This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Stretching more than 200,000 square kilometers (77,000 square miles) across southern Australia, the vast, flat plains of the Nullarbor mark one of the world's largest regions of limestone. It formed when an ancient shallow sea retreated some 14 million years ago.
Ultimately, this led to the familiar dry landscape of today, which has acted as a significant barrier for plants, animals and poorly adapted colonial Victorian-era explorers who described it as "the sort of place one gets into in bad dreams." In contrast, the Mirning People of the Nullarbor and Great Australian Bight have lived for tens of thousands of years on this southern margin. They have watched the landscapes change and sea levels fall and rise with the buildup and collapse of the last ice age, about 20,000 years ago. To the untrained eye, the Nullarbor Plain appears deceptively simple and featureless.
However, beneath the immense plain lies a remarkable, largely hidden underground world. Over millions of years, water has eaten away at the limestone and created complex cave networks that can extend for kilometers underground. Sadly, the caves remain poorly understood, partly because they're only really known and accessible where they breach the surface.
Our new study, published in Communications Earth & Environment, reveals a new way to track these cave systems even when they are deeply buried. Our work helps explain the formation of previously mysterious, shallow trench features on the Nullarbor. It also provides a new way to identify hidden caves elsewhere—even beyond our own planet.
Scattered across the Nullarbor are telltale signs of its vulnerability to being dissolved—small cave openings and shallow depressions. But there are also structures of previously unknown origin and significance: long (up to 20 km [12 miles]), shallow (a few meters) trenches that trend roughly north-south. They're almost invisible from the ground, but we can clearly see them in modern digital landscape models.
These shallow trenches look somewhat like flat-bottomed valleys, but they were not carved by rivers. They begin and end abruptly and are not connected to existing rivers or drainage networks that extend into the upland areas around the Nullarbor. They also lack typical river branching patterns, and the sediments within them don't show any evidence of being deposited from flowing water.
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