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Articles 1 - 6 of 6
Full-Text Articles in Physical Sciences and Mathematics
Long-Term African Dust Delivery To The Eastern Atlantic Ocean From The Sahara And Sahel Regions: Evidence From Quaternary Paleosols On The Canary Islands, Spain, Daniel R. Muhs, Joaquín Meco, James R. Budahn, Gary L. Skipp, Kathleen R. Simmons, Matthew C. Baddock, Juan F. Betancourt, Alejandro Lomoschitz
Long-Term African Dust Delivery To The Eastern Atlantic Ocean From The Sahara And Sahel Regions: Evidence From Quaternary Paleosols On The Canary Islands, Spain, Daniel R. Muhs, Joaquín Meco, James R. Budahn, Gary L. Skipp, Kathleen R. Simmons, Matthew C. Baddock, Juan F. Betancourt, Alejandro Lomoschitz
United States Geological Survey: Staff Publications
Africa is the most important source of dust in the world today and dust storms from that continent frequently deposit sediment on the nearby Canary Islands. Many investigators have inferred African dust inputs to Canary Islands paleosols based only on the presence of quartz. However, some local rocks do contain this mineral, so quartz alone is insufficient proof of dust deposition. Further, it is not known whether the Sahara Desert or the Sahel region is more important as a dust source. We address these issues by study of sequences of Pleistocene aeolian sands on the islands of Lanzarote and Fuerteventura. …
Testing Glacial Isostatic Adjustment Models Of Last-Interglacial Sea Level History In The Bahamas And Bermuda, Daniel R. Muhs, Kathleen R. Simmons, R. Randall Schumann, Eugene S. Schweig, Mark P. Rowe
Testing Glacial Isostatic Adjustment Models Of Last-Interglacial Sea Level History In The Bahamas And Bermuda, Daniel R. Muhs, Kathleen R. Simmons, R. Randall Schumann, Eugene S. Schweig, Mark P. Rowe
United States Geological Survey: Staff Publications
Part of the spatial variation in the apparent sea-level record of the last interglacial (LIG) period is due to the diverse response of coastlines to glacial isostatic adjustment (GIA) processes, particularly where coastlines were close to the Laurentide Ice Sheet during the past two glacial periods. We tested modeled LIG paleo-sea levels on New Providence Island (NPI), Bahamas and Bermuda by investigating emergent coral patch reefs and oolitic/peloidal beach deposits. Corals with closed-system histories collected from patch reefs on NPI have ages of 128-118 ka and ooids/peloids from beach ridges have closed-system ages of 128-116 ka. Elevations of patch reefs …
Geochemistry And Mineralogy Of Late Quaternary Loess In The Upper Mississippi River Valley, Usa: Provenance And Correlation With Laurentide Ice Sheet History, Daniel R. Muhs, E. Arthur Bettis Iii, Gary L. Skipp
Geochemistry And Mineralogy Of Late Quaternary Loess In The Upper Mississippi River Valley, Usa: Provenance And Correlation With Laurentide Ice Sheet History, Daniel R. Muhs, E. Arthur Bettis Iii, Gary L. Skipp
United States Geological Survey: Staff Publications
The midcontinent of North America contains some of the thickest and most extensive last-glacial loess deposits in the world, known as Peoria Loess. Peoria Loess of the upper Mississippi River valley region is thought to have had temporally varying glaciogenic sources resulting from inputs of sediment to the Mississippi River from different lobes of the Laurentide Ice Sheet. Here, we explore a new method of determining loess provenance using K/Rb and K/Ba values (in K-feldspars and micas) in loess from a number of different regions in North America. Results indicate that K/Rb and K/Ba values can distinguish loess originating from …
Late Quaternary Uplift Along The North America-Caribbean Plate Boundary: Evidence From The Sea Level Record Of Guantanamo Bay, Cuba, Daniel R. Muhs, Eugene S. Schweig, Kathleen R. Simmons, Robert B. Halley
Late Quaternary Uplift Along The North America-Caribbean Plate Boundary: Evidence From The Sea Level Record Of Guantanamo Bay, Cuba, Daniel R. Muhs, Eugene S. Schweig, Kathleen R. Simmons, Robert B. Halley
United States Geological Survey: Staff Publications
The tectonic setting of the North America-Caribbean plate boundary has been studied intensively, but some aspects are still poorly understood, particularly along the Oriente fault zone. Guantanamo Bay, southern Cuba, is considered to be on a coastline that is under a transpressive tectonic regime along this zone, and is hypothesized to have a low uplift rate. We tested this by studying emergent reef terrace deposits around the bay. Reef elevations in the protected, inner part of the bay are ~11e12 m and outercoast, wave-cut benches are as high as ~14 m. Uranium-series analyses of corals yield ages ranging from ~133 …
Ice-Age Megafauna In Arctic Alaska: Extinction, Invasion, Survival, Daniel H. Mann, Pamela Groves, Michael L. Kunz, Richard E. Reanier, Benjamin V. Gaglioti
Ice-Age Megafauna In Arctic Alaska: Extinction, Invasion, Survival, Daniel H. Mann, Pamela Groves, Michael L. Kunz, Richard E. Reanier, Benjamin V. Gaglioti
United States Geological Survey: Staff Publications
Radical restructuring of the terrestrial, large mammal fauna living in arctic Alaska occurred between 14,000 and 10,000 years ago at the end of the last ice age. Steppe bison, horse, and woolly mammoth became extinct, moose and humans invaded, while muskox and caribou persisted. The ice age mega fauna was more diverse in species and possibly contained 6x more individual animals than live in the region today. Mega faunal biomass during the last ice age may have been 30x greater than present. Horse was the dominant species in terms of number of individuals. Lions, short-faced bears, wolves, and possibly grizzly …
Origin Of The Sinai-Negev Erg, Egypt And Israel: Mineralogical And Geochemical Evidence For The Importance Of The Nile And Sea Level History, Daniel R. Muhs, Joel Roskin, Haim Tsoar, Gary Skipp, James Budahn, Amihai Sneh, Naomi Porat, Jean-Daniel Stanley, Itzhak Katra, Dan G. Blumberg
Origin Of The Sinai-Negev Erg, Egypt And Israel: Mineralogical And Geochemical Evidence For The Importance Of The Nile And Sea Level History, Daniel R. Muhs, Joel Roskin, Haim Tsoar, Gary Skipp, James Budahn, Amihai Sneh, Naomi Porat, Jean-Daniel Stanley, Itzhak Katra, Dan G. Blumberg
United States Geological Survey: Staff Publications
The Sinai-Negev erg occupies an area of 13,000 km2 in the deserts of Egypt and Israel. Aeolian sand of this erg has been proposed to be derived from the Nile Delta, but empirical data supporting this view are lacking. An alternative source sediment is sand from the large Wadi El Arish drainage system in central and northern Sinai. Mineralogy of the Negev and Sinai dunes shows that they are high in quartz, with much smaller amounts of K-feldspar and plagioclase. Both Nile Delta sands and Sinai wadi sands, upstream of the dunes, also have high amounts of quartz relative …