154 M. Studer on the Geological Structure of' the Alps. 



are nnmmiilites, and species of cerithium, ampullaria, ostrea, 

 tiirbinolia, &c. Ammonites and belemnites are, however, 

 almost entirely awanting. The nummulitic limestone forms 

 the superior mass of the Dent de Morcles and of the Dia- 

 blerets, and continues along the northern side of the chain 

 which is crossed by the Cols of the Sanetsch, the Rawyl, and 

 the Gemmi, as far as the upper part of the lake of Thoune. 

 Some isolated nummulites are met with in the chain of 

 J^rienz ; and an accumulation of fossils similar to those of the 

 Diablerets occurs on the crest of the chain of Gadmen (Gad- 

 menflue)^ of which the Titlis forms a part. Lastly, the num- 

 mulitic limestone is largely developed in the mountains of 

 Schwytz and of Glaris, and in the chain which' separates the 

 canton Glaris from the valley of the anterior Rhine. 



Alpine Macigno. — A deposit of grey slates, which isfrequently 

 very thick, extends in many places over the nummulitic lime- 

 stone, and of itself forms separate masses, which are generally 

 wooded or covered by pastures to the summit. In a mineralo- 

 gical point of view, this rock does not differ in any respect from 

 the true flysch of the Alps, of the Valais, and of the Grisons. 

 The only organic remains it contains, are, moreover, fuci, similar 

 to the Fncus intricatus of A. Brongniart, and we might con- 

 sequently designate it under the name of flysch, in so far as 

 that term merely implies a petrographical character. But to 

 admit that this slate, which reposes on the nummulitic lime- 

 stone, is of the same age as the flysch which occurs between the 

 central masses, would be opposing probabilities to too great an 

 extent. In order to avoid all confusion, and to prejudge 

 nothing, we shall call this rock Macigno alpin, remarking at 

 the same time, that we recognise it neither mineralogically 

 nor geologically as the analogue of the macigno of the Apen- 

 nines. A depositofthis slate or macigno, having a breadth of 

 several leagues, extends behind the chain of Brienz, along the 

 western side of the Lake of Sarnen, towards Alpnach, and 

 occupies a large portion of the Entlibuch and of Obwalden. 

 Other deposits exist in the neighbourhood of Beckenried, and 

 to the south of Einsiedeln. Lastly, this formation attains a 

 large development in the south of the canton of St Gall, and 

 in the Prettigau* 



