Professional Paper - United States Geological Survey, 79–80. numberThe Survey, 1913 |
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abundant alteration Ambocœlia umbonata andesite anhydrite Atrypa beds biotite Cactus Camarotœchia cf carbonate Cayuta shale member chalcopyrite characters Chemung Chemung formation Chonetes collector containing copper covellite crystals Cypricardella bellistriata Dalmanella Delthyris mesicostalis deposits Devonian difference E. M. Kindle east elevation Enfield shale member evidence expressed fault fauna faunules feet above sea figures fissures fluctuation fossils genera genus geologic Hamilton formation Harford Mills Hill Horn Silver hornblende intrusive Ithaca Ithaca member Ithaca shale member lavas Leiorhynchus Leptodesma limestone magnetite minerals Modiomorpha muscular scar Orbiculoidea orthoclase outcrop oxidized pedicle pedicle valve plagioclase Pleurotomaria plications Portage formation Productella pustules pyrite quadrangles quartz monzonite quartzite range recurrent fauna recurrent zones representatives Rhipidomella vanuxemi rhyolite rock samples San Francisco sandstone Schizophoria striatula sea level sediments shell silicates specimens sphalerite Spirifer marcyi sulphate sulphide surface Tropidoleptus carinatus Tropidoleptus zone umbonata V. H. Barnett wurtzite zinc
Popular passages
Page 118 - ... will simultaneously go into solution. As a rule the reaction is the more nearly complete the farther apart the two metals are in the series. In a series which he regards as showing the "relative affinity" of the heavy metals for sulphur Schuermann includes antimony, arsenic, and tin. This series is palladium, mercury, silver, copper, bismuth, cadmium, antimony, tin, lead, zinc, nickel, cobalt, iron, arsenic, thallium, and manganese. Those last named have the least affinity. Schuermann's results...
Page 101 - An irregular, wavy, lenticular seam of stratified bowlder-clay, not in horizontal position, and varying in thickness from a few inches to a foot or more. 3.
Page 86 - Not only is it impossible to formulate these features, by the aid of any hypothetical denudation, in such a system of undulations and foldings, as the Messrs. Rogers have so thoroughly demonstrated in Pennsylvania and Virginia, but the structure of the western Cordillera system stands in strong contrast to that of the Appalachians. In the latter, corrugation has been produced commonly by folding, exceptionally by faulting; in the former, commonly by faulting, exceptionally by flexure.
Page 44 - I have often had occasion to emphasize these early accessions which I think cannot be denied. The recent literature contains little to make a change of opinion necessary. BS Butler,14 for instance, says of the Frisco district, Utah, that "in general the minerals of the contact zones appear to have formed at essentially the same time, though in some places metallic minerals have formed later than the silicates as well as contemporaneously with them.
Page 25 - SCHRADER, FC, Mineral deposits of the Cerbat Range, Black Mountains, and Grand Wash Cliffs, Mohave County, Ariz.: Bull.
Page 24 - Kawich and Amargosa ranges and the Bullfrog Hills indicates that rugged islands rose above the surface of the lake. Wherever the former shores of the lake are now seen it is evident that the surface of the older rocks was uneven and that each island was surrounded by islets. The climate must have been moist and the presence of fossilized wood in the lake beds shows that trees flourished near its shores. While the lake was thus for the most part fresh, periods of aridity alternated with those of comparative...
Page 86 - ... in the former, commonly by faulting, exceptionally by flexure. In the latter few eruptive rocks occur; in the former volcanic phenomena abound and are intimately associated with ridges of upheaval. The regular alternations of curved...
Page 87 - The frequency of these monoclinal detached blocks gives abundant warrant for the assertions of Powell and Gilbert that the region is one prominently characterized by vertical action; yet when we come to examine with greater detail the structure of the individual mountain ranges, it is seen that this vertical dislocation took place after the whole area was compressed into a great region of auticlinals with intermediate synclinals.
Page 69 - The mineral is a canary-yellow earthy looking material commonly mixed with other secondary lead and copper minerals, but occasionally in small masses that appear to be composed of a single mineral. Such masses are easily crushed in the fingers. Under the high power of the microscope the material is seen to be crystallized in distinct hexagonal plates. These are too small for accurate measurement of the crystal angles or determination of the optical character. The refractive index of the light ray...
Page 24 - ... andesites and dacites, and these by unimportant rhyolites, immediately preceding the deposition of the Siebert lake beds in the Pahute Lake. It was probably during this general period that the most important ore deposits in the Tertiary rocks were formed, presumably by waters heated by the still-hot magmas. "Between the outflow of the rhyolite and the formation of the Pahute Lake erosion was probably continuous, partially accounting for the formation of the lake basin which in the main, however,...