Nature Notes

Vol. V September 12th, 1927 Summer Season No. 11


This is not an advertisement for a new kind of shoe-polish, although if one had the glacier, and the patience, no doubt one could shine shoes this way. Rather, this is a description of some very brilliantly polished rocks found near the terminus of Paradise-Stevens glacier.

The rocks have been known for several years, but the writer's attention was first called to them by F. A. Warren who collected some samples this summer. The rock is a dark andesite lava and is more or less jointed and fractures. No so very many years go the Paradise-Stevens Glacier rode over the outcrop. This glacier has been receding extremely rapidly of late, and there is no reason to doubt that the andesite outcrop in question was ice-covered a few score years ago. At present it displays a billowy surface, which resembles somewhat the backs of a flock of sheep. For this reason the French and Swiss call such a rock mass "roche moutonee". The truly remarkable feature of this "roche Moutonee" is the brilliant polish of the surfaces. The rocks glisten as though wet, and the dazzle can be seen far away.

There is no doubt that this polish is glacial. The same rocks are striated in the line of glacial flow, and it is the surfaces upon which the ice impinged that are polished. The surface is too billowy, due to faulting or slipping of the rocks. Perhaps the reason that rocks highly polished by glaciers are unusual is because the polish wears off after a few centuries. The comparatively late date at which the ice probably melted away from this rock may account for the preservation of the polish.


For year the glaciers have been receding on Mount Rainier. Some of them are known to have receded a thousand feet or so in thirty years. As this goes on, trees and flowers occupy land that once was ice-covered. In reality the advances of the trees and the retreat of the glaciers are due to a common cause, milder climatic conditions. Just what causes the milder climate, and how long it will last are unanswered questions.

On a recent visit to Timberline Ridge above Paradise Valley, the naturalist discovered a recent advance of the trees. The wind-swept line that clings to the rim of the valley had sent out an outpost. Fully a hundred yards from the nearest large tree was a little alpine fir. Though rooted in broken rocks, the seedling seemed to be thriving. Its propagation seems rather remarkable in light of the fact that it was not only a hundred yards above timberline, or what used to be timberline, but uphill. That it was in the direction of our strongest winds is probably sufficient explanation.

<<< Previous
> Cover <