Monumento natural Pichasca, Natural monument in Río Hurtado, Chile

Pichasca is a 128-hectare natural monument in the Río Hurtado valley, Coquimbo Region, Chile, between 711 and 1,072 m above sea level. It protects a Late Cretaceous formation (about 80 million years old) called Viñita, with lower conglomerates and volcanic sandstones and upper andesitic lavas and breccias. Fossilized tree trunks and leaf imprints of gymnosperms and angiosperms, plus bone remains of titanosaurs of the genus Antarctosaurus, have been found here.

In 1972, Article 53 of Law No. 17,699 declared the petrified forest of Pichasca a national park, without setting its area or boundaries. In 1981 the state granted 128 ha of fiscal land to CONAF for renewable five-year use, and Decree 123 of 17 October 1985 made it a natural monument. Excavations at the Casa de Piedra rock shelter found human presence dating back about 9,920 years, a hunter-gatherer complex.

At the Casa de Piedra rock shelter, stratified deposits show human presence dating back about 9,920 years, attributed to a hunter-gatherer complex. Later groups painted abstract pictographs there, and the overhang was subsequently used by herders settled nearby.

Access is by private vehicle: the paved route leaves Ovalle past the Recoleta reservoir dam to Samo Alto, 2 km from the Pichasca village and 55 km from Ovalle. The site lies between 711 and 1,072 m, with marked slopes; January highs reach 30 °C and June lows 4 °C. A 20 km stretch of the Sendero de Chile crosses the monument between San Pedro de Pichasca and Las Minillas.

The dinosaur bones found here belong to titanosaurs of the genus Antarctosaurus, possibly Antarctosaurus wichmannianus, alongside fragments of turtle shells. The grey sculpted dinosaur at the site recalls these finds, which make the monument a centre for palaeontological research in a country where the discipline is little developed.