Ch.XI.] LOESS OF THE VALLEY OF THE RHINE. 153 
since we find the loess lower down the valley, on the flanks of 
the Siebengebirge. 
We have stated that stratification is almost entirely wanting, 
but the movement of the muddy waters appears in some places 
to have torn up the subjacent soil, and then to have thrown 
down again the foreign matter, thus mingled with the loess, in 
layers and strata. An alternation of gravel and loess has 
resulted from this cause in the lower part of the section before 
alluded to at Heidelberg. . 
I observed a similar blending of the loess, and the variegated 
sandstone and red marl underlying it at Zeuten and Odenau, 
in a valley on the right bank of the Rhine, at a short distance 
from the Bergstrasse, between Wiesloch and Bruchsal, a loca- 
lity pointed out to me by Professor Bronn. Near Andernach 
there is a similar intermixture and alternation of the lower beds 
of loess, with volcanic ejections such as are strewed over that 
country, a phenomenon from which some observers have too 
hastily inferred that the volcanic eruptions and the deposition 
of the loess were contemporaneous. 
The Rhine throughout a great part of its course between 
the lake of Constance to the falls of Schaffhausen traverses a 
tertiary deposit, called in Switzerland molasse, which consists in 
some places of stratified yellow loam. At Stein, near CE frin- 
ge n, this loam is 150 feet thick; and resembles exceedingly the 
loss before described, except in being regularly stratified. If 
we could suppose the waters of a great lake like that of 
Constance to have been suddenly let free by an earthquake, 
and in their descent into the valley of the Rhine to have 
intersected such strata, we might imagine the waters to have 
become densely charged with loam, with which they may have 
parted as soon as their velocity was diminished by spreading 
over a wider space. 
The catastrophe which brought down the loess must, for a 
time, have desolated the country, but, in the end, it has 
enriched the soil, constituting the most fertile parts of Alsace 
