﻿Vol. 6 1.]. OF THE NORTHUMBERLAND AND DURHAM COALFIELD. 



85 



and Blyth (with its tributary the Sleekburn), all of them post- 

 Glacial, having cut their way through rock or Boulder-Clay since 



the„Iee-Age. 



(e) The Druridge-Bay Depression. (Fig. 9.) 



The Boulder-Clay is exposed along the coast for about 4 miles in 

 Druridge Bay. This would seem to indicate the presence of 



Pig. 9. — Map of the ' Druridge Valley? 



DRURIDGE 

 BAY 



[The height of the rock-surface above, or its depth below, sea-level is 

 indicated at the various points at which it has been ascertained by borings. 



The shading indicates those parts of the country where the rock comes 

 to the surface ; the other parts are occupied by superficial deposits. The 

 arrows indicate the probable direction of the pre-Grlacial valleys. 



The position of Acklington and Widdrington illustrates the fact, that a 

 great number of the villages in Northumberland are built upon masses of 

 sandstone which rise above the level of the surface-deposits. 



The relation of the post-Glacial Coquet to the p re-Glacial valley is 

 clearly elucidated.] 



another valley of pre-Glacial origin ; if, however, one does exist 

 here, it must be broad, but not very deep. There are two borings, 

 one about a mile, and the other 2 miles from the coast, and in a 

 direct line with the centre of the bay, which prove the rock-surface 

 to lie at depths respectively of 45 and more than 47 feet below 



