Nullarbor Plain trenches revealed as signs of collapsing underground caves

Researchers have discovered that the long, linear trenches found on Australia’s Nullarbor Plain are not ancient, dried-up riverbeds as previously thought. Instead, a study published in Communications Earth & Environment reveals these features are the surface expressions of underground cavities and cave systems slowly collapsing upward over millions of years.

The Nullarbor Plain is a vast limestone region covering more than 200,000 square kilometers in southern Australia. Formed by a retreating shallow sea approximately 14 million years ago, the landscape hides complex networks of caves created by water erosion. The study, led by geographer Matej Lipar, identifies five major north-south oriented trenches that stretch between several and 20 kilometers in length.

This new method of detecting deeply buried cave systems through subtle surface depressions offers significant scientific potential. Beyond understanding Earth's geology, these detection techniques could be used to locate groundwater or identify hidden cave structures on other planets, such as Mars.