112 REPORT—1858. 
The rocky contents of this blue clay are of considerable interest, as they consist of 
rolled or far-travelled stones. At Nether Green, these are chiefly sandstones of great 
hardness, and of polished surface. At Woodhouse Moor, these hard rolled sandstones 
are in great numbers, and occasional masses of chertz from the mountain limestone. 
The nearest locality for this chertz is 25 miles, but it may probably have travelled 50 
or 80 miles. At Adel, along with the hard polished sandstones, boulders of chertz and 
of mountain limestones occur. ‘These must have been drifted over the higher ranges 
of land between the Aire and the Wharfe, and not swept down the valleys. Portions 
of trap-rock have also been found in the blue clay at Adel, and also a piece of red 
porphyry, which cannot have been derived from a nearer source than Westmoreland. 
At Yeadon the hard polished sandstones occur with abundance of chertz from the 
mountain limestone. 
2. The Yellow Clay.—This clay is invariably found overlying the blue clay, 
wherever they co-exist, and resting on the coal-measures only in the places where 
they have been denuded of the blue clay. It is spread out more extensively than the 
blue clay, but like the latter, its distribution is irregular from the effects of denudation. 
It occurs low in the valley at Leeds, and ranges on the heights north and south of the 
Aire, to the elevation of 300 feet at Woodhouse Moor, 375 feet at Adel, 420 feet at 
Yeadon, and 600 feet at Adwalton ; in all these localities it may be seen overlying the 
blue clay. At similar elevations it is often seen resting on the coal-measures, where 
they have been denuded of the blue clay. The yellow clay has much influence in 
modifying the features of the country near Leeds. It tends greatly to soften the 
harshness of outline which the abrupt outbreaks of the member of the coal forma- 
tion would have occasioned. 
The rocky contents of the yellow clay are particularly deserving of notice. These 
stones, often of large size, are for the most part angular or subangular, derived from 
rocks in the neighbourhood. ‘These are not far-travelled stones, but still they are 
travelled stones, and are not resulting from the mere disintegration of the rocks in 
situ from aérial causes, This may be proved by an examination of such stones in the 
yellow clay as can be identified with the parent rock. A good illustration of this 
occurs at Headingley, in the grounds of Mr. Hewitson, who kindly directed diggings 
to be made to assist me in these investigations. In one of these the yellow clay, 8 or 
9 feet thick, rested on the sandstone shale of the coal formation. At this place the 
clay contained great numbers of stones, known as “ calliards.” These are sandstones 
of great hardness, occurring generally in masses of subrhomboidal form. The bed of 
rock which furnished these calliards is well kuown in the district, and has its out- 
break from a quarter to half a mile north of Mr, Hewitson’s diggings. The stones 
therefore must have travelled this distance. These stones have had the sharpness of 
their angles somewhat blunted; they vary in size from a few inches to 2 or 3 feet. 
Along with these calliards, in the same clay occur great numbers of stones of millstone 
grit, somewhat more rounded than the former, but not polished by long travel. ‘These 
stones are easily recognized as being derived trom the parent rock at Weetwood, 
where we find a bed of very coarse millstone grit, easily disintegrated, having its out- 
break from half a mile to three-quarters of a mile north of Mr. Hewitson’s. Similar 
observations might be made in reference to other known rocks of the district occurring 
in the yellow clay. 
3. The Warp.—Under the name of warp, I would describe the true valley deposit 
of the Aire at Leeds. The deposit is familiarly known to the workpeople of the 
district under this name. 
In position, the warp overlies the yellow and the blue clays whenever the three 
co-exist. It is frequently seen resting on the yellow clay, or resting on the blue clay 
when it has been denuded of the yellow, or resting on the coal-measures where they 
have been denuded both of the blue and yellow clays. At Dickens Street, New Wort- 
ley, it occupies a trough formed by denudation, resting on the yellow and blue clay 
ou each side, and on the coal-measures in the middle. At Beeston Vale it rests suc- 
cessively on the yellow clay, the blue clay, and the coal-measures; a similar arrange- 
ment is observed near Sheepscar Bar, and in other localities, The warp is spread 
over the valley of the Aire, producing a flat-looking surface, gently sloping upwards 
at the sides of the valley, and downwards towards the estuary, At the sides of the 
Vale of Leeds, the warp shelves off a little below the sea-level of 150 feet, and is not 
a 
