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



greensand, is a whitish grey rock, in which Umestone of conchoidal 

 fracture and hght colour, forms small and flattened concretions in a 

 light grey earthy base, or rather the shale of this colour wraps in 

 thin coatings over the calcareous undulations, the whole splitting 

 into flagstones six to eight inches thick, and occasionally into much 

 stronger beds. Like the greensand and neocomian limestone on 

 which it rests, this rock seems here to be the exposed portion of a 

 dome, which, as far as can be seen, dips to the N.E., E., S.E., and 

 S.S.E. To the east it is denuded along the bank of the little river, 

 and is extensively quarried as a building-stone. We were fortunate 

 enough to discover (we believe for the first time) Inocerami in this 

 sewer-kalk, fragments of which fossils are to be detected by those who 

 will carefully look for them, even from the lowest beds which rest upon 

 the greensand, to the upper portion of the quarries. The dominant 

 species (two or three specimens of which I brought home) seems to be 

 the Inoceramus or Catillus Cuvieri. In following these beds as they 

 fold over to the S.S.E., and where they descend into the Muotta-thal 

 at about 25°, there is a hidden space of about fifty paces only, in 

 which the succession is not observed (e), but they are then succeeded 

 in perfectly conformable apposition by beds (/) of sandy greenish- 

 grained limestone, abundantly charged with nummulites, chiefly the 

 Nummulina planospira or assilinoides, which alternate with marly 

 shale, which becomes sandier and more flag-like upwards, and are 

 finally surmounted by sandy marlstone charged with Orbitolites, 

 Pectens, &c. 



The broad valley watered by the Nieten and the Muotta streams 

 has evidently been excavated in the soft beds of flysch and sandstone 

 superior to the nummulite bands ; for after traversing to Ingolboldt, 

 on the external slope of the opposite mountains, the first strata met 

 with at that village, are the very same beds of sandy rotten marlstone 

 with large Orbitolites, Pectens, and casts of other fossils, which there 

 occur in highly inclined strata dipping to the north, and thus form 

 a portion of the opposite side of a trough, as seen in the general section 

 (fig. 12). The flank of the ridges extending from Brunnen up the 

 left bank of the Muotta is much obscured by woods, fallen cliffs, and 

 vegetation ; but there are spots in which portions of the nummulitic 

 rock are also seen to be underlaid by the sewer-kalk, greensand, and 

 by upper and lower neocomian, the latter forming the nucleus of the 

 great dome-shaped calcareous mountain Morschach, on the east side 

 of the Altorf branch of the Lake of the four cantons, immediately to 

 the south of Brunnen (fig. 12)*. 



Reserving for another part of this memoir the consideration of the 

 enormous flexures and breaks to which this whole series of rocks, 

 together with the Jurassic limestones, have been subjected at the upper 

 extremity of the Altorf lake, I would now merely remark, that the wood- 

 cuts figs. 11 and 12, the one detailed, the other general, clearly indi- 

 cate that the Sewen limestone (d), with its Inocerami, lying between 



* Near the spot called Gumpisch, this lower neocomian dark limestone is loaded 

 with Gryphaa Couloni, Rhynconella {Terehr alula) depressa (D'Orb.), and Spa- 

 tangus relusus. 



