A Jurassic world frozen in stone
The arid Patagonian steppe of Santa Cruz holds the remains of a forest that witnessed dinosaurs. Scattered across the desert landscape are the massive, fossilized trunks of Araucaria mirabilis, an extinct conifer species that grew here during the Middle Jurassic Period, approximately 160 million years ago. Some of these stone logs measure up to 3 meters in diameter and reach 35 meters in length. When alive, these trees stood as giants, reaching heights of up to 100 meters.
The preservation of this ancient ecosystem is the result of a cataclysmic geological event. Before the Andes mountains existed, this region was a humid, temperate part of the supercontinent Gondwana. Moist winds from the Pacific Ocean supported a lush forest. This changed dramatically when a series of massive volcanic eruptions buried the landscape in silica-rich ash and tuff. The volcanic material entombed the trees, and over millions of years, silica-rich groundwater seeped into the wood. This process of permineralization replaced the organic material molecule by molecule with minerals like quartz, creating perfect stone replicas of the ancient trunks.