On Fluvio-Glacial and Interglacial Deposits in Switzerland

Abstract

I. I ntroduction. I n a paper published in the Geological Magazine for January 1894, I showed that the Swiss Alps had been visited not only by two, but by three general glaciations, of which the first may be referred to Pliocene, the second to Middle Pleistocene, and the third to Upper Pleistocene times. The evidence consists chiefly in a number of glacial and so-called fluvio-glaciM deposits which I had examined in the Swiss lowlands, and notably in the vicinity of the Lake of Zürieh, where, perhaps more than in any other part of Switzerland, such deposits are laid open within a comparatively small and easily accessible area. The first suggestion of certain gravel-beds at the foot of the Italian Alps being older than the two Pleistocene glaciations then generally accepted may be said to have emanated from Stoppani, Desor, and notably from Renevier, as early as 1875. In 1882, Prof. Penck succeeded in showing, on the evidence of Deckensehotter or plateau-gravel, that the Bavarian and Austrian Alps had been visited by three different glaciations; but as regards the Swiss Alps, even such distinguished glacial geologists as Prof. Helm hesitated to adopt that view until quite recently, namely in 1891 Dr. Léon Du Pasquier, of Neuehhtel, showed in a valuable memoir that the fluvio-glacial gravels deposited in the valleys of the principal river-systems in the North of Switzerland admit of being classed in three distinct categories, to wit, Cavernous Nagelfluh (the Swiss equivalent for Deckenschotter),Upper Terrace-, and Lower Terrace-gravels. Dr. Du Pasquier