Scientists have discovered a 31 kilometre diameter crater in the Saharan desert.The newfound crater was created by an impact of an asteroid roughly 1.2 kilometres wide. As yet the exact date of when it occurred has not been determined.
The crater was discovered in satellite images by Boston University researchers Farouk El-Baz and Eman Ghoneim. The crater has two rings, and two river beds cut through the formation.
(10000 years ago, Gilf Kebir hosted a much wetter climate than today)

Source

Discovery of the largest impact crater field on Earth in the Gilf Kebir region, Egypt (Ed -actually there is one bigger)

Philippe Paillou a,*, Ahmed El Barkooky b, Aly Barakat c, Jean-Marie Malezieux d,
Bruno Reynard e, Jean Dejax f, Essam Heggy g

Abstract
Using orbital imaging radar, we have detected a large number of circular structures in the southwestern Egyptian desert, covering more than 4500 km2 close to the Gilf Kebir plateau in sandstones of Upper Cretaceous. Fieldwork confirmed that it is a new impact crater field: 13 craters from 20 m to 1 km in diameter were studied. The impact origin is confirmed by the observation of shock-related structures, such as shatter cones and planar fractures in quartz grains of breccia. Considering the extension of the crater field, it was possibly created by several meteorites that broke up when entering the atmosphere.

The area extends over 75 km × 60 km, between latitudes 23.10deg N–23.40 deg. N and longitude 26.50 deg E–27.35 deg E.

Read more (PDF)

Another view... (volcanic)

http://www.tlc-exped.net/LDSG.html (Libyan Desert Silica Glass used as tools 130.000 - 40.000 years ago)

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Gilf Kebir crater field: Google Map, described in "Read More" Discovery of the largest impact crater field on Earth in the Gilf Kebir region, Egypt (PDF about 1 megabyte)

Newly found crater: Google Map, described in "Source" MSNBC: Satellite spots monster crater in Egypt

[Edit: separate maps for Gilf Kebir crater field and newly found crater]

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Tnx,


eXPAND (39KB, 560 X 318)
Position Latitude 24.691773° Longitude 24.972456°

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Hum,
it seems that the sandstone impact site is the source of the Libyan desert glass, which has already been dated to 28.5 million years ago.

“The terrain in which the crater resides is composed of 100 million year-old sandstone – the same material that lies under much of the eastern Sahara. The researchers hope that field investigations and samples of the host rock will help in determining the exact age of the crater and its surroundings.”

There was no other exposed sandstone in the area...

http://www.bu.edu/phpbin/news/releas...ay.php?id=1073

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What about the much larger and more prominent features at 22deg 06' 37"N 24d 48' 29"E, and the less prominent, but circularoid structures just north of them? Impact or eruption? These seem to be in Libya.
John

22deg 06' 37"N 24d 48' 29"E they look like they`re volcanic

Compare with these...

24°34'14.88"N 24°24'50.65"E Oasis crater
25°19'6.98"N 24°18'33.60"E BP Structure
22° 2'36.42"N 23°43'7.74"E Arkenu1 crater
22° 5'48.85"N 23°47'48.08"E Arkenu2 crater

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BA Blog: The Purloined Crater

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Scientists believe they have solved the mystery surrounding a piece of rare natural glass at the centre of an elaborate necklace found among the treasures of Tutankhamun, the boy pharaoh.

They think a fragile meteorite broke up as it entered the atmosphere, producing a fireball with temperatures over 1,800C that turned the desert sand and rock into molten lava which became glass when it cooled.
Experts have puzzled over the origin of the yellow-green glass — carved into the shape of a scarab beetle — since it was excavated in 1922 from the tomb of the teenage king, who died about 1323BC. It is generally agreed that it came from an area called the Great Sand Sea but there has been uncertainty over how it was formed because there is no crater to back up the idea of a meteorite strike.
Now it is thought that the meteorite responsible was not intact but made up of loose rubble.

"A fireball moving quicker than a hurricane force would have meant a blast of air so hot it could melt all the sand and sandstone on the ground" - Mark Boslough, an expert on impact physics based at the Sandia National Laboratories in New Mexico.

Source

Attached Images

Libyan glass.jpg (40.7 KB, 9 views)

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That's pretty neat. So what about a non-fragile metor impact, as per this thread's topic? Wouldn't it really kick some glass, or was there no sand there at the time?

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

How anyone can find an impact crater by just looking satellite images? There are many volcanic processes that can create circular formations that look almost like impact craters.

Only way to confirm it as an impact crater is to search for shock structures in the rock (shatter cones for example) and map possible gravitational and magnetic anomalies. After that one can say if it really is an impact crater or not.

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Science is a way of trying not to fool yourself. The first principle is that you must not fool yourself, and you are the easiest person to fool.
-- Richard Feynman

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Hum,
i just watched the BBC Horizon programme.
The programme puts forward a very persuading case that the Kebir crater was not the origin of the desert glass, rather it was formed by an air burst of a 100 metre sized asteroid.

Seemingly these airbursts generate temperatures similar to the sun, and blow a huge plume of gas out into space. The damage isn't from the crater, if a crater is formed at all , but from the fireball that will fry huge areas of the surface.

“Attempting to blow up an incoming asteroid, Hollywood style, could well make things worse by increasing the number of devastating airbursts.”

(see link above)

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BBC article

It's easy to see how - meteoritic impact hits sand, san fuses to glass - glass used in Tut's bling bling

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Damien,
International Baccalaureate Physics teacher
Optics, Photogrammetry and Remote Sensing Instrumentation Major
Admin: Pacific Science and Art

Hum,
see Kebira Crater

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`Irony` actually does mean `metal like`...

My apologies... Moderators/Admin please delete this thread

bye

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Damien,
International Baccalaureate Physics teacher
Optics, Photogrammetry and Remote Sensing Instrumentation Major
Admin: Pacific Science and Art