Penny Blood: Serial Sensation and Working-Class Entertainment — page 153: what you’re looking at

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

. 136 DISTURBED TRACT. [cH. x. it will afterwards behave as if it were rigid. Suppose at this stage that the centre of gravity of the displaced fluid 1s brought to H. This point will evidently be to the east of G@. The upward pressure of the fluid at H will tend to produce rotation round G7’, raising the tract to the west, and depressing it towards the east. One of two effects may be expected to result. Either the crust will break off at RS and perhaps also at PQ, where before the change of pressure it was only just able to bear the downward stress, or else, as in the diagram, the limits of the depressed tract will be shifted eastward to P’Q’ and RS’. In either case, an additional volume of the crust will be depressed into the fluid towards the east, and the effect will be, that the centre of gravity of the displaced fluid will be also shifted towards the east; in which direction it will move, until equili- brium is restored by its arriving beneath CG’. The centre of gravity of the tract will thus continually travel eastwards, as more and more sediment is deposited in that direction. And since the centre of gravity is the point, about which the tract will tend to rotate under the action of the shifted and of the additional weight above, and of the fluid pressure beneath, it follows that, if the ends of the tract at PQ and RS are not tilted upwards and downwards, as would happen if the tract were rigid, there will be a kind of wave of eleva- tion travelling from west to east, whose crest will carry with it the centre of gravity of the tract. We see then a prior that ‘the region which receives the sediment from A will sink, but at the same time A from which it came will nse, and if there be additional sediment brought from distant regions, these effects, not only the sinking of the sedimented parts, but the rise of A, will be intensified. We might even expect, that some of the sediment earliest deposited nearest the west, might be raised above the ocean by this rotational action alone. We will now endeavour to obtain a somewhat closer insight into the character of the movements, in doing which we shall for simplicity neglect the weight of the ocean. If a mass floats in a fluid, as we have supposed our tract virtually to do, the densities being respectively p and o, we commiclsoolkks (CO) \ —— » Oe ee Oruw—- _7@& - rd