318 T. Mellard Reach— Glacial Geology. 



Now the odd thing happens that the largest collection of the most 

 perfect shells are found just in the place where they are least 

 wanted on the ice-sheet hj'pothesis. Obviously a safe means of 

 transport must be provided, and this is supposed to be ensured by 

 the working up of the sea-bottom material into the ice-sheet, and 

 these delicate shells, solidly encased in ice, are pushed safely an 

 unknown distance over the sea-bottom and then uphill and down 

 dale to be eventually melted out and deposited uj)0u the summit of 

 a hill 1100 feet above sea-level. 



There is yet another if a minor question of a physical nature that 

 obviously requires answering. If the ice-sheet possessed sufficient 

 power to force sea-bottom 1400 feet up the slopes of Snowdonia and 

 within five miles of its highest centre, why should the snows from 

 the mountains of Denbighshire and Flintshire be sufficient to divert 

 one lobe of it over the plains of Cheshire, and the other along the 

 Welsh coast ?^ Kather one would expect that the whole of Flintshire 

 and Denbighshire would have been overwhelmed with an ice-covering 

 marching irresistibly towards the Midlands. 



Nor must we lose sight of the fact that near Macclesfield and on 

 the Thi-ee-Rock Mountain, near Dublin, shelly sands and gravels 

 have been found at a level of about 1200 feet above the sea. These 

 places are on the same parallel of latitude and about 190 miles apart. 

 If the transport was by land ice, the ice-sheet filling the Irish Sea 

 must have had here a front of not less extension than 200 miles, and 

 a minimum depth of say 2000 feet; but on this head we have very 

 little to go by. We may very well ask how a snow-field in Scotland 

 of a less width than the distance between these two places, even 

 assisted by the bordering fields of England and Scotland, could have 

 generated a glacier which not only displaced the water of the Irish 

 Sea, but after spreading out 190 miles still maintained such an 

 enormous depth as to be capable of forcing up sea-bottom laterally 

 on either side to the height of 1200 feet; and in the case of the 

 Three-Rock Mountain against the contributory glaciers of Irish origin. 



Distribution of the Sands and the Matrix of the Boulder-clay on the 

 Ice-sheet Hypothesis. 



If the Drift occupying Lancashire, Cheshire, and Shropshire has 

 been carried there by an ice-sheet it would show in its constitution 

 little or no relation to the water-sheds in which it occurs ; whereas, 

 as I have shown, the contrary is the case. The clays would not 

 preponderate as they do in the lower part of the basin of the Mersey, 

 nor would the sands be found lying upon the New Red Marl as they 

 do in Cheshire and Shropshire. 



If an ice-sheet had passed over the Red Marl of Cheshire we 

 ought naturally to look for a great mass of Boulder-cla^'s further 

 south ; instead of this sands and gravels preponderate. The waste 

 of the New Red Marl of Cheshire has flowed in a northerly direction 



1 Mr. Strahan shows that the Drift of the upper part of the Vale of Clwyd has 

 travelled North-East. — Memoir of the Geological Survey, Geology of the neigh- 

 toiiihood of Flint, Mold, and Euthin. 



