Gweni-Fada crater
Gweni-Fada is a meteorite crater in Chad, Africa. The Gweni Fada structure was first noted on the map NE 34 X Fada of the IGN (National Geographic Institute France) and aerial photographs in the 1950s of IGN by Alain Beauvilain (Paris X- Nanterre University). In April 1995, at the initiative of CNAR (National Center to Help Research of Chad) a team of French geologists (Pierre Vincent, University of Clermont-Ferrand, Alain and Najia Beauvilain, CNAR Chad) visited the site and reported evidence of shock metamorphism within rock samples they had collected inside the structure. Centered at  17°25′N and 21°45′E, being slightly wider in the NW-SE direction (cf. topographic map), the asymmetric structure is deeply eroded. A broad depression (ø 12 km) forms a crescent around two thirds of the inner complex zone. On the northern side, an elevated outer ring of outward-dipping sandstones surrounds the depression. In its south, the external depression is absent. The inner zone (ø 10 km) consists of a rugged terrain with hills several hundred meters in height. The latter may be remnants of the central uplift (see topographic map). The age is estimated to be  less than 345 million years (Carboniferous). It is older than that of Aorounga because its coverage of impactite has disappeared as a result of erosion.