1848.] MURCHISON ON THE STRUCTURE OF THE ALPS. 159 



shells*. These indisputable data were in fact the groundwork of the 

 opinion afterwards applied to the Austrian Alps in natural sections, 

 amidst some of the interior valleys, as well as upon their northern 

 flank. Again, it was impossible to consider the shelly deposits of 

 the Vicentine in any other light than older tertiary deposits, as laid 

 down by Brongniart ; and if they were of that age,* they must, we 

 argued, have equivalents in other parts of the Alps. In relation, 

 even, to the deposits of Gosau, we then recognized, that their lower 

 shelly beds were cretaceous by their fossils ; but influenced both by 

 the presence of an overwhelming quantity of associated gasteropoda, 

 which usually abound in tertiary deposits (said to be of that age by 

 conchologists), and also by the facies of the soft and incoherent de- 

 posits, which were so strikingly contrasted with the subcrystalline 

 secondary rocks on which they reposed, we concluded that the upper 

 shelly portion of the group also represented a transition from cre- 

 taceous to supracretaceous rocks, analogous to that seen on the 

 flank of the Venetian Alps. My last visit to Gosau in 1847t ^^s 

 convinced me that my former view must be abandoned. I now believe 

 that the marly and earthy fossiliferous beds of that valley are the 

 equivalents of the gault, upper greensand and lower chalk :t^. But if the 

 shelly portion of the Gosau deposits proved to be cretaceous, the 

 sections of Bassano and Asolo remained, as well as those of Unters- 

 berg and Kressenberg, to establish the existence of other and superior 

 strata. And even when I say, that the Gosau deposits are essentially 

 cretaceous by their fossils, I must guard against the inference that 

 the overlying sandstones and schists of that valley are also of that 

 age. The principal change of classification I have to make, is in respect 

 to the comparison formerly suggested (though then not without con- 

 siderable doubt), that the great band of green sandstones, impure lime- 

 stones, and calcareous shale, &c. which occupy the external zone of the 

 north-eastern Alps under the name of " Flysch " or Vienna sandstone, 

 was the representative of the greensand and chalk of England and 

 France. It is needless now to explain all the reasons for having em- 

 braced an opinion, which my colleague and self shared in common 

 with other geologists of that day. In the absence of fossils, we could 

 not, indeed, avoid being somewhat guided by mineral characters, par- 

 ticularly in the Eastern Alps, where the whole of this green sand- 

 stone zone abruptly succeeds to masses of what was then termed the 

 "Alpine Limestone," the higher portion of which was considered by 

 our precursors to represent the Upper Jura. 



Once impressed with the conviction that the great greensand group 

 succeeding to the supposed Jurassic rocks was cretaceous, and finding 

 nummulites associated with it, we naturally concluded that these 



* See Phil. Mag. and Annals, with coloured sections, June 1829, and Proceed. 

 Geol. Soc. Lond. vol. i. p. 137. 



t On this occasion I was accompanied by M. de Verneuil. 



X M. Boue argued that the fossil beds of Gosau were of the age of the lower 

 greensand, whilst my colleague and self considered that these beds were both 

 cretaceous and lower tertiary. M. Boue, as well as myself, now considers the 

 tiuramulitic and flysch rocks as supracretaceous. 



N 2 



