Bulletin of the United States Geological Survey, Issue 586U.S. Government Printing Office, 1914 - Geology |
Other editions - View all
Common terms and phrases
analyses andalusite angles Arvonia Bangor biotite black slate brilliant aggregate polarization calcite Cambrian carbonaceous carbonaceous matter carbonate chlorite chlorite scales cleavage strikes cleavage surface cold dilute hydrochloric color constituents County crystals descending order dilute hydrochloric acid east feldspar fissility folds graphitic gray green slate greenish hematite hydrochloric acid inch Lehigh lenses lime limonite magnetite matrix of muscovite measuring mica mica slate microscope it shows miles mill stock mineral muscovite muscovite sericite named in descending order of abundance Ordovician oxide parallel particles Pawlet Peach Bottom Pennsylvania plagioclase planes Plate plicated purple slate pyrite quartz quartz grains quartzite red slate rhombs ribbons rock roofing slate rutile rutile needles schist sea-green sericite shale shear zones shows a matrix slate belt slate quarries slaty cleavage slip cleavage sonorous spherules square millimeter syncline texture thin section tourmaline U. S. Geol unaided eye unfading green veins vertical zircon
Popular passages
Page 175 - The pieces were supported in a horizontal position, upon wooden knife edges 22 inches apart and the loads were applied upon another knife edge placed half way between the supports. This load being applied by means of sand running out of an orifice in a box, at the rate of 70 pounds per minute, the flow being checked by means of an electric attachment the moment rupture took place.
Page 67 - ... inches) of material differing in composition from the mass of the slate. They are in general more siliceous than the normal slate, and do not furnish merchantable material. Their geologic interest arises from the fact that they represent differences of original sedimentation. The plane of the ribbons in a slate quarry is, therefore, the plane of original bedding. In the Eureka quarry, and, indeed, throughout the roofing-slate belt, the plane of original bedding seems to be usually within 10°...
Page 51 - A. Renard, Recherches sur la composition et la structure des phyllades ardennais; Bull.
Page 62 - In color this slate is somewhat darker than the "red" slate of New York. To the unaided eye it has a minutely granular texture and a roughish, speckled, almost lusterless surface. Contains very little magnetite, does not effervesce with cold dilute hydrochloric acid, is sonorous, splits readily, and has some argillaceous odor.
Page 175 - D'Arsonval type, and had a working constant of 70,533 millimeters on the scale 1 meter distant through 1 megohm resistance. The electromotive force was furnished by storage cells and was kept constant at 42 volts during the experiment. "The connections were made as shown in the figure. "To avoid leakage over the surface of the slate a guard wire was connected as shown. All readings were taken after the deflections became constant; in some cases they did not become so until half an hour after electrification.
Page 164 - Shenandoah limestone" in a series of folds represented in the folio as overturned to the west. The rock is generally a dark-grayish shale, weathering into a yellowish -or white clay, known locally as "soapstone.
Page 85 - Greenish-gray slate from Mena. In color this resembles the sea-green slate of Vermont. To the unaided eye it has a fine texture, a roughish cleavage surface, and a waxy luster; does not show pyrite on sawn edge, contains very little magnetite; does not effervesce with cold dilute hydrochloric acid, and is somewhat sonorous. Under the microscope it shows a matrix of muscovite (sericite), with a brilliant aggregate polarization and is of very fine texture and homogeneity, but the cleavage is crossed...
Page 204 - ... slate from that port from 1876 to 1888. The export of manufactured slate is also shown in this table, and is almost entirely the value of school slates. Value of exports of roofing and other slate from the port of New York from 1876 to 1888, inclusive. The following table, taken from the report of the Bureau of Foreign and Domestic Commerce, Department of Commerce, shows the value of exports of roofing slate from the United States, by fiscal years from 1884 to 1904 and by calendar years from...
Page 47 - Thus there seems sufficient reason to believe that a pressure very rapidly applied, producing primary ruptures attended by shock, will be immediately followed by secondary ruptures in the same direction as the others at intervals dependent upon the wave length of the impulse. In much the same way a high explosive shatters a rock far more than black powder. A phenomenon of which no explanation has been offered in this paper is that of thick slates and of those flags which are to be considered as...
Page 64 - Eldorado County. The quarries which have been opened in this district are located along a line running about N. 15° W. from Placerville, at distances of 1 to 6 miles from that town. The location and geographic and geologic relations of the slate deposits and quarries can best be understood by reference to the maps included in the Placerville folio of the United States Geological Survey.