A treatise on the coal field of South Wales, explanatory of a new theory of the position of the measures therein

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Ivey and Pearse, 1849 - 156 стор.
 

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Сторінка 137 - ... objections may not be urged against the probable existence of such vast bodies of fresh water as would be of sufficient extent and depth to receive the beds of many coal-fields ; but the absence of marine remains throughout vast depths of strata in coal-fields is a remarkable fact, well deserving of the most careful investigation. That the terrestrial vegetable matter from which coal has been formed has in very many instances been deposited in the sea is unquestionable. from their alternations...
Сторінка 99 - ... in ruins, when the rain ceased, and this moving mass of earth was arrested in its progress.! A still more astonishing fact of this kind is related :>a part of the mountain Goima, in the Venetian State, detached itself during the night, and glided along, with several houses, which were carried into the neighbouring valley ; in the morning the inhabitants, who had felt nothing, were extremely astonished, when they awoke, to see themselves at the bottom of a valley, and for a long time imagined...
Сторінка 134 - ... from the horizontal position in which they must have been deposited to that inclination they now have. In these coal-beds, at more than ten distinct levels, are stems of trees, in positions at right angles to the planes of stratification ; that is, which must have stood upright when the coal-measures were horizontal. No part of the original plant is preserved except the bark, which forms a coating of bituminous coal, the interior being a solid cylinder of sand and clay, without traces of organic...
Сторінка 51 - ... succession of convex and concave flexures, subsequently laid open by denudation. The component rocks are of great thickness, all referable to the Silurian, Devonian, and Carboniferous formations. There is no principal or central axis, as in the Pyrenees and many other chains — no nucleus to which all the minor ridges conform ; but the chain consists of many nearly equal and parallel foldings, having what is termed an anticlinal and synclinal arrangement (see above, p.
Сторінка 46 - ... condensation to be communicated from the air to the metal, which will be thereby more or less raised in temperature above the surrounding atmosphere, let the piston be suddenly retracted and the air restored to its original volume in an instant. The whole apparatus is now precisely in its initial situation, as to the disposition of its material parts, and the whole quantity of heat it contains remains unchanged. But it is evident that the distribution of this heat within it is now very different...
Сторінка 118 - ... to remark this general fact, that the greater number of the principal mountains have one of their sides very steep, and the other of a very gradual slope.* The Alps, for example, are much more rapid in their descent on the Italian side than on that of Switzerland. On the contrary, the Dophrines, or Scandinavian Alps, have a much steeper declivity to the. west and north-west, than towards the south and east. The Pyrennees are steeper towards the south than the north ; the mountains of the Asturias...
Сторінка 135 - ... without traces of organic structure, as is usually the case with Sigillaria, and like the upright trees in the coal-measures cut through by the Bolton Railway. The trees, or rather the remains of stems of trees broken off at different heights above the root, vary in height from six to twenty-five feet, and in diameter from fourteen inches to four feet. There are no appearances of roots, but some of the trees enlarge at the bottom. They rest upon, and appear to have grown in, the mass which now...
Сторінка 71 - That very law* which moulds a tear, And bids it trickle from its source, That law preserves the earth a sphere, And guides the planets in their course.
Сторінка 117 - Mountains are seen most frequently in groups. Sometimes chains branch out from a common centre in angular directions. Sometimes the centre mass itself is a lofty chain, straight or curved, whence, at different periods, secondary chains have apparently been formed ; — the Alps may he placed in this class.
Сторінка 137 - Pittsburg seam mentioned in page 170) ; and freshets bring down gravel, and sand, and mud, as well as plants and trees. They must occur several times a-year in every river ; but many years must have elapsed during the gradual deposit of the sandstones and shales that separate the seams of coal.

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