Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/728

 of the water, this would presume a mass eight times this size below the surface ; and assuming this comparatively small size for those bergs, we should have them extending to the depth of 400 feet beneath the water. The floating of such a mass of ice is altogether incompatible with the idea that these blocks were carried over Stainmoor, when the sea was about 1500 feet higher than at present.

If we assume a greater height of sea-level, and one sufficient to float such icebergs, then we place the whole granitic area of Wastdale Crag considerably below the water-level, and in such a position as to render it unavailable to furnish materials for transport.

Another objection to the iceberg theory is furnished by the mode of occurrence of the blocks themselves. Their insulated and superficial position is] strongly antagonistic to this idea. If we suppose icebergs, bearing mineral matter, to have been stranded in the areas where the Wastdale-Crag blocks are found, the melting of these, either wholly or partially, would have left some of the earthy mud and sand so abundant among ice-transported materials ; and in such mud and sand the blocks would have been seen. Nothing of this kind, however, occurs ; for the blocks alone seem to have been the materials transported.

There yet remains to be considered another agent which could have transported the blocks of "Wastdale Crag : this is coast-ice ; and this agent seems less liable to objection than either the action of glaciers or the operation of icebergs.

Such an agent is now in action in high latitudes ; and the effects which result therefrom, both in Europe and America, have been well described by Sir Charles Lyell *.

If we suppose the sea-level, at the period of the transportation of the Wastdale-Crag granite blocks, to have been at the height previously assumed, namely, 1500 feet higher than at present, although a large portion of the granite area, as it is now seen, would have been beneath the sea-surface, there would still remain sufficient above and near the surface to have afforded blocks.

These blocks, when frozen in ice-sheets, would be in a position easily capable of transport, when the sheets became broken up. Blocks imbedded in and lying upon such ice-rafts would require no great depth of water for their transport.

These ice-rafts would be dependent upon winds and currents for their direction : their course west was impossible, as the land lay on that side. There remained, however, a north, south, and east course for them to take.

With reference to the former, the northern course, there is evidence which supports the inference that in this direction their motion would be materially interfered with by currents setting in from the north-west and north. The evidence of the existence of such currents during the period of the transportation of the Wastdale- Crag blocks, is indicated by the occurrence of blocks of Criffel


 * Principles of Geology, 10th ed. vol. i. p. 383.