The Rocks of Chamangá include the highest concentration of rock paintings existing in the area of the River Plate Basin. 44 have been identified on record to date.
The rarity and exceptional value of the paintings is due to their location on granite blocks in open fields, and not in caves or eaves, as is the case with most of these manifestations in other parts of the world. Its antiquity is estimated to be between 900 and 1000 years. The paintings are reddish, with strokes and abstract geometric shapes, and were made with hematite (iron oxide), mixed with some organic material, possibly animal fat, to enable its adhesion to the rocks. The conservation of these lines is due to a “microscopic exudate" of silicates, a mineral that composes granite, and forms a kind of protective film that incorporates the hematite to the substrate, and does not allow the removal of organic material.
Geologically, the area is mainly composed of soft, rolling hills of around 100 meters in height. They are cut by small valleys or streams that feed the basins of the Chamangá, Maciel and Los Molles rivers.