154 MONCKMAN : THE GLACIAL GEOLOGY OF BRADFORD. 
as indicated by the sand and pebble beds in the clay at T3'ersal 
and at Woodroyd. 
The Leventhorpe beds themselves show the same, the upper 
plane at Leventhorpe Hall being about level with Wibsey Bank, 
and the lower at the mill with the gap at Laisterdyke. 
It appears therefore most probable that the lake was formed 
when the ice was retreating. 
If you refer to the map (Plate XXIV.), you will find that 
the places where limestone has been found lie on a fairly straight 
lin(; from a point above Leventhorpe Hall, through Lidget Green, 
Grange Road, Manchester Road, to Bowling Tunnel and Wood- 
royd, and this appears to be the end of a track from some 
place higher up Airedale. 
As there is no light-coloured limestone on the south side of 
the Aire Valley and no Silurian rock, the specimens found at 
Grange Road must have come either from the north side at Malham 
or fi-om Ribblesdale. 
It is difficult to explain how they could cross the Aire 
Valley, hence we are driven to the conclusion that the Ribbles- 
dale glacier was forced over the low water-parting at Hellifield, 
and so down the Aire Valley. The western moraine in Ribbles- 
dale would then become the southern one in the latter valley, 
and the rocks that would fall upon the ice from the hills on the 
west side as it passed down by the side of Ingleborough, and those 
that would be added by the Crummack Dale ice, would be of the 
same nature as those found by me at Grange Road excavations. 
I am informed by Mr. Howarth that there is evidence near 
Hellifield that the ice has passed over the dividing ridge. 
Since writing the above, I have got some additional indications 
that the line is continued in the direction suggested in this paper. 
I examined the workings at Many Well Springs, and found, 
with abundance of angular sandstones and grits that were evidently 
foreign, one piece of encrinital limestone in the clay. Mr. Tatham, 
who has charge of the farm, showed me a considerable number of 
pieces of weathered limestone in the walls of the fields. We 
examined them, and concluded that they could not have been 
