Penny Blood: Serial Sensation and Working-Class Entertainment — page 296: what you’re looking at

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

CH. XX1I.] SUMMARY. 279 thickness is greater than this. Again, taking the temperature of melting slag at 3000° F., such a temperature would be met with at the depth of from 28 to 30 miles, and we can hardly suppose the temperature of the substratum to be so high as that of melting slag. Hence we place, roughly, the +k ckness of the undisturbed crust as a first attemft ‘Petwebn, $b estimates, at about 25 miles. 0? *> compression ; and that about two-fifths of the thigknegs ER up, and three-fifths goes down. If it were to Pemaih ‘hr th * ) position, we should have the ratio of the part above the effective level of the fluid to the part below it as 2 to 3. This would be impossible if 1t floated; just as it would be impossible that an iceberg should stand 200 feet above the water while only 300 feet were immersed. But the tract of crust does not exactly float ; for it is held up to some extent by its attachment to the neighbouring crust. Nevertheless it cannot be held up long in what would be so constrained a position. It must then sag downwards ; and the most thickened part would sink the most. Hence depressions would arise on both sides of the ridge, and the ocean, which covers the general surface, would be deeper than elsewhere along two channels parallel to, and at some little distance from, the ndge. But should the ridge be steeper on one side than on the other, as seems inevitable, the ocean would be deeper on the steeper side. This relative position of the depths of the ocean to mountain-chains is in accordance with nature. Next suppose the ridge thus elevated to be denuded. The chief streams will be formed on the less steep side, and the ‘sediment will go partly into the sea and be deposited along the shore line, and partly on to the lower lands. This will depress that portion, and it will sink; and the whole tract will be more or less tilted down on that side, and up on the other, because it will turn about an axis through its centre of gravity, which will be situated somewhere beneath the ridge. The ridge also, owing to the great downward protuberance, will stiffen the tract, and give it rigidity to bear this tilt. The r Begg 44S Y » > \ Now supposing a tract of the crust crushe | tOyether FABiny yp GONG oOo SS (CO)