🇦🇷 Argentina · Cuyo
Ischigualasto, popularly known as the Valley of the Moon, is one of the most astonishing places in Argentina: a provincial park of some 63,000 hectares in northeastern San Juan, where erosion carved a desolate, lunar landscape of impossible shapes in greys, ochres and reds. Declared a UNESCO World Heritage Site — together with its neighbour Talampaya, in La Rioja — it looks like another planet dropped into the middle of Cuyo.
But Ischigualasto is not only a spectacular landscape: it is one of the most important fossil sites in the world. Its rocks hold an almost complete sequence of the Triassic period, from more than 200 million years ago, and have preserved the remains of some of the first dinosaurs and of the ancestors of mammals. Herrerasaurus, one of the oldest dinosaurs known, was discovered here, among others. Walking through Ischigualasto is travelling back to the dawn of the dinosaurs.
The park is visited on a traditional circuit of about 40 km, in your own vehicle and in convoy, following an accredited guide, with stops at the most famous rock formations: El Submarino, El Hongo, La Cancha de Bochas, El Valle Pintado. There are also bike routes, hikes and, on certain dates, the magical visit under the full moon. Geology, palaeontology and absolute silence: Ischigualasto is one of the great natural experiences in the country.
Ischigualasto Provincial Park protects a unique geological landscape and one of the most complete records of the Triassic period in the southern hemisphere. More than 200 million years ago this area was a humid environment of rivers and vegetation where the first dinosaurs and the ancestors of mammals lived; their fossils were preserved in the rock. The province of San Juan declared it a protected area on 3 November 1971 for its palaeontological value, and on 30 November 2000 UNESCO declared it a World Heritage Site together with neighbouring Talampaya National Park. Primitive dinosaurs such as Herrerasaurus were found here. The full geological and palaeontological story is on our history page.
Read the full history ↓The province of sun and wine in the heart of Cuyo: Huarpe land, birthplace of Sarmiento, rebuilt after the devastating earthquake of 1944, of Syrah wineries, high cordillera and the lunar landscape of Ischigualasto.
Read the history of San Juan →No exact prices: a scale from $ (budget) to $$$$$ (luxury), with 2-3 options per category.
Origins, formation and what the sources say.
To understand Ischigualasto you have to travel far back in time: more than 200 million years, to the Triassic period of the Mesozoic era. What is today an arid, desolate desert was then a very different environment: a humid region crossed by rivers, lagoons and abundant vegetation, teeming with life. In those ecosystems lived the first dinosaurs and the ancestors of mammals, at a key moment in evolution, when these groups were only just diverging.
Over millions of years, sediments carried by the rivers buried the remains of those animals and plants, layer upon layer, preserving them in the rock. The result is extraordinary: Ischigualasto holds a nearly complete sequence of the Triassic period, one of the most complete in the southern hemisphere and perhaps in the world. It is, quite literally, an open book on the dawn of the dinosaurs, written in stone.
Ischigualasto's great scientific value lies in its fossils. Its rocks have yielded remains of Triassic vertebrates such as rhynchosaurs, dicynodonts, cynodonts (ancestors of mammals) and other animals that lived in the area more than 225 million years ago. But most celebrated of all are its primitive dinosaurs, among the oldest known on the planet.
The story of the discovery has specific names and dates. In 1957 the Argentine paleontologists Galileo Scaglia and Leocadio Soria came upon the first fossils of what would later be called the Ischigualasto Formation. The following year the American paleontologist Alfred Romer, of Harvard, arrived in the area and took part of the material back to the United States, an episode that caused some resentment in the Argentine scientific community. In response, the paleontologist Osvaldo Reig organized his own expeditions to Ischigualasto between 1959 and 1961 together with a young technician named José Bonaparte —who would in time become one of Argentina's most important paleontologists— and with the key collaboration of Victorino Herrera, a local guide and muleteer who knew the terrain like no one else and who showed the scientists where to find the bones. In his honor, Reig named the site's most famous fossil Herrerasaurus ischigualastensis: a bipedal predator some 230 million years old, one of the oldest dinosaurs ever found on the planet.
The most celebrated find would come more than three decades later. In 1991, an expedition led by the Argentine paleontologist Ricardo Martínez and the American Paul Sereno (University of Chicago) found in Ischigualasto the remains of a tiny dinosaur, barely a meter long, that was nearly discarded as just another rock until someone on the team noticed it had teeth. Formally described in 1993, it was named Eoraptor lunensis —'the dawn thief, of the moon'— a reference both to its age (231 million years) and to the Valley of the Moon itself. Eoraptor is today one of the strongest candidates for the most primitive dinosaur known, a kind of missing link that helps explain what the ancestors looked like of the whole lineage that, millions of years later, would produce Tyrannosaurus and Argentinosaurus. Between Herrerasaurus and Eoraptor, Ischigualasto became the world's reference site for studying the very dawn of the dinosaurs.
If the fossils tell the story of life, the landforms tell the story of erosion. Over millions of years, water, wind and great climatic shifts wore away the layers of sedimentary rock —of differing hardness, composition and color— deposited in that ancient Triassic landscape. The result is the desolate, lunar spectacle that gave the park its popular nickname: the Valley of the Moon.
Differential erosion —which bites hardest into the soft rocks and leaves the more resistant ones standing— sculpted the geoforms that astonish visitors today: the Submarine, the Mushroom, the mysterious Cancha de Bochas or 'bocce court' (a field strewn with almost perfect stone spheres), the colorful Painted Valley. The grays, ochres, reds and off-whites, and the impossible shapes, make Ischigualasto one of the strangest and most photogenic landscapes in Argentina, a place that seems to belong to another planet.
Recognition of Ischigualasto's exceptional value led to its protection. On November 3, 1971, the Government of the Province of San Juan declared it a protected area, mainly for its paleontological value, creating Ischigualasto Provincial Park, with some 63,000 hectares in the departments of Valle Fértil and Jáchal, on the border with La Rioja.
International consecration came on November 30, 2000, when Unesco declared Ischigualasto a World Heritage Site, jointly with neighboring Talampaya National Park, in La Rioja. Together the two parks form a geological and paleontological unit of global importance. Today, Ischigualasto is visited on guided circuits —the traditional vehicle circuit, plus bike outings, treks and the magical full-moon tour— that let visitors experience this unique testimony to the origin of the dinosaurs while protecting its fragile heritage.
Ischigualasto sits in the middle of the desert, but its base town is exactly the opposite: San Agustín del Valle Fértil, founded on April 4, 1788 by Pedro Pablo de Quiroga, owes its name to the Indigenous expression of Diaguita origin 'Chaj-Paj-Nai', meaning 'green country'. The contrast is no accident: while the park unfolds a lunar landscape, arid and mineral, just 73 kilometers away the town sits in a hill-country valley of abundant vegetation, vineyards, olive groves and citrus orchards —limes, oranges, grapefruit— with a microclimate far milder than the surrounding Andean environment. That combination of opposites, a green oasis at the gates of a lunar desert, is part of what makes the journey to this region of San Juan unforgettable.
For much of its history, Valle Fértil lived off a traditional rural economy: goat and cattle raising, vineyards and grain crops, and a life fairly isolated from the rest of the province. The declaration of Ischigualasto as a protected area in 1971 and, above all, its recognition as a World Heritage Site in 2000 changed that equation: the town became the obligatory logistical base for tens of thousands of visitors a year who come to see the Valley of the Moon, driving the growth of hotels, inns, restaurants and a tourism-services economy that now coexists with the farming life of old. The San Agustín reservoir, with fishing and boat rides, and the nearby Valle Fértil Natural Park, with trails and archaeological traces of the Indigenous cultures that inhabited the area before the Spanish arrived, round out an offering many travelers use to add an extra day before or after Ischigualasto.
Today, every April, Valle Fértil celebrates its founding anniversary with festivities that bring the community together and honor that double identity of 'green country' and gateway to the lunar desert. For anyone visiting the park, understanding this history helps put the whole trip in perspective: it is not just about touring ancient geoforms in a day, but about crossing, in barely an hour on the road, two landscapes and two human histories that could not be more different within the same province of San Juan.