Earth’s rocks are missing more than a billion years of history in some places, and the slow rise and fall of continents may explain how those chapters disappeared.

A study led by University of Wollongong (UOW) PhD candidate Santosh Dhungana suggests that the slow rise and fall of continents helped create the Great Unconformity, a vast gap in Earth’s geological record. Published in Nature, the research links this missing history to currents of hot rock in the mantle that moved continents vertically over hundreds of millions of years.

Normally, rock layers preserve a sequence of events, with younger deposits accumulating above older ones. At the Great Unconformity, that sequence jumps: sedimentary rocks from around the beginning of the Cambrian period, roughly 540 million years ago, rest directly on much older crystalline rocks, including granite more than a billion years old.