LAMPLUGH: GLACIAL SECTIONS. 
251 
section just beyond the South Pier (shown in Part II., fig. 1) ; and 
in this way there may have been a connection with the similar hollow 
seen in section near Sands Cottage on the north of the town. 
It is thus that I would account for the low level gravels, 2a, of 
the sections. 
There remains now to be considered the high-level series of 
Bridlington and Sewerby, with their supposed extension, the Hilder- 
thorpe Sands. 
We may safely assume that the formation of these beds followed 
very closely on glacial times, if indeed, not themselves actually 
glacial, for it is an open question whether they were not, in part 
at least, contemporaneous with the Boulder Clay.* This allows us 
as the period for their formation the time of storms and melting ice, 
when the yield of water from the valley would attain its maximum, 
and the whole of the low country might be flooded to a considerable 
depth; for the dam of Glacial Clays across the mouth of the valley 
at that time reached higher levels than at present in its extension 
seaward, and not only stemmed back the flood, but also may have 
diverted into it part of the drainage of the Bempton Valley. 
The effect of this would be to create a wide lake with strong 
currents, between the Wold slope and the coastwise glacial bar, in 
which the swift flood-waters, stayed in their course, would rapidly 
throw down their burden in the order that we find it, the rough 
sub-angular gravels at the lower levels near the mouth of the valley 
where the torrent was first sta,jed (the Bridlington Gravels), the 
smaller gravel carried forward and banked against the gentle slopes 
of Boulder Clay at the curvef ( the Sewerby Gravels J, and the finer 
material deposited from the eddying waters after sweeping into the 
lake, J as crossbedded and ripple-marked sands and warps (the 
Hilderthorpe Sands). 
* Mr. J. R. Dakyns supra, cit. 
t For the supposed effect of the ice-laden currents on the slopes near the 
curve, see conclusion to Part I. of this paper in Yorks. Geol. and Polyt. Soc, 
1881, p. 395, et seq. 
X I should expect the same results if the level of the sea at this time stood 
high enough to form an estuary at this spot, but the evidence is against the sea 
being higher than at present and favours the view that it was lower. 
