8 Matching Results

Search Results

Geologic History of the Yosemite Valley

Description: The principal result of the investigations upon which this report is based is the determination within narrow limits of the preglacial depth of the Yosemite Valley and of other facts concerning its preglacial development which permit fairly definite estimates of the proportionate shares of work performed by stream and by glacier. The investigations comprise a detailed survey of the glacial and geomorphologic features of the Yosemite region and an equally intensive study of its rock formations, supplemented by reconnaissance work of both kinds in adjoining parts of the Sierra Nevada.
Date: 1930
Creator: Matthes, Franc╠žois E.
Partner: UNT Libraries Government Documents Department

Shorter Contributions to General Geology, 1929

Description: From introduction: This report describes the deposits of analcite in the Green River formation, to compare them with other similar deposits, and to present them with other similar deposits, and to present the observations and inferences that led him to explain them as alteration products of volcanic ash that fell into an ancient saline lake. The report also records the occurrence of several thin beds of sepiolite, or meerschaum, in the Green River formation and presents new data on the molds of saline minerals of the Green River formation whose determination affects directly the interpretation of the analcite and sepiolite deposits.
Date: 1930
Creator: Mendenhall, W. C.
Partner: UNT Libraries Government Documents Department

Shorter Contributions to General Geology, 1941-42

Description: Preface: The author of this paper gives a thorough description of a complex of very unusual igneous rocks and associated hydrothermal deposits.
Date: 1942
Creator: Geological Survey (U.S.)
Partner: UNT Libraries Government Documents Department

Shorter Contributions to General Geology, 1928

Description: From introduction: The district discussed in this report embraces the entire northern peninsula of Michigan and the parts of northern Wisconsin and northeastern Minnesota that were covered by a re-advance of the Superior lobe of the Labrador ice sheet late in the Wisconsin stage of glaciation.
Date: 1929
Creator: Mendenhall, W. C.
Partner: UNT Libraries Government Documents Department

Gold Quartz Veins of the Alleghany District, California

Description: From Outline of the Report: The Alleghany district, in the southern part of Sierra County, Calif., has long been famous for the high-grade gold ore of its quartz veins. The oldest rocks of the district (pp. 6-17) are of sedimentary and volcanic origin and correspond to part of the Calaveras formation as mapped in the Colfax and Downieville folios of the Geologic Atlas of the United States. These rocks are divided into five formations, of which three-the Blue Canyon, Relief, and Cape Horn formations follow the definitions laid down by Lindgren in the Colfax folio, and two-the Tightner and Kanaka formations-are new units required by the more detailed nature of the present study. It is thought possible that a conglomerate which forms the basal part of the Kanaka formation is of glacial origin. Intrusions of gabbro and more basic rocks, the latter now completely serpentinized, crop out over nearly half the area in which pre-Tertiary rocks are exposed. Small granitic dikes of later age than the basic intrusives are found in the western part of the district. Overlying and largely concealing the older rocks are auriferous gravel of Eocene and Miocene age, andesitic breccia of probable Miocen age, basalt flows of probable Pleistocene age, and minor amounts of Pleistocene and Recent gravel.
Date: 1932
Creator: Ferguson, Henry G. & Gannett, Roger W.
Partner: UNT Libraries Government Documents Department

Geology of the Eastern Part of the Santa Monica Mountains, Los Angeles County, California

Description: From abstract: The Santa Monica Mountains lie only a few miles northwest of the city of Los Angeles and comprise one of the prominent structural features that adjoin the Los Angeles Basin, one of the most prolific oil-producing districts of California. Even though the eastern part of these mountains may yield no oil, information concerning the rock types, structural character, and detailed geologic history of this area should be of value to petroleum geologists. The area described in this report, which lies between Topanga Canyon on the west and the Los Angeles River on the east, presents a section of varied rock types including coarsely crystalline plutonic rocks, basic and acidic intrusive and pyroclastic rocks, metamorphic slate and schist, and a wide assortment of sedimentary rocks.
Date: 1930
Creator: Hoots, H. W.
Partner: UNT Libraries Government Documents Department