In the hills outside the small village of Sexi, Peru, a fossil forest holds secrets about South America’s past millions of years ago.
When we first visited these petrified trees more than 20 years ago, not much was known about their age or how they came to be preserved. We started by dating the rocks and studying the volcanic processes that preserved the fossils. From there, we began to piece together the story of the forest, starting from the day 39 million years ago when a volcano erupted in northern Peru.
Ash rained down on the forest that day, stripping leaves from the trees. Then flows of ashy material moved through, breaking off the trees and carrying them like logs in a river to the area where they were buried and preserved. Millions of years later, after the modern-day Andes rose and carried the fossils with them, the rocks were exposed to the forces of erosion, and the fossil woods and leaves again saw the light of day.
