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Argentine Patagonia: the petrified forest of Jaramillo

In the most extreme part of South America. In the heart of Argentine Patagonia, in the province of Santa Cruz. There is a natural wonder that comes directly from the age of the dinosaurs: the petrified forest, the Parque Nacional Bosques Petrificados de Jaramillo. The park includes an area of over 63,000 hectares of Patagonian steppe and an area of about 15,000 hectares of the Natural Bosques Petrificados Monument for a total of over 78,000 hectares of protected territory. The area is very isolated. There are only a few farms (estancias) and the nearest inhabited center – the village of Jaramillo which has just over 400 inhabitants – is 135 km away. The nearest town Caleta Olivia is located along the coast 220 km away.

The landscape of the park is typical of the Patagonian steppe. A semi-desert landscape, created by a very extreme climate. Arid at all times of the year and in winter, whipped by a very freezing wind, with wide daily temperature variations. Average daily temperatures reach 19 ° C in summer (with maximum temperatures that can reach up to 40 ° C) and 7 ° C in winter (with minimum temperatures that can reach up to -15 ° C). Average annual rainfall barely reaches 200 mm, and is concentrated in winter. Despite the climate, the vegetation has managed to adapt by creating a low carpet of shrubs that manage to survive in this extreme climate.


In this park of the petrified forest of Jaramillo are the fossilized remains of a prehistoric petrified forest. What these fossils tell us is a world very different from the current one both in terms of climate and environment. In this area about 150 million years ago, that is at the time of the dinosaurs in the middle of the Jurassic period, there was a completely different climate from the current one, with heavy rains and humidity. This climate allowed the birth of a rich araucaria forest, trees similar to our pines and firs. Giant plants over 35 meters high and with trunks of about 3 meters in diameter.

Fossil trees were formed due to volcanic eruptions that occurred in the early Cretaceous years. These eruptions were caused by the beginning of the lifting of the Andean mountain range. In the middle of the dinosaur era, the territory of the park was buried with ash and lava from eruptions. Trees and forests were violently cut down by a frightening volcanic eruption. Subsequently, the infiltration of rainwater into the ground caused the trunks to fossilize over a period of some tens of miles of years. Following these events the trunks of the trees of the forests were petrified. The effect of water impregnated with silicon and minerals turned the wood into silicates.


In the park of the petrified forest of Jaramillo there are remains of huge trunks of petrified trees that reach even 20 meters in length. The fossilization was so perfect that even today after 150 million years it is still possible to identify the structure of the wood with the knots and even the rings. Remains of ancient fossilized pine cones, animal footprints, woodworm holes in fossilized wood and fossil traces of raindrops that fell during the dinosaur era were also found. The petrified forest re-emerged in the sunlight probably around 9,000 / 13,000 years ago. In fact, prehistoric men used fossil wood to make spear and arrow points.

In this park it is therefore possible to go back in time and walk among the remains of a forest of the time of the dinosaurs. The ideal seasons to visit the park are spring and summer, that is, the months between October and March.

Prices and timetables: Entrance to the park is free. From April 1st to September 30th, the park is open from 10am to 5pm. From October 1st to March 31st, the park is open from 9am to 7pm.

Information: Oficina de Bosques Petrificados: Ameghino S / N ° Jaramillo, Deseado, Provincia de Santa Cruz, Argentina. Tel: (0297) 483 1201. E-mail: bosquespetrificados@apn.gov.ar