96 THE GLACIAL PHENOMENA OF THE COUNTRY 



escape between the Ridge and the ice. Such an arrangement 

 as this must be hypothecated to account for the Darras Slack. 

 The water, after emerging from this slack, possibly flowed 

 away over the ice itself, for it has left no certain records of its 

 subsequent course. 



A slight movement of the ice over the Dinnington Ridge, 

 together with a general recession eastwards, now caused the 

 Pont Lake to drain away by Callerton, cutting the slack of that 

 name, and a further retreat brought about the erosion of the 

 Luddick Slack by the overflow waters. 



The next recession of the ice-sheet is interesting in so far as 

 it probably resulted in bringing the waters of the Wansbeck 

 into the Tyne. Of the conditions of the Wansbeck valley up 

 to this, with respect to land and ice distribution, we have little 

 or no evidence, but at this stage, apparently, our ice-sheet 

 stretched across the valley, damming up the waters therein, 

 and the resulting lake overflowed across the Whalton Ridge 

 by Edington into the Pont Lake. The Shilvington Slack, 

 which was cut in this way, ceases to make any feature at 

 about 260 feet, which possibly marks the level of the Pont 

 Lake at this period ; and as the Woolsington Slack takes-in 

 at about the same height, it may be inferred that it was the 

 overflow channel of the lake when the latter was fed by water 

 from the Wansbeck, flowing in through the Shilvington Slack. 



To the same period may be ascribed the formation of New- 

 biggin Dene, which mouths at the same height (250 feet) as 

 the Woolsington Slack. It would appear that the ice-sheet 

 resting on the Kenton Ridge had caused a small lake to be 

 formed between it and its spur, which lake, overflowing at the 

 lowest point, caused the slack at Newbiggin to be cut. 



The final mode of escape of the waters which breached the 

 Dinnington Ridge is by no means clear, though it seems 

 likely that they reached the Tyne valley by way of Dewley, 

 where the watershed is low. It seems probable that the 

 eastern ice-sheet completely blocked the Ouseburn valley 

 during one portion of this period, and that the Pont waters 



