From Jáchal, Ruta 150 continues west before joining Ruta 76 south toward Parque Provincial Ischigualasto — also known as the Valle de la Luna, a name coined by an early foreign visitor who noted that one section of the park floor looked like the surface of the moon, and which has since eclipsed the official name in common use. The park sits in the northeast corner of San Juan province, sharing its northern boundary with Talampaya in La Rioja; together the two protected areas cover the same continuous geological formation and were jointly inscribed as a UNESCO World Heritage Site in 2000.
Ischigualasto preserves the world's only complete stratigraphic sequence of continental sediments from the Triassic period — the 50-million-year era that preceded the Jurassic, during which the first dinosaurs appeared. Some of the oldest dinosaur remains ever found anywhere on earth were excavated here, including Eoraptor lunensis, a small bipedal predator dating to around 231 million years ago, recovered in the early 1990s and now one of the most significant paleontological finds of the 20th century. The work continues: the park remains an active research site and the fossils visible in the landscape are real, not reconstructions.
The standard circuit is 40 km of gravel road covered in the TR4, in a guided caravan. A park guide rides in the lead vehicle; caravans depart every hour and the circuit takes approximately three hours with five designated stops. No advance booking is needed for the traditional circuit — entry is in order of arrival. The five stops cover the park's main formations, each given a popular name that captures its shape with varying degrees of imagination: Valle Pintado (Painted Valley), a ridgeline of multicoloured sedimentary layers; La Cancha de Bochas (the Bocce Court), a flat grey field strewn with near-perfect spherical grey concretions, formed over millions of years as mineral deposits accumulated around buried nuclei; El Hongo (the Mushroom), a balanced rock eroded into a distinctive stem-and-cap shape; El Submarino, a dark elongated formation rising from the valley floor; and the Museo de Sitio Dr. William Sill, a small interpretive centre at the park base named for the American paleontologist who was central to establishing Ischigualasto's international scientific reputation and who, by his own request, is buried within the park boundaries.
The centre of the circuit — La Cancha de Bochas — is the image most people carry away: dozens of smooth grey spheres scattered across a pale, cracked plain under an enormous sky, with no vegetation, no sound, and no obvious explanation for how they got there. It looks like the set of something rather than a place that exists.
Deleting this waypoint is permanent and cannot be undone.