A word must here be given to explain the salient character of the country. Originally a vast region in Périgord--the Black Périgord, as it was called from its sombre woods and deep cleft ravines, was one plateau of hard chalk, raised from six hundred and fifty to nine hundred feet above the sea. At some geologic period difficult to define an immense rush of water passed over the plain and tore every rent formed by the upheaval of the chalk into gorge and gully, down which the furious waters poured, scooping out the sides and tearing themselves away. The course taken by the flood is easily recognisable by this fact--that it has left its wash on the tops of the plateau, where to the present day lies a film of caoline, that is to say of feldspathic clay, the produce of the granite ranges to the north and north-east; and this caoline lies in some places in considerable pockets, white as chalk, and only distinguishable from chalk by the experienced eye, and lies in sufficiently important beds to be worked and exported to porcelain factories. Nay, more than this: on the top of these great plateaux of chalk are strewn boulders and pebbles of volcanic production, that were derived unmistakably from the far away Auvergne mountains. The flood that swirled over the chalk plains not only tore them into islets, and ate out paths through every chink, but also left the surfaces undulating, having washed away what beds were soft and left those which were hard. These plateaux are more or less untenanted by human beings, because more or less soilless. They are given over to forest or to baldness. The ravines, the river-valleys, are walled in by precipices with gulfs here and there in their sides where the rock has crumbled away, or caverns have collapsed, and which allow, as lateral combes, access to the riverside. Up such a combe did the peasants now toil, zigzagging, corkscrewing their way, far to the rear of the headland of l'Eglise Guillem, and wholly invisible from it. The Captain had so far paid attention to the challenge conveyed by the scorched glove as to give the sentinel on the gate-tower warning to be on the alert, but he had neglected to post anyone on the top of the cliff that overhung his eagle nest. He anticipated no danger from that quarter, for his castle was inaccessible thence, unless, what was inconceivable, assailants should descend on him like spiders from above, at the end of ropes. "Bah!" scoffed the Chieftain; "a boor! What is Del' Peyra but a country clown? I will teach him such a lesson in a day or two as will make him skip. There is not a Seigneur in the land will lend him half-a-dozen horsemen." There was, however, an incident in the past that had entirely escaped the memory of Guillem, even if he had heard of it.