516 Professor T. G. Bonney—Presidential Address— 
have discussed in the British lowlands. That Scandinavia was at one 
time almost wholly buried beneath snow and ice is indubitable; it is 
equally so that at the outset the land stood above its present level, 
and that during the later stages of the Glacial Epoch parts, at any 
rate of Southern Norway, had sunk down to a maximum depth of 
800 feet. In Germany, however, erratics are scattered over its plain 
and stranded on the slopes of the Harz and Riesengebirge up to about 
1400 feet above sea-level. The glacial drifts of the lowlands some- 
times contain dislodged masses of neighbouring rocks like those at 
Cromer, and we read of other indications of ice action. I must, 
however, observe that since the glacial deposits of Moen, Warnemiinde, 
and Riigen often present not only close resemblances to those of our 
eastern counties but also very similar difficulties, it is not permissible 
to quote the one in support of the other, seeing that the origin of each 
is equally dubious. Given a sufficient ‘head’ of ice in northern 
regions, it might be possible to transfer the remains of organisms from 
the bed of the Irish Sea to Moel Tryfaen, Macclesfield, and Gloppa; 
but at the last-named, if not at the others, we must assume the 
existence of steadily alternating currents in the lakes in order to 
explain the corresponding bedding of the deposit. This, however, is 
not the only difficulty. The‘ Irish Sea glacier’ is supposed to have 
been composed of streams from Ireland, South-West Scotland, and the 
Lake District, of which the second furnished the dominant contingent ; 
the first-named not producing any direct effect on the western coast of 
Great Britain, and the third being made to feel its inferiority and 
‘* shouldered in upon the mainland”’. But evenif this ever happened, 
ought not the Welsh ice to have joined issue with the invaders a good 
many miles to the north of its own coast? Welsh boulders at any 
rate are common near the summit of Moel Tryfaen, and I have no 
hesitation in saying that the pebbles of riebeckite-rock, far from rare 
in its drifts, come from Mynydd Mawy, hardly half a league to the 
E.S.E., and not from Ailsa Crag. 
During the last few years, however, the lake-hypothesis of Carvill 
Lewis has been revived under a rather different form by some English 
advocates of land-ice. For instance, the former presence of ice- 
dammed lakes is supposed to be indicated in the upper parts of the 
Cleveland Hills by certain overflow channels. I may be allowed to 
observe that, though this view is the outcome of much acute observation 
and reasoning,’ it is wholly dependent upon the ice-barriers already 
mentioned, and that if they dissolve before the dry light of sceptical 
criticism the lakes will ‘‘leave not a rack behind”’. I must also 
confess that to my eyes the so-called ‘overflow channels’ much 
more closely resemble the remnants of ancient valley-systems, formed 
by only moderately rapid rivers, which have been isolated by the 
trespass of younger and more energetic streams, and they suggest that 
the main features of this picturesque upland were developed before 
rather than after the beginning of the Glacial Epoch. I think that 
even ‘Lake Pickering’, though it has become an accepted fact with 
1 Pp. F. Kendall, Quart. Journ. Geol. Soc., vol. lviii, p. 471, 1902. 
