Ch. XL] 



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 Schaff hausen traverses a 

 tertiary deposit, called in Switzerland molasse, which consists in 

 some places of stratified yellow loam. At Stein, near (Enin- 

 gen, 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 



