Geology of the Austrian Alps. 25 



and sandstones, but also rounded fragments of primary and 

 secondary crystalline or slaty rocks, which are foreign to the 

 alpine geology. No one but will at once see the high interest 

 of such a composition ; and he will find, without surprise, frag- 

 ments of this rock in the more recent nagelfluhs. Now, these 

 peculiar rocks appear as if dipping under the alpine limestone, 

 while, on the contrary, as along the Lake of Zug and else- 

 where, the molasse appears to dip under the first deposite ; 

 but no one has been able to confirm the truth of this double 

 position, and nobody ever found in the ancient nagelfluhs any 

 of the shelly beds of the tertiary molasse. For these rea- 

 sons, we still remain persuaded that it is a secondary deposite, 

 and that its peculiar position in regard to the neighbouring 

 masses of rocks is only an accident, caused by the upheaving, 

 which affected not only the calcareous chain, but also the hori- 

 zontal tertiary beds. The same peculiar nagelfluh rocks have 

 been found under thegreensand of the Voralberg and the Allgau, 

 and again north of Salzburg, and even to the south-east of that 

 town. Lastly, in the middle of the Austrian Alps, the alpine lime- 

 stone appeared to us to support here and there chalky deposites, 

 at the base of which limestone were seen naglefluh rocks asso- 

 ciated with molasse-like rocks. In this last case, as to the north 

 of Salzburg, they contained rolled masses foreign to the moun- 

 tains composing the Alps. In those places where these foreign 

 boulders were wanting, the chalky deposites were so isolated 

 amongst lofty limestone hills, or surrounded by them as in basin, 

 a situation which sufficiently explains the absence of such boul- 

 ders or transported rocks, which no force could have brought 

 into such hollows. All these facts brought to our recollection 

 the rocks in the vicinity of the Swiss nagelfluh, and we ima- 

 gined that we saw there the same connexion of these problema- 

 tical masses with greensand rocks, as to the south of the Rigi, 

 at the foot of the Pilatus, at Thun, at Saarnen, at the Voirons, 

 &c. We wait now for the dissent or assent of alpine geologists 

 to this statement. 



Lastly, We come to our controversy in regard to the age of 

 the Gossan deposite. In their section (Fig. 1.) they have well 

 expressed its unconformable and overlying position upon the 

 alpine limestone, and in a deep and large cavity of that forma- 



