278 Proceedings of Royal Society of Edinburgh. [june 20 , 
than 500 metres in some sub-Alpine regions, whilst the upper 
yellow sands (Astian) in the vicinity of the Alps were at certain 
points raised more than 560 metres. In the sub-Apennines, 
facing the Alps, the same deposits were uplifted 700 metres, 
and in Southern Italy over 1000 metres. This movement, as I 
believe (and not that which closed the Miocene period), was 
the last great elevation of the Alps. It is to this Pliocenic 
movement that I attribute the general orographic settlement of 
the Alps. And it is to this last great elevation of the Alps 
that I chiefly assign the formation of the existing lake-basins of 
the sub-Alpine regions. These I believe to be due partly to 
faults — often bifurcating as they pass down the valleys, — and 
partly to the accentuation or formation of synclinal folds, and to 
local uplifts and subsidences. 
After this period of great elevation the Alpine glaciers, which 
had already in the second stage of the Pliocene become strongly 
developed, were now, owing to the changed orographic conditions, 
compelled to form in cirques differing in shape from those of 
Pliocene times, and to seek new paths in their descent to the low 
grounds; but, erelong, making their way through deep valleys 
newly opened, and preceded by the deposition of diluvial deposits 
from the waters escaping from them, they reached the plain, and 
piled up their great end moraines, forming the well-known morainic 
amphitheatres opposite the mouths of the great Alpine valleys. 
Underlying these terminal moraines, therefore, we always find a 
more or less thick accumulation of diluvial conglomerate — the in- 
duration of the deposits being due sometimes to infiltrated calcareous 
matter, and sometimes apparently to the pressure exerted by the 
glacier-ice which overflowed the gravels. 
During the somewhat rapid descent of the glaciers to the low 
grounds it seems obvious that the terrestrial waters which escaped 
from them would accumulate in the lake-basins, the bottoms of 
which would thus tend to be raised ; while the glaciers themselves, 
when they reached those basins, would take some time to fill them 
up. Before the glaciers could escape from the lacustrine troughs, 
very considerable masses of gravel and shingle would be swept out 
by the rivers and torrents, and spread over the low grounds that 
extend outwards from the mountains. When at last the glaciers 
