What Are Shatter Cones?

Appearance

• Shatter cones are cone-shaped rock formations. According to the School of Environmental Sciences at the University of Guelph in Canada, shatter cones can be as small as 2 cm or as large as 2 meters high. The Planetary Science Institute's Explorer's Guide to Impact Craters states that their width ranges from 1 cm to 5 meters. They feature distinct converging fracture lines, which the Explorer's Guide describes as resembling a horse's tail.

Formation

• Shatter cones are the result of extreme pressure. According to the website Ernstson Claudin Impact Structures, they require between 2 and 20 gigapascals of pressure to form. The Explorer's Guide to Impact Craters claims that the exact mechanism of shatter-cone formation isn't known, but what is known is that an extreme pressure will cause a shock wave. This shock wave will, in turn, cause the rock to fracture, creating a shatter cone.

Causes

• The Explorer's Guide to Impact Craters explains that shatter cones can be created naturally or artificially. They can be created naturally by a meteorite hitting the Earth's surface. When the meteorite strikes a rock surface, the extreme pressure causes shatter cones to form. Shatter cones can be created artificially with a nuclear explosion. This occurred for the first time in 1959, during an underwater nuclear explosion.

Importance

• According to meteorite hunter Geoffrey Notkin, shatter cones give researchers insight into history. Meteorites are high in iron, so they decompose and disappear over time. Shatter cones are made of solid rock, so they can last for billions of years. This allows researchers to learn about historic meteorite impacts, even if the meteorite is long gone.