152 DAVIS : SOURCE OF BOULDERS IN CALDER VALLEY. 
disposed indiscriminately with smaller ones throughout the 
whole section. 
That the latter theory is probably the correct one, 
receives additional support from the occurrence of erratic 
boulders in the valleys which branch from that of the Calder, 
as, for example, the Colne. It is quite impossible that these 
could have come from the west ; the river rises on the high 
moorlands of Millstone Edge and Holme Moss, nearly 2,000 
feet above the sea-level, and falls rapidly to its confluence 
with the Calder at about 200 feet above the sea-level. 
Some other peculiar circumstances may possibly be 
accounted for if we suppose the land to have been submerged 
to about 400 feet lower than its present level, and at the 
same time these facts act reciprocally in affording evidence 
that such was really the case. There are numerous beds of 
gravel and well-rounded boulders, composed entirely of 
rocks of local origin, millstone grit, flagrocks, pieces of coal, 
and the harder shales, and, where the peculiar siliceous sand- 
stone called Calliard occurs in the vicinity, it is found in the 
gravel or drift. These beds occur on the hill-sides bounding 
the valleys, and generally at a height of 350 feet, a little 
more or less, above the present level of the sea. Examples 
may be seen at Kirklees Park, near Mirfield, at Exley, in 
the Elland Cemeteiy, at Mytholm, in a branch valley west 
of Halifax, and in other places as far westwards as Hebden 
Bridge. These gravels are quite distinct from those in the 
bottom of the valley, and are usually found occupying a 
plateau formed by a gritstone, from which the softer 
superincumbent shales have been denuded. In each of the 
situations cited above they are at least a hundred feet higher 
than the present level of the valley. Where exposed in 
section, they are current-bedded, with thin layers of sand 
intermixed, and present every appearance of having been 
subjected to tidal action. The presence of these beds has 
