Landscape and Landforms of the Vredefort Dome: Exposing an Old Wound

Abstract

A striking 100 km-long crescent of ridges and valleys straddling the Vaal River along the border between North West and Free State provinces near the towns of Parys and Vredefort is the most obvious remnant of one of the most remarkable geological events in Earth‘s history. The Vredefort impact event 2,020 Ma ago into the ancient rocks of the Kaapvaal craton is estimated to have left a crater that was originally at least 250 km wide and over 1 km deep. The crater and its infill of broken and melted rocks have long since been stripped away by erosion, rendering the crater margins largely invisible today. However, a central region of rock that was domed upward during the impact event and that bears numerous scars of the catastrophe is still visible. The crescentic Vredefort Mountainland forms a portion of this geological feature, which is referred to as the Vredefort Dome . The landscape of the Dome owes much of its current dramatic topographic relief to the 300 Ma Dwyka glaciation , evidence of which is now being exhumed by the modern Vaal River. Large potholes , sand-blasted rock pavements and the remnants of ancient dune fields testify to more recent shifts in climate in the Mesozoic and Cenozoic. Part of the Vredefort Dome was inscribed as a UNESCO World Heritage Site in 2005.