Results 181 to 190 of about 9,430 (230)
New Zealand Journal of Geology, and Geophysics, 2003 A 10 mm thick, c. 15 700 calendar yr BP (c. 13 100 14C yr BP) rhyolitic tephra bed in the well-studied montane Kaipo Bog sequence of eastern North Island was previously correlated with Maroa-derived Puketarata Tephra.
Phil Shane +2 more
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Revisiting the Borrobol Tephra
Boreas, 2016The Borrobol Tephra has been identified as one of the key tephra horizons for the Lateglacial time period but it also exemplifies many of the promises and problems of tephrochronology. Additional horizons with similar major element composition and approximately the same age have been identified around the North Atlantic region.
Lind E. M. +3 more
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Geological Society, London, Special Publications, 1998
Abstract Our understanding of the spread of volcanic ejecta from eruption columns has evolved significantly since the first quantitative studies. Given recent advances, it is possible to describe much of the physics of tephra dispersal, and to construct a relatively robust model for the spread of tephra in the proximal region of a volcanic ...
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Abstract Our understanding of the spread of volcanic ejecta from eruption columns has evolved significantly since the first quantitative studies. Given recent advances, it is possible to describe much of the physics of tephra dispersal, and to construct a relatively robust model for the spread of tephra in the proximal region of a volcanic ...
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American Journal of Archaeology, 1974
I. The problem: According to studies on Mediterranean deep-sea cores by Ninkovich and Heezen,' tephra from two violent volcanic eruptions must have fallen on Crete in prehistoric times. The first of these eruptions occurred at least 25,000 years ago, and its tephra apparently fell on all parts of Crete.
Charles J. Vitaliano +1 more
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I. The problem: According to studies on Mediterranean deep-sea cores by Ninkovich and Heezen,' tephra from two violent volcanic eruptions must have fallen on Crete in prehistoric times. The first of these eruptions occurred at least 25,000 years ago, and its tephra apparently fell on all parts of Crete.
Charles J. Vitaliano +1 more
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A second tephra isochron for the Younger Dryas period in northern Europe: The Abernethy Tephra
Quaternary Geochronology, 2015Abstract Visible and non-visible (cryptotephra) volcanic ash layers are increasingly being used to underpin the chronology and high-precision correlation of sequences dating to the last glacial–interglacial transition (LGIT). As the number of sediment records analysed for tephra content rises, and methodological developments permit the detection ...
A. MacLeod +4 more
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1981
A dark tephra layer, named “a”, is found in soils in East and Northeast Iceland. Its volume is approximately 2 km3 and it covers about 40% of Iceland. An isopach map and grain-size study suggests that the tephra deposit forms a distinctly two-lobed layer and was erupted in the year 1477 from the central volcano Kverkfjoll, at the northern margin of ...
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A dark tephra layer, named “a”, is found in soils in East and Northeast Iceland. Its volume is approximately 2 km3 and it covers about 40% of Iceland. An isopach map and grain-size study suggests that the tephra deposit forms a distinctly two-lobed layer and was erupted in the year 1477 from the central volcano Kverkfjoll, at the northern margin of ...
openaire +1 more source
1981
Tephra studies would benefit greatly from the development of simple, inexpensive, approximate-dating methods that would allow us to estimate the age of a tephra sample in the field office. Colleagues outside the discipline, whose main interest in tephra layers lie in the dates they represent, would benefit also.
openaire +1 more source
Tephra studies would benefit greatly from the development of simple, inexpensive, approximate-dating methods that would allow us to estimate the age of a tephra sample in the field office. Colleagues outside the discipline, whose main interest in tephra layers lie in the dates they represent, would benefit also.
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1984
The transport modes of subaerial fallout tephra are (1) by ballistic trajectory and (2) by turbulent suspension. Energy is supplied initially to fragments by the eruption and later by wind. Tephra that falls from the atmosphere onto land is called subaerial fallout or airfall tephra.
Richard V. Fisher, Hans-Ulrich Schmincke
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The transport modes of subaerial fallout tephra are (1) by ballistic trajectory and (2) by turbulent suspension. Energy is supplied initially to fragments by the eruption and later by wind. Tephra that falls from the atmosphere onto land is called subaerial fallout or airfall tephra.
Richard V. Fisher, Hans-Ulrich Schmincke
openaire +1 more source