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Early descriptions of pro-talus ramparts

Published online by Cambridge University Press:  20 January 2017

David J. Unwin*
Affiliation:
Department of Geography, University of Leicester, Leicester LE1 7RH, England
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Abstract

Type
Correspondence
Copyright
Copyright © International Glaciological Society 1988

The Editor, Journal of Glaciology

Sir,

Early descriptions of pro-talus ramparts

I refer to the correspondence in Journal of Glaciology Vol. 33, No. 114, involving Butler, Porter, and Ballantyne, concerning the scientific primacy of the recognition of the pro-talus rampart as a (moderately) distinct land form. Like Porter, I think that the description by Reference DrewDrew (1873) of forms in the upper Indus, which was taken up by Reference WardWard (1873) to explain fossil features in the English Lake District, should be accorded primacy.

These descriptions are both part of much more general regional accounts, so it would be a pity to let this correspondence close without drawing attention to a little known paper by Reference KendallKendall (1893) which is entirely devoted to a detailed description of such a form. Both the title of the work, “On a moraine-like mound near Snowdon”, and the following quotation:

“at the close of the Glacial Epoch, when the Welsh glaciers had entirely passed away, there would be perennial snow banks in a thousand such sheltered corners. The nearer to the time of the great severity the more considerable would the snow banks be. Suppose now, we imagine a huge snow wreath banked up against the cliffs of Cwm Du. The weather would attack the lofty scarps, water would percolate between the columns of lava, and, freezing, force them upward, so that the stone showers so familiar to Alpine travellers would be produced here under conditions highly favourable to their development; but when the stones come down they would find the base of the cliffs pre-occupied by a talus of snow, therefore they would roll further out from the base and form a fringe of rock debris”

Fig.1. The pro-talus rampart in Cwm Du, Snowdonia, North Wales.

gives little doubt what Kendall had in mind.

The photograph ( Fig.1), taken in the mid 1960s, shows the feature which is at grid reference (OS) SH 536553. Since Kendall’s visit, the site has been mapped by myself (Reference UnwinUnwin, 1975, fig. 2) and more recently still by Reference GrayGray (1982) who puts it into its regional and chronological context.

References

Drew, F. 1873 Alluvial and lacustrine deposits and glacial records of the Upper–Indus basin. Quarterly Journal of the Geological Society of London, 29, 44171.CrossRefGoogle Scholar
Gray, J.M. 1982 The last glaciers (Loch Lomond readvance) in Snowdonia N. Wales. Geological Journal, 17, 11133.Google Scholar
Kendall, P.F. 1893 On a moraine–like mound near Snowdon. Glacialist Magazine, 1, 6870.Google Scholar
Unwin, D.J. 1975 The nature and origin of the corrie moraines of Snowdonia. Cambria, 2(1), 2033.Google Scholar
Ward, C. 1873 The glaciation of the northern part of the Lake District. Quarterly Journal of the Geological Society of London, 29, 42241.Google Scholar
Figure 0

Fig.1. The pro-talus rampart in Cwm Du, Snowdonia, North Wales.