The Great Unconformity, a striking break in the geological record visible in the Grand Canyon, may have formed through movements deep within Earth, according to a study published in Nature. Researchers Santosh Dhungana and Nicolas Flament of the University of Wollongong used simulations to examine how the mantle could have shaped continents over time.
The feature was noted during John Wesley Powell’s 1869 scientific expedition through the Grand Canyon. There, rocks nearly 2 billion years old meet much younger layers, with a vast span of geological history missing between them. Earlier explanations have included erosion during global “Snowball Earth” glaciations and processes linked to the breakup of supercontinents.
The researchers’ simulations indicate that mantle convection lifted parts of the continents during the Neoproterozoic, between roughly 1 billion and 540 million years ago. That prolonged uplift exposed rock to erosion. The land then gradually subsided during the Phanerozoic, allowing seas and sediments to cover the worn surface and preserve the boundary seen today.
The authors suggest that substantial continental uplift was followed by rapid subsidence early in the Cambrian, when large volumes of sediment accumulated. They note that these changes occurred around the time of the diversification of animal life, raising the possibility that the geological processes also affected that development. The study does not establish a direct cause, but identifies the relationship as a subject for further research.
Geologists commenting on the proposal described its connection between deep Earth dynamics and surface erosion as significant. They also pointed to a limitation: the simulations rely on tectonic reconstructions that remain uncertain, including the past positions of continents and plate boundaries.
Sources: elDiario.es.