Landforms of Kakadu's Southern Hills and Basins
The southern hills and basins cover a large area in the south of the park, including the headwaters of the South Alligator River. Rocks here have been exposed from beneath the retreating Arnhem escarpment; they are of volcanic origin and are extremely old (2500 million years).
This landform is characterised by rugged strike ridges separated by alluvial flats. Its features can be easily observed from the top of Gunlom Falls and on the Yurmikmik walking tracks.