Volcanoes of North America: A Reading Lesson for Students of Geography and GeologyMacmillan, 1897 - 346 Seiten |
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acid active adjacent Alaska basalt beds beneath Bogosloff canic Cascade Mountains Central America Cinder cone Columbia lava composed condition Conseguina cooling coulée crystals Deccan trap deep deposits diameter dikes earth earth's crust elevation erosion escape explosions extruded fissures formed fractures fragments frequently fumaroles gases glaciers hardened height highly heated hypothesis igneous rocks instances interior intruded sheets island Ixtaccihuatl Izalco known Krakatoa lake lapilli lava flows lava sheets lava streams layers liquid lava magma mass material Mexico miles molten rock Mono craters Mono valley moun North America numerous observed occur origin Paoha Island peaks pile plastic plutonic Popocatepetl portion pressure pumice reached recent region rhyolite rise scoriaceous sedimentary seen sides slag slopes steam Stromboli summit surface tain temperature thick tion trachyte U. S. Geological Survey vapor vents Vesuvius volcanic belt volcanic dust volcanic eruptions volcanic mountains volcanic rocks volcanoes VOLCANOES OF NORTH
Beliebte Passagen
Seite 255 - ... as the last of the molten materials from the now extinct volcanoes. There were no visible cones or vents from which these floods of basalt could have proceeded. We rode for hours by the margin of a vast plain of basalt, stretching southward and westward as far as the eye could reach. It seemed as if the plain had been once a great lake or sea of molten rock which surged along the base of the hills, entering every valley, and leaving there a solid floor of bare black stone.
Seite 160 - Bogota, over an area of one thousand five hundred miles in diameter. The noise of the explosions was heard nearly as far, and the Superintendent of Belize, eight hundred miles distant, mustered his troops, under the impression that there was a naval action off the harbor. All Nature seemed overawed ; the birds deserted the air, and the wild beasts their fastnesses, crouching, terror-stricken and harmless, in the dwellings of men. The people for a hundred leagues groped, dumb with horror, amidst the...
Seite 63 - In a word pahoehoe is formed by small offshoots of very hot and highly liquid lava from the main stream, driven out laterally or in advance of it in a succession of small belches. These spread out very thin, cool quickly, and attain a stable form before they are covered by succeeding belches of the same...
Seite 16 - I might boast of the fact that not a groan or a cowardly word fell from me in all the dreadful peril, if I had not believed that the world and I were coming to an end together. This belief was a wretched and yet a mighty comfort in this mortal struggle. At last the murky vapor rolled away, in disappearing smoke or fog. Soon the real daylight appeared; the sun shone out, of a lurid hue to be sure, as in an eclipse. The whole world which met our frightened eyes was transformed. It was covered with...
Seite 255 - ... the whole journey. We found that the older trachytic lavas of the hills had been deeply trenched by lateral valleys, and that all these valleys had a floor of the black basalt that .had been poured out as the last of the molten materials from the now extinct volcanoes. There were no visible cones or vents from which these floods of basalt could have proceeded. We rode for hours by the margin of a vast plain of basalt, stretching southward and westward as far as the eye could reach. It seemed...
Seite 155 - Eruptions of mud, and especially of strata of clay enveloping balls of decomposed basaltes in concentrical layers, appear to indicate that subterraneous water had no small share in producing this extraordinary revolution. Thousands of small cones, from 6 to 10 feet in height, called by the natives ovens (hornitos), issued forth from the Malpays.
Seite 155 - It is continually burning, and has thrown up from the north side an immense quantity of scorified and basaltic lavas containing fragments of primitive rocks. These great eruptions of the central volcano continued till the month of February 1760.
Seite 151 - Livingston, who was a little in advance, suddenly recoiled with an exclamation of pain, having all at once reached a layer of stones so hot as to blister his hands at the first touch. We paused for a moment, and I was looking to my footing, when I was startled by an exclamation of terror from my companion, who gave simultaneously an almost superhuman leap down the side. At the same instant a strange roar almost deafened me ; there seemed to be a whirl of the atmosphere, and a sinking of the mass...
Seite 14 - ... August that my mother called his attention to a cloud of unusual appearance and size. He had been enjoying the sun, and after a bath had just taken his lunch and was lying down to read; but he immediately called for his sandals and went out to an eminence from which this phenomenon could be observed. A cloud was rising from one of the hills (it was not then clear which one, as the observers were looking from a distance, but it proved to be Vesuvius), which took the likeness of a stone-pine very...
Seite 161 - For some leagues around the volcano, the sand and ashes had fallen to the depth of several feet. Of course the operations of the volcano could only be known by the results. A crater had been opened, several miles in circumference, from which had flowed vast quantities of lava into the sea on one hand, and the Gulf of Fonseca on the other. The verdant sides of the mountain were now rough, burned, seamed, and covered with disrupted rocks and fields of lava.