JOWETT A^T> MUFF : GLACIATION OF BRADFORD, ETC. 227 
the col at Trough Lane, was about 1,050 feet above O.D., from 
which level it gradually sank to 1,020 feet before the channel 
was deserted. The col to the south of Sentry Hill is at a height 
of 1,180 feet above O.D. It is not cut through by a channel, 
but is a good example of an ordinary saddle-shaped col. It 
is evident that the Oxenhope Lake never discharged over this 
col, and the glacial deposits do not suggest that the Trough 
Lane channel was ever blocked by the ice. The driftless character 
of the moorlands to the south has already been remarked upon 
(see p. 215). 
The next lake higher up the dale was one held up at the 
head of the Worth Valley between two ice-dams. The over- 
flow of this lake into the Oxenhope Lake cut a deep gap across 
S 
Fig. 1. 
SECTION ALONG PART OF THE SUMMIT OF THE RIDGE WEST OF THE 
HARDEN VALLEY. 
the spur of Haworth Moor at Harbour Hole, 2^ miles S.W. 
of Haworth. This notch has been cut down from about 1,260 
feet to 1,230 feet. A slight retreat of the ice-front allowed 
the water to escape at a considerably lower level, and the Worth 
Lake sank to 1,115 feet above O.D. 
The immediate result of the lowering of the level of Lake 
Worth was to lay bare the col (1,175 feet) between Combe and 
Crow Hills, and henceforth the Worth Lake was held up by 
one ice-dam only. The ice on the Lancashire side, standing 
close up to the watershed, forced water from the melting ice 
and the neighbouring slopes to flow over on to the Yorkshire 
