lamplugh: buried cliff at sewerby. 
389 
Inter glacial , as I think the evidence tells strongly towards their 
Pfpglacial age — that is, if the term Preglacial may be applied to 
beds older than the oldest trnly glacial deposit known in East York- 
shire. 
There is this serious difficulty in understanding the stratigraphical 
relations of the beds ; — the boulder clay which rests on the chalk 
or chalk-rubble in the clilf-sections east of Sewerby, has always been 
considered to belong to the lower division of the Purple clay : and 
it is this clay which, as I have recently found, passes down over the 
blown-sands to the foot of the cliff west of Sewerby. But at 
Bridlington Quay a still lower boulder-clay, with well-marked 
lithological and palfeontological peculiarities, known as the Base- 
ment " clay, is seen, and can be traced in the cliff eastward for 
a short distance and then disappears beneath the beach. — Now, these 
bone-beds, though they are undoubtedly older than the Purple clay,, 
are they also older than the Basement clay ? And if so, what has 
become of the Basement clay? Is it entirely absent from our 
section ? 
There is so much slipped ground and obscurity in the cliff 
between Bridlington Quay and Sewerby, that one cannot be quite 
positive that the boulder-clay (3c. of Fig. 2) which overlaps the bone- 
beds is not the Basement clay that has re-appeared, especially since 
boulder-clays in general show such a noble disregard for levels and 
horizons. But 1 do not think this to be the case, and am inclined to 
believe that, if the Basement clay is present at all, it is represented 
by the band of chalk-rubble (4) which also passes down from the top 
of chalk to the shore, thickening very materially as it sinks. This 
rubble seems to have resulted in some way from the action of ice on 
the surface of bare chalk, and its formation may well have been 
contemporaneous with that of the Basement clay on the lower ground. 
This is a point which I hope to elucidate in our next year's excava- 
tions, and I will withhold further comment on it till then. 
Had there been any pre-existing glacial beds in the neighbour- 
hood when the old beach was being formed, they could scarcely have 
escaped erosion, and would have yielded a plentiful scattering of 
erratic pebbles in the ancient shingle just as in the recent beach. 
