Ancient geographers appear to have generally regarded the remarkable headland which descends from the Maritime Alps to the sea between Nice and Monaco as the limit of Italy in that direction, and in a purely geographical point of view it is probably the best point that could be selected.
It soon becomes the boundary for a while between the departments of the HautesAlpes and of the Basses-Alpes, and receives successively the considerable Ubaye river, flowing from near the foot of Monte Viso past Barcelonnette (left), and then the small stream of the Luye (right), on which, a few miles above, is Gap. It enters the Basses-Alpes shortly before reaching Sisteron, where it is joined (right) by the wild torrent of the Busch, flowing from the desolate region of the Devoluy, and receives the Bleone (left) (on which Digne, the capital of the department, is situated) and the Asse (left), before quitting the department of the Basses-Alpes just as it is reinforced (left) by the Verdon, flowing from the lower summits of the Maritime Alps past Castellane.
The other strange feature is that from near Isola in the upper Tinee valley southwards the political frontier does not coincide with the physical frontier, or the main watershed of the Alpine chain; the reason (it is said) is that in 1860 all the higher valleys of the Maritime Alps (on both sides of the watershed) were expressly excepted from the treaty of cession, in order that Victor Emmanuel II.
The northernApennines are generally distinguished (though there is no real solution of continuity) from the Maritime Alps at the Bocchetta dell' Altare, some 5 m.
While the Alps thus constitute the northern boundary of Italy, configuration and internal geography are determined almost entirely by the great chain of the Apennines, which branches off from the Maritime Alps between Nice and Genoa, and, after etching in an unbroken line from the Gulf of Genoa to the Adriatic, turns more to the south, and is continued throughout Central and Southern Italy, of which it forms as it were the back-bone, until it ends in the southernmost extremity of Calabria at Cape Spartivento.
