TROL EOTARAIN AGHEA CRATE LOEAZO SU T:S). 253 
which of the glacial accumulations represented the epoch of 
maximum glaciation. Here, fortunately, there was no difficulty. 
For many years geologists have agreed that the lower bowlder- 
clay of Britain and the corresponding lower diluvial accumula- 
tions of the Continent are the products of the epoch of greatest 
cold. It was not going beyond the limits of cautious induction 
to infer that the epoch of maximum glaciation in northern 
Europe must have been contemporaneous with the same epoch 
in the Alpine Lands and other mountainous districts on the 
Continent. Nothing, I should think, can be more probable than 
that the diluvial accumulations of the most extensive Scandina- 
vian mer de glace, which advanced into Saxony, must be on the 
same horizon as the moraines of the outer zone at the foot of the 
Alpine Lands. We may consider the Saxonian, then, a well- 
determined horizon. The next step was to ascertain what 
relation the deposits of that stage bore to other glacial accumu- 
lations. In Britain we have long heid that our lower bowlder- 
clay is the product of the first and greatest glacial epoch, for 
hitherto no older deposit of the kind has been recognized in 
these islands. But although that be true for Britain it is not so 
for Scandinavia. In southern Sweden a still older bowlder-clay 
exists—the groundmoraine of a former great Baltic ice-sheet, 
which overflowed Scania from southeast to northwest—a direc- 
tion at right angles to that followed by the mer de glace of maxi- 
mum glaciation. Again, in the Alpine Lands, as Professor Penck 
and his coadjutors have shown, the epoch of maximum glacia- 
tion was similarly preceded by a yet earlier ice age of very con- 
siderable severity—the glaciers descending to the low grounds, 
but not flowing so far as those of the glacial epoch that followed. 
Further, it has been ascertained that between the groundmoraines 
of those two successive epochs there intervene fossiliferous 
deposits—the plants of which denote a much more genial 
climate than is now experienced in the valleys of the Alps. 
Moreover, the amount of contemporaneous’ valley-erosion 
demonstrates that this interglacial stage was one of prolonged 
duration. It was only reasonable to infer that such climatic 
