Penny Blood: Serial Sensation and Working-Class Entertainment — page 136: what you’re looking at

Machine-transcribed from the original scan — historical spelling and the odd misread are preserved.

CH. X.] DISTURBED TRACT. I19 Under these circumstances we may suppose that, upon the pressure increasing at any place, the crust will give way first at some place where it is weakest. It cannot give way at two places at once. Once having given way, the weak condition will be propagated from that place, but more in one direction than the opposite. In which direction this will be, will depend upon the nature of the first rupture ; for it is not likely that it should be perfectly symmetrical: and if not so, this will render the neighbouring crust weaker on one side than on the other, and in that direction we may expect the disintegrating process to extend. The pressure approximately horizontal will produce a shear more or less vertical, It will become a question there- fore whether the compression 1s to be compensated by great elevation above, and great depression below the mean levels for a short horizontal space, or by lesser elevation and de- pression for a longer. But the resistance to be overcome in shearing will increase as the thickening increases, for not only will a higher column of rock then have to be pushed up against gravity above the upper mean level, but also the resistance to depression below the lower mean will be increased on account of the increased upward pressure of the fluid down into which the lighter rock is forced. The friction will be increased also. There will therefore arise some relation between the amount of vertical shear, and the strength of the crust. In other words, 2 (a) — %(b) + (8) —X(a) being equal to kle, the length J of crust, broken up to give the necessary relief by the formation of the inequalities represented by these symbols, will depend upon the strength of the crust; such length being greater or less according as the crust is weaker or stronger, because, if strong, it will resist further fracture, and the part already dis- turbed will be utilised to satisfy any subsequent additional com- pression. | The horizontal force causing a compression which as already remarked will be relieved rather by crushing or corrugating the rocks than by flexing the crust as a whole, will not as a primary consequence produce the hollows belonging to %(6) and (a). It will rather result in a swelling of the crust up- wards and downwards. GONG IOoO SS (CO)