Penny Blood: Serial Sensation and Working-Class Entertainment — page 69: what you’re looking at

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

52 ELEVATIONS AND DEPRESSIONS. [cH. v. than its own, which is necessarily limited to that of the sea- level where the deposit 1s goingon. The test of such a mode of action would be to ascertain whether any portion of the strata, which ought to lie beneath the thick deposit, can be discovered in a contorted condition abutting upon it. Thus far, for the sake of perfect generality, it has been as- sumed that the disturbed upper strata rest upon a liquid, or at least a plastic, substratum. In what follows, the enquiry will be made whether this condition of the subjacent rocks is probable. And the method taken will be to consider whether the contrary supposition, that the subjacent rocks are solid, will account for the amount of inequalities which the earth actually exhibits. If the earth had cooled as a solid body, the outer layers at any epoch having attained their complete amount of contraction sooner than the interior, would have been too large to fit the interior after the cooling had proceeded further. They would therefore become corrugated. But in this case the corrugation would have necessarily taken place wholly in an upward direc- tion, the solidity resisting the intrusion of corrugations into the lower regions; and there could be no places where any portion of the surface could have become depressed below the datum level. Hence upon this hypothesis we may introduce into our datum-level equation the supposition that >(B)=0. And it becomes 8arr*ke = 2% (A). Since 4arr* is the area of the globe, it follows from this rela- tion that 2ke is the average height of all the elevations above the datum level, which make up the volume %(A). In other words, if all the elevations were levelled down, they would | form a coating above the datum level whose thickness would be 2ke. The actual amount at which we may estimate this quantity is of great importance to the argument we are about ta adduce regarding the physics of the earth’s crust. We will now en- deavour to obtain a fairly reliable measure of it from the data obtainable. IZ Md commiclsoolkks (CO)