170 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [DeC. 13, 



The view of M. Haidinger is, I apprehend, to be accounted for by 

 an attempt to identify rocks by mineral resemblances, and by com- 

 paring strata in broken and inverted positions with others (sup- 

 posed to be the same) which lie in their normal state. Finding 

 certain sandstones which resemble the '* Wiener sandstein" really 

 plunging under the alpine limestone and lias, and containing keuper 

 plants, and further seeing that the great mass of the Vienna grits 

 external to the chain which are of similar appearance also seem to 

 plunge under the same limestone ridge, a conclusion has been arrived 

 at which I apprehend my distinguished friend M. Haidinger will 

 abandon, as applied to most of the large and widely spread masses in 

 question. For, if all the Vienna grits so intercalated between the 

 great masses of secondary and tertiary rocks, be the representatives 

 of the keuper, then all the "flysch" of Switzerland, the grits and 

 sandstones on the flanks of the Carpathians, and the upper macigno 

 of the Italians, may on such reasoning be similarly grouped. Now, 

 although a band of true keuper sandstone with plants may crop out in 

 the localities cited, it is physically impossible that all the great ex- 

 ternal zone to which I have alluded, and which, as I shall presently 

 show, truly forms the last member in ascending order of the great 

 chain of the Alps, can be referred to the keuper, a natural system 

 which is now well understood in the Eastern Alps, and not one of 

 whose fossils has ever been found in that external zone of Vienna 

 sandstone, which forms the continuation of the Swiss and Bavarian 

 *'flysch" on all preceding maps*^. 



In the extension of the trias westward through the North Tyrol, 

 its presence is only as yet recognizable to a very limited and doubtful 

 extent. In short, it may be stated, that no discoveries have been 

 made, either in the central Swiss Alps or in Savoy, which can lead 

 us to think that the trias has had any existence there. Still, 

 judging from the analogy of the Eastern Alps, it is possible that a 

 spot or two may be found where the limestone is so little penetrated 

 by metamorphic action as to have left some intelligible evidence 

 of the triassic group. Leopold von Buch inclines, I believe, to the 

 opinion that such a group will be detected. 



* M. Morlot's map of the North-Eastern Alps is, as I conceive, quite correct in 

 representing these Vienna grits to be a prolongation of the " flysch " of Switzer- 

 land, and in placing them in their true overlying position. But since its publica- 

 tion, M. Morlot has abandoned that opinion, and has adopted the view of M. Hai- 

 dinger. See a brief notice (Sulla Conformazione geologica dell' Istria, Giornale 

 dell' Istria, Nos. 61, 62, 1847). Again, in a communication to M. Haidinger on 

 the position occupied by the " Wiener sandstein " or fucoid grits, he endeavours 

 to show, that in following it from Istria into the interior of the Alps up the valley 

 of the Isonzo, that formation is seen near Raibl to take, as he says, ** its place 

 between the lower muschelkalk (?) and upper alpine limestone," and thus represents 

 the Keuper (Reports of the Meetings of the Friends of Science, Vienna, Haidinger, 

 vol. iii. Oct. 1847, p. 334), Whilst these sheets are passing through the press, 

 the author has received M. Morlot's detailed mcnoir and map of Istria, " Natur- 

 wissenschaftliche Abhandlungen, vol. ii. p. 257." Ills descending order is, — 

 1. Eocene or nummulitic rocks; 2. Chalk; 3 TasicHo. I have some difficulty 

 in reconciling this order either with some of the sections or with the colouring 

 of the map of Istria by M. Morlot. 



