A perfect trap for space rocks
The Nullarbor Plain is the world's largest single exposure of limestone, a 200,000 square kilometer relic of a former shallow seabed. This flat and arid landscape creates ideal conditions for preserving and finding meteorites. The plain's geology is important. Formed from Miocene-era limestone, its pale, uniform surface makes the dark, fusion-crusted rocks from space stand out. The dry climate drastically slows the rusting process that would normally destroy iron-rich meteorites, preserving them for tens of thousands of years.
The stability of the landscape is another factor. Much of the Nullarbor Plain has remained largely unchanged by erosion for millions of years, allowing a vast accumulation of meteorites over deep time. This makes the region a record of cosmic history, where specimens can be found that fell to Earth across different geological periods. The plain is so effective at preservation that it is one of the most prolific meteorite recovery sites in the world, outside of Antarctica. Researchers can walk systematic transects across the featureless terrain, and dark meteorites are easily spotted against the light-colored limestone.
A harvest of cosmic iron and stone
While occasional meteorites were found by rabbit trappers and prospectors for decades, systematic recovery efforts began to reveal the true scientific wealth of the Nullarbor. Since 1971, several thousand individual meteorite specimens have been recovered from the region. One of the most significant finds is the Mundrabilla iron meteorite. The first small pieces were found in 1911, but in 1966 geologists R.B. Wilson and A.M. Cooney discovered two massive fragments weighing 12.4 and 5.44 tonnes. The total known weight of the Mundrabilla strewn field now exceeds 22 tonnes, making it one of the largest meteorite finds on Earth.
The finds are not limited to large irons. The region has yielded hundreds of distinct meteorites, including many rare types of stony meteorites called chondrites and achondrites. For instance, the discovery of two rare ureilites on the plain nearly doubled the worldwide total of that meteorite type at the time. More recently, amateur meteorite hunter Robert Towers single-handedly increased the number of known South Australian meteorites from 248 to 386 by meticulously documenting his finds. These recovered space rocks provide direct samples of asteroids, allowing scientists to study the formation of the solar system, which began about 4.6 billion years ago. The Bunburra Rockhole meteorite, whose fall was captured by cameras in 2007, was traced back to a previously unknown asteroid that was shattered by collisions between 3.4 and 3.6 billion years ago.