242 THE JOURNAL OFVGEOLOGY. 
most cursory acquaintance with the phenomena which they 
sought to explain. That their diluvial notions should have 
appeared reasonable to themselves and satisfactory to their 
disciples, who knew less, need not surprise us. Even in our 
own day we may see how the same doctrines can appeal to one 
who has merely a superficial literary acquaintance with the sub- 
ject. The copious outpourings of Sir H. H. Howorth, if they 
have neither aided nor retarded the advance of glacial geology, 
have at least shown what a large field of profitless labor the 
pseudo-scientific wise men of Gotham have hitherto neglected to 
cultivate. 
Long after the various diluvial hypotheses had been aban- 
doned, and the glacial origin of the so-called Diduvium had been 
recognized, the deposits included under that term continued to 
be lumped together. Certain accumulations in mountainous 
countries, it is true, were believed to be moraines of local 
glaciers, but the ‘‘great northern drift” of the European low- 
grounds was looked upon as iceberg-droppings, and the whole 
diluvial formation was considered one and indivisible. Even 
after the dressed rock-surfaces and bowlder-clays of lowland 
regions had been assigned to the action of glaciers and ice- 
sheets, geologists continued in the belief that the Diluvium was 
the product of one protracted period of cold conditions. Fora 
long time the only classification attempted was the subdivision 
of the drift series into morainic and marine accumulations. No 
one had as yet suspected the existence of what are now known 
as’ interglacial: beds. ~ Some of ‘these, it. 1s) toue, vhad tbeen 
examined and described, but their true relation to the glacial 
deposits had not been recognized. Thus, up to a recent date, | 
geologists—whatever their views might be as to the subglacial 
or submarine origin of the ‘drift’? as a whole—did not doubt 
the unity of the Glacial Period. It was in Switzerland that the - 
true meaning of interglacial deposits was first ascertained. 
Morlot, Heer, and others have put on record the observations 
which led them to conclude that the Alpine Lands have been 
subjected to two successive glaciations—the one separated from 
