BETWEEN THE TYNE AND THE WANSBECK 



107 



Applying this rule to the sequence on the Dinnington Ridge 

 we 2fet : — 











Name and 





Height of 



Depth of 





Height (IN feet) 





Intake 



Swire 





of Intake of 



Name of 



IN Feet. 



IN Feet. 



Sum of 



Next Higher 



Swire. 



(A) 



(B) 



A. &B. 



Swire. 



Woolsington 



... 268 



26 



294 



Luddick, 298. 



Luddick 



... 298 



40 



338 



Callerton, 340. 



Callerton 



... 340 



55 



395 



Heddon, 400. 



These considerations only hold, naturally, when the re- 

 cession of the ice-dam is so slow that the lake is always full 

 to overflowing, and it may be noted as another consequence 

 of them that the ice-dammed lake becomes lowered in level 

 gradually, not per saltum ; the close agreement between the 

 corresponding figures in the last two columns of the table 

 above would seem to prove that the eastern ice-sheet retreated 

 quite regularly from Heddon to Woolsington, a distance of 

 four miles.* 



The data connecting the intakes and outlets of the swires 

 enable us, further, to estimate the relative rates of lowering of 

 the Pont and Ouseburn Lakes. We have seen reason to think 

 (p. 102) that the Ouseburn Lake sank in level 30 feet during 

 the period of complete erosion of the Luddick and Woolsing- 

 ton Slacks ; for its level was 280 feet when the Callerton Slack 

 had just been cut, and 250 feet when the Woolsington Slack 

 had just ceased to carry off the Pont Lake waters. During 

 the same time the level of the Pont Lake must have sunk 

 from 340 feet to 268 feet (the intakes of the Callerton and 



* Since the above was written an excellent paper on " The Glaciation 

 of East Lothian south of the Garleton Hills " (Trans. Roy. Soc. 

 Edin., vol. xlvi., pt. I, no. l) by Kendall and Bailey has appeared, from 

 which it is evident that the authors have come to the same conclusions as 

 myself concerning what one might term the mechanism of ice- retreat and 

 swire-formation, though the data quoted in the paper are used to confirm 

 their view of an ice-sheet retreating, not uniformly, but with occasional 

 advances. It is a great satisfaction for me to find my deductions from 

 Kendall's hypothesis confirmed by the originator of the hypothesis and his 

 collaborator. 



