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17th Ann andesite ankerite aperture aplite augite average beds brecciated calcite canal carbonates Carlos Cantu cavity chalcopyrite chlorite coal member crosscut crossings crystals cuyahoga deposition diabase diameter dikes Dilco district drift east Empire Eocene epidote feet figure flabellula footwall Gabb Galeodea Gallup genus Geol geologic Glossina gold gouge granodiorite Grass Valley Hall and Clarke Hill vein holotype hornblende Hosta Idaho-Maryland irvinensis Lindgren Lingula locality Mancos shale Mesaverde formation Mexico millimeters minerals mines Nevada City North Star vein northeast Ohio Pennsylvania plagioclase plate porphyrite Priscoficus pyrite quadrangle quartz veins regressive rudistids sandstone sandstone member sculpture sericite serpentine shaft sheared shell showing shown species specimen sphalerite spiral stopes strike sulphides surface Survey thick thin Titanosarcolites Trigonoglossa Tubulostium U. S. G. S. station Upper Cretaceous vein fracture vein walls vugs Waldemar wall rocks waverlyensis whorls width York Hill zone
Page 13 - The use of this mailing label to do so will be official business and no postage stamps will be required UNITED STATES PENALTY FOR PRIVATE USE TO AVOID DEPARTMENT OF THE INTERIOR PAYMENT OF POSTAGE.
Page 19 - This work was completed with the aid of a grant from the Penrose Bequest of The Geological Society of America.
Page 47 - A dagger (t) preceding a geologic name indicates that the name has been abandoned or rejected for use in classification in publications of the US Geological Survey. Quotation marks, formerly used to indicate abandoned or rejected names, are now used only in the ordinary sense.
Page 168 - A reconnaissance survey of the western part of the Durango-Gallup coal field of Colorado and New Mexico : US Geol. Survey Bull.
Page 33 - Shell small and fragile; spire elevated; columella slender, slightly bent; aperture large, elongate, ovate or subelliptical ; volutions three, marked on the periphery by three distinct carinae or subangular revolving ridges, the upper one marked with closely arranged longitudinally elongate nodes, the others simple; entire surface marked by very fine revolving lines, which are somewhat fasciculate below the lower carina, there being three finer ones between each large one.
Page 163 - ... that they should not be postulated unless unmistakably required by evidence in the rocks. "In the southwestern part of the San Juan Basin, near Gallup, the Mancos shale is 725 feet thick and consists principally of more or less sandy shale with several subordinate sandstones. Overlying it is about 1,800 feet of the Mesaverde; the upper part of the formation has been removed by erosion. The Mesaverde comprises sandstones, clays, and coal beds, and is predominantly of continental origin. In this...
Page 233 - The stone was a reddish quartz, filled with rich veins of gold, and far surpassing the specimens brought from North Carolina and Georgia. Some stones picked up on the top of the quartz strata, without particular selection, yielded two ounces of gold to every twenty-five pounds.
Page 278 - Law, can be expressed as follows: In brittle materials, the acute angle formed by the shearing planes is bisected by the axis of maximum compression, and the obtuse angle by the axis of minimum compression which is generally negative, representing tension.