The Student's Handbook of Physical GeologyG. Bell and Sons, 1884 - 514 pages |
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accumulated acid action altered alumina amount angles anticlinal augite basalt beds blocks bottom calcareous called carbonate of lime chalk chemical clay cleavage cliffs coal coast colour consists containing coral cracks crystalline crystals denudation deposits depth described detrition distance district dolerite dykes earth elevation erosion eruption fault feet felspar fissures Foraminifera formation formed fragments Geol Geology glacier glauconite gradually granite greensand ground hills horizontal hornblende igneous rocks iron island joints Jukes lake land lava layers less Leucite limestone magnesia mass material matter metamorphic metamorphic rocks mica miles mineral mountain occur Old Red Sandstone origin Orthoclase outcrops oxides particles pebbles planes porphyritic portion present pressure produced quartz rain reef river sand sandstone shale shells shore side silicate Silurian slope solution sometimes stone strata stratified rocks stream structure surface thickness tide tion tuffs valley vertical volcanic
Popular passages
Page 43 - 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.
Page 192 - The sands whereon Yarmouth is built first became firm and habitable ground about the year 1008, from which time a line of dunes has gradually increased in height and breadth, stretching across the whole entrance of the ancient estuary, and obstructing the ingress of the tides so completely, that they are only admitted by the narrow passage which the river keeps open, and which has gradually shifted several miles to the south.
Page 105 - On entering the narrow ravine where the water foams down the two cataracts, we are entirely shut out from all view of the surrounding country; and a geologist who is accustomed to associate the characteristic features of the landscape with the relative age of certain rocks, can scarcely dissuade himself from the belief that he is contemplating a scene in some rocky gorge of very ancient date.
Page 107 - Puy is rather one of utter bewilderment. The upsetting of all one's previous estimates of the power of rain and rivers is sudden and complete. It is not without an effort, and after having analysed the scene, feature by feature, that the geologist can take it all in. But when he has done so, his views of the effects of subaerial disintegration become permanently altered, and he quits the district with a rooted conviction that there is almost no amount of waste and erosion of the solid framework of...
Page 276 - In this paper the author showed, that, when artificial crystals are examined with the microscope, it is seen that they have often caught up and enclosed within their solid substance portions of the material surrounding them at the time when they were being formed. Thus, if they are produced by sublimation, small portions of air or vapour are caught up, so as to form apparently empty cavities ; or, if they are deposited from solution in water, small quantities of •water are enclosed, so as to form...
Page 1 - In the words of one of the most devoted adherents of our science, we might say, " without impropriety, that all the physical sciences are included under two great heads — astronomy and geology; the one comprehending all those sciences which teach us the constitution, the motions, the relative places, and the mutual action of the astra, or heavenly bodies, while the other singles out for study the one astrum on which we live, namely, the earth.
Page 210 - The nitrate of soda was now selling at the ship's side at fourteen shillings per hundred pounds : the chief expense is its transport to the sea-coast. The mine consists of a hard stratum, between two and three feet thick, of the nitrate, mingled with a little of the sulphate of soda, and a good deal of common salt. It lies close beneath the surface, and follows for a length of one hundred and fifty miles the margin of a grand basin or plain...
Page 44 - Chile; nor is this improbable, as it is known that the surface of a vibrating body is affected differently from the central part. It is, perhaps, owing to this same reason, that earthquakes do not cause quite such terrific havoc within deep mines as would be expected. I believe this convulsion has been more effectual in lessening the size of the island of Quiriquina, than the ordinary wear-and-tear of the sea and weather during the course of a whole century.
Page 406 - It was as if the great plain had been filled with molten rock, which had kept its level, and wound in and out along the bays and promontories of the mountain slopes as a sheet of water would have done.
Page 92 - If the crack is near the cliff the half detached mass being now heavier, owing to the addition of the water, while the cohesion of the attached portion is lessened, slips down to the shore below, sometimes almost unbroken, sometimes breaking off by parallel cracks into a series of terraces, or even in part creeping down among the fallen stiffer masses, as a glacierlike mud flow.