I spent a good part of today walking in the Forest Run area and was reminded about shatter cones – because I saw so many! These are really special rock structures that are found only at meteorite impact sites. Indeed, they are the fingerprint of a large-body impact and were the deciding factor in declaring the Vredefort Dome a World Heritage Site. When a comet or meteorite strikes, it releases an enormous amount of energy, which evaporates, melts and fractures the surrounding rocks. Shatter cones are formed by the shock waves that spread from the impact and can range in size from macroscopic to several meters. These images show pieces of shatter cone in quartzite (left) and arenite (right) rocks from the Vredefort Dome.