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Full-Text Articles in Physical Sciences and Mathematics
Bermuda Solution Pipe Soils: A Geochemical Evaluation Of Eolian Parent Materials, Stanley R. Herwitz, Daniel R. Muhs
Bermuda Solution Pipe Soils: A Geochemical Evaluation Of Eolian Parent Materials, Stanley R. Herwitz, Daniel R. Muhs
United States Geological Survey: Staff Publications
Solution pipes found in the Quaternary eolian and marine carbonates of Bermuda are filled with reddish to reddish-brown soil material. The bulk of the soil is composed of clay and silt-sized quartz and aluminosilicate clay minerals. The carbonates are of high purity and, therefore, are not likely to have been the parent material. Previous workers have hypothesized that Saharan dust may have been the soil parent material. The fine-grained component of loess from the Mississippi River Valley of North America also could have contributed. Paleoclimate models indicate that both North Africa and North America could have been important source areas …
Carbonate Deposition, Pyramid Lake Subbasin, Nevada: 2. Lake Levels And Polar Jet Stream Positions Reconstructed From Radiocarbon Ages And Elevations Of Carbonates (Tufas) Deposited In The Lahontan Basin, Larry Benson, Michaele Kashgarian, Meyer Rubin
Carbonate Deposition, Pyramid Lake Subbasin, Nevada: 2. Lake Levels And Polar Jet Stream Positions Reconstructed From Radiocarbon Ages And Elevations Of Carbonates (Tufas) Deposited In The Lahontan Basin, Larry Benson, Michaele Kashgarian, Meyer Rubin
United States Geological Survey: Staff Publications
Most of the tufas in the Pyramid Lake subbasin were deposited within the last 35,000 yr, including most of the mound tufas that border the existing lake. Many of the older tufas (> 21,000 yr B.P.) contained in the mounds were formed in association with ground-water discharge. The radiocarbon (14C) ages of the older tufas represent maximum estimates of the time of their formation. Lake Lahontan experienced large and abrupt rises in level at ~ 22,000, 15,000, and 11,000 yr B.P. and three abrupt recessions in level at ~ 16,000, 13,600, and 10,000 yr B.P. The lake-level rises …
Evidence Of Active Dune Sand On The Great Plains In The 19th Century From Accounts Of Early Explorers, Daniel R. Muhs, Vance T. Holliday
Evidence Of Active Dune Sand On The Great Plains In The 19th Century From Accounts Of Early Explorers, Daniel R. Muhs, Vance T. Holliday
United States Geological Survey: Staff Publications
Eolian sand is extensive over the Great Plains of North America, but is at present mostly stabilized by vegetation. Accounts published by early explorers, however, indicate that at least parts of dune fields in Nebraska, Colorado, Kansas, New Mexico, and Texas were active in the 19th century. Based on an index of dune mobility and a regional tree-ring record, the probable causes for these periods of greater eolian activity are droughts, accompanied by higher temperatures, which greatly lowered the precipitationto- evapotranspiration ratio and diminished the cover of stabilizing vegetation. In addition, observations by several explorers, and previous historical studies, indicate …
Geomorphic And Geochemical Evidence For The Source Of Sand In The Algodones Dunes, Colorado Desert, Southeastern California, Daniel R. Muhs, Charles A. Bush, Scott D. Cowherd, Shannon Mahan
Geomorphic And Geochemical Evidence For The Source Of Sand In The Algodones Dunes, Colorado Desert, Southeastern California, Daniel R. Muhs, Charles A. Bush, Scott D. Cowherd, Shannon Mahan
United States Geological Survey: Staff Publications
The Algodones dunes of southeastern California comprise one of the largest active dune fields in the United States. The source of sand of the Algodones dunes is controversial, and the source of stabilized aeolian sand in the adjacent East Mesa area has not been investigated at all. We used mineralogical compositions and trace element concentrations to ascertain the most likely source of sand for these active and stabilized dunes. Results indicate that alluvium derived from the San Bernardino Mountains, which enters the Salton trough to the northwest of the dune fields, and alluvium derived from the Chocolate Mountains, which is …