Petrified Forest of José de Ormachea, Natural monument in Sarmiento, Chubut Province, Argentina.

The Petrified Forest of José de Ormachea is a natural monument in Sarmiento, Chubut Province, Argentina, containing fossilized tree trunks from ancient coniferous species. The site spreads across the Patagonian steppe and displays remains of forests that grew millions of years ago.

The petrified forest was discovered in 1927 and opened as a tourist attraction from 1970. In 1973 Provincial Law No. 2161 declared it a protected natural area, and in 2001 Provincial Law No. 4780 gave it the status of natural monument. A 1991 proposal for a tourist train from Sarmiento was abandoned after the Comodoro Rivadavia–Sarmiento branch line was dismantled between 2005 and 2006.

The visitor center displays fossils and artifacts that tell the story of how this Patagonian region changed over time. These collections help travelers understand the ancient landscapes and life forms that once thrived here.

Visitors walk along marked paths through the petrified trees, and guided tours help most people understand the fossils better. It is wise to bring comfortable shoes and sun protection, as the route crosses open steppe with little shade.

The petrified trunks lie in volcanic sediments where pollen grains were also preserved, letting researchers reconstruct a temperate-to-tropical climate with high humidity. Besides trunks, the reserve holds leaves, branches, fruits, splinters and seeds. A 1991 plan to run a tourist train here from Sarmiento on the old Comodoro Rivadavia line never prospered.