Physics of the Earth's CrustMacmillan and Company, 1881 - 299 стор. |
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amount andesite anticlinal appears assumed basalt become bore-hole cause centre of gravity chapter column compression condition consequently continents cooling corrugations crushing cubic cubic foot datum level density denudation deposits depression depth diminished disturbed earth earth's crust earth's surface effect elevated equal equation equilibrium eruption estimate existing extravasation fault feet fissure fluid substratum force fused geological globe greater heat Hence horizontal hypothesis igneous rock increase of temperature inequalities interior lava layer less liquid lower magma Mallet mass mean level melting temperature miles mountain neutral zone nucleus observations perature phenomena portion present produced Prof radial contraction radius rate of increase regions result rhyolite rigid rise rock sediment solid globe solidification specific gravity strata stratum sufficient suppose supposition theory thickness tion trachyte tract upper vapour vertical volcanic volume Waltershausen water-substance weight whole
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Сторінка 77 - In fact, it is this unequal contraction which appears to have caused the hollows in the external surface which have become the basins into which the waters have flowed to form the ocean.
Сторінка 76 - There must, therefore, be some excess of matter in the solid parts of the earth between the Pacific Ocean and the earth's centre which retains the water in its place. This effect may be produced in an infinite variety of ways ; and therefore, without data, it is useless to speculate regarding the arrangement of matter which actually exists in the solid parts below.
Сторінка 227 - ... crushing of portions of that shell, which compressions and crushings are themselves produced by the more rapid contraction by cooling of the hotter material of the nucleus beneath that shell, and the consequent more or less free descent of the shell by gravitation, the vertical work of which is resolved into tangential pressures and motion within the shell.
Сторінка 60 - Such is, on the whole, the most probable representation of the earth's present temperature, at depths of from 100 feet, where the annual variations cease to be sensible, to 100 miles; below which, the whole mass, or all, except a nucleus cool from the beginning, is (whether liquid or solid) probably at, or very nearly at, the proper melting temperature for the pressure at each depth.
Сторінка 145 - ... distance from it, we ought to be prepared to expect no effect whatever, or in some cases even a small negative effect. The reasoning upon which this opinion is founded, inasmuch as it must have some application to almost every investigation of geodesy, may perhaps merit the attention of the Royal Society. Although the surface of the earth consists everywhere of a hard crust, with only enough of water lying upon it to give us everywhere a couche de niveau, and to enable us to estimate the heights...
Сторінка 146 - I conceive that there can be no other support than that arising from the downward projection of a portion of the earth's light crust into the dense lava; the horizontal extent of that projection corresponding rudely with the horizontal extent of the tableland...
Сторінка 291 - The existence of dry land proves that the earth's surface is not a figure of equilibrium appropriate for the diurnal rotation. Hence the interior of the earth must be in a state of stress, and as the land does not sink in, nor the sea-bed rise up, the materials of which the earth is made must be strong enough to bear this stress.
Сторінка 88 - ... to a certain depth ebullition would cease, and a crust be formed ; but that more water would be ready to separate to a greater depth when its affinity for the rock became lessened through the abstraction of heat, or diminution of pressure owing to the crust being partially supported by corrugation. If such was the condition of the interior in the early stages of the cosmogony, a large portion of the oceans now above the crust may once have been beneath it, and thus we gain a novel conception...
Сторінка 23 - But now thrice to slay the slain ; suppose the earth this moment to be a thin crust of rock or metal resting on liquid matter. Its equilibrium would be unstable ! And what of the upheavals and subsidences? They would be strikingly analogous to those of a ship which has been rammed : one portion of crust up and another down, and then all down.
Сторінка 291 - Earth have about the strength of granite at 1,000 miles from the surface, or that they have a much greater strength nearer to the surface. This investigation must be regarded as confirmatory of Sir William Thomson's view, that the Earth is solid nearly throughout its whole mass. According to this view, the lava which issues from volcanoes arises from the melting of solid rock, existing at a very high temperature, at points where there is a diminution of pressure, or else from comparatively small...