Its a meteor impact site, where the crater walls which were formed
142M years ago have weathered away, but the rebound crater remains.
Its about 6km in diameter and about 200m high
[IMG]http://i215.photobucket.com/albums/cc103/soils1111/
gossesbluffpano.jpg[/IMG]
http://en.wikipedia.org/wiki/Gosses_Bluff_crater
John R