1848.] MURCHISON ON THE STRUCTURE OF THE ALPS. 185 



A. splendensi ; Hamites alternatus (Sow.) ; Nautilus, small species ; 

 Avellana incrassata (D'Orb.) ; Inoceramus sulcatus (Sow.) ; Sola- 

 rium ornatum ? (Sow.) ; and a new species, together with various 

 EchinidcB (Discoidea, Galerites and Micraste?', Ag.). 



In laying these fossils before the Society I also present a certain 

 number from Sassonet, near Bonneville, and the Reposoir, which Pro- 

 fessor Pictet kindly gave to me. The mere view of these fossils will 

 convince English geologists that the rock of which I am now speak- 

 ing fairly represents their gault and upper greensand*. A band of 

 this age which I shall indicate in other natural sections in the Swiss 

 and Bavarian Alps containing some of these characteristic fossils, is 

 at intervals traceable far into the recesses of the higher mountains. 



Inoceramus Limestone {Sewer-kalk), equivalent of the chalk of 

 Northern Europe. — When I visited the Savoy Alps, it was still to 

 be ascertained whether they contained any equivalent of the white 

 chalk of Northern Europe, which surmounting the upper greensand 

 was there fairly intercalated between that formation and the great 

 "Terrain a Nummulites." In entering that region last summer 

 I was indeed led to believe, from the first sections I observed around 

 Chambery, that there was little chance of meeting with so full a 

 succession of all the cretaceous strata as would exhibit any equiva- 

 lent of the white chalk, for there the nummulitic rocks, as above 

 stated, repose at once, as pointed out to me by the Canon Cha- 

 mousset, on neocomian limestone. Moreover, in his very last me- 

 moirf, Prof. Favre had described the nummulitic zone in Savoy as 

 independent of the cretaceous system on the one hand, and of the 

 overlying macigno or flysch on the other. That geologist had doubt- 

 less reasons for such an inference, in seeing that the nummulitic 

 rocks, where he examined them, reposed in one place on Jura lime- 

 stone and at another on neocomian ; but such reasoning in a region 

 which has been subjected to many dislocations, is liable to be over- 

 turned by the discovery in an unbroken tract of the beds supposed to 

 be wanting. Such, in truth, I found to be the case in a very clear 

 natural section exposed at Thones in Savoy, which I examined in 

 company with M. Pillet of Chambery in a traverse from Annecy by 

 the valley of Thones and the Grand Bornand to the Col du Reposoir, 

 and thence to the valley of the Arve. 



In entering the valley of Thones from the west, I perceived, near 



* The fossils given to me by Prof. Pictet from the ahove localities and from the 

 Perte du Rhone, where the same species occur, — in all three places usually in a bed 

 of a few feet thick only, — are^. inJlatus{^ov^.),A. Candollianus (Pict.),^^. varicosus 

 (Sow.), A. Mayorianus (D'Orb.), A. Lyellii (D'Orb.), A. momle (Sow.), A. mille- 

 tianus (D'Orb,), A. regularis (Leym.), A. latidorsatus (}A\c\\Q\\n), A. Huyardianus 

 (D'Orb.), Hamites rotundus (Sow.), H. virgulatus (Broiign.), Turriliies Bergeri 

 (Brongn.), Avellana incrassata (D'Orb.), Inoceramus concentricus (Sow.), /. sul- 

 catus (Sow.), Cucullcsa fibrosa (D'Orb.), Area, three species, Terebratula orni- 

 thocephala (Sow.), T. plicatilis (Sow.), Ceromya infiata (Ag.), with Micraster 

 and other Echinoderms. See M. Pictet's excellent work, " Description des Mol- 

 lusques Fossiles des gres verts des environs de Geneve," 1"^ livr., 1847. 



t " Sur la position relative des Alpes Suisses occidentales et des Alpes de la 

 Savoie."— Bull, de la Soc. Geol. Fr. vol. iv. p. 996. 



