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DR. WOOLACOTT ON THE SUPERFICIAL DEPOSITS, ETC. 



Feb. 



I9°5 = 



area, and although most of them were partly filled up by Glacial 

 deposits, their coarse can be followed from the higher ground. As 

 in the case of the main pre-Glacial valleys of the great Northern 

 Coalfield, they have gently-sloping sides, and thus bear witness to 

 the protracted action of the forces of subaerial denudation. Some 

 of them are called ' Hopes,' and many are dry. Subsequent to the 

 Glacial Period, indeed after the formation of the raised beach, 

 several streams have developed courses, their upper parts being 

 superimposed on the already-existing pre-Glacial valleys, and their 

 lower cutting down through the raised beach and Boulder-Clay 



Pig. 11. — View of Haivtliorn Dene, looking from the sea. 



[Hawthorn Dene is a post-Glacial valley, superimposed on a pre-Glacial one, 

 cut in Magnesian Limestone. Upon this rests Boulder-Clay, overlain by 

 a raised beach.] 



into the Magnesian Limestone. In consequence of the uplift that 

 produced the beach, these streams have in their lower reaches cut 

 deep, gorge-like valleys which are now called ' Denes,' such as those 

 of Ryhope, Hawthorn (fig. 11, above), and Castle Eden (17). 



There is another point worthy of discussion in connection with 

 the superficial deposits of the Northern Coalfield, and that is the 

 widespread occurrence in them of flints. They have been fonnd in 

 the so-called 'raised beach' near Newbiggin, which is either pre- 

 Glacial or Glacial, at the base of the Boulder-Clay near Trow Rocks, 

 also lying above that clay near Newcastle, and in the raised beaches 



