Vol. 58. ] GLACIER-LAKES IN THE CLEVELAND HILLS. 495 
& Rosedale Memoir the species is recorded in Eskdale at Egton, at 
Far Carr Wood, and at a pit near Egton Church with other shells, 
and again in the Lealholm moraine (see p. 506). In the Memoir 
on the country between Whitby and Scarborough, Vellina balthica 
is recorded as occurring in the Middle Sands at Robin Hood’s Bay; 
and in the Memoir on the country to the south of Scarborough, it is 
stated that great numbers of shell-fragments occur in gravels on the 
north side of the Vale of Pickering, about Wykeham and Ayton. 
VII. Tse Icr-SHeEets. 
It will greatly facilitate the line of argument which I propose to 
develop in the following sections, if I state at the outset the con- 
clusions to which my studies have led me regarding the course and 
distribution of the ice-currents that operated about the margins 
and, to some extent, over the ridges of the Cleveland area. I may 
first remark, that I have been unable to detect any signs of the 
presence of the sea in the area at any time during the Glacial 
Period; and the occurrence of fragmentary and a few whole shells I 
ascribe to the invasion of the country by the edge of an ice-sheet, 
which advanced on to the land after traversing a sea-floor strewn 
with shells. I have elsewhere stated pretty fully the reasons 
which have weighed with me in arriving at this conclusion, and 
it is satisfactory to find that many of the a priori objections urged 
against the possibility of glacier-ice picking up, transporting, 
and redepositing marine shells derived from deposits over which it 
has passed, have been dissipated in a decisive way by the obser- 
vations of Profs. Garwood & Gregory upon the Ivory-Gate Glacier." 
The same observers also proved in a conclusive manner that shells 
and other materials picked up by a glacier could be transported 
to a higher level than the bed from which they were 
obtained. 
The principal facts with which I started out were—firstly, the 
occurrence of three groups of erratics derived respectively from the 
west, the north, and the east ; secondly, the distribution of the Drift 
as a continuous sheet on the west, north, and east of the Cleveland 
Hills, and not in the central part, except in the Esk Valley; and, 
thirdly, the striations and the nature of the deposits. 
I will consider the western group first. 
It has long been known, mainly thanks to the accurate researches 
of Mr. J. G. Goodchild, Mr. W. Gunn, and the late Prof. Carvill 
Lewis, that at one stage of the glaciation of England, so great a 
condition of congestion existed in the Irish-Sea basin, that a great 
volume of ice bore in upon the Solway, and being joined on the one 
hand by ice from the Southern Uplands of Scotland, and on the 
other by that from the Lake District, it filled the Vale of Eden to 
overflowing. One immense stream swept over the Tyne watershed 
and invaded Northumberland, while at the other end of the Crossfell 
* Quart. Journ. Geol, Soc. vol. liv (1898) pp. 205, 206, 219, ete. 
