VALLEYS OF DENUDATION IN CENTRAL GERMANY. 213 
which these stupendous operations which have taken place in Switzer¬ 
land were brought about. 
Baron Yon Schlotheim, in his Nachtrage zur Petrefactenkunde, 
1822, describes, in the following terms, the valleys of denudation 
which traverse the plains of Saxony, on the south-west of Leipsig. 
And I remember to have been myself struck with them as being very 
remarkable in the vicinity of Jena, where they afford some of the 
most decided examples of deep valleys and gorges excavated entirely 
by diluvial action which I am acquainted with in Germany. 
“ The deep narrow valleys and defiles prevailing in the neigh¬ 
bourhood of Jena, in the valley of the Muhl, and further towards 
Drakendorf and Kostritz, clearly show the power with which the 
ancient waters raged when these channels were excavated, in which at 
present flow the Saale, the Elster, and the adjoining smaller streams. 
It is manifest that during the course of this operation large tracts of 
the limestone superincumbent on the gypsum, as well as of the new 
red sandstone, were torn and swept away.” 
M. Schlotheim is disposed to consider these as local occurrences, 
and to attribute them to the bursting, at successive periods, of 
the barrier of some fresh-water lakes. But this solution is in¬ 
admissible, unless we assume the existence of similar lakes at 
the head of every stream, and of every valley in the world; for 
there are none in which the effects of similar denudation are not 
apparent: and Mr. Weaver, in his comment on this passage, most 
judiciously remarks, that lakes in the present course of nature have 
a tendency to fill up, by a gradual accumulation on their bottoms, 
