Vol. 58. ] GLACIER-LAKES IN THE CLEVELAND HILLS, 521 
The overflow first came into operation at an elevation of a little 
over 800 feet, and it cut down to below 775 feet, probably about 
750 aeress the watershed. There is no stream at present flowing 
in the upper half-mile, but where the slope steepens a small stream 
emerges from the peat-moss and trickles down through the dried 
peat of the steeper region, sometimes in an open channel. Often 
for considerable distances, however, it is arched over by peat, and 
down to the confluence with Black Beck it can be bestridden at any 
place. The usual features observable in the meanders of oyerflow- 
channels are seen in this gorge, and there are lofty crags along the 
west side for a considerable distance. Near the confluence with 
Black Beck, at 625 feet O.D., is a great mass of gravel which has 
yielded many erratics, including Cheviot porphyrites, and one 
example of the Norwegian rhomb-porphyry. 
This gravel-mass then spreads out and forms two distinct terraces 
(see p. 512), at 600 feet and 575 feet O.D. respectively. These 
represent the two halts in the lowering of Lake Eskdale. 
So great an overflow as this, might be expected to bear some 
relationship to a correspondingly extensive lake-area on the north- 
ward, and this expectation is fully realized by an examination of 
the outer slopes of the hills. Not only is the intake connected with 
a large recess in the hills, but a suite of ‘ severed spurs’ show that 
upon if converged the drainage of a considerable chain of lesser 
lakelets. The evidence of the distribution of Drift-deposits is 
consistent with that of the overflows. Mr. Barrow’ remarks 
‘There can be no doubt that this high ground [above Guisborough, on Moors- 
holme High Moor, and on Danby Low Moor] at present more than 850 feet 
above sea-level, has not been glaciated, as not a single foreign pebble can be 
found .... Briefly, the Drift becomes very thin at 600 feet above sea-level, and 
disappears altogether above 850 feet.’ 
On the Lockwood Hills, up to 867 feet, I found a great spread of 
gravel forming a fringe to a lower area of Boulder-Clay ; and at the 
entrance to Ewe-Crag Slack, Drift-sands and gravels reach the 
watershed. These gravels yield fragmentary marine shells and 
many foreign stones, especially Cheviot porphyrites, and out of a 
small patch of Boulder-Clay on West Rigg at 810 feet, Mr. J. 
W. Stather obtained the specimen of rhomb-porphyry already 
mentioned (p. 498). Scattered erratics may often be found on the 
moors above the limit of the continuous Drift-sheet, but except on the 
Lockwood Hills I found none above, or even up to 850 feet O.D. 
The overflows aligned to the Ewe-Crag-Slack overflow are few in 
number, but of great interest. 
On the Lockwood Hills (Stanghow Moor) there is a shallow and 
rather obscure channel falling eastward into Seavy Sike. It barely 
indents the 850-foot contour. This carried, for a very brief period, 
the overflow from a lake at the head of the Boosbeck Valley, into a 
iesser lake, with which it later became confluent, held up by a lobe of 
ice that stood against the spur called Moorsholm Rigg (see fig. 15, 
p- 920). The Moorsholm lakelet was of long duration, for its over- 
* Mem. Geol. Surv. ‘ North Cleveland’ 1888, p, 66. 
