The Montagne Noire, the northern limit of the gap, is well named, for it is all of dark slatey rock. The Corbières, on the contrary, are of white limestone, and a man standing a little way above the valley floor can see behind them the snow peaks of the high Pyrenees. To the west of Carcassonne the hills are lower but the gap continues none the less, with Montreal and Fanjeaux, each on an outstanding buttress of hill, for sentinels upon its southern side. Of these two Montreal stands out against the horizon as one looks west from Carcassonne, and in turn hides Carcassonne as one looks east from the height of Fanjeaux. West from Fanjeaux the hills become mere downs, and the landscape quite loses its Mediterranean look and becomes that of the Toulousain. About Carcassonne itself the landscape is of an intermediate sort between the Mediterranean and the Toulousain. Between the bare hills one still sees the olive, but more rarely than on the Mediterranean side, and (as in the Toulousain) grain fields begin to alternate with the vine. The Toulousain, although it is altogether of the south, is a different sort of country from the Mediterranean slope. In the first place it is not a mere strip of land between sea and mountains, but a broad, fan-shaped arrangement of valleys running together in the general neighbourhood of Toulouse, and separated only by ridges or downs regular in outline and no great height. As on the Mediterranean side the ground is minutely and intensely cultivated; still one sees more trees and shrubs growing freely, although by no means as many as in Northern and Central France. The type of cultivation, too, is different. One no longer sees the olive, and the vineyards are outnumbered by grain fields. Furthermore, it is not the valleys alone that are cultivated, the flat or gently rolling summits of the downs are worked as well. Although the people are the same, their houses are different from those of the Mediterranean in that their material is brick. Indeed, one sees no masses of rock in the Toulousain, and the bits of stone in the larger buildings are brought from outside the district.