I02 THE GLACIAL PHENOMENA OF THE COUNTRY 



Heddon Slack and Walbottle Dene are of late glacial age. 

 During the period of maximum giaciation the "Ouseburn" 

 Valley was partly filled with drift, and near the end of the Ice 

 Age the temporary lake in the Pont Valley, overflowing by 

 Heddon, caused the slack of that name to be cut. It seems 

 likely that the Ouseburn Valley was still choked with ice at 

 this period, for the waters issuing from the Heddon Slack, at 

 an elevation much above that of the watershed near Dewley, 

 have left no traces of their subsequent course. The recession 

 of the ice-sheet in the Pont Valley corresponded to its with- 

 drawal from the Ouseburn Valley, and it seems not improbable 

 that while the Pont Lake was draining through Darras Slack 

 the kaim of Dewley Hill was being formed at the edge of this 

 ice-sheet. When the level of the Pont Lake had fallen to that 

 of the Callerton overflow, the Upper Ouseburn Valley was free 

 from ice, and the waters entering it through Callerton Slack, 

 somewhat augmented by those of the Dewley Burn which had 

 now come into existence, being dammed by the eastern ice- 

 sheet formed a lake, which overflowing near Dewley initiated 

 the erosion of Walbottle Dene. This Ouseburn Lake 

 apparently sank in level by the cutting-down of its outflowing 

 waters from a maximum of about 280 feet to 266 feet when 

 the Pont Lake drained into it through Luddick Slack, and 

 finally to 250 feet when it was fed by the Pont Lake through 

 the Woolsington Slack, and by the Newbiggin Lake through 

 Newbiggin Dene. 



With the further recession of the ice-sheet the Ouseburn Lake 

 drained away naturally eastwards, the channel of Walbottle 

 Dene became the permanent outlet for the Dewley Burn, and 

 the Ouseburn, shorn of its true head-waters by their diversion 

 through Walbottle Dene, took its rise on the swampy lake- 

 bottom (locally and aptly called "The Bogs ") just east of the 

 head of this Dene. 



Summary and Deductions. 



Assuming that the main hypothetical statements made in 

 the foregomg account are justifiable, we are now in the 



