534 MR. P. F. KENDALL ON A SYSTEM OF [ Aug. 1902, 
gorge 30 to 40 feet deep, which forms a very conspicuous breach in 
the line of watershed at Barton ‘Howl.’* The overflowing stream 
commenced to cut at about 680 feet, and ceased at about 665. These, 
then, may be regarded as the approximate water-levels of a small 
lakelet on the iceward side of the watershed. ‘This lakelet had a 
maximum area not exceeding 3 or 4 square miles. 
At the easternmost extremity of the Hutton-Mulgrave amphi- 
theatre,just above the village of Aislaby, twosmall valleys cutthrough 
aspur at about 630 and 580 feet respectively. The former of these, 
Galley-Hill Slack, has much the appearance of a lake-overflow, but 
so large a volume of water at present descends from springs and 
surface-drainage, as to suggest the possibility that the valley may be 
the product of normal drainage. The latter valley displays features 
so lacking in distinction that, without the corroboration of other 
members of a related series, I should not venture to include it in my 
enumeration of Glacial overflows. 
The last evidence of constrained drainage in Eskdale that 
demands notice, is the actual ontlet of the River Esk at Whitby. 
The river here flows through a rock-gorge about 100 feet deep, and 
so narrow as to forbid the supposition that this was its ancient 
course. lLandslips frequently take place, and it is evident that the 
channel is very modern. Mr. Barrow has called attention to this 
case in his fine Memoir on Northern Cleveland, and has drawn the 
same conclusion. He says*:— 
‘The River Esk at Ruswarp is approximately in the centre of its old course 
and shows no rock. But further north it begins to flow between steep rock- 
banks, which, near Whitby, are nearly vertical. Its pre-Glacial course was to 
the west of the town and into the sea, where the cliffs are entirely composed of 
Glacial deposits. A deep well sunk in this old line of flow went down a great, 
depth without meeting with any rock, but the exact details we were unable to 
obtain.’ 
Whether this deviation was due merely to the fact that the old 
valley was packed with Boulder-Clay and other Glacial materials | 
so as to be completely obliterated, or whether the post-Glacial Esk 
was, like so many other streams in the district, constrained to take 
a course along the outer edge of the ice, ] am unable to say. Many 
facts could be cited in favour of either view. 
The drainage of that part of the south side of the Esk Valley 
which lies east of the Murk-Esk Valley must now be considered. 
It has already been explained that a lobe of the great ice-sheet at 
the maximum extension overflowed the northern watershed, and 
welled up the Murk-Esk Valley as far as the moorland south of 
Goathland. I have remarked that the evidence that Kempston Rigg 
was ever completely overridden seems inconclusive, and the phe- 
nomena seen on the southern side of Eskdale may perhaps find an 
easier explanation upon such an assumption, though it does not 
appear to me to be probable. 
1 An eccentric spelling of the word ‘ Hole.’ 
* Mem. Geol. Surv. ‘ North Cleveland’ 1888, p. 69. 
