A good road leads down the Ardèche to the Pont de l'Arc, one of the great natural curiosities of the south of France. The river in descending the ravine between walls of Jura limestone encountered a long spur that barred its way, and drove it to describe a great loop. But the limestone is full of holes, caves, and cracks, and the torrent rushing down and beating against the great escarpment, impatient to get through and resenting the detour, bored till at last it burst a way through, and having once penetrated proceeded to enlarge the portal, till the river even in its greatest floods can rush through. The measurements are 193 feet from side to side, 110 feet to the crown of the arch, and to the summit of the rock 215 feet. Formerly the people of the country used this natural bridge to pass from one side of the river to the other. In the sixteenth century a fortress was erected on it, the possession of which was sharply contested by Catholics and Protestants, and Louis XIII. had it destroyed. The passage can still be made by means of a very narrow path cut in a ledge of the rock, but only one person, and he with a steady head, can traverse it. Louis XIII. had this path broken down, but the gap has been bridged over by poles. The descent of the cañon is made from Vallon to S. Martin, and takes from five to eight hours according to the amount of water in the river, and costs 30 francs. Rapids are numerous, and some not a little dangerous. The gorge, cut through the lower cretaceous limestone, has not its walls as lofty as those of the famous cañon of the Tarn, but the scenery in it is more varied, and it is of the wildest beauty. Opposite old Vallon, as already mentioned, is Salavas. Hérail de Merle, son of the great Huguenot captain, abjured Protestantism, and married the daughter of Montréal, chief of the Catholics of the Vivarais. Profiting by his absence, his Huguenot vassals in Vallon revolted, and aided by a locksmith of Salavas entered the castle and butchered all the garrison. They captured the baroness and her children. But as Salavas was unimportant as a stronghold without the Tour du Moulin in the river, the Calvinists brought the Baroness Lagorce and the children under its walls in a boat, drew their long knives and threatened to cut all their throats unless the tower surrendered.