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Temimichat crater, Tenoumer crater
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| A Few months prior to our trip, we received a call from a friend who informed us about a possible correlation in the alignment of some geological structures in Mauritania. The structures are the Temimichat, Tenoumer and Aouelloul impact craters and a particular circular structure called Richat. A line drawn 208° S-SW between the Temimichat and Tenoumer crater, themselves separated by 166 kilometers, intersects the exact center of the Richat structure, 390 km away. This apparent alignment was reason enough to plan a trip to this region. Could all these structures be part of the same impact event? |
| The 40 km diameter Richat structure is visible from space with an unaided eye! |  |
| Our trip started in the Alps Mountains. Utilizing a 6WD truck Pinzgauer, we drove 2000 km up to South Spain (Gibraltar) to cross the Mediterranean sea and then another 2000 km thru Morocco and along the Atlantic side of Western Sahara finally reaching the Mauritanian border located on the Tropic of Cancer. The only customs facility to enter Mauritania via the North is on the Laayoune-Nouadhibou road.
Our friend waited for us in Morocco along with his girl friend and their Prairie Dog (on vacation in Sahara). Their 4WD off-road vehicle was a highly modified Italian truck with large wheels in which the springs were replaced by an air suspension system. After traveling five days thru Morocco and Western Sahara, we cross the Tropic of Cancer and entered Mauritania. |
| My last trip to Mauritania was ten years ago and never included a visit to the northern part of the country. Northern Mauritania is composed of flat plains and sand dunes, this geography is not conducive for finding meteorites but has its own rewards. |
Mauritania
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The first night in the Sahara is always very impressive. After Morocco, it's a welcome change... only you and the stars above your head. If you prefer the outdoors and a good camp fire under starry skies as opposed to hotel living, than this is the place for you. |
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We start the off-road segment of our journey. Here, the desert track runs alongside the railway line of the longest train in the world. This "iron ore" train is two kilometers long!
During the still of the night in the desert, you can hear the train more than ten kilometers before seeing the train headlights. The sound is loud and penetrating... its vibrations propagated by the very soil itself... a most impressive experience. |
| The advantage of trucks over 4wd automobiles is the reliability of the transmission for driving on top of soft sand and rocks, the possibility to lock each wheel for full traction, the freedom that carrying 600 liters of gas provides as well as the living space that is afforded. Travelling by truck on highways can be a problem due to noise and speed restrictions. However, once off-road such vehicles are magic as they ply you over sand dunes with nothing else than the desert around you for hundreds of kilometers. |
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Tenoumer crater
diameter 1.9 km N 22°55' - W 10°24' After leaving the small city of Ouadane, our off-road journey really starts. Our goal is to find Tenoumer crater situated 224 km distant on a heading of 28° N-NE. Satellites photos show the crater to be quite visible but our Russian maps, reputed to be the best for Saharan countries, leave much to be desired as to the locality of the Tenoumer crater. In this situation, with the GPS programmed on the crater, I am just driving, absorbing in the scenery and thinking of nothing in particular. Twenty kilometers from the goal we set out find, I finally realized that this hill I was seeing for the last 10 kilometers, was in fact the crater itself. |
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| The energy necessary to create such a crater must have been tremendous. The energy released by the Hiroshima bomb paled by comparison! The crater's diameter is approximately 2 kilometers wide and the rim height is 100 m high. The asteroid would have to have had a diameter between 20 and 50 meters. This size doesn't seem like much, but with an impact speed approaching 70 km/s, the kinetic energy is colossal. Blocks of impact material weighing several tons were projected in all directions. | ||
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Black impactites, with clasts of gneiss and granite embedded in a vesicular matrix, are found around the crater's rim. |
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Temimichat crater
diameter 750 m N 24°15' - W 9°39' Temimichat crater is quite similar to Tenoumer crater with the exception that there is no lava present. |
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Only shocked granitic rocks with dark glassy veins are to be found at Temimichat.
(scale 1) |
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| The presence of grass in the crater is unusual. Rains prior to our visit were the most important since 1947, a month prior to our arrival saw a small lake in the crater. | ||
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| We have a "rendezvous" with the moon. It is the night of a total lunar eclipse and what better place in the world to view such a spectacular celestial alignment phenomenon than on the rim of a meteoritic crater, alone in a "lunar" landscape. Progressively the moon is transformed into a deep red celestial garnet. |  |
| We continue our journey the next day traveling 50 km, expecting to find a smaller impact feature that is not visible on satellite photos, without success! |
More information on African impact craters
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It is now time to head for the black hills of Zouerat, the most important iron mine in the world. The mountains here are made of iron ore and a 700 km railroad crosses the Sahara from Zouerat to Nouadhibou on the Atlantic coast. |
Atar and Chinguetti |
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Here is a "quartz mine" being dug by ants. An unusual layer of white sand lies beneath the orange colored sand and it is the white grains that the ants bring to the surface. |
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We cross the dunes of Al Hamami and reach Atar, the greatest city in central Mauritania. Stickers of Osama Bin Laden are on the walls of restaurants and shops in this part of Mauritania.
The following day we visit the old city of Chinguetti where the oldest manuscripts of the Sahara are kept in darkness behind wooden doors of private stone houses. |
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| Mauritania is a very sandy country which is not conducive for finding meteorites. The abrasive action of wind and sand grains act like an ever present abrasive paper. Friable achondrites such as eucrites stand no chance to survive and iron meteorites appear without fusion crust and oxidation. Interior features such as Widmanstatten patterns are visible on their surface due to abrasive actions and the difference of hardness in the metal structures. |
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