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 DenudationDodd, Mead, 1890 - 399 Seiten |
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activity American Journal augite basalt basin beneath black ledge boiling border bottom Brigham cavities centre chrysolite cinder-cones cinders Coan coast condition cone cooling coral crust crystals deep depth diameter discharge dome down-plunge earthquakes east eastern ejections eruption evidence facts fathoms feet high feldspar fifty feet fires fissures floor flow forms glass Haleakala Halema'uma'u Hawaii Hawaiian Islands heat height Hilo inches jets Journal of Science Kauai Kilauea labradorite lake lava-column lava-lakes lava-streams layer letter liquid lavas lower pit magnetite mass Maui miles moisture Mount Kea Mount Loa nearly Niihau Oahu observed outflow pahoehoe Pele's hair plagioclase Plate precipice probably projectile action region ridge rock scoria side slopes southwest specific gravity specimens stalactites stream subsidence sulphur summit crater surface thick thousand feet tion tufa valley vapors vesiculation Vesuvius volcanic mountains Volcano House walls Wilkes Wilkes's
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Seite 382 - Towards the foot of the mountain, the excavating power gradually ceases when the stream has no longer in this part a rapid descent, - that is, whenever the slope is not above a few feet to the mile. The stream then consists of two parts, the torrents of the mountains and the slower waters below, and the latter is gradually lengthening at the expense of the former. (/) After the lower waters have nearly ceased excavation, a new process commences in this part, that of widening the valley. The stream...
Seite 382 - ... in height; but the process begun, it goes on with accumulating power. The descending waters in this spot add their whole weight, as well as a greatly increased velocity, to their ordinary force, and the excavation below goes on rapidly, removing even the harder layers. The consequences are, a fall of increasing height, and a basinlike excavation directly beneath the fall.
Seite 141 - ... (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 53 - On reaching its base, we judged it to be one hundred and fifty feet high, a huge, irregularly shapen, inverted funnel of lava, covered with clefts, orifices, and tunnels, from which bodies of steam escaped With deafening explosion, while pale flames, ashes, stones, and lava, were propelled with equal force and noise, from its ragged and yawning mouth.
Seite 9 - 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 68 - 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 188 - ... 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 87 - 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 380 - ... 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...
Seite 315 - that particular rocks have no necessary relation to time, excepting so far as time is connected with a difference in the earth's temperature or climate and also in oceanic or atmospheric pressure, for, if the elements are at hand, it requires only different circumstances as regards pressure, heat, and slowness of cooling to form any igneous rock the world contains.