356 Professor Sedgwick and Mr. Murchison on the 



The following section of this group was obtained from the side of a torrent 

 descending into the valley of llussbach. 



a. Coarse conglomerate at the base of the group ; the whole thickness not visible. 



b. Beds of red and green marl ; with some white, granular gypsum ; also with some irregular 

 layers containing plates and regular crystals of seienite. 



c. Red and green marl like the preceding, with bauds of blue marl containing small crystals 

 of seienite. 



d. Red conglomerate, with a calcareous cement, containing many qnartz pebbles. 



e. Deep red-coloured marls of irregular thickness, and mixed with conglomerates like the 

 preceding. On the N.W. side of the Horn these red marls are immediately surmounted by in- 

 durated, blue marls containing Cerithia (the first shells seen in the ascending section), and alter- 

 nating with bands of calcareous and micaceous grit. 



The preceding group has probably in some places a thickness of two or 

 three hundred feet; neither its subdivisions nor its thickness appear, however, 

 to be by any means constant. 



2. A group immediately superior to the preceding ; of the computed thickness of 1 50 feet, and 

 probably in some places thicker ; composed of arenaceous limestone or calc.grit, here and there 

 in strong bands, alternating with beds of pebbles and great masses of marl. In its beds arc fossils 

 of the genera Exogyra, Trigonia, and Inoccramus, — a Pecten not perhaps to be distinguished 

 from the P. quinqueco status oi i\\e green-sandj to which we may add two species of Hippurites, 

 a large Nerinea, Tornatella gigatitea, &c.* So far the fossils might be considered of a secondary 

 rather than a tertiary age. But along with the genera enumerated are found Corals, (Fungiag,) 

 shells of the genera Cerithium and PIcurotoma, &c. ; which in their mode of preservation, as well 

 as their specific characters, resemble fossils of tertiary formations. 



The section of this group on the N.W. side of the Horn is as follows : 



a. Indurated, blue marlstone, with bands of calcareous and micaceous grits. It contains a 

 few Cerithia, and immediately overlies the highest division (e) of the preceding group. 



b. Conglomerate of rounded quartz-pebbles, alternating with beds of calcareous grit. 



c. Slaty sandstone, more or less calcareous, with carbonaceous stains apparently derived from 

 plants. 



d. Thick beds of shale with a few bivalves, and a few siliceous pebbles scattered through the mass. 



e. Bands of grey, calcareous grit. 



/. Compact, blue marlstone, with white veins of carbonate of lime. 



The total computed thickness of the beds in this section is about 150 feet. 



The following ascending section, taken at the Wegshad Graben, on the road 

 leading over the Pass Geschitt to Abtenau, is very nearly on the same parallel, 

 but is of greater thickness. 



a. Blue marls with bands of grit. In this division are traces of shells. 



b. Fine conglomerate. The upper part formed of rounded, black, siliceous pebbles in a cal- 

 careous cement. 



* Plate XXXVIII. fig. 9. 



