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This Nagelfluh is the deposit of a succession of mountainrivers, the succession being due to continued elevation.
This explanation has only come to me after two months ofwork and careful study of the subject. These old rivers drainedinto the Danube .
The elevation of the Alps in late pleiocene and earlyglacial times also elevated the Jura, and reversed the drainageof the Rhine, elevating the Sandgau and the old Rhine bed.This accords with the conclusions of Lyell (Elements of Geo-logy), Desob (Bull. Soc. Giol. de France, 2e ser. t. viii., p. 69,1850), Mulleb (Verh. Natmf.-Gesells. Basel, 2, p. 848),Koechlin (Bull. Soc. Geol. de France, 2e ser., t. xvii. p. 92),Koechlin , Sohn (Geologic du Ilaut-Bhin, pp. 100, 101).
I again cross the moraine, now from north to south. It isvery wide, and without conspicuous hills, and would not benoticed by a geologist who was not experienced in glacial studies,in its great width and comparative flatness it is like portions ofthe Rhone glacier moraine, which on that account has been over-looked by geologists. Professor Chamberlin says of the Ameri-can moraine that it is distinguished by the amount of driftrather than by any sharp ridge-like form ; and this is clearly acharacteristic of all great glaciers as distinguished from smallerglacial tongues.
Medial moraines are sharper and more hummocky, this beingdue, as I saw at Grindelwald , to the actual forcing up of the iceinto great waves, a hundred or more feet high.
This is not the case with terminal moraines.
I take the train. We pass into the moraine beyond Waldsee,the moraine curving, and in the railway cuttings find an abund-ance of great boulders, often scattered, which project through thegrass, as I saw so frequently in England.
At the station at Rossberg some large erratics have beenpiled up in the garden. One of these is of granitic gneiss,fully 15 feet high and 6 feet wide, the largest erratic preservedin South Germany ; and another is almost as large.
About Wolfegg the moraine is enormously developed, and ofgreat thickness, being here probably medial between two ice-lobes. Large hills are thrown up, and are cut through by therailway before we reach Wolfegg Station. The depth of thedrift is seen in a gorge ; it must be 400 feet thick.
This is an excellent example of the tumultuous character
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