7 44 CU oS) 73 owe Instityy~y 
\ 
WOON OF GEOLOGY 
FOING AUGUSTE TSOS 
Tip UolEMRIOK BASIS OE LIME “DIVISIONS AND 
TE CLASSIFICATION OF “GEOLOGIC HISTORY. 
Ir was intimated in the introduction to the symposium on 
the classification and nomenclature of geologic time divisions 
published in the last number of this magazine that the ulterior 
basis of classification and nomenclature must be dependent on 
the existence or absence of natural divisions resulting from 
simultaneous phases of action of world-wide extent. If there 
have been such universal phases and if they can be detected, 
they must ultimately be accepted not only as the true basis of 
division, classification and nomenclature, but their exposition 
must constitute the major work of research and of instruction. 
The most vital problem before the general geologist today is 
the question whether the earth’s history is naturally divided 
into periodic phases of world-wide prevalence, or whether it is 
but an aggregation of local events dependent upon local con- 
ditions uncontrolled by overmastering agencies of universal 
dominance. 
That there were no universal breaks in sedimentation or in 
the fundamental continuity of life is not only admitted but 
affirmed without hesitation. The old doctrine of physical 
cataclysms attended by universal destruction of life has passed 
beyond serious consideration. And so, in the judgment of the 
' writer, have all doctrines which attribute profound effects on the 
life of the globe or the progress of sedimentation to the violence 
of physical disturbances of any kind. That sedimentation has 
Viol Vlg NOs 5: 449 
N54. 
onal Musey 
“Yeats, 
“4 
2390422 
*% 
