150 M. Studer oti the Geological Structure of the Alps, 



afterwards losing their inclination, they become horizontal in 

 proportion as their distance increases from the central mass ; 

 and then they rise to the north, so that, in fact, they assume 

 the form of a vast basin with a flat bottom. It results from 

 the discordant stratification of the gneiss and the limestone, 

 that these two rocks are generally separated by a valley, one 

 of whose walls ascends towards the icy regions of the central 

 mass, offering, by means of deep gorges, outlets for its gla- 

 ciers and for its torrents, while the opposite wall presents the 

 vertical precipices of the calcareous deposits. The extent of 

 these vallej'S is very variable ; sometimes they are prolonged 

 from the highest summits down to the inhabited districts, and 

 down to the level of our lakes, following all the sinuosities of 

 the central mass. Thus, therefore, if a traveller, following the 

 northern limit of the group of the Finsteraarhorn, were to pro- 

 ceed by the valley and the glacier of Lotsch towards the valley 

 of Gastern, to traverse the glacier of Tschingel, in order to 

 reach the bottom of the valley of Lauterbrunnen, to ascend 

 the high valleys which separate the Jungfrau from the Silber- 

 horn and the Monch from the Eiger, afterwards to arrive at 

 the nev6 and the lower glacier of Grindelwald, to mount the 

 Col ef Urhach by the glacier of Rosenlaui, to descend the val- 

 ley of the same name as far as Hoff, then to go up the valley 

 of Gadmen, and across the glacier of Wenden, proceeding 

 along the southern slope of the Titlis, next to pass into the 

 valley of the Reuss, and thence into the valley of Maderan, in 

 order to arrive at the eastern limit of the central mass of the 

 Finsteraarhorn, in the neighbourhood of the Todi, — such a 

 traveller would have almost constantly on his left hand verti- 

 cal walls of limestone, often several thousand feet in height, 

 and on his right the central group, sometimes crowned by 

 nevh and glaciers, sometimes covered with forests and pas- 

 tures, and rarely presenting inaccessible escarpments. Behind 

 this belt, which is developed round the central mass like the 

 walls of a crater around a central volcano, we frequently re- 

 mark traces of a second and a third rampart, exhibiting the 

 same inclination of the beds, that is to say, presenting its ver- 

 tical walls to the central mass, and dipping in the opposite 

 direction. The escarpments of the Gemmi belong to such a se- 



