226 JOWETT AND MUFF : GLACIATION OF BRADFORD, ETC, 
from the fact that its lower portions rest on boulder-clay. The 
delta at the maximum extension of the ice being formed in 
the narrower part of the valley, was washed down and 
deposited at a lower level when the surface of the Bradford 
Lake sank (see p. 229). 
A deposit probably laid down as the delta of a stream 
entering the Bradford Lake when at its highest level, was ex- 
posed in the valley of a small tributary stream in Clayton. The 
level of the ground was a little above 700 above O.D. The 
section exposed is : — 
Soil 1 ft. 
Yellow (weathered) sandy clay, with sand- 
stone blocks near its base ( ? rainwash) . . 2 ft. 
Stratified gravel, consisting of pebbles of 
sandstone, flakes of shale, and a few pebbles 
of grit 6 ft. 
Yellow loamy sand . . . . . . . . 2 ft. 
The grit boulders which occur in the bottom of the Thornton 
Valley, above Leventhorpe, were probably dropped from icebergs 
broken off from the ice-front which held up the Bradford Lake. 
When the ice-margin stood against Harrop Edge it must 
also have reached up to the spur between Harrop Edge and 
Denholme, as represented on the map. The altitude of the 
spur is 930 feet — higher than the top of the gorge at Bell Dean. 
Hence the Harden Lake was separated from a lakelet at Stream 
Head. They were connected by a stream flowing along the 
ice-front in the shallow channel which cuts across the spur 
near Wood Manywells. As the difference in level between 
the two lakes was only about 25 feet, this channel is not deeply 
cut. When the ice-front retreated off the spur, the level of 
the Harden Lake would sink to the level to which Bell Dean 
had cut, and then to the level of Stream Head col. 
A long narrow lake, held up against the hills above Oxen- 
hope, discharged into the Harden Lake by a sharply- cut valley 
situated between Whinny and Sentry Hills to the south-east 
of Oxenhope. This channel is streamless, and the road running 
along its floor is known as Trough Lane (Fig. 1). The level of 
the Oxenhope Lake, as determined by the original height of 
