Page:Book of the Riviera.djvu/24

6 once, the line passes out of the rocky portal, and the traveller enters on another scene altogether, the vast triangular plain limited by the Alps on one side and the Cevennes on the other, and has the Mediterranean as its base. To this point at one time extended a mighty gulf, seventy miles from the present coast-line at the mouth of the Rhone. Against the friable limestone cliffs, the waves lapped and leaped. But at some unknown time a cataclysm occurred. The Alps were shaken, as we shake a tree to bring down its fruit, and the Rhone and the Durance, swollen to an enormous volume, rolled down masses of debris into this gulf and choked it. The Durance formed its own little crau along the north of the chain of the Alpines, and the Rhone the far larger crau of Aries, the pebbles of which all come from the Alps, in which the river takes it rise. But, in fact, the present craus represent but a small portion of the vast mass of rubbish brought down. They are just that part which in historic times was not overlaid with soil. When this period was passed, the rivers relaxed their force, and repented of the waste they had made, and proceeded to chew into mud the pebbles they rolled along, and, rambling over the level stretches of rubble, to deposit upon it a fertilising epidermis. Then, in modern times, the engineers came and banked in the Rhone, to restrain its vagaries, so that now it pours its precious mud into the sea, and yearly projects its ugly muzzle further forwards. When we passed the rocky portal, we passed also from the climate of the North into that of the South, but not to that climate without hesitations. For the sun beating on the level land heats the pebble bed, so that the air above it quivers as over a lime-kiln,