318 
KENDALL : THE GLACIATION OF YORKSHIRE. 
The condition of low grounds south of the York glacier is another 
of the problems calling for solution. I do not think there can be 
much doubt but that a very large lake existed, the Lake Humber of 
Carvill Lewis, in much of the region between York and the Trent 
valley, running up into the tributary valleys on the one side and 
penned by the ice on the other, but what its limits were, and to what 
height it rose, I do not think we are at present in a position to say. 
Much of the " warp " of the lower part of the Vale of York is, I 
think, clearly the deposit of such a lake, and in a cutting near Selby 
I saw, some few months ago, several large blocks of Jurassic sand- 
stone which had been dug out of it, and which I should explain by 
the drifting of small icebergs from the York glacier. I would point 
out that this deposit is just such an one as might be expected to be 
laid down in water receiving the grindings of glaciers, and is very 
like the Clyde Clays, but wholly different from Boulder Clay. 
The anomalous occurrence of boulders of Shap granite and of drift 
deposits at Royston, near Barnsley, may perhaps be similarly 
explained. 
The valleys of the Pennine Chain, from Swaledale southward to 
Airedale, appear to have been occupied by glaciers, some of which 
were confluent with that of the Vale of York, but towards the 
southern end of the Chain they finished as simple valley-glaciers, 
and lobes of the great extra-morainic lake may have ascended a short 
distance but all details are yet wanting, and I merely mention these 
points in order that they may not be lost sight of in any attempts to 
solve the problems which I have put before the Society. 
Map. — The geological information is transferred from the Drift 
edition of the official maps, and I have added merely the 100, 200, 
and 300 feet contours. 
