248 
LAMPLUGH: GLACIAL SECTIONS. 
in this direction to its head beyond Helperthorpe, a total length of 
about 21 miles. The hills which surround it rise to a height of from 
200 to 600 feet above the sea level. 
Nearly the whole of its drainage area is bare chalk, and the 
porous nature of that rock which absorbs all the rain that falls on it 
and prevents surface drainage, causes the quantity of water now 
coming" down the valley to be extremely insignificant. The upper 
half of the valley is practically dry ; whilst the stream, the Gypsey 
Race, which commences at Wold Newton and flows to Bridlington 
is, in ordinary winters, a mere brook, and in dry seasons ceases to 
flow at all. 
But that this has not always been the condition of things is 
clearly shown, not only by the thick and widespread gravels which 
now cover the bottom of the valley, but, indeed, by the very fact 
that there is a valley at all, for its features show that it must be in 
some degree the result of running water, and at present there is 
absolutely no erosion (save chemical) going' on in it, the Gypsey 
now everywhere flowing over its old gravel and nowhere over bare 
chalk, the water in it barely sufficing to keep its own channel clear. 
Yec if we could imagine that, from one cause or another, the surface 
of the chalk were rendered impervious so as to shed the moisture 
descending' on it, the ' dry bones ' of the valley would live again ; 
and we should, even with the present rainfall, soon have a respect- 
able river coursing along its bottom and swooping' down into the 
Holderness country in the open light of day, instead of, as at 
present passing silently underground into the sea. 
At one time 1 was inclined to beheve that the chalk might have 
been rendered impervious during glacial times by a waterproof 
covering of drift-clays, of which it might since have been denuded. 
But the evidence for the passage of ice over the higher Wolds is so 
slight, and on the other hand, the proofs of an ice-flow, glacier or 
floating ice, skirting the coast, partially over-riding the headland of 
Flambro', and then passing along the inner edge of the Wold, are so 
strong, that I am now disinclined to entertain any view which 
necessitates the complete submergence of the district beneath land- 
ice. 
