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www.niger-meteorite-recon.de
Libya 2004 - illustrated report
go to page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | Team | Area Map
The HaH meteorite field after 20 years of prospecting - as published in the November 2004 issue of Meteorite Magazine
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The German explorer Heinrich Barth was the first to notice a remarkable geological feature of the Hammada al Hamra. Pushing forward his way to the knee of the River Niger in late 1850, his caravan came across a vast gravel-plain spanning from Garyat in the north to the Wadi Schati in the south. On his path towards the plateau Barth was puzzled by the omnipresence of a dark rock, building the underlying stratum of the bright marine deposits that form the top layer of the HaH plateau.
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Southern edge of the HaH plateau, revealing its composition of Cretaceous sandstone (bottom) and bright calcite layers (top) |
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At first sight mistaking the stratum for basalt, he soon recognized that the basement of the Hammada is actually built of Jurassic and Cretaceous sandstone. The explorer's misconception was evoked by a mysterious black coating covering the exposed rocks. Further up on top of the plateau, where limestone and calcite sediments form a solid bedrock, the black coating disappeared.
Barth described a phenomenon today's meteorite prospectors are unpleasantly familiar with. Known as "desert varnish" the black patina forms on rock surfaces over hundreds to thousands of years. Due to its omnipresence, it hampers the recognition of meteorites in the affected areas severely. Desert varnish is composed of clay minerals plus manganese and iron oxides, which are produced through microbial activity. Since the bacteria perform best on near neutral pH-values, the phenomenon is widespread in the Sahara. Only few surfaces with basic dolomite and limestone are spared this black coating. Among those rare environments is the vast gravel plain of the Hammada al Hamra.
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German explorer Heinrich Barth (1821-1865). Together with Adolf Overweg, a Prussian astronomer, and James Richardson, an explorer of the Sahara he had been selected by the British government to open up commercial relations with the states of the central Sudan. After the deaths of Richardson (1851) and Overweg (1852) Barth managed to carry on the mission alone. He returned to Europe in September 1855, after one of the most fruitful expeditions ever undertaken in inner Africa.
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One hundred thirty-five years after Barth's crossing of the Hammada, the first series of meteorite discoveries were reported from the area. It didn't take long for the inhospitable region in the east of the Libyan Sahara to become a center of attraction for meteorite aficionados hoping for an extraterrestrial bonanza.
Not every expedition achieved success. For some the adventure ended with the bite of a sand viper or the sting of the black scorpion. Others ran their vehicles on mines while crossing the Algerian border or got into trouble with bandits from Mali or Chad who felt the quietness of their hideouts disturbed by the increasing meteorite-tourism.
Despite these obstacles in March 1997, Dar al Gani 262 was found. The 513 g fragment was the first lunar sample to be recovered from the northern hemisphere. Today the Catalogue of Meteorites lists around 1,400 single finds from the Libyan strewfields, lunars and martians included. More than 360 finds alone from the HaH.
After 20 years of prospecting this is reason enough for us to search in the area and find out whether the terrain still yields any secrets.
In February 2004 we finally succeed to gain the support of the local authorities.
Supported by the Institute of Planetology at the University of Muenster a small scale recon expedition is planned, a one man mission,
backuped by local assistance.
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The southern and eastern edge of the HaH plateau is limited by a passless lybyrinth of wadis and ravines.
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Arriving in the
small town of Sebha in the Libyan south in late April, I meet with a local agent, whom I know from a previous expedition in the Ténéré desert.
Together we choose my companions, Saleh, a local clan chief and Ammul the cook, whos people live in the Air Mountains at the edge of the Ténéré in the Republic of Niger. Both men are of the legendary Touareg tribe, the "blue lords of the Sahara" and reputed for their desert skills.
www.niger-meteorite-recon.de
Libya 2004 - illustrated report
go to page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | Team | Area Map
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