378 
MORTIMER : SECTIONS OF DRIFT. 
that this gorge itself was considerably widened, and possibly in part 
excavated through the upper beds of the outcropping chalk, by the 
pressure eastwards, during the height of the great glaciation. 
Possibly this was the narrowest and weakest place in the whole 
ridge of outcrop between Flamborough Head and the Wash. 
That at one time all the water did not pass through the present 
channel seems to be proved by the two or three sections shown in 
the face of the large chalk pit near Hessle Station, 40 to 50 ft. above 
the present bed of the Humber, which I take to be old river beds 
filled with drift. Besides we have proof that large masses of the 
upper beds of the chalk have, in places, been crushed and bodily 
removed by the great pressure of land-ice. 
At Driffield, the main drain exposed a large mass of this crush- 
ed and displaced chalk, extending from the river head to the Albion 
flour mill. Part of this mass can now be seen in the bed of the 
stream : and in other parts of Driffield, disturbed chalk was observed, 
as shewn in the sections. A little to the north-east of Wharram 
Station, on the brow of the hill, close by the side of the road to the 
village of Wharram, is a pit showing nothing but crushed chalk. 
And at Hutton Cranswick, three miles south of Driffield, is a large 
outstanding boss of chalk, the uj>per beds of which, to a depth of 
about 12 ft,, and over a considerable area, are much shaken, and 
seem to have been displaced. In one of the Hutton sections, the 
upper portion of the disturbed chalk contained, the last time I saw 
it, two drum-shaped pockets of sharp sand and small gravel complete- 
ly enclosed in disturbed chalk. Numerous other instances of 
removed chalk could be given, and probably a close examination 
made in the neighbourhood of the Humber gorge, would discover 
traces of crushed chalk, indicating great displacement from the sides 
of the gorge. This grinding and displacing action of the ice I 
believe to have been confined mainly to the inner portion of the 
chalk hills, and to the sides of the valleys having a free and easy 
opening into the sea. . 
The intricate ramification of the dales, completely filled up 
