Dr. D, Woolacott—The Interglacial Problem. 63 
Scandinavian Drift a quite friable granite, and decomposed and 
weathered granites occur in other boulder-clays. 
(2) Because of the less Arctic character of the fauna of the shell- 
bearing Kaims when compared with the Scandinavian Drift, 
Dr. Trechmann has suggested that the former were deposited on 
the edge of the Tweed—Cheviot glacier at a later period of glaciation 
than the maximum extension of the Scandinavian ice, an Inter- 
glacial shore-line having been formed during the epoch.t 
Arguments from derived faunas can never be very conclusive, as 
the shells in the Scandinavian Drift may not only have been brought 
from a greater depth than those in the Kaims, but they may also 
be from deposits formed at a different period. It is, however, 
probably from a consideration of the faunas in the different 
Pleistocene deposits in the north-east of England that the surest 
evidence is to be obtained as to whether the Glaciation-interval 
between the deposition of the foreign and British drifts is an Inter- 
glacialone. As the shell-bearing Kelsey Hill deposits 2 appear to have 
been pushed inland at the same time as the Durham Kaims were 
formed, 1.¢. the period when the Tweed-Cheviot and other ice was 
being forced along the coast, a comparison of the faunas in these 
two deposits would be of interest in connexion with this subject ; 
and as there is a possibility that the Sewerby Raised Beach is an 
Interval-deposit, a comparison of its fauna with that of the Durham 
Kaims would be worth considering; indeed, it would be of value 
if complete comparative lists of the faunas of all the Pleistocene 
deposits in Durham and Yorkshire were published and critically 
examined, including the deposits mentioned and the Scandinavian 
Drift of Holderness (which may be of later formation than that of 
Durham), the Bridlington Crag, and the raised beaches of the 
Durham coast. Ifit can be proved that a shore-line with a temperate 
fauna was formed between the deposition of the Scandinavian 
Drift near Castle Eden and the British boulder-clays it would con- 
siderably support the argument for an Interglacial period having 
occurred between these formations. 
In connexion with the material composing the Kaims there is 
one piece of evidence that might have been advanced in favour of 
the view that they belong to a later period of glaciation than the 
Scandinavian Drift, and that is that if a shore-line was formed it 
would have probably contained boulders of Scandinavian rocks 
derived from the basement Drift, and therefore the Kaims should 
contain such rocks. I have never seen any undoubted Scandinavian 
pebbles in the Kaims near Sunderland nor in the Sheraton mounds, 
but Trechmann records “a fragment apparently of a rhomb 
porphyry ” from the latter. It would be of interest to know 
1 Op. jam cit., p. 189. 
* Geology cf Holderness (Mem. Geol. Surv.), 1885, p. 53. 
% Quart. Journ. Geol. Soc., vol. Ixxi, pt. i, 1915, p. 74. 
