A timeline of the earth's history indicating when the Vredefort crater was formed in relation to some of the other important South African geological events. W indicates when the Witwatersrand Supergroup was laid down, C the Cape Supergroup, and K the Karoo Supergroup. The graph also indicates the period during which banded ironstone formations were formed on earth, indicative of an oxygen-free atmosphere. -- Vredefort crater - Wikipedia
Young earth v. old earth: If this had happened sometime within the last 6,000 years, I kind of think it would have been noticed. :) "The multiple-ringed Vredefort Crater - The asteroid that hit Vredefort is estimated to have been one of the largest ever to strike Earth (at least since the Hadean Eon some four billion years ago), thought to have been approximately 5–10 km (3.1–6.2 mi) in diameter. The bolide that created the Sudbury Basin could have been even larger."
Meteor Crater, also known as Barringer Crater, in Winslow, Arizona, measures nearly a mile wide and 570 feet in depth. There are more than 160 known meteorite craters on the surface of Earth. PHOTOGRAPH REPRODUCED BY PERMISSION OF PHOTO RESEARCHERS, INC.
Vredefort crater - South Africa The asteroid that hit Vredefort is estimated to have been one of the largest ever to strike Earth (at least since the Hadean Eon some four billion years ago), thought to have been approximately 5–10 km (3.1–6.2 mi) in diameter. The bolide that created the Sudbury Basin could have been even larger. The original crater was estimated to have a diameter of roughly 300 km (190 mi), although this has been eroded away. It would have been larger than the 250…
Vredefort Dome, approximately 120 km south-west of Johannesburg, is a representative part of a larger meteorite impact structure, or astrobleme. Dating back 2,023 million years, it is the oldest astrobleme yet found on Earth. With a radius of 190 km, it is also the largest and the most deeply eroded. Vredefort Dome bears witness to the world’s greatest known single energy release event, which had devastating global effects including, according to some scientists, major evolutionary changes.