LAMPLl iJII : LAND-SHKLLS IX INFRA-KLACIAL CHALK-RUIJBLE. 95 
One point of consequence in the occurrence of the land- 
shells now found in the chalk-rubble is that their position on 
the shore is several feet below the level of the ancient beach, 
and furthermore that the bed in wliich they are enveloped is 
known to descend at least 25 feet lower than this level,* and is 
probably prolonged to a still greater depth. We thus obtain 
definite proof that an elevatory movement, already postulated 
on less direct evidence.! has followed the stage of slight 
depression marked by the Sewerby Buried Cliff. 
Another point of great interest is the close correspondence 
which can be now established between the Infra- (or pre-) Glacial 
beaches of South Wales, as described by ^Ir. R. H. TiddemanJ ; 
of County Cork, recently discovered by Messrs. Muff and 
Wright §; and of East Yorkshire. In eacli case the old beach 
is covered by blown sand, and then by a wash of local rubble 
or " head," and the whole series hidden under boulder-clay ; and 
in each case there is proof of some degree of elevation before 
the invasion of the country by ice. 
The presence of the flints and of occasional extraneous 
fragments, and especially of the grit boulder, in the chalk- 
rubble, together with the extraordinary poverty of the fauna 
(if, indeed, this be not merely an accident of preservation), 
point to the likelihood that the ice-margin was already not far 
distant from the neighbourhood when the bed was being formed. 
We have still much to learn about the succession of events 
during the early stages of the Glacial Period in England ; and 
therefore every little glimmering fact that may aid in dispeUing 
the obscurity has its value. 
* Proc. Yorks. Geol. and Polytec. Soc, vol. xi., p. 284. 
t " Drifts of Flamborough Head," op. cit., p. 410. 
; Rep. Brit. Assoc. for 1900 (Bradford), pp. 760-702. 
§ Rep. Brit. Assoc. for 1903 (Southport). 
