Tres Cruces

Tres Cruces Natural Monument is an inland protected area in Chile's Coquimbo Region, set in the Andean foothills (precordillera) of the Elqui Valley in the commune of Paihuano, around 27 kilometres from the town of Vicuña via Route D-485. ^[1] Officially created on 11 December 2024, it was the first protected area established under Law 21,600, which set up Chile's new Biodiversity and Protected Areas Service (SBAP), and it covers roughly 708 hectares. The monument safeguards an exceptional combination of paleontological, geological, cultural and biological heritage, protecting Early Jurassic fossils alongside the distinctive desert and precordilleran scrubland of the Elqui foothills. Far from the coast, it has no marine environment; instead it represents Mediterranean desert scrub and tropical Andean low scrubland ecosystems. With more than 113 plant species and over 200 vertebrate species recorded, Tres Cruces protects a biodiverse Andean-foothill landscape in a region where very little territory had previously been formally protected.

Tres Cruces protects a surprisingly rich terrestrial fauna for an arid Andean foothill setting, with more than 200 vertebrate species recorded along with over 105 species of arthropods. ^[1] Birds are the most diverse group, while mammals and reptiles combined account for around 37 species, and only about three amphibian species are represented, reflecting the dry environment. The fauna is that of the desert and precordilleran scrublands of the Elqui Valley, adapted to heat, aridity and rugged terrain rather than to any coastal or marine habitat. Lizards and other reptiles are well represented among the rocks and scrub, while birds exploit the cacti, shrubs and seasonal resources of the foothills. This concentration of vertebrate and invertebrate diversity in a relatively small area underscores the monument's role in conserving the wildlife of an Andean-foothill ecosystem that had been largely unprotected in the Coquimbo Region.

The monument supports more than 113 plant species characteristic of the Mediterranean desert scrub and tropical Andean low scrubland of the Elqui precordillera. ^[1] Columnar cacti are a defining feature, including the copao (Eulychnia acida) and the quisco (Echinopsis chiloensis), alongside Puya bromeliads and a variety of desert shrubs such as Flourensia thurifera, Colliguaja odorifera, Adesmia hystrix and Ephedra breana. Several of the recorded species carry conservation classifications, with a number listed as endangered, vulnerable or near threatened, reflecting the botanical importance of the site. This precordilleran scrubland, shaped by aridity, strong sun and seasonal water from the Andes, is distinct from any coastal vegetation and represents an inland foothill flora. The protection of this plant community helps fill a significant gap in the conservation of the Coquimbo Region's dryland ecosystems.

Tres Cruces is notable above all for its geological and paleontological richness, set in the Andean foothills of the Elqui Valley. The monument preserves Early Jurassic marine fossils — part of the Tres Cruces Formation, dated to the Sinemurian through Pliensbachian stages (approximately 199–184 million years ago) — including ammonites, bivalves, brachiopods, gastropods and ichthyosaurs preserved in sandstone, conglomerate and fossil-rich limestone deposited in an ancient marine setting. ^[1] The terrain also features distinctive white quartz embedded in sandstone, a structural and mineralogical curiosity that adds to the site's geological interest and has contributed to its recognition as a geological heritage location (geositio) by Chile's National Geology and Mining Service. ^[2] The landscape is one of precordilleran ridges and scrub-covered slopes typical of the Elqui Valley's transition from desert lowlands toward the high Andes. This combination of fossil-bearing Early Jurassic strata, quartz-in-sandstone formations and foothill topography makes geology the cornerstone of the monument's protection.

The monument lies in the semi-arid Andean foothills of the Elqui Valley, where the climate is dry and sunny with strong day-night temperature contrasts typical of inland precordilleran zones. ^[1] Rainfall is scarce and concentrated in the cooler months, while skies are clear for much of the year, a quality that has made the wider Elqui Valley famous for astronomy. Summers are warm to hot in the lowlands, while elevation in the foothills moderates conditions and brings cooler nights. Water in this landscape comes largely from seasonal Andean runoff feeding the Elqui system rather than from abundant local rain. The desert and scrubland vegetation, including cacti and bromeliads, is closely adapted to this arid, high-sun regime, surviving long dry periods and exploiting the limited moisture available in the precordilleran environment.

The Elqui Valley around Paihuano has a long human history rooted in agriculture, pisco production and a strong cultural identity, and the Tres Cruces area reflects this heritage. The valley was inhabited and worked by Indigenous and later mestizo communities, and its precordilleran lands hold cultural as well as natural significance. The monument's modern story is tied to the discovery of its fossils by a local farmer in the 1960s, whose finds revealed the area's paleontological wealth and eventually drew the attention of researchers and the local community. ^[1] For years the site was promoted locally as a paleontological park, with PROVALLE (the corporation for the development of the Elqui Valley) receiving a land concession toward that goal, and its protection became a long-standing aspiration of the Paihuano community and local government, reflecting a grassroots commitment to safeguarding the valley's scientific and cultural heritage.

Tres Cruces was formally declared a Natural Monument on 11 December 2024 by Chile's Ministry of the Environment, protecting about 708 hectares of the Elqui precordillera in the commune of Paihuano. ^[1] Its creation was historic as the first protected area established under Law 21,600, the legislation that created the Biodiversity and Protected Areas Service (SBAP), marking a new chapter in Chilean conservation administration. The designation grew out of decades of local effort, beginning with the fossil discoveries of the 1960s and the community's long campaign to protect the site as a paleontological park. By granting it Natural Monument status, the state recognized the area's exceptional paleontological, geological, cultural and biological values and addressed a notable shortfall in protected land within the Coquimbo Region, where only a tiny fraction of territory had previously been conserved.

The monument's central attractions are its fossils and geological features, set amid the cacti and scrub of the Elqui precordillera. Visitors are drawn by the Early Jurassic marine fossils — ammonites, bivalves, brachiopods, gastropods and ichthyosaurs — preserved in outcroppings of sandstone and limestone, and the unusual white quartz embedded in sandstone, features that earned the site recognition as a geological heritage location and gave rise to its earlier identity as a paleontological park. ^[1] The desert and precordilleran landscape itself is a draw, with columnar copao and quisco cacti, Puya bromeliads and sweeping foothill scenery characteristic of the Elqui Valley. The clear skies of the region, renowned for astronomy, add to the appeal of the area. As a newly established monument in the foothills near Paihuano, its visitor experience centres on fossil and nature interpretation and the scenery of an Andean-foothill ecosystem rather than on extensive built facilities.

Tres Cruces is located in the commune of Paihuano in the Elqui Valley, roughly 27 kilometres from Vicuña via fully paved Route D-485, and reachable from the regional centre of La Serena through Route 41-CH connecting to Paihuano. ^[1] As a very recently created protected area, established at the end of 2024, its visitor infrastructure is still developing, and access arrangements may evolve as the new Biodiversity and Protected Areas Service and CONAF organize its management. The inland foothill setting means hot, dry, sunny conditions, and visitors should be prepared for an arid environment with limited shade and water. Because the monument is new, prospective visitors should confirm current access, opening status, guiding arrangements and any restrictions with the relevant authorities before travelling. Its position within the well-travelled Elqui Valley, a popular tourism and astronomy destination, makes it relatively reachable by regional standards.

Conservation at Tres Cruces focuses on safeguarding an exceptional bundle of paleontological, geological, cultural and biological values within a single 708-hectare monument in the Elqui precordillera. ^[1] Its protection preserves Early Jurassic marine fossils of the Tres Cruces Formation, distinctive quartz-in-sandstone geology, more than 113 plant species, over 200 vertebrate species and more than 105 arthropod species, several of them under conservation classifications such as endangered, vulnerable or near threatened. As the first area created under Law 21,600 and the new Biodiversity and Protected Areas Service, the monument carries symbolic weight for Chile's evolving conservation framework. It also helps remedy a stark protection gap in the Coquimbo Region, where only a small fraction of territory was previously safeguarded. Driven by years of local advocacy, its sustainable management aims to balance scientific study, education and community involvement with the protection of fragile fossils and dryland ecosystems.