Bulletin - United States Geological Survey, Ausgabe 354

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Seite 217 - ANTICLINE. A term applied to granite sheets or sedimentary beds that form an arch. APLITE. Fine-grained granite, usually occurring in dikes and containing little mica and a...
Seite 40 - The impact of the hammer breaks up the granules on the immediate surface so that the light falling upon it is reflected, instead of absorbed, and the resultant effect upon the eye is that of whiteness. The darker color of a polished surface is due merely to the fact that through careful grinding all these irregularities and reflecting surfaces are removed, the light penetrating the stone is absorbed, and the effect upon the eye is that of a more or less complete absence of light or darkness. Obviously...
Seite 40 - Merrill a explains the cause of these contrasts very satisfactorily : The impact of the hammer breaks up the granules on the immediate surface, so that the light falling upon it is reflected, instead of absorbed, and the resultant effect upon the eye is that of whiteness. The darker color of a polished surface is due merely to the fact that, through careful grinding, all these irregularities and reflecting surfaces are removed...
Seite 10 - ... but also powerful expansive pressure from below. Had this molten matter been extruded at the surface it would have cooled so rapidly that but few of its constituent molecules would have had time to arrange themselves in geometric order. The process of crystallization would have been arrested by the sudden passage of the material into the solid state and the product would have been a volcanic glass somewhat resembling that which forms cliffs in Yellowstone National Park. In granite, however, the...
Seite 30 - The spacing of the joints varies considerably, ranging from 1 foot to 500 feet, but usually from 10 to 50 feet. In some localities the jointing is very irregular. The granite is broken up into various polygons, which at the surface, where weathering has made inroads, resemble bowlders. Quarries opened in such places are called bowlder quarries. Another sort of irregularity in joints consists in their discontinuity or intermittence, their strike and dip for the short spaces in which they occur being...
Seite 26 - ... wood used is 15 hundredweight. The average thickness of stone is 5 inches and its specific gravity is 2.62. These data show that 30 pounds of stone are quarried with 1 pound of wood. Some plates are taken out in inclined position. The action of fire is independent of the original surface of rock ; also of the direction of lamination (the granite is gneissose) and of veins. The uniformity in the thickness of the sheets is attributed to the regulating influence of preexisting cracks. Van Hise,...
Seite 22 - ... any irregular folding. The curves are arranged strictly with reference to the surface of the masses of rock, showing clearly that they must have been produced by the contraction of the material while cooling or solidifying.
Seite 37 - Vinalhaven, 20 feet below the surface in the face of the quarry there is a bed of granite sand 18 inches thick between two sheets, which at that point dip about 10° into the hill. On the southeast side of the Longfellow quarry, near Hallowell, some of the sheets within a wide heading include granite sand beds 10 inches thick. At the Shattuck Mountain quarry, near Kedbeach (see p.
Seite 218 - HOLE. A circular drill hole with two opposite vertical grooves which direct the explosive power of the blast. LEWIS HOLE. An opening made by drilling two or three holes near together and chiseling out the intervening rock. LIMONITE. A hydrous oxide of iron (2Fe2O3, 3H20); a hydrated hematite, which, when scratched or powdered, gives a brownish rust color.
Seite 16 - Elasticity," and fountl that slabs of gaged lengths of 20 inches in passing from a cold-water bath at 32° F. through a hot-water bath at 212° F., and back again to cold water at 32° F., expanded from 0.0017 to 0.0059 inch, averaging 0.0040 inch. Porosity. — Granite contains and absorbs water, which is held in microscopic spaces both within and between its constituent minerals.

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