Advanced Text-book of Geology Descriptive and IndustrialWilliam Blackwood, 1867 - 478 pages |
Other editions - View all
Common terms and phrases
abundant accumulations areas argillaceous arrangement basalts beds bituminous bones breccia calcareous carbonate carboniferous chalk chemical chiefly clay coal coal-fields coal-measures colour composed composition conglomerates corals cretaceous crust crustacea crystalline deposits Devonian distinct districts drift earth elevation England eocene epoch estuaries existing extinct feet felspar fishes flint formation forms fossil fresh-water genera genus geological geologists globe gneiss granite gravel greensand greenstone grits heat hence igneous rocks islands known lakes laminated land lava layers less lias lignites lime limestone lower magnesian marine marls masses matter metamorphic mica-schist mineral miocene mountain nature numerous occur ocean old red sandstone oolite organic origin paleozoic peculiar period Permian plants and animals pleistocene pliocene present quartz regions remains reptiles rivers sand schists shales shells siliceous silt Silurian slates species stone strata stratified structure student surface term tertiary texture thickness tion Triassic upper vegetable volcanic Wealden
Popular passages
Page 131 - Bright ran at one time a great hazard, and suffered considerable pain from accidentally plunging one of his legs into the hot clay. * From whatever spot the sulphur is removed, steam instantly escapes ; and, in many places, the sulphur was so hot that we could scarcely handle it. From the smell, I perceived that the steam was mixed with a small quantity of sulphurated hydrogen gas.
Page 191 - The stratified rocks of the highest antiquity, such as the oldest gneiss or quartz rocks, have very seldom borne gold ; but the sedimentary accumulations which followed, or the Silurian, Devonian, and Carboniferous (particularly the first of these three), have been the deposits which, in the tracts where they have undergone a metamorphosis or change of structure by the influence of igneous agency or other causes, have been the chief sources whence gold has been derived.
Page 324 - It often attains a thickness of many thousand feet, and extends from the Alps to the Carpathians, and is in full force in the north of Africa, as, for example, in Algeria and Morocco.
Page 334 - ... place in the Eocene series, we are struck with the comparatively modern date to which some of the greatest revolutions in the physical geography of Europe, Asia, and northern Africa must be referred. All the mountain chains, such as the Alps, Pyrenees, Carpathians, and Himalayas, into the composition of whose central and loftiest parts the nummulitic strata enter bodily, could have had no existence till after the middle Eocene period."— Manual, p. 232. A still more marked case follows on the...
Page 375 - ... with beds of oysters, muscles, and other shells adhering to the rocks on which they grew, the fish being all dead, and exhaling most offensive effluvia.
Page 251 - Their forms. Rounded pebbles are exceedingly rare. They are angular or subangular, and have those flattened sides so peculiarly characteristic of many glacier-fragments in existing moraines, and also of many of the stones of the pleistocene drifts, and the moraine matter of the Welsh, Highland, Irish, and Vosges glaciers. 3. Many of them are highly polished, and others are grooved and finely striated...
Page 131 - At the bottom of this hollow we found a caldron of boiling mud, about fifteen feet in diameter, similar to that on the top of the mountain, which we had seen the evening before ; but this boiled with much more vehemence. We went within a few yards of it, the wind happening to be remarkably favourable for viewing everv part of this singular scene.
Page 29 - ... like flies walking over a great hill. All that can be seen from the top of the highest mountain to the bottom of the deepest mine is not more in comparison than the mere varnish on the outside of a school-globe.
Page 238 - ... water ; but the case is somewhat different with beds of coal. This mineral, being chiefly composed of carbon, hydrogen, and oxygen — the same elements which enter into the composition of plants — and revealing in its mass evidence of vegetable structure, no doubt is entertained of its organic origin. But whether the plants of which it is composed were drifted down by rivers, and deposited along with layers of mud and sand in estuaries, or whether dense forests and peat-mosses were submerged,...
Page 370 - Their surfaces were at a nearly uniform inclination of descent of 5°, and their breadth either 12, 24, 36, or some other multiple of twelve paces. This imposing series of ledges carried you in forty-one gigantic steps to an elevation of 480 feet ; and as the first rudiments of these ancient beaches left the...