1848.] MURCHISON ON THE STRUCTURE OF THE ALPS. 229 



with partial conglomerates, the whole reposing upon older rocks, 

 and dipping away under the younger deposits of the adjacent lower 

 countries. But when we pass to the north flank of the Alps, par- 

 ticularly in Bavaria and Switzerland, the physical relations are mani- 

 festly different. 



In speaking of Switzerland I must not only refer to the well-known 

 and excellent work of M. Studer on the Molasse, but also to the valu- 

 able additions to it recently made by M. Arnold Escher de Linth*. 

 In the former we have set before us numerous derangements of this 

 great deposit, and also the variations in its composition in different 

 tracts. In the grand pebbly accumulations of the Rigi, for example, 

 several thousand feet of which are clearly exposed, there are pebbles 

 of granite and porphyry whose parent rocks f are now wholly un- 

 known to the mineralogist in the Alps. At the same time it is clear, 

 that the chief heaps of such materials have been derived from the 

 well-known adjacent ridge of secondary limestone, mixed up with an 

 extraordinary qiiantity of " flysch," which rock has also afforded 

 materials for a large portion of the calcareous sandy matrix of the 

 nagelflue. M. Escher points out that this great system of nagelflue 

 and molasse is divisible into three zones. The lowest visible portion 

 of the inferior zone is exposed along a great axial line, which, accord- 

 ing to M. Escher, passes from near Rheineck on the north-east, by 

 Herisau, Watteville, Jonen east of Rapperschwyl, on the north bank 

 of the lake of Zurich, and Hutten on the south-west. Thence it runs 

 between the lakes of Egeri and Zug immediately to the north of the 

 city of Lucerne, whence it is presumed it may be followed further to 

 the south-west, to the west end of the lake of Thun and the valley of 

 the Sulg. Along this line molasse sandstone is seen in vertical or 

 highly-inclined positions, throwing off overlying conglomerates of 

 enormous thickness. If the masses of nagelflue which constitute the 

 Rigi mountain near Lucerne, and the still loftier Speer (figs. 12 & 

 14, pp. 1 95, 200) near Wesen be included in one group, their thickness 

 must be enormous, certainly exceeding 6000 or 8000 feet. This axial 

 line trends from W.S.W. to E.N.E., and is, I would remark, perfectly 



which I examined in his company in the museum of Gratz, bespeak a Medi- 

 terranean chmate and a miocene age. It is eighteen years since I furnished 

 M. Adolphe Brongniart with the plants of the Haring tertiary coal deposit in the 

 Tyrol. 



* For M. A. Escher's account of the molasse of Eastern Switzerland see Mit 

 theilungen der Naturforschenden Gesellschaft in Zurich, No. 7, May 1847. In this 

 memoir M. Escher states, that although a powerful deposit of marine molasse 

 (not less than 1000 feet thick near Berne) is interpolated between the lower and 

 upper freshwater molasse and nagelflue, he is unaware of any zoological distinction 

 in the two last-mentioned members of this great series. A warm climate, which 

 permitted the growth of palms and large Cycadece, seems to have prevailed during 

 the tvhole of the molasse period, and the species of Helix, Lymnea, Planorbis, 

 Melania, appear to be the same in the strata above as well as in those below the 

 marine molasse. 



t Professor Studer believes that the parent granite, from whence such pebbles 

 were derived, protruded along the great line of dislocation between the molasse 

 and the chain, and was lost by subsidence en masse when the great accumulations 

 of nagelflue were formed. — (Letter to myself.) 



