We have the Space Shuttle to thank for photographs that were taken in 1994 which confirmed the presence of the Aorounga crater in Chad. Like so many other meteor impact craters around the World, this one is also situated in an extremely remote area. Actually it is found in the Saharan Desert within a terrain that you could be forgiven for thinking looks more like the Martian surface.
The Aorounga crater is one of the oldest meteor impact craters known to exist on this planet. In actual fact, it is thought that it may date as far back as 345 millions years and if this is accurate, this would place this event into the Carboniferous period of the Palaeozoic era. This would have been at a time when animal life was just starting to get going and plant life was flourishing on land more than any other period in this planet’s history, as a result of the fact that there were high levels of oxygen in the atmosphere. This plant life would go on to become the fossil fuels that are in such demand today.
As so much time is thought to have transpired, since the Aorounga crater was formed, the impact site would have been filled with sediments for much of its history. However, more current erosion has now worn away at this sediment and this has helped to reveal the original circular rims of the crater.
This specific area is of even more importance to scientists, as the Aorounga crater is thought to be one of a chain of craters that exist within this vicinity of northern Chad. In fact, this may well be an area that provides one of only two recognizable examples of a “crater chain” on this planet. A crater chain is known to occur when a comet of asteroid breaks up, usually as a result of tidal forces. This then leads to craters being formed in a string across the planet’s surface. Chains may also occur where such a huge section of strata has been ejected from the impact, that this is then displaced to another area close by, which results in a further impact crater.
So far, two other smaller impact craters have been discovered close to the Aorounga crater by the photographs which have been taken by the Space shuttle. Given the immense amount of time that has passed, since this occurrence, there may very well be more craters that have become filled in by gathering sediments.
The Aorounga crater has been measured at 12.6 km in diameter, so this would be indicative of a quite significant meteor impact event. If the scientists are right and the original extra-terrestrial body had broken up before hitting the planet, this crater could have been so much larger if it had been forced to take the full impact of the entire original asteroid.