286 LAMPLUGi: : glacial sections near Bridlington. 
wliich stripped away the shingle off the shore, and washed a clear 
section at the base of the cliff (too soon again obscured), I was able 
to carry the lines across this region of difficulties, and to emerge with 
them clear on the other side where it is comparatively easy-going. 
As I now read the section in this space the Upper and Lower 
divisions of the Purple Clay come together, owing to the fading out 
of the intermediate gravel, and these form the Upper Clay at Sewerby. 
The laminated clay below the Purple Clay thins out or passes into a 
contorted mixture of chalky gravel and stratified Boulder-clay, and 
the Basement, with some local change in character, and especially in 
the nature of its inclusions, which become chiefly sub-angular, chalky 
rubble rises into the cliff foot as we approach Sewerby, and finally 
mounts to the top of the chalk by a long slope, whereon it is seen to 
over-ride, and partly to inosculate with the thick chalk-rubble which 
lies over the Buried Cliff-beds and over the solid chalk ; and it is clear 
now that the lowest Boulder-clay between Sewerby and Danes Dyke, 
seen in section, at heights varying from 30 to 80 feet above sea level, 
is the Basement Clay. At Danes Dyke, the cliff intersects a pre- 
glacial valley, which has been filled in with a great accumulation of 
glacial sand and gravel, and afterwards partly re-excavated, a feature 
observable at several other places on the headland. On the west 
side of this valley the Boulder-clays thin away into narrow bands, 
and the greater part of the drift consists of gravels, some chalky, 
and others chalkless, or nearly so, but on the east side we are able 
again to recognize the Basement Clay, and to follow it without 
interruption for another mile, to the South Sea Landing, where again 
the phenomenon of a buried pre-glacial valley presents itself. The 
section at this point becomes very complicated and difficult to corre- 
late, but the opportune discovery last summer of a seam of greenish 
sand with glacial shells in a band of Boulder-clay on the further 
side of the hollow, not only yielded the needed clue, but confirmed 
beyond doubt the presence of the Basement Clay in these cliffs. 
The fossiliferous sand occurs as a narrow contorted streak, surrounded 
by a few inches of fine plastic clay, in which the original bedding is 
nearly obliterated by the numerous planes of shearing, the whole 
being embedded in a narrow band, at this point six feet thick, of 
