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fluctuations of an interesting character, and which are so far 

 somewhat obscure to the scientists investigating them. Eskdale, 

 then, had an ice block at each end — the ice being possibly about 

 1,000 feet in thickness, or perhaps considerably more. As a rule 

 the water from the Guisbrough side flowed into the Eskdale 

 lake, and the outlets were in the direction of Goathland. But, 

 I have recently discovered that there was almost certainly an 

 overflow at one time from the Eskdale lake into Sowerdale — the 

 dale between the Eoman " Castle," at Easby and Captain Cook's 

 monument. Anyone looking at Sowerdale will be able to see 

 that the denudation of it cannot well have been entirely due to 

 the insignificant stream which now percolates through it. 



I have before described how at one time at least during what 

 is known as the "Glacial Period" or the '-Great Ice Age," a 

 great barrier of ice blocked the Ingleby end of Eskdale, so that 

 the water of the Eskdale lake flowed over into Sowerdale and 

 helped to form that dale. Somewhat later this water was able 

 ■to flow out at a lower level between the ice-mass and what is now 

 Easby Castle Hill. As the ice gradually shrunk the out-flow 

 came to be at a progressively low level, but still hugged the 

 Castle Hill, clearing away from the slopes of that hill as it 

 gradually descended, the drift material which had accumulated 

 there. And so when the ice had quite gone the Leven had cut 

 its channel close under the hill instead of flowing out in the 

 direction of Battersby Junction, as it probably did before the ice 

 age, and as it might be expected to do under circumstances of 

 normal denudation. 



There is a world of interest involved in the tracing of pre- 

 glacial river courses. We find, for example, that the Swale was 

 once a tributary of the Tees, but I cannot stop at present to tell 

 the tale how it was captured by " the all-devouring Humber." 

 It concerns us more to notice at present that the stream flowing 

 flown the upper part of Kildale is aiming directly for the Esk. 

 Why does it all of a sudden change its mind and twist round to 

 the Tees ? That it went into the Esk once there can be no 

 doubt. This query is probably connected with another which 

 was put to me one day at dinner by a distinguished geologist who 

 sat next to me ; whether did the Scandinavian ice or the Tees- 

 dale ice retreat first from the Cleveland Coast ? Of course, the 

 Scandinavian ice was the larger mass, but it was further from 

 home. So my friend's query cannot be answered on a priori 

 grounds. To answer it one must go into the field and use one's 

 eyes as well as one's reasoning powers. I think that it is possible 



