LAMPLUGH : GLACIAL SECTIONS. 
395 
It is noteworthy that the distortion is greatest under the 
marls ; that is, where the clay and gravel lie lowest ; as already 
mentioned, in proceeding northward the disturbances cease when 
a higher level is reached. This, combined with other evidence, I 
think suggests a lacustrine origin for the force movements on 
the frozen bottom of a shallow lake perhaps. 
That an extensive lake, or more probably an extensive series 
of lakelets with marshy ground between, once existed over the 
site of Bridlington, and extended for some distance southward, 
has been abundantly demonstrated during the drainage works in 
the town ; such conditions were once common to the whole of 
Holderness — the "mershe countree," as Chaucer calls it — and 
lasted from an indefinite period almost up to the present time ; a 
state of things brought about, not only by the low level of the 
district and the hummocky irregularity of its surface, but also, I 
believe, by the former existence of higher ground between it and 
the sea. This ridge made up of glacial beds, would form a drift- 
barrier, such as still dams up the seaward edge of the Vale of 
Pickering and throws back its drainage into the Humber, and such 
as we have indeed nearly all along the coast north of Flambro', 
even on the top of the highest Speeton Cliffs. The former exis- 
tence of this rim is, I think, indicated by the slope of the ground 
along the Holderness Coast, which is nearly always from the sea ; 
thus causing the drainage of Holderness to flow inland, and finally 
empty itself into the Humber. The high ground still remaining 
at Dimlington and at one or two other points on the coast, I look 
upon as the last remnants of this barrier. 
Lacustrine and marshy conditions would in this case date 
from the close of the glacial period ; and at that time volumes of 
water were probably pouring down all the wold valleys, scooping 
and deepening them — clearing away from them the relics of the 
hard times past, and spreading their burden of chalky gravel over 
the low land — bearing often it may be, huge masses of ice and 
urging forward rough blocks of frozen gravel, to be crushed and 
