It was established on December 10, 1991, to protect the natural features, representative of the Semiarid Chaco and the High Monte ecoregions.

[1] In San Luis, the ecotone between the mountains and the Chaco is located west of the 400 mm (16 in) isohyet and covers about 800,000 ha (2,000,000 acres).

[3] Sierra de las Quijadas is located in the San Luis Basin, whose surface is composed of sedimentary, metamorphic, and igneous outcrops of various ages.

[5] During the Tertiary, the layers that had been deposited 120–100 mya were raised and folded by the tectonic processes associated with the formation of Sierras Pampeanas.

The uplift began 25 mya, and the Quijadas still rise, as the South American Plate continues its westward migration.

Deposited 110 mya, the formations contribute to the bulk of the area's relief, formin reddish, whitish and gray cliffs and gorges.

The rocks originate in the high-energy fluvial environments, associated with rivers that once flowed from the ancient Sierra del Desaguadero mountains.

The formations are made up of layers of conglomerate, sandstone, claystone and gypsum and are partly covered by modern fill.

[7] Lagarcito Formation, deposited around 100 mya, is found at the eastern slopes of the mountains, gradually diving into the surrounding plain.

[8] The park has a very pronounced drainage network, generated by stormwater runoff affecting the area, so the surface rocks are very susceptible to erosion.

[3] Sierra de las Quijadas is the only protected area in the Chaco – Monte ecotone, preserving flora and fauna of the San Luis Province.

[11] Within the park, 416 species have been identified, including 17 that are introduced, of which the French tamarisk is the most prominent, forming dense stands along the stream banks.

[12] The location of the national park in the Chaco – Monte ecotones entails the presence of representative species of both biomes.