Characteristics of Volcanoes: With Contributions of Facts and Principles from the Hawaiian Islands, Including a Historical Review of Hawaiian Volcanic Action for the Past Sixty-seven Years, a Discussion of the Relations of Volcanic Islands to Deep-sea Topography, and a Chapter on Volcanic-island Denudation

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Dodd, Mead, 1890 - 399 Seiten
 

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Seite 270 - The lava of the walls is in part scoriaceous ; but on the south and southwest sides it was commonly a very compact, rather light gray variety of basalt, like that of the projected blocks about some of the cones. The layers of compact basalt had often one or more parallel planes of fine or coarse vesiculation, sometimes at intervals of one to three or four feet. At one locality on the ascent of the mountain the solid gray rock...
Seite 139 - ... (1) a rising in level of the liquid lavas and of the bottom of the crater ; (2) a discharge of the accumulated lavas down to some level in the conduit determined by the outbreak ; (3) a downplunge of more or less of the floor of the region undermined by the discharge.
Seite 7 - ... twenty-five to forty feet above the general surface. The size of the masses is from an inch in diameter to ten feet and more. The lava is compact, usually less vesiculated than the pahoehoe, not scoriaceous; but...
Seite 7 - There is the ordinary smooth-surfaced lava called pahoehoe, the term signifying having a satin-like aspect. The surface of the lava cooled as it flowed. Through one means and another the surface is usually uneven, being often wrinkled, twisted, ropy, billowy, hummocky, knobbed, and often fractured The other most prominent kind of lava stream is the aa. The aa streams have no upper flow-like surface; they are beds of broken...
Seite 194 - ... a description that not only reads well, but I feel sure is to the life, like the most of Miss Bird's word-pictures ; then, " with a roar like the sound of gathering waters, nearly the whole surface of the lake was lifted up, by the action of some powerful internal force, and its whole radiant mass rose three times in one glorious upward burst, to a height, as estimated by the surrounding cliffs, of six hundred feet. . . . After this the fountain played as before.
Seite 64 - The large cauldron, in place of its bloody glare, now glowed with intense brilliancy, and the surface sparkled with shifting points of dazzling light, occasioned by the jets in constant play.
Seite 184 - ... should stand at the foot of Niagara Falls, or on the rocky shore of the Atlantic when the sea is lashed by a tempest, in order to get the most terrific element in this sublime composition of the Great Artist. For you may easily conjecture that the dynamical force necessary to raise 200,000 to 500,000 tons of lava at once into the air would not be silent in its operation. The eruption of which I have written broke out on the morning of the 18th of February, at about 3 o'clock, and continued twenty...
Seite iv - It has learned that pit-shaped craters are characteristic of true basalt-volcanoes, and a result of the free mobility of the lavas, whether the action in the lava-lakes within be fountain-like or boiling-like ; that floating islands of solid lava may exist in the lakes ; that a regular oscillation between fusion and cooling takes place at times in the thin crust of lava-lakes; that the solid lava of the margin of a lake may be re-fused, and also even the mass of a floating island, and the blocks...
Seite 83 - I shook myself and jumped back, looking at my watch to note the time, for I thought a great eruption at hand, and then stood gazing at the strange scene for some time before I thought of calling my companions. " The whole surface of the lake had risen several feet, and was boiling violently, and dashing against the sides, throwing the redhot spray high over the banks, causing the providential rain of fire which awoke me to see this grand display.
Seite 368 - ... other summits. Here volcanic action has had a smoothing effect, and by its continuation to this time, the waters have had scarcely a chance to make a beginning in denudation. Mount Kea, which has been extinct for a long period, has a succession of valleys on its windward or rainy side, which are several hundred feet deep at the coast and gradually diminish upward, extending in general about half or two-thirds of the way to the summit. But to the westward it has dry declivities, which are comparatively...

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