97 
Eeaching from Exley to Elland, on a plateau of grit rock, 
about thr 63- quarters of a mile by one-quarter, there is a 
deposit of rounded stones and sand, all of wbich. may have 
been derived from the rocks above or in the immediate 
neighbourhood. At the highest part, the bed is 350 feet 
above the sea level, from thence it covers the hill side as far 
as the level of the railway, which is 100 feet lower. A 
good section of it is got at the Elland Station, where it rests 
on the shale a little above the rough rock. It is about eight 
or ten feet in thickness. There is no clay present, nor do 
any of the stones present the sKghtest appearance of striae ; 
a few stones may be found of a subangular character, but 
by far the greater portion are rounded, and appear to be 
water-washed. 
A similar mass of debris occurs in the Mytholm valley 
below ,Hipperholme Station, and another in Kirklees 
Park, near Mirfield, these three being all with which I am 
acquainted. 
We have thus two distinct series of water-washed boulders. 
The first forms the level lands in the bottom of the valley 
in which the river has cut out its present course, and contains 
numerous travelled boulders ; the second forms local patches 
of much smaller extent at considerably higher elevation, and 
contains only boulders derived from rocks in the neigh- 
bourhood. 
The facts we have now before us point to at least three 
periods of deposition. The first was a period of extensive 
glaciation, during which an immense sheet of ice covered 
the northern parts of England and Scotland, in some 
places attaining a thickness of one or two thousand feet. 
This ice- sheet, moving in a southerly direction from the 
mountains of the Lake District, appears, in all probability, 
to have been divided into two principal parts by the 
Penine chain of hills dividing Yorkshire from Lancashire. 
