Its Bearing on Glacial Geology. 19 
subject to flux and reflux twice a day to consequent change of 
current for every hour of the day. Its surface, and anything floating 
thereon, is affected by winds, changeable, but having a more or less 
prevalence of direction. 
All the conditions necessary to satisfy the problem of boulder 
distribution are here, if we add floating ice; but the explanation so 
close at hand, and so complete, is thrown aside, ostensibly because 
it involves submergence of the land to a greater or less extent. 
What Marine Drift in Eskdale tells us. 
As I have shown in the preceding pages, Marine Drift is found 
in Eskdale and Miterdale up to a level of 400 feet above the sea. 
This Drift is similar to, and the equivalent of, the Marine Drifts 
found up to the same level on the coast of North Wales. The 
supporters of the Irish Sea glacier hypothesis contend that these 
sands, gravels, and clays, together with similar Drift at higher 
levels on Moel Tryfaen, Halkin Mountain, between Minera and 
Llangollen, and on Gloppa, have been pushed up in opposition to 
the local Snowdonian and North Wales glaciers by the hypothetical 
Trish Sea glacier after traversing the sea bottom. This explanation 
will not, however, account for the presence of Marine Drift in 
Eskdale and Miterdale. 
The Permian sandstone-pebbles found up to a level of 320 feet 
above O. D. could not have been pushed up by land-ice from the 
Trish Sea against the general flow of the valley-ice. The ice-sheet 
bearing down from Scotland would have had to turn sharp round at 
right angles and flow up Eskdale to have effected this. If such an 
extraordinary thing did happen, in what way, we may ask, have 
Lake District rocks got conveyed to the Isle of Man,' or how have 
Eskdale granite boulders and pebbles been carried north-westerly 
in direct opposition to the hypothetical ice-flow, as far as St. Bees ? 
Test it in any way we may the ice-sheet explanation breaks down 
here. 
Extent of the Submergence. 
Although in this district I observed no evidence of submergence 
higher than 400 feet above mean sea level, it must not be inferred 
that that was its maximum limit.? It would take a very careful 
survey of a much larger area of the Lake District to offer an opinion 
worth having as to the extent of the maximum submergence. The 
glaciated gravels at the top of Screes, Wast Water, and down to a 
level of 1300 feet above the sea are of an altogether different type 
to the marine gravels of Hskdale, and appear to be a purely glacial 
1 «¢ There is abundant evidence too of a strange intermingling of foreign rocks in 
the till, which must have travelled from the coast of Cumberland (the italics are mine), 
the South of Scotland and the North of Ireland” (Sketch of the Geology of the 
Isle of Man—Horne—Trans. of Edinburgh Geol. Soe. vol. 11. part ill. 1874). 
2 The late Mr. Clifton Ward (Geology of the Northern Part of the English Lake 
District, Mem. Geol. Survey) considered there were evidences of very great sub- 
mergence, but as I have not visited the localities he names, and am not clear as to 
the grounds on which he judged the Drifts he mentions to be Marine, I cannot use 
his observations. 
