204 



According to Barrow (Survey Memoir, p. 67) these gravels 

 can be seen passing under the Upper Boulder Clay in Eskdale, 

 and that, therefore, they are of middle glacial age. But the 

 exact relation of the red Upper Boulder Clay to the position 

 of the ice front at the period of maximum glaciation is a very 

 difficult question to settle and to which I have not yet been 

 able to devote sufficient attention. It may be remarked 

 that as the ice margin at its maximum extension is frequently 

 indicated by gravel mounds not overlain by the red Upper 

 Clay, it seems difficult to understand why gravel beds should 

 underlie the red Clay on the lower grounds — supposing the 

 two to be continuous — unless this clay indicates a readvance 

 of ice at a later period but not to so great an elevation. 

 Barrow states that very little Upper Clay exists at heights 

 much above 400 feet but the patch noted in the Tranmire 

 section occurred at an elevation of 700 feet. 



Gravel mounds occur at Greenhow, near Ellerby Bank 

 Top at Stump How, just north of Mickleby, and just north 

 of East Barnby at Wade's Hill. These seem to form a line 

 of irregular moraine, a fact rendered more probable from the 

 circumstance that the watershed from Ellerby Bank Top to 

 Wade's Hill is trenched by several shallow grooves falling 

 and deepening on the slopes above Lythe Beck. They are 

 probably due to streams flowing from the melting ice margin 

 as it stood along the watershed. 



Overflow channels, with two exceptions, appear to be 

 completely absent from the area, a fact that is somewhat 

 surprising, seeing that the country is intersected by valleys 

 whose drainage must have been obstructed by the retreating 

 ice. The two exceptions are very insignificant but perfectly 

 distinct. The most westerly occurs at the end of the ridge 

 between Roxby and Borrowby Becks and stands at 550 feet, 

 falls eastwards and is about 25 feet deep. Its chief peculi- 

 arity is the fact that the intake to the west is bifurcated, 

 forming what Mr. Kendall has termed a "lateral intake." 

 It arises from a retreat of the ice front at the intake end of 

 the overflow, the impounded drainage then running into the 

 first channel from another position. The channel thus some- 

 what resembles a letter Y laid horizontally, the two arms 

 forming the intake. Although on a very small scale, it is, 

 I believe, the only example of its kind in Cleveland. 



