Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/727

 for about three miles ; after which, had the area been land, it would have accommodated itself to what is now the valley of the Lowther, and assumed a northerly direction.

Independently of the direction of these old valleys, which must have influenced the courses of the glaciers, the outline of the country, with its slopes between Wastdale Crag and that portion of the Pennine chain which has been crossed by the granite blocks, is altogether hostile to the idea of a glacier having been the transporting agent of these masses of granite. The prominent escarpments fronting this glacier would have diverted it from an eastern course ; otherwise these escarpments would have been planed down by its action, and all traces of the north and south striae which now mark the faces of the rocks would have been obliterated, and their places occupied by others of a more recent date, running from west to east ; yet no such markings are to be found. The idea, therefore, which suggests a glacier as the agent of the transport of these blocks has very little to support it.

Another cause has been looked upon as the transplanting agent of the Wastdale-Crag blocks, namely, icebergs ; and this certainly is a much more probable means of dispersion than the action of glaciers. There are, however, some difficulties attendant on the iceberg theory, which seem to render it by no means easy of acceptation. If we assume glaciers to have occupied valleys on the north and south sides of Wastdale Crag (and of this there is very little reason to doubt), and if we are to attribute icebergs to such glaciers, the greatest portion of the mass of Wastdale Crag, which has furnished the blocks, would have been under the surface of the water on which those icebergs floated. By far the largest portion of Wastdale Crag is at a lower level than 1500 feet above the sea ; in fact very little of the hill, except its western side, attains an elevation equal to that portion of Stainmoor over which the blocks have passed in their route to the valley of the Tees. Assuming icebergs to have been the agents of transport, it would have required the sea to have been at least 1500 feet above its present level, otherwise there would not have been a sufficient depth of water to have enabled blocks to have floated over Stainmoor into the valley of the Balder.

[In the accompanying map (Pl. XXXV.), the outline which the land would assume if the sea were 1500 feet above its present level is shown by the portion marked with perpendicular lines. The whole of the area left blank, and also that marked with broken lines, would, under such circumstances, be under water].

If it be assumed that the granite of Wastdale Crag rose to a higher level than it does at the present time, during the period of the distribution of the granite blocks, still that higher level would hardly suffice to furnish materials to a glacier, portions of which would be detached and float away as icebergs.

There is another difficulty with reference to the iceberg theory of transport. This is the size of the bergs themselves. If we suppose these to have had an average of 50 feet in height above the surface