﻿Vol. 6 1.] OP THE NORTHUMBERLAND AND DURHAM COALFIELD. 91 



are the Druridge, Whitley, and Whitburn Bays, those at the 

 end of the ' Sleekburn ' and Tyne Valleys, and that south of Blyth. 

 In between these, which are very distinct features of the coast, the 

 sea-front is formed of rock generally capped by a* thin covering of 

 Boulder-Clay. 



The escarpment of the Magnesian Limestone, which runs through 

 County Durham from South Shields to Pierce Bridge, would in 

 pre-Glacial times be much more pronounced than at present (fig. 10), 

 as many of the inequalities of the country lying to the west have 

 been masked by superficial deposits. The triangular patch of 

 country between this line and the sea is not so thickly covered by 

 Boulder-Clay as the surrounding district. The steep, but not very 



Fig. 10. — Section across the Fulivell Valley, from Corny Hill, 

 South Shields, to West Boldon. 



100 200 300 400 FEET 



VERTICAL SCALE 



S.S. = South Shields; H. = Harton Colliery ; B. = Bold on Colli ery ; W.B.=West 

 Boldon; 1 = Coal-Measures ; 2=Perrnian Yellow Sands, Marl-Slate, and 

 Magnesian Limestone. 



[The above section shows clearly that the Permian escarpment must have been 

 much more pronounced in pre-Glacial times than it is now.] 



high escarpment, seems to have acted as a barrier to the passage of 

 the ice from the west and north ■ a similar phenomenon is, I under- 

 stand from Prof. Watts, observable in the ice-sheets of the present 

 day. In pre-Glacial times the escarpment seems to have been 

 broken through only between Fulwell and Cleadon Hills, and since 

 then the Wear Valley alone has been cut through it (PI. IX). 



Even before the Glacial Period, the drainage of this eastern part 

 of the county of Durham was quite distinct from that of the west. 

 One or two obsequent streams flowed down from the Magnesian- 

 Limestone escarpment into the Wear between Bishop Auckland and 

 the city of Durham, and they have their counterpart at the present 

 day ; but the main drainage was carried eastward along the dip- 

 slope of the Permian rocks. A number of small streams flowing in 

 that direction appear to have denuded a series of valleys in this 



