Friday, 4 March 2011

the parallel roads of glen roy

A picnic near the Zermatt Glacier
Louis Agassiz, from Etudes sur les glaciers, 1840
I recently learnt of the work of Louis Agassiz, the Swiss paleontologist, glaciologist and geologist and occasional artist. Agassis was an important figure in describing the movements and motions of glaciers, and whilst it was understood that much of our landscape is formed through glaciation, that ice had the power to shape the land, move vast boulders great distances and to grind down rock, he was the first to propose that the earth had recently undergone an ice age, and that vast tracts of land in europe had, in gelogical time, recently been covered with ice.

Hugi's hut on a medial moraine of the lower Aar glacier
Louis Agassiz, Etudes sur les glaciers, 1840
Rocks polished and striated by a glacier
Louis Agassiz, from Etudes sur les glaciers, 1840
One of his more significant discoveries was made in Scotland when Agassiz finally unlocked the mystery of the parallel roads of Glen Roy when he proposed that the "roads" were not of a marine nature, as was erroneously proposed by Darwin, but were in fact caused by the rapid damming by a glacier of a loch in the period of the Loch Lomond stadial (a mini ice age around 12000 years ago, and lasting for a brief 600 years) and it's subsequent melting, in three stages.

the parallel roads of Glen Roy
I've spent much time walking and camping during winter in Glen Roy and have a favourite wild camp spot near Fersit. It's amazing to think that in the relatively recent past, this familiar valley would have been hidden under water, and my wild camp buried under a glacier near the head of Loch Trieg. I've seen the parallel roads marked on the Ordnance Survey maps, always rather assuming that they were indeed "roads", perhaps forestry tracks or some system of roads where a higher track existed to avoid boggy ground, but of course, that would eliminate the need for the lower tracks. Instead, they are completely natural, and lie on the horizontal, mapping, marking and measuring dramatic moments in the valley's past where the ice dams spectacularly broke and the glacial loch drained.

Stob Coire Easain (near Fersit), Dec 19th 2007

1 comment:

  1. Agassiz was actually not the first to propose a theory of continental glaciation. See Cristophe Irmscher's "Louis Agassiz: Creator of American Science" pp. 64-65 for a brief description of the ideas and contributions of Karl Friedrich Schimper, for example.

    Agassiz WAS the first to popularize the notion but, as Irmscher points out, he did so in his characteristic fashion of failing to credit work done by others before him.