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Post Info TOPIC: 2800 BCE Flood
Blobrana


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Burckle Crater
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Contrary to recent hypothesis, 'chevrons' are not evidence of megatsunamis

A persistent school of thought in recent years has held that so-called "chevrons," large U- or V-shaped formations found in some of the world's coastal areas, are evidence of megatsunamis caused by asteroids or comets slamming into the ocean.
University of Washington geologist and tsunami expert Jody Bourgeois has a simple response: Nonsense.
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But the theory that these chevron dunes are due to tsunamis has been challenged by geologist Jody Bourgeois; using a computer model to simulate a tsunami, she believes the structures are more consistent with aeolian processes.
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Blobrana


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Posts: 131433
Date:
Mega-tsunami chevrons
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A persistent school of thought in recent years has held that so-called "chevrons," large U- or V-shaped formations found in some of the world's coastal areas, are evidence of mega-tsunamis caused by asteroids or comets slamming into the ocean.
University of Washington geologist and tsunami expert Jody Bourgeois has a simple response: Nonsense.
The term "chevron" was introduced to describe large dunes shaped something like the stripes you might see on a soldier's uniform that are hundreds of meters to a kilometre in size and were originally found in Egypt and the Bahamas.
But the discovery of similar forms in Australia and Madagascar led some scientists to theorise that they were, in fact, deposits left by huge tsunami waves, perhaps 10 times larger than the devastating Indian Ocean tsunami of December 2005.
Such huge waves, they suggest, would result from the giant splash of an asteroid or comet hitting the ocean. They also suggest one such impact occurred 4,800 to 5,000 years ago, and that chevrons in Australia and Madagascar point to its location in the Indian Ocean.
But Bourgeois said the theory just doesn't hold water.

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Blobrana


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The Holocene Working Group
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While tiny asteroids are bombarding the Earth’s atmosphere all the time, the idea of a large-scale meteor striking us is, to put it simply, not a cause for concern. The scientific community has for a long time echoed this sentiment, estimating that major meteor impacts — the kind theorised to have killed off the dinosaurs — only occur once every 500,000 to 1,000,000 years.
But according to the Holocene Working Group, an international team of researchers, that may not be the case. Their research suggests that major impacts, which can produce catastrophic environmental results, strike the earth much more frequently — about every thousand years.

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Blobrana


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Posts: 131433
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Burckle crater
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61.91154E_31.13040S61.85798E_31.13333S

Expand (67kb, 802 x 541).......................Expand (802 x 541)

Latitude: 31.13333°S, longitude: 61.85798°E

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Blobrana


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RE: 2800 BCE Flood
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Title: Multidisciplinary Methods of Finding and Verifying Abyssal Impact Craters: Results and Uncertainties
Authors: Dallas H. Abbott, Christy A. Glatz, L. Burckle, Alice A. Nunes

Because they are vulnerable to erosion and deformation that obscures and removes them, only about 1/6 of the impact craters that formed during the last 120 Ma have been discovered. Until recently, all of these craters were found on land or on the continental shelf. This left 59% of the Earth (the abyssal ocean basins) with no known impact craters. Abyssal impact craters form on true oceanic crust, typically at water depths of 2000 meters or greater. Because they are covered by water and are on strong oceanic lithosphere, abyssal impact craters are less vulnerable to erosion and deformation than continental impact craters. Thus, abyssal impact craters should preserve a nearly complete ejecta blanket and impact melt body that could potentially provide great insight into impact processes. Another issue is the importance of Ir in identifying impact layers. Although there are a number of strewn tektite fields with an inferred or known submarine source crater, only the Eltanin impact layer has a documented Ir anomaly and an inferred abyssal source crater.

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Blobrana


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Title: IMPACT CRATERS AS SOURCES OF MEGATSUNAMI GENERATED CHEVRON DUNES
Authors: ABBOTT, Dallas H.1, MARTOS, Suzanne1, ELKINTON, Hannah1, BRYANT, Edward F.2, GUSIAKOV, Viacheslav3, and BREGER, Dee4, (1) Lamont Doherty Earth Observatory of Columbia University, Oceanography 103A, 1000 Rt. 9W, Palisades, NY 10964, dallas@ldeo.columbia.edu, (2) School of Geosciences, University of Wollongong, Wollongong, NSW 2522, Australia, (3) Tsunami Laboratory, Institute of Computational Mathematics and Mathematical Geophysics, Novosibirsk, 630090, Russia, (4) Dept. of Materials Science, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104

Chevron dunes are not formed by wind. Chevron dunes are not oriented in the direction of the prevailing wind, they can form where there are no beaches, and they contain grains larger than 2 mm in diameter. Chevrons are produced by megatsunamis originating from point sources, i.e. landslides, impact craters, and volcanic explosions. We have assembled data on chevrons worldwide. Most are best explained as the result of tsunami generated from large impact cratering events. We now have data confirming an impact origin of two chevron sources. In the Indian ocean, chevron dunes in Western Australia, India, and Madagascar point towards the 29 km Burckle Crater at 30.865S, 61.365E. The impact ejecta from Burckle crater contain meteorite fragments, impact glass, oceanic mantle fragments, and impact spherules. The impact spherules are >200 microns in diameter, consistent with a 29 km crater. The impact glasses have no K and cannot be continental in origin.
In the Gulf of Carpentaria, we found impact ejecta that contain impact glass and meteoritic material: merrillite, high Ni metal, and probable melted carbonaceous chondrite. We also found abundant magnetite impact spherules with a bimodal size distribution.
This implies two source craters for the chevrons: the 18 km Kanmare (Serpent) crater at 16.58S, 139.057E and the 12 km Tabban (Rainbow) crater at 17.125S, 139.86E. In the Mediterranean, a megatsunami source near the Rhone delta is of undetermined origin. All other sources are impact crater candidates and require more study. We found the following: the 1 km Judge crater candidate in Long Island Sound at 41.17N, 72.405W, the 10 km Quetzalcoatl crater candidate in the Caribbean at 22.04N, 96.32W, the 18 km Grendel crater candidate in the North Sea at 58.16 N, 5.86E, the 5 km Kangaroo crater candidate at 39.0465S, 141.285E and the 4 km Joey crater candidate at 39.16S, 141.21E.

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Blobrana


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Posts: 131433
Date:
Burckle Crater
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Burckle abyssal impact crater
29 ±1 km wide

Latitude: 30.87°S, longitude: 61.36°E

IMAGE (173kb, 1200 x 1057)

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Blobrana


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Fenambosy
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Fenambosy, Madagascar.

Fenambosy
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Latitude: -25.038415° Longitude: 44.187888°

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Blobrana


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Madagascar Flood
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At the southern end of Madagascar lie four enormous wedge-shaped sediment deposits, called chevrons, that are composed of material from the ocean floor. Each covers twice the area of Manhattan with sediment as deep as the Chrysler Building is high.
On close inspection, the chevron deposits contain deep ocean microfossils that are fused with a medley of metals typically formed by cosmic impacts. And all of them point in the same direction - toward the middle of the Indian Ocean where a newly discovered crater, 18 miles in diameter, lies 12,500 feet below the surface.
The explanation is obvious to some scientists. A large asteroid or comet, the kind that could kill a quarter of the world's population, smashed into the Indian Ocean 4,800 years ago, producing a tsunami at least 600 feet high, about 13 times as big as the one that inundated Indonesia nearly two years ago. The wave carried the huge deposits of sediment to land.

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Blobrana


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Posts: 131433
Date:
RE: 2800 BCE Flood
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44.24116E_25.11113S
Expand (27kb, 802 x 535)

Latitude: -25.15000 Longitude: 44.30000

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