GEOLOGY 



FROM the mouth of the Tyne to that of the Tees the county of 

 Durham is bounded by the sea, and the long coast-line is for the 

 most part one of fine and instructive cliff-sections. This coast- 

 line forms the broad base of the rough triangle in which the 

 county is shaped. The apex of this triangle is situated among the high 

 hills of the Pennine range to the west not far from Cross Fell. From 

 this point the northern boundary follows generally the valleys of the 

 Derwent, Stanley Burn and the Lower Tyne ; and the southern limit is 

 practically the River Tees from Crook Burn, near Caldron Snout, to the 

 sea. From the Pennine highlands to the coast about midway between 

 Tyne and Tees the valley of the Wear, somewhat irregular in its trend, 

 divides the entire area into two fairly equal portions, one northern and 

 one southern, whilst the tributaries of the three main rivers, most of 

 them deeply sculpturing the surface, afford numberless exposures by 

 means of which an insight into the rocky structure of the region may 

 be readily gained. Here, as elsewhere, it is this structure which has 

 determined the main topographical features. Thus the highest ground, 

 to the west, consists of the hard rocks of the Lower Carboniferous Series, 

 the comparatively low ground between Gateshead and the Aucklands is 

 occupied by the outcrops of the less resisting Coal Measures, and the 

 bold, though not very high, undulating country which fringes the coast 

 as far south as the Hartlepools is due to the remarkable development of 

 the Permian Magnesian Limestone in that district. The low, red- 

 soiled country between Darlington and Seaton Carew owes its soft out- 

 lines and striking colour to the easily crumbled salt-bearing strata of the 

 Upper Permian and Trias. 



There are thus four topographical and geological regions in Dur- 

 ham equally distinct as to surface features and vegetation, as to their 

 stratigraphical constituents, and, one may add, also as to the chief occu- 

 pations which are followed within them. They may be briefly defined as 

 follows : — 



A. The Lower Carboniferous Region, including the upper vale of 

 Derwent as far as Shotley Bridge, Weardale as far as Witton-le-Wear, 

 and Teesdale as far as Piercebridge. This is the lead mining country. 



B. The Coal Measure Region, including the lower portion of the 

 Derwent Valley, the whole of the Team Valley, and the valley of the 

 Wear from Witton-le-Wear, past Durham and Chester-le-Street to Clax- 

 heugh. This is the chief coal district. 



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