Vol. 58.] GLACIER-LAKES IN THE CLEVELAND HILLS. 565 
venture to say; but if it did, its sojourn must have been brief, and 
the resolution of the conflicting pressures and movements in the 
area to the northward soon brought in the third element, the 
Scottish-Northumbrian ice, as a buffer. 
The immense abundance of erratics of Cheviot volcanic rocks has 
only within the last three or four years been fully recognized by 
geologists in Yorkshire; and I cannot think that their occurrence 
can be ascribed to anything short of actual contact with the 
Yorkshire uplands of ice which came by a fairly direct route from 
the Cheviot Hills, and probably out of Tweeddale. These rocks 
can be found at all altitudes, and while they are very common 
on the coastline, they attain to a far greater prominence in the 
deposits at high levels. These facts have been impressed most 
strongly upon me during my work in Cleveland, and my friend 
Mr. J. W. Stather, F.G.8., has found the same conditions to prevail 
in Holderness and on the Chalk Wolds. The uppermost fringe of 
the Drift contains a quite exceptional proportion of Cheviot rocks. 
I have previously pointed out that, in the high-level deposits, Mag- 
nesian Limestone of the type found on the coast of Durham is also 
exceptionally abundant, while Carboniferous rocks are propor- 
tionately rare. These facts are consistent with the view that the 
Cheviot ice passed over the comparatively small outcrop of Carboni- 
ferous rocks of Northumberland and out to sea; then, describing a 
great curve, re-invaded the land somewhere between the Tyne and 
the Tees, bringing in stones, such as flints, from the bed of the 
North Sea, and marine shells in a more or less smashed condition, 
from the same source. Some of the boulders of basalt and dolerite 
found in. Yorkshire may, not improbably, have been derived from 
Northumberland. The movement of the northern ice-stream down 
the coast appears to have been very extensive and protracted, and it 
may have extended even to Lincolnshire, where the characteristic 
erratics are found as far south as Horncastle. 
Inland, the extension of the Cheviot ice was, in my opinion, coin- 
cident with the limit of a maximum glaciation from the Wykeham 
moraine right round to Scarth Nick; but if it reached to the very 
edge of the Vale of York, I can see no reason why it should not 
have even contributed its quota to the great glacier that descended 
to York. This, however, is a topic which cannot be conveniently 
discussed in the present communication, but must be reserved for 
another paper in which I propose to deal specially with the Vale of 
York. 
The direction of movement seems to have been straight upon the 
northern face of the Cleveland Hills, with a westerly component at 
the western end, while at the seaward end an easterly direction was 
imparted by the form of the ground, and especially by the North- 
Sea depression. I am unable to indicate the position of the point 
where the westerly passed into the more easterly movement— 
doubtless it would fluctuate incessantly throughout the whole 
period of ice-occupation, as one or another of the component elements 
of the ice-sheet waxed or waned. 
Q.J.G.8. No. 281. 2a 
