216 JOWETT AND MUFF : GLACIATION OF BRADFORD, ETC. 
it is generally thinner and limited in distribution, whilst above 
Denholme Station no glacial deposits have been found. 
Weathered boulder- clay more than three feet thick occurs at 
Manjrwell Heights (nearly 900 feet above O.D.), and clay with 
limestone pebbles near the old Copperas Works above 900 feet. 
These localities, together with the moraine mounds on Hallas 
Rough Park (p. 205), are the highest localities at which drift 
has been noticed in the Harden Valley. 
In the Cottingley Valley boulder- clay with limestone and 
Millstone Grit boulders extends right up the floor of the valley, 
and thin drift or scattered drift-pebbles may be found up to 
the crest of the ridge at Allerton. The moundy features at 
Sandy Lane Bottom are partly boulder-clay and partly a coarse 
boulder-gravel. Half a mile above Cottingley the beck has 
cut a small gorge in the Coal Measures, and has exposed in 
section its pre-giacial valley, now fiUed up with boulder-clay. 
It appears to be somewhat larger than the present channel and 
has rather less precipitous sides. Higher up the valley the 
boulder-clay is generally underlaid by a bed of coarse gravel 
two to three feet thick. 
On the high ground between the Cottingley and Bradford 
Valleys there is very little drift. An exposure, however, near 
the Chellow Heights Reservoir, almost on the summit of the 
ridge (850 feet), showed yellowish boulder-clay with limestone, 
chert, grit, and gannister (striated). Further, large blocks of 
Millstone Grit are scattered through the fields, and others have 
been broken up and used in constructing the walls. As these 
hills consist wholly of the Lower Coal Measures, the grit blocks 
must have been either uplifted from the valleys or carried across 
from the hills to the north-west. The ice must have surmounted 
this ridge at least as far as Allerton (900 feet). On Thornton 
Heights (1,025 feet) and Swill Hill (1,320 feet) both boulder-clay 
and scattered blocks of grit are wanting. These hills lie outside 
the glaciated area. 
A thick deposit of blue till lies along the western side of 
the Bradford Valley between Shipley and Bradford. On the 
north side of Red Beck at Shipley Fields, cuttings for drains 
exposed about 20 feet of stiff bluish boulder-clay resting on 
