Geology Picture of the Week Extra: GoogleEarth searcher finds pristine impact crater in Egypt

The header link goes to the article on space.com. Basic story is that an Italian guy who sounds like a hobbyist (former curator of a science museum) found the feature while tooling around on GoogleEarth. Since it's in the remote desert, it's hardly changed since impact -- even has ejecta rays. There's a problem here; most models indicate that an object the likely size of this object should disintegrate in the atmosphere. This one obviously didn't.

Now, this last link has a GoogleEarth locator pin. If you zoom out, you can see the ejecta rays. If you zoom out further, you can see how amazing it is that Mr. Vincenzo de Michele (the former museum curator) found it and recognized it.

I watched on TV a nature channel show called The History Of The Earth two evenings ago. The program discussed the Sahara desert. According to the program– up until 3 million years ago the Sahara was underwater. For the last 3 million years the Sahara has gone from wet savanna with many lakes bigger than the great lakes — to desert — and back again. This has occurred every 20,000 years. Why? the Earth wobbles on its axis every 20,000 years and shifts its position enough to make the the African monsoons shift north. Scientists found that the shift of the earth axes coincided with shifts in sedimentary cores in the Atlantic. That is, every 20000 years the Atlantic cores would show sand intrusions from the Sahara that would stop abruptly at 20000 year intervals at the time when the earth wobbles on its axis.

The Atlantic cores show that the Sahara was a verdant savanna with many huge lakes–more lakes and bigger than the great lakes– up until 5500 years ago or 3500 BC. Then abruptly–in less than 200 years–the Sahara dried up. This coincided with the last wobble of the earth on its axis.

As well, this coincides with the emergence of the old Kingdom in Egypt and (very roughly) the earliest parts of Stonehenge.(I’ve thought for about a decade that about 5000 years ago for the first time people all over the world looked up. I thought the triggering event might have been a destructive comet but a big change in the night sky caused by earth’s wobble would make better sense.)

The show concluded that the sandstone rocks of the Sahara contain immense aquifers of water that could pumped up to turn the deserts there green. Scientists were uneasy about draining the desert of its archaic water because a wholesale program that did turn North Africa green would deplete its archaic water supplies in 100-200 years. And there’s another 15,000 years before the rains return.

imho considering that well water is cheaper than desalinated water–so cheap that it could be used for agriculture now — the best bet to turn north Africa green is well water. In time desalinated water will be cheap enough to replenish the ancient aquifers.

Is there any info/estimate of the possible age of this crater? It has the potential to be the cause of the 1st, 2nd or 3rd Intermediate Periods in Egypt, or perhaps the strange weather of Cassiodorus in the 500s AD. I saw an old National Geographic from the 1970s were a man traveled deep into the great southern desert of Saudi Arabia and found an iron meteor about 4 ft cubed. There were legends of how a wicked city in this area had been destroyed. Sounded a bit like Sodom and Gamorrah. The name Warab, Wahab, or or Wabar comes to mind for the name of this crater or event. Don’t hold me to it, memeory is getting aged.

The remains of Lake Tritonis were still there when Herodotus toured Egypt etc, so, 2500 years ago. I wouldn't put much stock in periodicity or any other uniformitarian model for the desertification of the Sahara. :')

The African Source Of The Amazon's Fertilizer

additional sidebar:

Evolution in Your Face
by Patrick Huyghe
Omni
Lake Victoria, Africa's largest lake, is home to more than 300 species of cichlids. These fish, which are popular in aquariums, are deep-bodied and have one nostril, rather than the usual two, on each side of the head. Seismic profiles and cores of the lake taken by a team headed by Thomas C. Johnson of the University of Minnesota, reveal that the lake dried up completely about 12,400 years ago. This means that the rate of speciation of cichlid fishes has been extremely rapid: something on average of one new species every 40 years!

Good memory, btw:

Wabar Impact
SciAm
Nov 1998
Deep in the legendary Empty Quarter of Saudi Arabia-the Rub' al-Khali-lies a strange area, half a square kilometer (over 100 acres) in size, covered with black glass, white rock and iron shards. It was first described to the world in 1932 by Harry St. John "Abdullah" Philby, a British explorer perhaps better known as the father of the infamous Soviet double-agent Kim Philby. The site he depicted had been known to several generations of roving al-Murra Bedouin as al-Hadida, "the iron things." What he found was neither the lost city of Ubar nor the basis for the Qur'anic story. But it was certainly the setting of a cataclysm that came out of the skies: the arrival of a meteorite. Judging from the traces left behind, the crash would have been indistinguishable from a nuclear blast of about 12 kilotons, comparable to the Hiroshima bomb. Wabar-size meteoroids are much more common-and harder for astronomers to spot-than the big monsters. Ironically, until the Wabar expeditions, we knew the least about the most frequent events. The slag and shocked rock in the deserts of Arabia have shown us in remarkable detail what the smaller beasts can do.

There is also tektite glass used for some stuff for King Tut, and the source of that has apparently been identified. :')

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