468 ProJ\ Bucktaiid'on the Structure of the Alps, [Junb, 



mils are composed of alpine limestone : their ordinary form is a 

 slaty micaceous sandstone, resembling red grey wacke, alternating 

 with beds of marly sandstone and red marl ; in the two latter, 

 there occur abundantly beds and nodules of gypsum, and of 

 yellow Siindy magnesian limestone. A similar deposit of red 

 marly sandstone may be well seen at Halstad between the sali- 

 ferous gypsum and lias. 



; : In Switzerland, the usual state of this stratum is more com- 

 ^ct, forming a hard micaceous slaty sandstone, resembling red 

 greyvvacke slate, and variegated with spots of green. It occu- 

 pies a very considerable extent in this country, running in a line 

 parallel to all the other great formations from Notre Dame 

 •b'Abondance, in Savoy, to the Valley of the Rhine, on the east 

 of Glarus, and being visible in the Nieder Simmen Thai on the 

 eouth-west of Thun ; in the Melch Thai, near Lake Sarnen ; in 

 the Valley of Unterchachen, near Altorf; at Schvvanden, in 

 Glarus ; and at Weistannen and Mels, near Sargans, above the 

 ihead of the Lake of Wallenstadt. Large blocks of it have been 

 <irifted down from this last named district over the hills of 

 tertiary formation that border on the Lake of Zurich. It occurs 

 also in the same compact slaty form, accompanied by gypsum, 

 and lying above gTeywacke, at Werfen, in the Tyrol, 50 miles 

 on the south of Saltzburg. 



2. New Bed Conglomerate {old Red Sandstone, or Rothe Todtt 

 Liegende of Werner). — As in England and Germany, so also in 

 Switzerland, and the Tyrol : the lower strata of the new red 

 sandstone formation pass into a coarse conglomerate, containing 

 fragments of the adjacent rocks older than itself, united by an 

 argillaceous or siliceous, and sometimes by a semiporphyritic 

 cement. The same characters which this rock presents near 

 Exeter and Teignmouth, in Devonshire, and at the base of the 

 Thuringer-vald, in Germany, are maintained by it in the Alps. 

 It occurs in Italy, near Lugano ; in the Tyrol, near Botzen, and 

 Cavalese ; and in Switzerland, in the Mount Neisen, near Lake 

 Thun ; and at Schwanden, in Glarus. The relative position of 

 this conglomerate, and the new red sandstone, may be seen to 

 advantage in the steep sides and escarpments of the Glarus 

 mountains, between Schwanden and Matt, where they appear 

 beneath well characterized strata of the elder alpine limestone 

 formation, and incumbent on true transition rocks ; i. e. the 

 greywacke and greywacke slate of Blattenburg. 



3. New Red Porphyry, — In Switzerland, the conglomerate of 

 Scliwanden seems almost, but not quite, to pass into the state of 

 new red porphyry, its cement and many of its concretions being 

 imperfectly crystalline ; but no decided porphyry of this forma- 

 tion occurs on the north frontier of the central Alps. On their 

 south side, however, near Botzen, there is an extensive range of 

 low mountains, composed exclusively of this porphyry : it may 

 be seen reposing on the new red conglomerate by the road side 



