THE GLACIAL GEOLOGY OF NORTHUMBERLAND 105 



(300 feet), the flooded Ouseburn valley discharging its waters 

 to the south through Walbottle Dene [18]. 



The line of cleavage between the two sheets after crossing 

 the Wansbeck swept towards the west along the high ridge 

 parting the Font from the Lyne, Tod and Forest Burns. The 

 northern sheet appears to have itself divided in an easterly 

 direction, causing the Pont waters to flow through A 7 (250 

 feet), and the Wansbeck waters through A 8 (240 feet), 

 initiating thus the course of the Sleekburn. Further recession 

 of the two portions then brought about the opening up of the 

 post-glacial reaches of the Ouseburn, Blyth and Wansbeck. 



The position of the parted ice-sheets north of the Wansbeck 

 is first indicated by the swire A 9 (340 feet). This is the only 

 channel which drains in two ways, from which it would appear 

 that slight oscillations of the sheets caused the pent-up waters 

 to flow at various times from west to east and vice versa. 

 The slow retreat of the northern sheet towards the Coquet 

 opened up the important channel of Haredene, A 10 (480 feet), 

 and a more rapid recession gave rise to the less important 

 gaps An to A 17, the heights of the intakes of which are, in 

 order, 460, 380, 320, 280, 270, 190, and 170 feet. Of these it 

 seems probable that A n, A 12, and A 13 were in operation 

 simultaneously. The next stage of retreat is marked by the 

 melting of ice in Lower Coquetdale and the initiation of the 

 post-glacial portion of the Coquet. 



Coming now to the western sheet, the first opportunity for 

 the production of ice-dammed lakes at its edge occurred, as 

 indicated above, at the position A 9 (or B 1). Further recession 

 of the edge flooded the valley of the Newbiggin Burn, the 

 northern tributary of the Font, and the overflow of the lake 

 produced a fine series of swires, B2 to B 6, at 900, 750, 720, 

 600, and 525 feet respectively. Probably at some time during 

 this stage a slight advance of the ice-remnant on Simonside 

 caused the blocking of the Ousen Sike and the notching of 

 the ridge parallel to this hill, producing thus the deep cleugh of 

 Selby's Cove, B7 (1,090 feet), one of the most perfect of the 



