282 Proceedings of Royal Society of Edinburgh. [june 20 . 
perpendicular to the axes of the Alpine chain, and are sometimes, 
as in the case of Lake Constance, bifurcated downwards, like not 
a few Italian lakes. 
6. In the more eastern part of Switzerland the phenomena referred 
to in the preceding paragraph were complicated by the proximity of 
the Jura Mountains, a chain which runs parallel to that of the 
Alps. Hence the deep lake-basins were formed rather parallel than 
normal to the axes of those chains. 
7. It is -worthy of note that the orographic axes of the syn- 
cline of the valley of the Po lies near the base of the Alps. 
This explains why the lacustrine troughs, lying for the greater 
part in solid rocks, shelve olf and end near the plain. We 
must remember also that the Post-pliocene elevation of the Apen- 
nines, where the Pliocene strata often reach an elevation of more 
than 700 metres, must have been more intense than the contem- 
poraneous movement of the Alps, where the Pliocene marine beds 
do not rise more than 400 metres above the sea. It is highly 
probable that a similar relation obtained between the Jura and the 
Swiss Alps. Nor can I doubt that if the Apennines had approached 
the Alps as closely as the Jura, we should have found the typical 
direction of the Italian lacustrine basins modified in some cases. 
Instead of being all perpendicular to the axis of the Alps, some of 
them would have resembled the Lake of Geneva, the upper reaches 
of which are normal, while the lower are parallel to tire main axis 
of the mountains. 
8. I admit the existence of a relation between the great Alpine 
basins and the glaciers of Quaternary times ; but in my opinion this 
relation is due neither to excavation by ice nor obstruction by 
morainic debris, but simply to the conserving action of the glaciers. 
The troughs, I believe, were occupied by the glaciers, and thus their 
filling up by the fluvio-glacial detritus of the first half of the 
Quaternary age was prevented. 
In the following table I bring into one view the general conclu- 
sions arrived at in the paper : — 
