Northumberland and Durham. 11 



Coquet, near that river's junction with the sea, and bounds the coast 

 of Northumberland in a south-south-eastern direction for 23 miles. 

 It then crosses the mouth of the Tyne ; after which the magnesian 

 limestone begins to cover a part of it, and continues to intrude more 

 and more upon it until both approach the Tees. The distance from 

 South Shields to Cockfield is 32 miles in a south-westerly direction. 

 The western side of this district cannot be so easily defined, since 

 many of the lead-mine measures strongly resemble those of the coal- 

 field ; but when the Mill-stone grit (a coarse-grained sandstone so 

 called) and the Blue Encrinal limestone, are seen cropping out, one 

 may then be sure that the boundary of the coal formation is passed. 

 However, if a line be drawn from the vicinity of Aldington on the 

 Coquet, to cross the Tyne at Bywill, the Derwent near Allansford, 

 and the Wear below Wolsingham, and to terminate at Cockfield, a 

 tolerably correct idea may be formed of its western limits. 



This district is characterized by low round-topped hills, which rise 

 gently from the sea, and increase in height towards the west. Pontop 

 pike, situated on the Derwent, not far from the western boundary of 

 the coal-field, is reckoned by Mr. Fenwick of Dipton, to be very near 

 1000 feet high, and a pit sunk near the summit proves that it cannot 

 be much less. That part of Newcastle Leases which lies close to 

 Spring Gardens, and the western turnpike gate, is ascertained to be 

 190 feet above the level of the Tyne, and 205 above the sea. Ben- 

 well hills to the west, and Gateshead Fell to the south, are some- 

 what higher. 



The inequality of the surface does not affect the dip or inclination 

 of the coal measures ; and when they are interrupted or cut off by 

 the intervention of a valley, they will be found on the sides of the 

 opposite hills at the same levels, as if the beds had been continuous. 

 Thus the Grindstone bed may be seen on Byker Jhill, Gateshead 



b2 



