Bulletin - United States Geological Survey, Ausgabe 313

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Seite 110 - The quarry, opened in 1865, measures 300 feet from north to south and '200 feet from east to west and ranges in depth from 10 to 50 feet. It is drained by occasional pumping. The stripping consists of 2 to 3 feet of drift. Rock structure: The sheets, from 3 to 8 feet in thickness, dip 10° W.
Seite 206 - B 303. Preliminary account of Goldfield, Bullfrog, and other mining districts in southern Nevada, by FL Rausome, with notes on the Manhattan district, by GH Garrey and WH Emmons.
Seite 36 - The foreman at this quarry was in the habit of calling certain sheets, marked by the absence of discoloration, "strain sheets," to distinguish them from the others. At one place a northwest-southeast compressive strain had actually extended the strain sheet about 5 feet, and also caused a vertical fracture that extended over 15 feet diagonally from the north-south working face to a point on a vertical east-west channel 5 feet back of the face, closing up the channel to half its original width.
Seite 22 - Sheets half an inch thick and 4 feet long may be bent, as noted in the description of the Lawton quarry, at Norridgewock, page 151. Whether flexibility in this case was conditioned upon a slight loosening of the grains by chemical and physical change is uncertain. Hardness. — As will be seen by reference to the tests for hardness described on page 64, granites differ greatly in hardness. This difference is due not merely to differences in the percentage of quartz, but also to variations in the...
Seite 186 - BOULDER QUARRY. One in which the joints are either so close or so irregular that no very large blocks of stone can be quarried. CHANNEL. A narrow artificial incision across a mass of rock, which, in the case of a granite sheet, is made either by a series of continuous drill holes or by blasting a series of holes arranged in zigzag order.
Seite 206 - minerals and water solutions, with special reference to geologic phenomena, by EC Sullivan.
Seite 203 - B 46. Nature and origin of deposits of phosphate of lime, by RAF Penrose, jr., with introduction by NS Shaler. 1888.
Seite 69 - The practice of foremen in the thirty principal granite quarries of Maine, as explained by them to the writer, was found to be as follows: Vertical blast holes almost as deep as the thickness of the sheet are "Bowman, Isaiah, Well-drilling methods: Water Sup.
Seite 43 - Dikes that strike in the northwesterly-southeasterly quadrants are most numerous. In color these dikes vary from bluish gray to light and dark reddish. The texture of some aplites is so fine that the mineral particles can not be distinguished with the unaided eye; that of others is so coarse that the feldspar and mica may be thus detected. Under the microscope the dimensions of the particles range from 0.05 to 0.75 mm., the average being about 0.16 mm. for the finer ones and 0.50 mm. for the coarser...
Seite 186 - A microscopic granular structure sometimes characterizing adjacent feldspar particles in granite in consequence of their having been crushed together during or subsequent to their crystallization. CUT-OFF. Quarrymen's term for the direction along which the granite must be channeled, because it will not split. Same as "hardway.

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