Page:Great Neapolitan Earthquake of 1857.djvu/232

182 and occasionally the layers are very thin. The most important point observable in these rocks is their strange position, so highly inclined to the horizon. The distinct development of the strata enables us to determine their degree of inclination and direction with great accuracy; yet as to their direction we have not been able to ascertain towards what point they are generally elevated, the direction of their inclination being found very various even in places separated by short distances. The angle of inclination also is very uncertain, varying often between 25 and 50 degrees; nor are instances rare in which it attains to 70 or more degrees, and in some places the strata might be called vertical. In no other of our sedimentary rocks have we better evidence of the great displacement which must have occurred, than in that which the great inclination of these strata presents, as it is impossible to conceive how they could have been deposited as they now appear. Yet it is in rocks of this series that we find the greatest difficulty in assigning the true cause of this fact. First of all, finding several strata of clay which crumble easily, on account of the softness which they acquire from the absorption of water, and the limestone and sandstone strata having, on account of their thinness, but little resistance, we are justly inclined to think that the elevation of the strata is the effect of the rents occasioned by the continual mining of subterranean water. Admitting the possibility of this reason, and maintaining that it may have in some measure effected the change of the primitive situation of the stratified rocks of this series, it is not probable that it alone, could have produced such great effects, and often in an uniform manner over a great space, as observation has made known to us. In many places it is entirely impossible that any other cause than that of plutonic forces, having their seat at a great depth beneath the terrestrial surface, could have, so strangely and throughout entire regions, elevated the enormous stratified masses, and thus discovered their internal structure; but for which we should never have been conveniently enabled to examine them, and perhaps might still have remained in ignorance. And now, for a clear explanation how catastrophes of a like nature appear to us to have happened, it is necessary to declare, that if, by relating facts as they first appear to sense, we have