ELGEE : GLACIATION OF NORTH CLEVELAND. 377 
Sowerdale falls to fche north-west and is a valley about 150 
yards wide at the top, and about 100 feet deep, cutting from 
550 to 450 feet. It has very steep sides, apparently composed of 
drift, and stiff clay is exposed by a ver}^ small stream, not 12 inches 
wide, on its floor. 1 do not think that this insignificant stream 
can be regarded as the agent wliich produced Sowerdale. Else- 
where in Cleveland much larger streams have eroded much 
smaller channels in the drift, and moreover, the Sowerdale 
rivulet is practically non-existent in the summer. The upper 
part of Sowerdale has a very steep ascent to the watershed, the 
floor of the south-easterly flowing channel above-mentioned. 
Here, therefore, on the same spur we have two overflows in 
opposite directions, and one on a very mucli larger scale than the 
other. 
At first sight it would appear that after Lake Kildale bad 
ceased to drain into Eskdale, it overflowed across the Easby 
spur and thus excavated Sowerdale. This was the opinion of 
Mr. Hawefl, e.nd he further adds : — " This water was able to 
flow out at a lower level between the ice mass and wliat is now 
Easby Castle Hill. As the ice gradually shrank, the outflow 
came to be at a progressively lower level, but still hugged the 
Castle Hill, and so when the ice had quite 
gone, the Leven had cut its channel close under the hill."* 
This explanation certainly fits the facts and explains the paraUel 
trend of Sowerdale and the River Leven, the latter of which 
hugs the Castle Hill slope in a most remarkable way. But if the 
Cheviot ice was the agent in causing these phenomena, where 
was the escajje for the overflowing waters to the north-west, 
an area covered by the glacier itself ? The overflows could not 
have travelled round the foot of the hill? to the Boosbeck Valley, 
since the overflows in that area indicate drainage westwards 
below 600 feet. To reconcile these apparent contradictions is 
difficult. The overflowing waters may have escaped over or 
under the ice, but that two opposite drainage lines could be in 
operation at the same time, along the same hill slopes, one of 
which escaped under or over the ice and the other did not, appears, 
to say the least, highly improbable. 
* Op. cir. 
