THE VALAIS. 
123 
Dents de Morales, which are a counterpart of the 
Dents du Midi on the south-west. The strata, as 
shown in Fig. 1 10, are inverted; the older Neocomian 
resting on tire younger Nummulitic, which again re- 
poses on Flysch. 
For some distance on each side of Martigny, from 
Outre-Rhone nearly to Saillon, the bottom of the 
valley presents a number of Sand-dunes, first de- 
scribed by Morlot. They resemble in miniature those 
of the desert, and of some sea coasts. The most 
considerable are near Charat, and reach a height of 
20 to 30 feet. They are formed especially in the 
spring when the Rhone is low, and leaves large sandy 
tracts uncovered. 
Shortly below Martigny on the left side two 
streams enter the Rhone valley — the Sallanches and 
the Trient — but there is this remarkable difference, 
that while the Sallanches forms a beautiful waterfall, 
the Trient has carved for itself a deep and narrow 
gorge. The rocks over which they flow are similar, 
and apparently of equal hardness, and the difference 
is probably due, partly to the fact that the Trient, 
draining a larger area, has a more considerable water 
power, and also that it brings down more pebbles 
and boulders, while the Sallanches is a clear 
