﻿96 SUPERFICIAL DEPOSITS OF THE NORTHERN COALFIELD. [Feb. I905, 



below Ordnance-datum, while borings in the immediate neighbour- 

 hood reached it at a considerably smaller depth ; the other, a wide 

 and open type, was represented by the Vale of York, the rock-floor of 

 which some 8 or 10 miles south of York would have a breadth 

 of several miles at the contour of 50 feet below Ordnance-datum. 

 In calling attention to this wide pre-Glacial valley beneath the 

 Yale of York, the speaker desired to point out that, from its form, 

 it must be an ancient valley, and must have required a prolonged 

 period for its excavation, during which the land stood at a higher 

 level than at present. 



The Author had mentioned that several of the pre-Glacial valleys 

 of Northumberland were apparently shallower near their mouths 

 than they were inland, and the same was the case in Yorkshire, 

 there being no records of any deep channel connecting the Vale of 

 York or the Barnby-Dun Gorge with the sea, although a large 

 number of records existed of boreholes (both in the neighbourhood 

 of the Humber Gap and also in the town of Hull) ; while farther 

 south, the solitary cutting through the barrier formed by the Oolite- 

 escarpment was Lincoln Gap, where the rock-floor lay at a depth of 

 only 23 feet below sea-level. 



With regard to the question of raised beaches, as pointing to a 

 post-Glacial uplift of the coast-region, the only available evidence 

 in Yorkshire was the pre-Glacial beach at Sewerby, which was now 

 at sea-level, and could not therefore be correlated with the great 

 depression of the Vale of York. 



In conclusion, the speaker enquired whether the valleys which 

 the Author had described were of the broad or narrow type. 



The Author expressed his thanks for the manner in which his 

 paper had been received. In reply to Capt. Dwerryhouse, he said 

 that the pre-Glacial valleys were all broad, the Tyne being 2 miles 

 wide at sea-level near its outlet into the North Sea. The difficulty 

 of the slope of the rock-surface of the Tyne not being uniformly 

 eastward, might be explained either by the borings not being made 

 in the middle of the valley ; or, more probably, by the fact that 

 there had been differential movements since pre-Glacial times. The 

 main conclusions drawn from the study of the pre-Glacial valleys, 

 namely: (1) that the land stood higher in pre-Glacial times, and 

 (2) that the valleys were produced by a series of eastward-flowing 

 streams — seemed to the Author indisputable. 



