Page:Great Neapolitan Earthquake of 1857.djvu/364

290 mortar joints but small. Applying to it the equation of overturning

with the value for $$\mbox{V}$$, (ascertained next day) for the emergent shock at Polla, it is certain that the split-off portions above $$b$$ and $$c$$, would not have rocked and returned to their places as found, but have been completely overturned, had the wave-path been at a less angle to the horizon than 61° nearly. The angle of emergence here, therefore, must have been as steep as that, at least, and may have been steeper.

Looking back from this point, and sweeping the mountain side to the westward of the gorge with the telescope, I see a large Casale—upon the slope of the hill distant about four miles—almost in ruins, and can plainly discern by a favourable light, that it has been overthrown by a shock, which there, had the same general direction as here.

The direction of the slope of the hills at both sides towards the southern entrance to the gorge, begins to change and to trend round to the S. W.; and a little further on I catch the first view down upon the grand Vallone di Diano, its plateau level as a sea, stretching away twenty-six miles to the south, and four or five miles wide, the Calore, folded along upon its central surface like a silver cord, losing itself in distance, and the mountains rising almost abruptly from the piano at either side, the further end closed in and surrounded, by pile over pile, of dark grey mountains and snow-clad sierras, at last shutting out the horizon.

I can now perceive that Campostrina gorge, is the hinge,