The Elements of Geology: Adapted to the Use of Schools and CollegesGould and Lincoln, 1852 - 198 oldal |
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abundant accumulation action amount animal argillaceous argillaceous slate basalt become carbonate carboniferous causes change of level clay cleavage climate color composed consists contain coral cretaceous crust crystalline denudation deposited depth dikes division earth earthquake earthy matter effect elevation eruption Europe evidence exist extend felspar force formation fossiliferous rocks fossils fracture furnished glacier gneiss granite greensand heat Hence hornblende hundred feet Hypersthene igneous rocks instances islands lakes land lava layers lignite lime limestone marine currents mass materials melted metamorphic metamorphic rocks mica miles mineral mountain nearly occur ocean Old Red Sandstone oölite organic particles peculiar phenomena portion principal probably produced quartz red sandstone regions remains river sand SECTION sediment sedimentary shales silurian slate solid solidified species specific gravity strata stratified rocks structure subsidence substances surface temperature tertiary period thickness thousand feet tion trappean rocks valley vegetable veins volcanic activity volcanic rocks
Népszerű szakaszok
98. oldal - ... of the current of water to the specific gravity of the gold, so easily separates the powdered matrix from the metal. The mud which passes from the mills is collected into pools, where it subsides, and every now and then is cleared out and thrown into a common heap. A great deal of chemical action then commences, salts of various kinds effloresce on the surface, and the mass becomes hard. After having been left for a year or two, and then rewashed, it yields gold; and this process may be...
28. oldal - Auvergne, and laid siege to its principle city, could hardly have failed to notice them. Had there been even any record of their existence in the time of Pliny or Sidonius Apollinaris, the one would scarcely have omitted to make mention of it in...
1. oldal - The volume is admirably suited to its uses, and is highly trustworthy. Messrs. D. Appleton & Co. continue to add new and most interesting volumes to their " Popular Library of the Best Authors.
137. oldal - Some of the fissures near the cliffs were a yard wide. Many enormous masses had already fallen on the beach, and the inhabitants thought that when the rains commenced far greater slips would happen. The effect of the vibration on the hard, primary slate which composes the foundation of the island was still more curious: the superficial parts of some narrow ridges were as completely shivered as if they had been blasted by gunpowder.
86. oldal - ... away. I entertain little doubt that, when this loftier portion of Scotland, including the entire Highlands, first presented its broad back over the waves, the upper surface consisted exclusively, from the one extremity to the other — from...
137. oldal - ... productions adhering to them, must recently have been lying in deep water, had been cast up high on the beach. One of these was a slab 6 feet by 3, and about 2 feet thick. The island itself as plainly showed the overwhelming power of the earthquake, as the beach did that of the consequent great wave. The ground was fissured in many parts, in north and south lines; which direction perhaps was caused by the yielding of the parallel and steep sides of the narrow island. Some of the fissures near...
77. oldal - Kegion. 4th. The Northern Region. " We can boast," he says, "of but few plants that are unknown out of the limits of our Flora." He names two or three that are so. He informs us, also, " that on the shores of the great lakes there are certain plants the proper station of which is the immediate neighborhood of the ocean, as if they had constituted part of the early Flora of those regions when the lakes were filled with salt water, and have survived the change that has taken place in the physical conditions...
135. oldal - ... rounded grains of quartzose sand : we perceive moreover much of the feldspar to be only imperfectly formed, as if congealed when in transitu, though the mica has more nearly reached the standard condition which it has in granite. In some of the coarser varieties of this white rock, small distinctly rounded pebbles of quartz are to be seen, giving unequivocal evidence, even to the naked eye, of its being an altered sandstone. Upon inspecting many varieties of this rock, we felt no hesitation in...
135. oldal - ... granite, and is itself in many parts concreted into a near approximation to a binary granite composed of distinctly developed quartz and white feldspar, with a few sparsely scattered specks of mica. In its weathered surfaces this rock wears a close resemblance to some fine grained quartzo-feldspathic granites, but upon inspecting a fresh fracture with a magnifier, we instantly perceive many rounded grains of quartzose sand: we perceive moreover much of the feldspar to be only imperfectly formed,...
2. oldal - In the Clerk's Office o[ the District Court of the District of Massachusetts.