On Silurian Erratics in Wharfedale

J. R. Dakyns
1871 Proceedings of the Yorkshire Geological Society  
formerly filled with ice to a depth sufficient to bury the Isle of Man, or 2,000 ft. But I doubt whether the conclusion of Professor Phillips follows from the facts. At the foot of a glacier the ice is of course less than that depth, so that it would not there crush at its base; and higher up the glacier, where the depth is sufficient to crush the base, the crushed ice could not escape since it would be confined by the uncrushed ice in front. It would, therefore, act like a fluid, and would
more » ... luid, and would assume the shape of the rocky basin. We may, perhaps, imagine that the crushed ice at the base of the glacier, might, in consequence of lateral pressure, crush its way through the icy barrier in front, and make its escape like water breaking down the banks of a reservoir; but it is doubtful whether crushed ice would thus transmit pressure equally in all directions. The most probable result would be that this barrier of ice, with its unfrozen stone, would be forced forward with all the pressure dammed up behind it, and would constitute an excavating tool of greater energy than any to be found in the present glaciers of the Alps. In an enclosed rocky basin the ice might certainly be of any depth. The paper was illustrated by numerous photographic views, shown with the oxy-hydrogen lantern.
doi:10.1144/pygs.6.159 fatcat:3eih35hdn5az3kn2czd55eefze