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likely, only a remnant of a mass of Till, perhaps never 
very large, which, has been almost entirely removed by 
denudation ; and it owes its preservation to the sheltered 
position in which it lies. Then the cold passed away ; the 
valley was partly re- excavated, and a stream flowed along it 
by whose agency river-deposits of warp, sand, and gravel 
were laid down. The angular blocks and scratched stones in 
these beds, may well have been derived from the Lower 
Boulder Clay, which formed the bed and slopes of the valley. 
The Upper Boulder Clay indicates a return of cold ; it is 
not easy to decide what were exactly the conditions under 
which it was formed ; being bedded, it was probably sub- 
aqueous, and its stones may have been carried by floating ice. 
Though the cutting just described is the only section 
we have of the drift deposits. Boulder Clay covers a consider- 
able area in the neighbourhood. Between the cutting and 
the villages of Carlton and Eoyston, the surface is seen to be 
formed of stifi" clay ; large angular blocks of carboniferous 
sandstone, and foreign rocks are plentifully sprinkled about. 
Among the strangers, boulders of highly metamorphosed 
breccias, which may well have come from the lake district, 
are not uncommon ; and in the village of Royston there is an 
angular block of granite, which agrees very well in character 
with the granite of Shap Fell. There are also several patches 
of fine, well-rounded gravel, composed mainly of carboniferous 
sandstone of the neighbourhood, but the relation of the 
gravel to the Boulder Clay could not be ascertained in any 
instance from want of sections. 
There are scattered over the generally driftless tract of 
the Yorkshire Coal-field, other patches of drift, but none, as 
far as I know, so large as the one just described, and in no 
other case have I been lucky enough to find a section, which 
allowed the character of the deposit to be minutely studied. 
But as in the one case when examination was possible. Till 
