reaching this handicap is will be realized 
when this paper is contrasted with those that follow. In considering 
the questions of classification and correlation of the later formations, 
fossils occupy a paramount position. It is true that the faunal breaks 
are often and probably are generally dependent upon physical causes, 
and the latter are frequently considered; but when the determinations 
are made, the fauna rather than the physical factors are given first 
place. 
In the classification and correlation of the pre-Cambrian our sole 
criteria are physical. ‘Therefore we have for the discriminations only 
those guides which for the fossiliferous rocks are commonly regarded 
as subordinate. It follows that with the pre-Cambrian rocks we are 
on less certain ground than with the later formations. However, 
t Read before Section E of the American Association for the Advancement of 
Science, December, 1908. 
Vol. XVII, No. 2 97 
