14 JS. H. Howorth — A Great Post- Glacial Flood. 



the Loess wliicli existed at Basle and SchafFhausen would necessitate 

 a dam 1,200 feet liigh to retain the waters of such a lake, — and, 

 further, that the lateral valley of the Lahn was itself filled with 

 Loess, — the difficulty of postulating any sufficient barrier became 

 obvious. But, apart from this, such a lake as was cited to explain 

 the Khine Loess could not explain its distribution on the flanks of 

 the Carpathians, on the great Polish plain, nor in China. Again, 

 the contents of the Loess are completely against a lacustrine origin. 

 Although it abounds in shells, none of them are lake shells. While 

 the great number of debris of land animals which it contains 

 precludes such an origin. Nor, again, can we understand such a vast 

 unstratified deposit accumulating in a lake. The reasons against 

 such a theory are paramount, and since Sir Charles Lyell wrote 

 against it, it has been abandoned both in England and on the 

 Continent. We next come to Lyell's own idea, which he sug- 

 gested in substitution for the lacustrine theory just quoted. This 

 is still a living theory with some geologists. Lyell suggested that 

 the Loess of the 'Rhine Valley is of fluviatile origin, and was 

 deposited by the Ehine itself. This notion assuredly makes 

 enormous demands on our credulity. First, the Loess in structure 

 is very different to the warp deposited by a river. Such warp is 

 essentially stratified, and we can trace the annual layers by which 

 it has been deposited ; while the Loess is several hundred feet thick, 

 and throughout is homogeneous and unstratified. Secondly, it is so 

 highly charged with carbonate of lime that it is incredible that a 

 I'iver should have deposited it unless its waters were actually 

 saturated with that material. But, as we have said, Bischoff, in 

 1855, showed that the Rhine at Bonn had virtually no carbonate of 

 lime in it at all. Thirdly, the contents of the Loess point strongly to 

 its not being a fluviatile deposit. Sir Charles Lyell argues against 

 its lacustrine origin, because the shells it contains are terrestrial 

 and amphibious. Surely this very argument ought to be conclusive 

 also against its fluviatile origin. The force of this argument is very 

 great, for these shells do not occur locally and sporadically, but in 

 great numbers, and characterize the Loess in China and Eastern 

 Europe, as well as in the Rhine Valley. Let us look more closely 

 at their evidence. 



I Out of 211,968 shells from the Rhine Loess examined by Braun, 

 there was only one brackish-water form and three sweet-water 

 forms ; Limnceus and Planorbis, with but thirty-two specimens in 

 kll. Of the rest there were 98,502 examples of two species of 

 Wuccinea, which is an amphibious species, and 113,434: specimens of 

 land shells belonging to twenty-five species of Selix, Fupa, Clausilia, 

 Bulimus, Limax, Vitrina (Deutsch. Zeits. fiir die gesammten Naturwiss. 

 Halle, vol. xl. p. 45). 



In the Bavarian Highlands Giimbel found one amphibious form 

 (Succinea) and 14 terrestrial ones, Helix, Pupa, Clausilia and Bulimus. 

 Engelhardt, who has described the Loess of Saxony, refers to 24 

 localities whence he has examined the shells of the Loess, in which 

 only land and amphibious shells are to be found, while in two only 



