Vol. 58. | IN SUBALPINE FRANCE AND SWITZERLAND. 463 
(6) The Rhone-Valley deposits of Deckenschotter which I have 
thus briefly described point to the following conclusions :— 
(i) The deposits indicate the existence, during and immediately 
after the Pliocene glaciation, of an extensive alluvial cone 
of Glacio-Fluviatile material, extending from Lausanne 
to Bellegarde, the Dombes district, and Lyons, that is, 
over a distance of about 160 kilometres (100 miles), and 
reaching to the right banks of the present Sadne and 
Rhone Valleys. 
(ii) The cone was deposited on a plateau the altitude of which 
was about 800 metres near Lausanne, 450 to 500 metres 
near Bellegarde, and 300 metres near Lyons. It had thus 
a fall of about 3 metres per kilometre (or, roughly, 16 feet 
per mile), and was formed by the waters of the Rhone 
and Arve Glaciers, the maximum extension of which 
probably did not reach beyond the present confluence of 
those rivers at Geneva. 
(ii) The fact that the deposits occur on the heights of both 
banks of the Sadne and of the right bank of the Rhone, 
even below the junction of the two rivers, affords 
proof that, at the time of the formation of the alluvial 
cone, the valleys of those rivers could not have existed 
in their present form and depth. The contour of 300 
metres, at which the conglomerate appears both on the 
Dombes plateau and at Lyons, further tends to prove 
that neither the basin of the Lake of Geneva, nor that of 
the Lac du Bourget, whose present altitudes are 373 and 
235 metres respectively, could have existed in their present 
form and at their present level, the minimum ratio of fall 
requiring that their level should be at least 200 metres 
higher. The same applies even to the basin of the Lake 
of Annecy, the present level of which is at 443 metres, 
while the deposits near Bellegarde and Chatillon appear 
at contours 450 to 500, and near Seyssel (the junction of 
the River Fier with the Rhone) would be about 440 metres, 
the fall being thus altogether insufficient. 
IV. Generat Conctustions. 
(1) If the evidence of the two precisely analogous and con- 
temporaneous phenomena of extensive Pliocene Glacio-Fluviatile 
alluvia deposited on the Subalpine plateaux of North-western 
Switzerland, and of the Rhone Valley between Lausanne and 
Lyons, is conclusive, it follows that at the advent of, and imme- 
diately after, the Pliocene glaciation, the principal river-valleys of 
‘ it will be noticed that the inclination of this Deckenschotter-cone is only 
half of that of North-western Switzerland. Yet it is considerably steeper than 
the general inclination of younger alluvial cones, and is, in this respect, charac- 
teristic of Deckenschotter. The mean fall of the present Rhone from the Lake 
of Geneva to Lyons (200 kilom.) is 1 metre per kilometre, or 54 feet per mile. 
