Volcanic blanket preserves ancient Andean landscape

Researchers from University College London studied a massive volcanic deposit in the Andes Mountains of northern Chile to understand how the landscape formed 22 million years ago.

The team examined ignimbrite, a sheet of volcanic rock from the Lauca Caldera, that covered an area nearly three times the size of Greater London and reached up to 1 kilometer deep.

By simulating ancient landscapes and comparing them to the volcanic deposit, scientists determined the terrain before the eruption was a gently sloping foothills area. This analysis revealed the Andes were rising slowly, at a rate of no more than 0.26 kilometers per million years, about an inch every 100 years.

This slow uplift rate challenges theories suggesting the Andes rose rapidly in the last few million years, supporting the idea of a long, steady growth over tens of millions of years. The researchers compared their findings with existing research analyzing temperature changes in rocks, confirming their estimate of uplift speed. Dr. Byron Adams explained this eruption acted like a larger version of the event that buried Pompeii, preserving a moment in Earth’s history.

The team believes this method of studying volcanic deposits could be used to reconstruct other buried landscapes around the world, providing insights into long-term climate change, as the Andes significantly influence regional and global climate.