THE LAST DECADE. 
405 
glacial clays, is evidence that an exposed chalk surface existed in the 
neighbourhood during the deposition of the boulder clays. 
In the third paper Mr. Lamplugh records the facts observed 
during the deep drainage of the town, and illustrates the geology of 
the town-site by giving actual sections as noted along extended 
lines of streets in various directions. These drawings, owing to 
their great length as compared with their depth, he was obliged to 
print on a scale reduced liorizontally to one-third of that of the 
previous sections, but the vertical scale remained unaltered. 
Mr. Lamplugh gave a summary of his previous work, and made 
a geological map of the town and its surroundings, to a scale of 
six inches to one mile. This map was reproduced in colours by the 
Society. In these concluding notes views are stated as to the origin 
of the beds, dealing more especially with the gravel and other deposits 
newer than the boulder clay. Reasons are given for believing that 
the ' Bridlington Gravels,' (certain rough gravels on the north side of 
the town), the * Sewerby Gravels,' (finer gravel, well seen in the cliff 
opposite Sewerby), and the * Hilderthorpe Sands,' (the sand and warp 
series lying south of the harbour), were contemporaneous deposits, 
the results of a strong current issuing from the main Wold Valley 
that here debouched either into a lake or estuary, more probably the 
former ; and the term Bridlington Series, is proposed to include the 
whole of these deposits. 
The view is put forward that the great flow of water down the 
valley during the deposition of -this series, as compared with the 
insignificant stream now running there, might be due not only to a 
greater rainfall, but also to the surface layers of the chalk, being 
saturated and frozen, and thus forming an impervious subsoil that 
shed the rainfall rapidly into the valley." 
An idea is given of the state of the neighbourhood during the 
deposition of the 'Bridlington Series' as a region of bleak frozen 
chalk wolds, silent and deserted, and deeply covered by snow in 
* This theory has been considerably strengthened by observations made 
by the Rev. E. Maule Cole during the winter of 1887, when the conditions 
required actually obtained on the Wolds, and resulted in floods. (See Proc. 
Yorksh. Geol. and Polyt. Soc, vol. ix., pt. iii., p. 343). 
