﻿86 DR. WOOLACOTT ON THE SUPERFICIAL DEPOSITS, ETC. [Feb. I905, 



sea-level. This probably indicates the existence of a pre-Glacial 

 valley running towards the centre of the bay, but it has not been 

 found possible to trace the watercourse so clearly as the others 

 already described. Other borings, both north and south of the 

 central area, also show that the solid rock lies below sea-level, 

 for instance, one of — 27 feet on the south and another of — 20 feet 

 on the north ; and all the data indicate a slope towards a medial 

 line, thus proving a distinct pre-Glacial hollow here, with possibly 

 one or two minor associated hollows. The existence, therefore, of 

 a pre-Glacial valley — the ' Druridge ' — at this point seems proven ; 

 but it is not so deep as either that of the ' Tyne ' or ' Sleekburn,' 

 if the borings give us a true idea of its greatest depth, which, 

 considering their number, seems tolerably certain. There is (as 

 proved by borings) a gradual decrease in the maximum 

 depth of the main pre-Glacial valleys as we proceed 

 northward from the Tyne: the pre-Glacial valley of this river 

 being 141 feet below sea-level, that of the Sleekburn 93, and that 

 of Druridge Bay 47. The difference amounts to 90 feet, and the 

 distance is 20 miles. The cause of this may be that the difference 

 in level between the pre- and the post-Glacial rock-surfaces is 

 possibly not so considerable in the north as in the south of the great 

 Northern Coalfield ; or, as seems more likely, the streams that 

 produced the northern valleys of the ' Sleekburn ' and ' Druridge ' 

 Bay were tributary to the Tyne, and hence their valleys were not 

 cut so deeply as the major one. 



The upper part of the Coquet Valley above Bothbury had been 

 developed before the Glacial Period, and as the valley running into 

 Druridge Bay is in a direct line with this one, we may conclude 

 that the Coquet prior to that period ran along the valley which we 

 are at present considering, and entered the sea about 4 miles to 

 the south of its present mouth. It is impossible to determine this 

 point exactly by borings, but the exposures of rock and the lie of 

 the Boulder-Clay prove it. The lower reaches of the Coquet, from 

 above Brinkburn to its present mouth, are of post-Glacial develop- 

 ment, since along this portion of its course the river cuts into solid 

 rock at several places, and turning northward it eventually reaches 

 the sea at Warkworth, after a meandering course over rock and 

 Boulder-Clay. 



The map of Druridge Bay 'and the neighbourhood, showing the 

 lie of the rock-surface as obtained by the borings, and the 

 exposures of rock, brings out very clearly the evidence for the 

 existence of a pre-Glacial valley at this point (fig. 9, p. 85). 



VI. General Remarks. 



Between Blyth and Seaton Sluice is a stretch of coast-line, 

 about 2 miles wide, formed of Boulder-Clay ; and on cursory ex- 

 amination it might appear that there was another pre-Glacial valley 

 here, similar to those of the ' Sleekburn " and ' Druridge.' The rock- 

 surface certainly slopes towards a centre, and it might be argued 



