Now only did Jean look up, and what he saw made him drop his half-finished shaft and forget it. What Jean saw was this: a girl at some distance above him on the face of the rock, swaying a long-handled hammer, with which she was striking at, and dislodging, the steps by which she had ascended, and by means of which alone could she return. The cliff was of white limestone, or rather chalk, not such as Dover headlands are composed of, and which have given their name to Albion, but infinitely more compact and hard, though scarcely less white. The appearance of the stone was that of fine-grained white limestone. A modern geologist peering among its fossils would say it was chalk. But the period of this tale far antedates the hatching out of the first geologist. The cliff was that of La Roque Gageac, that shoots up from the Dordogne to the height of four hundred and sixty feet above the river. The lower portion is, however, not perpendicular; it consists of a series of ledges and rapid inclines, on which stands clustered, clinging to the rock, the town of Gageac. But two thirds of the height is not merely a sheer precipice, it overhangs. Half-way up this sheer precipice the weather has gnawed into the rock, where was a bed of softer stone, forming a horizontal cavern, open to the wind and rain, with a roof extending some forty feet, unsupported, above the hard bed that served as floor. At some time unknown a stair had been contrived in the face of the rock, to reach this terrace a hundred feet above the roofs of the houses below; and then a castle had been built in the cave, consisting of towers and guard-rooms, halls and kitchens; a well had been sunk in the heart of the mountain, and this impregnable fastness had been made into a habitation for man. It could be reached in but one way, by the stair from below. It could not be reached from above, for the rock overhung the castle walls. But the stair itself was a perilous path, and its construction a work of ingenuity. To make the position--the eagle nest in the rock--absolutely inaccessible to an enemy, the stair had been contrived so that it could be wrecked by those flying up it, with facility, and that thereby they might cut off possibility of pursuit. The method adopted was this. Holes had been bored into the rock-face in gradual ascent from the platform at the foot of the rock to the gate-tower of the castle, nestled on the platform in the precipice. In each such hole a balk or billet of wood was planted, sliced away below where it entered, and this end was then made fast by a wedge driven in under it. From each step, when once secured, that above it could next be made firm. To release the steps a tap from underneath sufficed to loosen the wedge and send it and the balk it supported clattering down.