254 THE JOURNAL OF (GEOLOGY, 
changes could not have been confined to Scandinavia and the 
Alps. If interglacial and glacial conditions obtained in those 
regions it was obvious that our own islands must have been con- 
temporaneously affected. And the evidence of such climatic 
changes is found, as I think, in the ‘‘Weybourn Crag’”’ and 
‘“‘Chillesford Clay’? and the overlying ‘‘Forest-bed Series” of 
Norfolk—the former containing a well-marked Arctic marine 
fauna, while the latter is charged with the relics of a temperate 
flora, as well as of temperate and southern mammalian forms. 
To what extent Britain may have been glaciated when the Arctic 
shell-beds in question were being deposited we can only con- 
jecture—for the later ice-sheet of maximum glaciation made a 
clean sweep of almost everything. Were it not for the presence 
of these marine deposits there would be no evidence in Britain 
to show that the epoch of maximum glaciation was not the 
earliest of the series. But the existence of a great Baltic glacier, 
of an Arctic fauna in the North Sea, and of enormous snow-fields 
and glaciers in the Alps, implies the contemporaneous existence 
of considerable snow-fields and glaciers in Britain. It may be 
safely inferred, therefore, that the Saxonian stage, or epoch of 
maximum glaciation, was preceded by an earlier but less severe 
glacial epoch (Scanian stage), the genial Norfolkian stage sep- 
arating the one from the other. 
The next succeeding interglacial and glacial horizons have 
long been recognized. It is generally admitted by European 
glacialists that the epoch of maximum glaciation was followed 
by a more or less prolonged interval of genial temperate con- 
ditions. In most glaciated regions the Helvetian stage is repre- 
sented by fossiliferous deposits, which separate the diluvial 
deposits in which they occur into an upper and a lower series. So 
well marked is this division in northern Germany, that long 
before the significance of interglacial deposits dawned upon 
geologists, an upper and a lower Diluvium had been recognized. 
The flora and fauna of the Helvetian stage surely indicate con- 
ditions not less temperate than the present. Indeed, the plants 
occurring upon this horizon in middle Europe imply for the 
