1 20 Mr Lyell on the Loamy Deposit of the Rhine. 



to uie that the followhig conclusions may be legitimately de- 

 duced : — 



1^/, The loess is of the same mmeral nature as the yellow 

 calcareous sediment with which the waters of the Rhine are now 

 commonly charged.] 



2cZ/^, The fossil shells, contained in the loess, are all of recent 

 species, consisting par Jy of land and partly of fresh-water shells. 



Sdly, The number of individuals belonging to land species 

 usually predominates greatly over the aquatic, and this seems 

 now to be the case with the modern shells drifted down by the 

 Rhine. 



Wily, Although the loess in general evinces no signs of strati- 

 fication, we must yet suppose it to have been formed gradually, 

 for the shells contained in it are very numerous, and almost all 

 entire ; and sometimes beds of pure loess, fully charged with 

 shells, alternate several times with strata of gravel, or of volcanic 

 matter. 



5thly, Although, in general, the loess overlies every forma- 

 tion, including the gravel of the plains of the Rhine, and the 

 volcanic rocks, which have the most modern aspect, yet in some 

 cases, as at Andernach, the volcanic matter is so interstratified 

 as to indicate that some eruptions occurred during the deposition 

 of loess. 



These inferences seem to me sufficiently clear ; but if asked 

 to account for the manner in which the loess, considering it as a 

 fluviatile or lacustrine formation, was brought into the places 

 which it now occupies, I must confess that the more I have 

 studied the subject the more difficult I have found it to form a 

 satisfactory theory. 



If we begin to study the loess near Strasburg, we see large 

 masses of it at the foot of the Vosges, on one side of the great 

 plain of the Rhine, and at the base of the mountains of the 

 Black Forest, on the other side. The intervening plains ex- 

 hibit here and there remnants only of the same formation rest- 

 ing on gravel, for the loess has evidently suffered great denuda- 

 tion ; valleys having been hollowed out in it, and small ridges 

 of intervening: hills formed, much like those seen on the surface 

 of older horizontal tertiary formations. On following the loess 

 from Strasburg to Mayencc, we may trace it covering the rocks 



