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clay was unconformable, but here no unconformity can beproved.
Locherige Nagelfluh, in its ordinary character of a riverdelta deposit, is seen in an exposure in a gravel quarry near aspring, not far from the carriage road to Leutkirch, north-east of the town.
The pebbles here are all rounded, and no striae are seenon them.
Many of them are cracked by pressure.
Angular fragments are absent. An iceberg perhaps groundedat the former locality. There is not so much hornblendic gneisshere.
That icebergs grounded here is shown by two large erraticsof gneiss in the town, a yard long.]
[The Falls of the Rhine , then, are post-glacial, as are mostfalls.
The gravel in the Klettgau is in large part hardened intolocherige Nagelfluh ; here it is undoubtedly a river deposit, madebefore the greatest extension of the glacier, for the moraine madeat that time altered the drainage. The entrance of the oldRhine into the Klettgau seems to have been below the presentFalls. Here is another means for calculating the age of theglacial epoch.
At Waldshut we descend to the valley of the present Rhine ,which has greatly cut down its bed in post-glacial times, and, bycontrasting the height of the old and the new bed, we gain agood idea of the amount of erosive work done since the glacialepoch by the Rhine .
(I have seen the Klettgau , Sandgau, Tliurgau, Allgau, &c.)
Just before reaching Albert-Hanenstein Station is a largemass of yellowish clay full of boulders, often a foot long, thisbeing the Philadelphia brick-clay due to the drainage of theglacier. It lies high upon the valley like the Philadelphia brick-clay, and might at first be taken for till, but it lies upon non-glaciated rocks, and crags project through it.
Below here the river flows more quietly, and has not cutthrough its plain of Trenton gravel.
As below Trenton, so at Murg and Siickingen, cliffs of rivergravel occur, while back on the hills is the boulder clay, or brick-