Jura Lakes in Switzerland. 351 



by its exit stream, into the Muotta, which formed the big alluvial cone 

 of Ibach above Brunnen, and thereby banked Lake Lowertz ; indeed, 

 this cone was probably the primary cause of the Reuss being deflected 

 to its present course. The lake, greatly reduced in size, is at a level 

 11 metres above that of Lake Lucerne. Lake Sarnen, which is close 

 to the Briinig railway and 37 metres higher than the Alpnach basin 

 of Lake Lucerne, into which it drains, was, like Lake Lowertz, 

 banked by fluviatile alluvia, that is, by the cones of the Schlieren 

 and Melchtal-Aa torrents. The small Lake Lungern, 192 metres 

 above Lake Sarnen, now drains into the latter. 



4. Lake Moral (Sheet No. 2, Fig. IV) is an offshoot of Lake Neuchatel 

 and connected with the latter by the Broye, which is also its principal 

 feeder. As is seen from the sketch-plan, it formerly extended, at its 

 upper end, to double its present length, while at its lower end it 

 formed part of the Lake Neuchatel and Lake Bienne system, which 

 intercommunicated with the great lacustrine expanse formed by the 

 River Aare. It was obviously the alluvia of this river, reinforced 

 by the Sarine, which banked and separated Lake Morat and Lake 

 Neuchatel, and also barred Lake Bienne. Connected with the Aare 

 was also the great lacustrine expanse in the valley of the Emme 

 between Burgdorf and Soleure (Fig. IV), which valley is even at the 

 present day subject to partial submergence by periodical floods. 1 



III. Extinct Juea. Lakes. 



The Neuchatel Jura is remarkable for a number of interesting 

 examples of extinct or quasi-extinct lakes and dried-up basins, of 

 which the principal ones are shown in Sheet No. 2, Fig. IV. The one 

 at the highest altitude — 1,046 metres — is the La Chaux basin, 15 km. 

 in length and about 2 km. in width, of which the small Lac Taillieres — 

 1,038 metres altitude — is the only lacustrine 1 remnant. The latter, 

 about 10 metres deep, has no visible outlet, but it is reputed to have 

 an underground connexion with the River Reuss which issues at 

 St. Sulpice, at altitude 754 or 284 metres lower, the vertical distance 

 being 5 km., and the rate of fall, therefore, 1 in 2. It is, however, 

 probable that the Reuss derives its copious volume from several 

 underground sources. 2 Another extinct basin is that of Les Fonts, 

 near Chaux de Fonds, altitude 1,010 metres, about 10 km. in length 

 and 2 km. wide, which has a lakelet without exit. The same applies 

 to the basin of La Fraye, near Lignieres, at altitude 807, 4 km. in 

 length and 1 km. wide, with an exitless pool, and precisely similar 

 is the large basin of Val de Ruz above Lake Neuchatel at altitude 

 721 metres, 8 km. long and 3 km. wide, except that this basin has an 

 exit by a torrent, which, through the steep gorges of the Seyon, drains 

 into the lake. The history of all these basins is the same. Formed 



1 Incidentally it may be mentioned that Lake Morat, like Lake Pfamkon, is 

 noted for its remains of lake-dwellings. 



2 An interesting case of subterranean torrents so characteristic of the Jura 

 formation occurred a few years ago in the course of the works of the new tunnel 

 from Frasne to Vallorbe (Simplon route), when a torrent rising in Mont d'Or 

 and discharging normally by an underground passage near Pontarlier, suddenly 

 burst through the tunnel near Vallorbe and discharged into the Orbe. 



