It was unmistakably obvious, that the fractures had been produced by the transit of the earthquake, and that the push, of the vast piled-up mass of comparatively soft heavy clay beds, &c. to the north with which they had been forced against the barrier of these hard limestone beds that ramparted them in, had been of such force as to fracture the latter in many places. The hard unyielding rock had broken; the softer clay beds had merely been slightly compressed, and changed insensibly in form; hence they presented no evidence of the force that they had transmitted to the fractured rock. On ascending the slope of the clay beds, northward about 500 yards, however, I found confirmatory evidence of my conclusion, in great masses of fresh fractured and fallen sandstone from the thick beds at C. (Diagram No. 242.)
The N. E. face of the deep gorge beyond C, not shown in diagram, that brings another torrent down in a N. W. to S. E. direction, also showed great falls, of these soft sandstone cliffs in the bottom. I had great difficulty in descending the wet clay beds, which, devoid of a single pebble, presented no foothold whatever upon their unctuous and slippery slope, and a fall produced much the effect, of being dipped into a succession of paint pots.
This fact was to me one of peculiar interest: it was the first example I had found, of actual fracture of beds of hard rock in situ, by the impulse of au earthquake wave—a phenomenon in kind totally distinct, from such breaking off of great masses, as the rock falls of Campostrina, or the Arguilles of Padula. Here were beds of the very hardest and toughest rock, such as, with difficulty, I broke specimens from, with the hammer, fractured for many yards in
