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THE ORIGIN OF THE YORKSHIRE LAKES.* 
Prof. P. F. KENDALL, M.Sc., F.G.S., 
Though the four lakes in Yorkshire — Semerwater, Malham 
Tarn, Hornsea Mere, and Gormire — all owe their origin to the 
events of the Ice Age, all were essentially different in the mode 
of their formation. With regard to the pretty little lake of 
Semerwater, which lies in an arm of WensJeydale : in the Ice 
Age much of Yorkshire was buried beneath a great extension 
of ice, which extended from a centre about Howgill Fell". 
Some of this ice passed into the Kibble, but a great deal 
travelled eastward over Hawes into the Ure. This Ure 
glacier extended down the valley and encountered the great 
glacier occupying the Vale of York, to which it became tri- 
butary. During the decline of the Ice Age the Yale of York 
glacier continued in existence long after the tributary glaciers 
had . dwindled. As a consequence Wensleydale was blocked 
at its mouth, and there were certain evidences that it formed 
a lake of great siz.e with its water-level at a height of 1.000 feet 
above the sea. The local glacier ice carried such enormous 
■quantities of morainic material that it eventually obstructed 
the narrow valley of the River Bain and impounded per- 
manently, as Lake Semerwater, a portion of this great 
Wensleydale lake, though the rest of the waters were liberated 
b>y the removal of the Vale of York glacier. 
Malham Tarn marked another phase of the ice. Glaciers 
•came down from the heights of Fountain Fell toward the 
south, and the edge found a temporary halting-place on the 
high plateau above Malham Cove. There a ridge of glacial 
moraine was laid down, and within this, when the ice melted, 
was impounded a shallow sheet of water. The Tarn had 
"been artificiallv extended, but it was originallv enclosed at 
the outer edge by a dam of moraine, so that it lay within the 
line of the old moraine. 
Hornsea Mere, in Holderness, lay outside the final moraine 
of the North Sea ice, but within a tract the normal drainage 
of which was disturbed by several morainic lines formed by the 
ice W'hcn it pushed inland from the coast. One such line of 
moraine lay at Roos, another ran through Kelsey Hill and 
Burstwick. and a third w'as marked by the low hills of rock 
debris on the Holderness coast. 
Gormire had a different origin. When the Vale of York 
w^as occupied by a glacier twenty miles wide, the drainage being 
obstructed, the adjacent valleys of Cleveland were occupied 
by lakelets, which drained from one to another and cut channels 
* Abstract of address delivered at the Hull meeting of the Geological 
Section of the Yorkshire Naturalists’ Union, on Nov. 7th. 
Naturalist 
