Located in southern Senegal is a feature that appears to be a meteor-impact-generated structure, possibly millions of years old. It is a circular, multiple ring structure with an overall diameter of 48 km (30 miles) and centered about 12 km (7 miles) south-southwest of the town of Velingara. The high rim structure of the Velingara Crater encloses the Anambe Basin. Water previously flowing out the south end of the basin was harnessed behind a dam in the mid-1970s as a source of irrigation for rice and other crops. The 1984 image shows the early days of irrigation development. By 2001 intense agricultural systems had appeared near the center of the crater, contrasting sharply with the swampy areas nearby, and then extended. Leading to an increase of the settlement in the area.