HISTORY OF THE BROWNEY VALLEY 455 



Round this head swept two other ice streams from the 

 north-west, clearly defining the southern and northern limits 

 of this Durham glacier, the southern occupying most of 

 Teesdale, and the northern Tynedale. Thus the enclosed 

 fan-like area was wholly covered by local ice. All three 

 streams moved at first from west to east, from the range of 

 the Pennines to the North Sea. This Durham glacier has left 

 us an important deposit in the moraine of Hawthorn Dene ; a 

 travelled stone belonging to which I described at a Tyneside 

 Naturalists' Field Club meeting at Ravensworth Castle in 

 May^ 1879, and an account of which appeared in the Trans- 

 actions of that year. The mouth of the Dene is even yet 

 choked by materials brought from the west of our county, 

 just as the morainic and other deposits of the two bounding 

 glaciers are equally distinguished by the Shap granites in the 

 one case and by the Crififell granites in the other, mingled of 

 course in both cases with materials from our own western 

 uplands. 



The ice that invaded Durham county from outside came 

 from three distinct quarters, and at three distinct times, 

 dependent perhaps upon distance. In any case the nearest 

 came first, namely, that from the mountainous north-west, 

 by the valley of the Eden over Stainmoor and down into 

 Teesdale ; whilst another branch from South-West Scotland 

 came simultaneously, as the Solway stream of ice, over the 

 track of the present Carlisle and Newcastle railway, roughly 

 in the line of the great Roman Wall, till joining the glacier 

 of the South Tyne it swept down lower Tynedale towards the 

 sea. 



Had this been the only invasion the glaciation would have 

 been on the general plane of our county, from west to east ; 

 but there were two other invasions which exercised a con- 

 siderably modifying influence by directing their lower courses 

 southwards, as both came from the north. 



The nearer of these came from the Cheviots and South-East 

 Scotland, reaching our neighbourhood by the valley of the 

 North Tyne. The thrust of this ice-stream drove the western 



