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and great and sharp development of a medial moraine, as dis-tinguished from a terminal one.
The moraine has evidently altered the drainage here, andmade a watershed.
Formerly, probably, the Argen went by way of Leutkirch intothe Iller , or vice versa. There are no signs of glaciation here.]
That the extra-morainic drift is not older than the moraine,but due to the same cause, is indicated by the elevations; bothhave the same elevation above the sea. Both Fraas and Zittelthink that Bach ’s hypothesis of two ice periods to explain theBiberach drift is without sufficient proof (vide Sitz. d. math,phys. Classe, 7 November, 1884, p. 272).
Probst also ( Wurtt.-naturw. Jahreshefte, 1874, 40) is muchopposed to two glacial epochs.
The locherige Nagelfluh is striated by a glacier which passedover it near Schaftlarn, in Bavaria (Zittel, p. 279). Zittelnever observed glaciated stones or erratics in it.
[After visiting Schloss Zeil I examine a very instructive ex-posure behind a crucifix at the side of a wood, north of the castle.
Here a cutting shows locherige Nagelfluh with the charactersof a moraine. It is full of glaciated erratics, fragments of horn-blendic gneiss—often quite angular—scrafcchedlimestone boulders,sandy layers, &c.; greatly resembling a mass of till. Yet it isfirmly cemented into rock, and is somewhat rotted through thedissolution of the lime cement. It is cemented more on top thanbelow.
This is the very top of the locherige Nagelfluh, and here isan interesting transition from ordinary non-glaciated locherigeNagelfluh into glaciated fringe material. It is an importantlocality.
It connects the pre-glacial with the glacial age without abreak, and shows the passage of the rivers of the Nagelfluhperiod into the extra-morainic lake of the glacial period, therebeing here no unconformity.
Here also, at the side of Schloss Zeil , is a great pre-glacialvalley, where the old Rhine passed on its way to the Danube ,the Nagelfluh river continuing until it was dammed up by thegreat moraine below us, which is like an artificial dam across thevalley, and now makes a watershed. The Biberach glaciated