Ischigualasto Provincial Park

Ischigualasto is a dry basin in northeastern San Juan province where the ground itself reads like a book of the Late Triassic. Here, in rocks laid down roughly 231 to 226 million years ago, lie some of the earliest dinosaurs known anywhere — and around them a landscape so stripped and strange that by the 1940s it was already being called the Valle de la Luna, the Valley of the Moon. The name Ischigualasto is said to come from the Diaguita language, rendered either as "a place where there is no life" or "where the moon comes to rest".

The appeal is the scenery that erosion has carved out of soft grey, green, purple and red sediments. Bands of colour run across the Valle Pintado, the Painted Valley; on a bare plain called the Cancha de Bochas lie dozens of near-perfect stone spheres, concretions weathered out of the clay like balls left after a game; the Submarine rises from the flat ground like a conning tower; the Mushroom balances a wide cap on a slender stem. The Barrancas Coloradas, a long wall of red cliffs, close the horizon. The dark cone of Cerro Morado, an ancient volcanic chimney, can be climbed with a guide in about an hour for the view over the whole basin.

For palaeontologists the valley is a reference site of world importance. The Ischigualasto Formation has yielded more vertebrate fossils than any other layer of the basin, from beaked rhynchosaurs such as Hyperodapedon and mammal-like cynodonts such as Exaeretodon to the early dinosaurs Herrerasaurus and Eoraptor, whose discovery in the early 1990s reshaped ideas about how the dinosaurs began. Protected as a provincial park since 1971, it was added to the World Heritage List in 2000 together with Talampaya, the national park that adjoins it across the provincial border; a natural science museum in the park shows finds from the site.

Visits follow a circuit of about 40 km covered in around three hours, in your own vehicle in a convoy behind a park guide, which keeps the fragile ground untouched. The climate is harsh — summer temperatures can reach 45 °C, winter nights fall below freezing, and a steady wind blows from the south — so the low sun of morning and evening, when the formations throw long shadows and the colours deepen, is the time to see it at its finest.

Getting there

The nearest town is San Agustín de Valle Fértil, a little over 70 km away on provincial roads; Villa Unión in La Rioja is about 140 km by National Routes 76 and 150, and the city of San Juan roughly 300 km via Routes 40 and 150. Chilecito lies about 113 km away as the crow flies. The nearest airport is Capitán Vicente Almonacid Airport (IRJ) at La Rioja, about 135 km in a straight line and considerably farther by road. Tours run from San Juan, Valle Fértil and Villa Unión, and many travellers combine the park with Talampaya on the same trip.