New Record of Glacial Drift near Wakefield. 127 
These records, therefore, seem to indicate that an ice-sheet 
from an easterly source pushed up the valley as far as this 
point. On the other hand it might be suggested that as no 
true boulder-clay has been found here, these erratics reached 
their present position by means of icebergs, but this seems very 
improbable when it is seen later that the whole current of 
water would be in an opposite and easterly direction. 
The conditions in Airedale have been described by Messrs. 
Jowett and Muff, who state that ‘at the period of maximum 
glaciation, there stretched along the southern border of the 
Airedale glacier, a series of six lakes, the surface levels of which 
fell from about 1,325 feet in the north-west to about 700 feet 
in the Bradford basin. The overflowing waters from these 
lakes discharged into the head of the Spen valley, and so into 
Calderdale.’* : 
The quantity of water entering Calderdale at this period 
must therefore have been very considerable, including, as it 
did, probably the whole of the meltwaters from the southern 
edge of the Airedale glacier, and also that from the extensive 
series of glacier-lakes described by Dr. Jowett in East Lancashire. 
Though this water may have at first entered a glacial ‘ Lake 
Humber’ in the vale of York,} it must have been subsequently 
diverted by the presence of the ice, which is indicated by the 
scattered patches of boulder-clay around Barnsley and Don- 
caster. These deposits have been described by Mr. W. L. 
Carter, and according to him indicate that the ice at its maxi- 
mum extension reached as far east as the valley of the Dearne, 
and closed the present outlet of the Calder.t He further adds 
that ‘we cannot stop the movement short of Woolley Edge ridge, 
on the eastern slope of which, up to 250 feet, are several drift 
gravel-patches. A great lake would necessarily be formed in 
Calderdale, fed by the overflow from the Lancashire side by 
way of the Burnley and Summit valleys. This lake would 
gradually creep up to Mirfield, accounting for the great deposits 
of drift at 150 feet above O.D., with abundance of great angular 
blocks of ganister, and to Elland, where there are extensive 
detrital deposits in the valley, and up to Mytholmroyd, where 
it would account for the great delta from 330 to 360 feet above 
O.D.” § The bottom of the overflow channel between Woolley 
and Bretton is 405 feet O.D.,so that a very considerable glacial 
lake must have existed (cf. accompanying plan). The waters 
from this lake would be discharged at this period ‘into Lake 
Don by way of which they would pass by the Kiveton gorge 
‘* A. Jowett and H. B. Muff, Proc. Yorks. Geol. Socy., vol. XV., 1905, 
p. 228. ; 
+ P. F. Kendall, Quart. Journ. Geol. Socy., vol. 58, 1902, p. 567. 
¢ L. W. Carter, Proc. Yorks. Geol. Socy., vol XV., 1905, p. 434. 
§ Ibid. pp. 434 to 435. ° 
1915, April 1. 
