Page:Great Neapolitan Earthquake of 1857.djvu/324

266 be less than 25° the horizon, and may be much more. That of the fissure $$f$$ is still steeper. The "work done" by the shock, in originating the actual transport of material, due to these fissures is not very large; it amounts merely to reducing the friction and coherence of the mass, so as to permit the descent, through probably not more than 3 inches vertically, of several millions of tons of earth, the movement of descent being produced by gravity only.

The rain cuts these deep clays, here, (as everywhere in these provinces) into deep ravines or "nullahs." Some which I crossed in walking from the town of Auletta to Villa Carusso, which I next visited, were 30 to 40 feet in depth, with sides so steep and soil so greasy, that it was with great difficulty they could be crossed, and were it not for the hold on the brushwood at the sides, could not be ascended at all.