>«'() Charles Maclaren, Esq. on the 



N, the Lake of Neuchatel. 



B /, Mont Blanc. 



t' t, the Pennine Chain which bounds the Great Valley on the 



south. 

 v v, the opposite chain which divides the Bernese Oberland from 



the Great Valley. 

 r a c q d u p n y b, the dotted space thus marked is the Valley 

 of the Rhone (which, for distinction sake, I shall call the 

 Great Valley.) It is shut in on all sides by high mountains, 

 except at e, where the river escapes through a broad and deep 

 opening. The true breadth of the Great Valley is much 

 greater than that shewn in the map. e -oam 



y f x h i k, the western part of the Plain of Switzerland, and the 

 southern declivities of Mount Jura, over all which erratics, con- 

 sisting of blocks of granite, gneiss, serpentine, &c, are distri- 

 buted, which have been proved to be derived from the Great 

 Valley above mentioned. The area over which the transported 

 materials are spread extends fromMountSion ($), on the south- 

 west to a point near Soleure (A), on the east. Its length is 

 about 110 miles, its breadth from &to/30, and the blocks 

 ascend on the side of Mount Jura at /, to a height above the 

 plain which has been variously stated, but which, on the au- 

 thority of Elie de Beaumont, I put down at 3450 English feet 

 (1050 metres) above the sea, or 2015 above the lake of Neu- 

 chatel. 

 It is by means of certain rocks of a marked lithological character, 

 and therefore easily recognisable by a good mineralogist, that the 

 travelled boulders strewed over Jura and the Plain of Switzerland 

 have been traced to their primitive sites, and the course they pur- 

 sued in their migrations ascertained. The phenomena are much 

 more complicated here than in the Valley of Hasli, and also on a 

 much grander scale. The Great Valley, r a c q, &c, is 100 miles 

 long and 50 broad, and every part of it has furnished its contingent 

 of blocks and fragments. M. Guyot deduces from an elaborate in- 

 vestigation of the phenomena, that the boulders are not scattered 

 promiscuously over Mount Jura and the Swiss plain, but that a cer- 

 tain order prevails in their distribution, similar to that which pre- 

 vails among the materials brought down by glaciers, in the shape of 

 lateral, medial, and terminal moraines. (Bulletin de la Societe des 

 Sciences Naturelles de Neuchatel, Seances Mai, Nov., and Dec. 

 1 845.) The travelled masses relied on as evidence are, with one 

 exception, all igneous or mctamorphic — namely, granite of three 

 varieties, gneiss, chlorite slate, euphotide eclogite, serpentine, and 

 a peculiar conglomerate. These being spread over a district 

 (y f h i k) 9 composed of rocks entirely different (sandstone and 

 limestone), are easily discriminated. And even the precise locality 

 from which a block came can in some cases be ascertained. 



