62 Dr. D. Woolacott—The Interglacial Problem. 
generally agreed by European glaciologists, who accept a series of 
Interglacial periods, that the time of maximum extension of the 
Scandinavian ice or Second Glacial Epoch (Saxonian, J. Geikie) was 
contemporaneous with extensive glaciation in Hngland.! This 
difficulty does not occur if the loess deposit is an “‘ Interval-deposit ”’ 
marking an “ Interval-in-the-Glaciation ”’, and I submit that while 
appreciating the strength of Dr. Trechmann’s argument and 
admitting that his work has added considerable interest to the 
study of the glaciology of the north-east of England, until the 
evidence is more conclusive in the face of this difficulty it is better 
to regard it as such than as an Interglacial formation. 
The evidence for an “ Interval-in-the-Glaciation ’’ between the 
Scandinavian and the British Drift is founded on (1) an 
Interval-deposit of loess, with its decalcification and the weathering 
of contained rocks, (2) the possible formation of a shore-line from 
which jthe shell-bearing materials of the Kaims were derived, and 
(3) the possible erosion of valleys in the interval. I propose to 
discuss this evidence briefly :— 
(1) While admitting that the deposit at Warren House Gill is 
true loess and that it is an Interval-deposit of considerable interest, 
it may be doubted whether an Interglacial period is necessary to 
account either for its occurrence or the formation of concretions 
in it or the weathering of the contained boulders. Dr. Trechmann 
states that loess was formed on the edge of the advancing 
Scandinavian ice-sheet and was overridden and incorporated with 
the Drift.2 May not therefore the deposit at Warren House Gill 
have been formed on the margin of the ice-sheet, before the oncoming 
of the British ice on to the area? If so, it does not seem to demand 
a prolonged Glaciation-interval to account for its occurrence. 
I have noticed in the local drifts (and some years ago carefully 
examined) small pockets and spreads of finely divided material, 
which I have always regarded as the silt of glacial streams, and 
it seems possible to me that this deposit of loess was formed on the 
edge of the ice-sheet from the rock-flour carried off by waters from 
the margin of the ice.2 From my observations of the quickness with 
which certain processes may take place, the decalcification of the 
loess and the formation of concretions in it, while strengthening 
the argument for an Interval of some duration, do not necessarily 
imply an Interglacial period. Decomposed boulders in the loess 
are also evidence in favour of an Interval, but again are not con- 
clusive proofs of an Interglacial period. JI have obtained from the 
that the glacial deposits of North-East England will have to be critically re- 
examined if an Interglacial epoch between the Durham Scandinavian and the 
British Drifts is accepted as proved. 
1 J. Geikie, Great Ice Age. 
2 Op. jam cit., Quart. Journ. Geol. Soc., 1920, p. 176. 
3 J. Geikie, Address to the Geol. Section of the Brit. Assoc., Newcastle, 
1889, p. 19, where a similar view of the origin of the loess is given. 
