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Full-Text Articles in Physical Sciences and Mathematics
On The Importance Of Stratigraphic Control For Vertebrate Fossil Sites In Channel Islands National Park, California, Usa: Examples From New Mammuthus Finds On San Miguel Island, Jeffrey S. Pigati, Daniel R. Muhs, John P. Mcgeehin
On The Importance Of Stratigraphic Control For Vertebrate Fossil Sites In Channel Islands National Park, California, Usa: Examples From New Mammuthus Finds On San Miguel Island, Jeffrey S. Pigati, Daniel R. Muhs, John P. Mcgeehin
United States Geological Survey: Staff Publications
Quaternary vertebrate fossils, most notably mammoth remains, are relatively common on the northern Channel Islands of California. Well-preserved cranial, dental, and appendicular elements of Mammuthus exilis (pygmy mammoth) and Mammuthus columbi (Columbian mammoth) have been recovered from hundreds of localities on the islands during the past half-century or more. Despite this paleontological wealth, the geologic context of the fossils is described in the published literature only briefly or not at all, which has hampered the interpretation of associated 14C ages and reconstruction of past environmental conditions. We recently discovered a partial tusk, several large bones, and a tooth enamel plate …
Loess Records, Daniel R. Muhs, Stephen R. Cattle, Onn Crouvi, Denis-Didier Rousseau, Jimin Sun, Marcelo A. Zárate
Loess Records, Daniel R. Muhs, Stephen R. Cattle, Onn Crouvi, Denis-Didier Rousseau, Jimin Sun, Marcelo A. Zárate
United States Geological Survey: Staff Publications
Loess is aeolian sediment, dominated by silt-sized particles, that is identifiable in the field as a distinct sedimentary body. It covers a significant portion of the land surface of the Earth and as such constitutes one of the most important archives of long-term dust deposition. Large tracts of loess cover Europe, Asia, South America, and North America, and smaller loess bodies are found covering parts of Africa, the Middle East, New Zealand, and Australia. Loess thickness, particle size, and carbonate content decrease downwind from sources, trends that are powerful tools for reconstructing paleowinds. Many loess sections consist of relatively thick …
Geologic Setting And Stratigraphy Of The Ziegler Reservoir Fossil Site, Snowmass Village, Colorado, Jeffrey S. Pigati, Ian M. Miller, Kirk R. Johnson, Jeffrey S. Honke, Paul E. Carrara, Daniel R. Muhs, Gary Skipp, Bruce Bryant
Geologic Setting And Stratigraphy Of The Ziegler Reservoir Fossil Site, Snowmass Village, Colorado, Jeffrey S. Pigati, Ian M. Miller, Kirk R. Johnson, Jeffrey S. Honke, Paul E. Carrara, Daniel R. Muhs, Gary Skipp, Bruce Bryant
United States Geological Survey: Staff Publications
The geologic setting of the Ziegler Reservoir fossil site is somewhat unusual—the sediments containing the Pleistocene fossils were deposited in a lake on top of a ridge. The lake basin was formed near Snowmass Village, Colorado (USA) when a glacier flowing down Snowmass Creek Valley became thick enough to overtop a low point in the eastern valley wall and entered the head of Brush Creek Valley. When the glacier retreated at about 155–130 ka, near the end of Marine Oxygen Isotope Stage 6, the Brush Creek Valley lobe left behind a moraine that impounded a small alpine lake. The lake …
Chronology And Provenance Of Last-Glacial (Peoria) Loess In Western Iowa And Paleoclimatic Implications, Daniel R. Muhs, E. Arthur Bettis Iii, Helen M. Roberts, Stephen S. Harlan, James B. Paces, Richard L. Reynolds
Chronology And Provenance Of Last-Glacial (Peoria) Loess In Western Iowa And Paleoclimatic Implications, Daniel R. Muhs, E. Arthur Bettis Iii, Helen M. Roberts, Stephen S. Harlan, James B. Paces, Richard L. Reynolds
United States Geological Survey: Staff Publications
Geologic archives show that the Earth was dustier during the last glacial period. One model suggests that increased gustiness (stronger, more frequent winds) enhanced dustiness. We tested this at Loveland, Iowa, one of the thickest deposits of last-glacial-age (Peoria) loess in the world. Based on K/Rb and Ba/Rb, loess was derived not only from glaciogenic sources of the Missouri River, but also distal loess from non-glacial sources in Nebraska. Optically stimulated luminescence (OSL) ages provide the first detailed chronology of Peoria Loess at Loveland. Deposition began after ~27 ka and continued until ~17 ka. OSL ages also indicate that mass …