A Manual of GeologyScott, Webster, and Geary, 1840 - 268 páginas |
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Términos y frases comunes
abundant actinolite animals appearance argillaceous augite basalt beds calcareous carbonate Carboniferous chains chalk chlorite clay clay-slate coal Coal-Formation colour compact composed conchoidal conglomerate containing corals craters Cretaceous crust crystalline crystals deposits earth earthquakes elevated eruption extent feet felspar fissures formation fossil fracture fragments frequently fresh-water globe gneiss gradually granite granular green Greenstone grey greywacke gypsum hornblende hypersthene igneous igneous rocks iron kind lakes laminated land lava layers lime limestone lower lustre marine marls masses matter metallic mica mica-slate mountain-chains mountains named nature numerous occur ocean oolitic organic remains peat phenomena Pitchstone plants porphyry portion present primary produced quartz RECAPITULATION Red Sandstone ridges rivers sand secondary rocks shale shells Silurian simple minerals slaty sometimes species stone strata stratified rocks structure substances summits surface Syenite tains temperature TERTIARY texture thickness tion trachytic trap rocks traversed unstratified upper usually valleys varieties various vary vegetable veins volcanic
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Página 200 - This cause, so often the source of death and terror to the inhabitants of the globe, which visits, in succession, every zone, and fills the earth with monuments of ruin and disorder, is, nevertheless, a conservative principle in the highest degree, and, above all others, essential to the stability of the system.
Página 17 - That there is no notable difference in sea-water under different meridians. 4. That there is no satisfactory evidence that the sea at great depths is more salt than at the surface. 5. That the sea, in general, contains more salt where it is deepest and most remote from land ; and that its saltness is always diminished in the vicinity of large masses of ice. 6. That small inland seas, though communicating with the ocean, are much less salt than the ocean.
Página 133 - If we examine these creatures with a view to their capabilities of locomotion, and the means of offence and defence, which their extraordinary structure afforded to them ; we shall find combinations of form and mechanical contrivances, which are now dispersed through various classes and orders of existing animals, but are no longer united in the same genus.
Página 184 - Denon informs us in his Travels in Lower and Upper Egypt, that summits of the ruins of ancient cities, buried under these sands still appear externally; and that but for a ridge of mountains called the Lybian chain, which borders the left bank of the Nile, and forms, in the parts where it rises, a barrier against the invasion of these sands, the shores of the river, on that side, would long since have ceased to be habitable. " Nothing can be more melancholy...
Página 184 - Nothing can be more melancholy," says this traveller, " than to walk over villages swallowed up by the sand of the desert, to trample underfoot their roofs, to strike against the summits of their minarets, to reflect that yonder were cultivated fields, that there grew trees, that here were even the dwellings of men, and that...
Página 199 - The renovating as well as the destroying causes are unceasingly at work, the repair of land being as constant as its decay, and the deepening of seas keeping pace with the formation of shoals. If, in the course of a century, the Ganges and other great rivers have carried down to the sea a mass of matter equal to many lofty mountains, we also find that a district in Chili, one hundred thousand square miles in area, has been uplifted to the average height of a foot or more, and the cubic contents of...
Página 124 - ... so volatile as to be entirely expelled by heat, before any change is effected in the other constituents of the coal. The number and appearance of these cells vary with each variety of coal. In caking coal, the cells are comparatively few, and are highly elongated.
Página 134 - A similar remarkable combination of forms appears in this animal to that which distinguishes its preceding relative — the head of a lizard, the teeth of a crocodile, a neck resembling the body of a serpent, the trunk and tail of an ordinary quadruped, the ribs of a chameleon, and the paddles of a whale.
Página 65 - Coniferae ; increasing in the number and variety of its genera and species, at each suecessive change in the climate- and condition of the surface of the earth. This family forms about one three-hundreth part of the total number of existing vegetables.
Página 134 - I.— 12 which are now dispersed through various classes and orders of existing animals, but are no longer united in the same genus. Thus, in the same individual, the snout of a Porpoise is combined with the teeth of a crocodile, the head of a Lizard with the Vertebra; of a fish, and the sternum of an Ornithorhynchus with the paddles of a whale.