300 million BC: glass created from asteroid impact in central Australia

Scientists have discovered glass 2kms under the Warburton Basin, in a 400km-wide crater extending over South Australia, Queensland and the Northern Territory.

The Warburton Basin

The scientists - from the Australian National University’s School of Archaeology and Anthropology - believe that the glass was created when an asteroid hit the earth more than 300 million years ago, generating enough heat and pressure to melt rock into glass.

The resulting 400km-wide crater is the biggest asteroid impact zone yet discovered on Earth. It is significantly larger than the 180km-wide Chicxulub crater in Mexico, created some 66 million years ago in an event that is believed to have led to the extinction of the dinosaurs.

An asteroid hits Earth (NASA)

A new element in Australia's glass history
Prior to the Warburton Basin discovery, scientists had only speculated that natural glass could be found in Australia. They knew that asteroid impacts create natural glass and they knew that Australia has 26 craters created by asteroid impacts. However, until now there was no evidence that an asteroid impact in Australia had created natural glass.

The Warburton Basin discovery provides that evidence. It also provokes further speculation: is it possible that humans in what is now central Australia used asteroid-formed glass? Archaeological records indicate that humans started making articles such as knives and arrow heads from natural glass 75,000 years ago; how soon before we discover evidence that such practices took place in Australia?

(Original report in Tectonophysics; cited in NT News 24 March 2015)