Jaramillo Petrified Forest: A Guide to Argentina's Fossil Giants

The Jaramillo Petrified Forest protects the largest petrified trees on earth, araucaria trunks up to 3 metres in diameter and 30 metres long, lying across open Patagonian steppe in Santa Cruz Province. Entry is free, the park stays open year-round, and a single 2 km interpretive loop takes most visitors about two hours. Those trunks were buried by volcanic ash roughly 150 million years ago, in the Jurassic, long before the Andes existed.

Getting There and Orientation

The park sits in the Deseado Department of northeastern Santa Cruz, about 140 km north of the towns of Jaramillo and Fitz Roy and roughly 250 km from Puerto San Julián. Almost everyone arrives by car, and that is the first thing to plan around.

The Route From National Route 3

From RN3 at kilometre 2,074, you turn onto Provincial Route 49 — a gravel road. Expect about 39 km of ripio to the park boundary and another 11 km to the operational centre and public use area, so roughly 50 km of washboard and loose stone in each direction. A standard car manages it in dry weather; rain or snow can turn it slick, and a spare tyre plus a full tank are not optional extras here.

Drive times from the main hubs: Jaramillo 152 km, Caleta Olivia 234 km, Comodoro Rivadavia 312 km, Puerto San Julián 249 km, Río Gallegos 600 km. Comodoro Rivadavia has the nearest airport with regular connections, and from there it is a long day behind the wheel.

What Is Actually at the Entrance

The ranger post and the Guardaparque Peter Garrahan museum sit at the access area, and you register there before walking. There is no fuel for sale, no potable water, no food — only public toilets. Fill up in Caleta Olivia or Pico Truncado, carry at least 3 litres of water per person, and pack lunch. Camping is not permitted anywhere in the park.

The Fossil Forest and the Trail

The protected area totals 78,543 hectares, split between the 63,543-hectare national park and the 15,000-hectare natural monument, and it was first protected in 1954 before being reclassified as a national park in 2012. Very little of that is walked. The whole visit centres on one low-difficulty trail of about 2,000 metres.

What You Are Looking At

The trees are Araucaria mirabilis, ancestors of today's monkey puzzle trees, preserved when silica gradually replaced the organic tissue. Many trunks lie where they fell, some still upright as stumps. Look for the mineral colouring — reds, greys, amethyst — in cross-sections where the wood grain survives intact. A tip few visitors know: early morning or late afternoon light rakes across the grain and makes the colours far clearer than the flat midday sun.

Smaller fossils are scattered everywhere, including pine cones and fragments of other extinct plants. The museum adds the geology in plain terms, and it is worth 20 minutes before the walk, not after.

The Steppe Wildlife

The park protects Patagonian steppe as much as fossils. Guanacos graze the open ground, choiques (rheas) run across the approach road, and tucúqueres — the small Patagonian cavies — dart between bushes. Photography from the car is often more productive than on foot, because the animals keep their distance.

When to Go and What to Expect

November to April is the practical window. Summer highs can reach 40°C, and the westerly wind averages 70 km/h with gusts above 140 km/h — a hat and a windproof layer matter more than a camera strap. Winter brings −15°C nights, snow, and the risk of the gravel road closing.

Spring and autumn are my preference: shorter queues at the museum, softer light, and temperatures you can walk in for two hours without suffering. Annual rainfall is under 200 mm, so the sky is usually clear, but the weather flips fast on the plateau and there is no shelter along the trail.

Rules are enforced firmly. Do not step off the marked path, do not collect stones or fossils of any size, do not smoke, and do not bring pets. A ranger will ask you to empty your pockets if they suspect anything.

Frequently Asked Questions

Do I need to book or pay in advance?

No. Entry is free and there are no reservations — you register with the rangers at the access area when you arrive. Opening hours run roughly 9:00–19:00 in summer (October–March) and 10:00–17:00 in winter (April–September), though these change with conditions and staffing, so confirm the current schedule through Argentina's national parks administration before a long drive.

Can I visit without a car?

Realistically, no. Provincial Route 49 is gravel with no public transport, and the nearest towns are 140 km away. Some travelers reach the park on organised excursions from Puerto Deseado or Caleta Olivia, but independent visitors need their own vehicle and a full tank, since there is no fuel near the park.

How long does the visit take?

Plan two to three hours: around 20 minutes in the museum, 60–90 minutes on the 2 km trail, and time for the ranger briefing. The driving is the bigger commitment — about 50 km of ripio each way from RN3.