It is thought that the Nullarbor was formed 20 million years ago in a glaciation event which left the Nullarbor high and dry. During this period, the sea level dropped and a vast amount of limestone was laid down on what was the sea floor.
Prior to the last ice age, the Nullarbor was cooler and wetter than what it is today, supporting a vast open woodlands and a very different habitat. The cave would have formed when the above ground conditions were wetter and salt was left impregnated into the limestone. Rain water and the rising ground water would have worked to dissolve the salt, along with the calcium carbonate (limestone), causing tunnels and caves to burrow through the earth. As this process continued and the caves became drier, rainfall continued to seep down, causing sections of the limestone to collapse. Over time, this widened the caves. As the caves became wider, so too did the roof span of the caves, giving rise to more collapses.
The cave’s stalactites and stalagmites would have formed after the cave itself was formed. Water dripping down from above would have formed precipitates made of salts, which on contact with the air in the interior of the cave, would have formed into stalactites. Similarly, drops collected on the cave floor, through a process of evaporation, would have formed a calcium carbonate residue on the cave floor building upwards to form stalagmites.
The entire Nullarbor is like a honeycomb of caverns and empty spaces, with openings periodically emerging and collapsing to reveal these stable, but deadly, traps. The Thylacoleo would have fallen into this trap when there was a forest above. The Thylacoleo indeed lived in an environment in stark contrast to the one that will be witnessed by our team in the coming few weeks.