In a side gully, an hour’s walk southwest of Torotoro on the Cerro de las Siete Vueltas (Mountain of Seven Turns; so called because the trail twists seven times before reaching the peak), there is a major sea-fossil deposit. At the ravine's base you may see petrified shark teeth, while higher up, the limestone and sedimentary layers are set with fossils of ancient trilobites, echinoderms, gastropods, arthropods, cephalopods and brachiopods. The site is thought to date back about 350 million years.
There’s another significant sea-fossil site in the Quebrada Thajo Khasa, southeast of Torotoro.