On the south-eastern frontier the French Alps, which include Mont Blanc (15,800 ft.), and, more to the south, other summits over 11,000 ft.
Below Aosta also the Dora Baltea receives several considerable tributaries, which descend from the glaciers between Mont Blanc and Monte Rosa.
Forbes was also interested in geology, and published memoirs on the thermal springs of the Pyrenees, on the extinct volcanoes of the Vivarais (Ardeche), on the geology of the Cuchullin and Eildon hills, &c. In addition to about 150 scientific papers, he wrote Travels through the Alps of Savoy and Other Parts of the Pennine Chain, with Observations on the Phenomena of Glaciers (1843); Norway and its Glaciers (1853); Occasional Papers on the Theory of Glaciers (1859); A Tour of Mont Blanc and Monte Rosa (1855).
Thence for a short way the direction is north to the Col de la Seigne, and then north-east along the crest of the Mont Blanc chain, which culminates in the peak of Mont Blanc (15,782 ft.), the loftiest in the Alps.
In the case of the Western Alps (minus the bit from the chain of Mont Blanc to the Simplon, which followed the fortunes of the Valais), a prolonged struggle for the Alpine region took place between the feudal lords of Savoy, the Dauphine and Provence.
