These adjacent national parks are in the mountainous desert region of north-western Argentina. The spectacular red-coloured rocks were formed by layers of sediments deposited by rivers, lakes and swamps. The deposits contain Triassic fossils including the ancestors of mammals and dinosaurs and primitive crocodiles and plants. Though in the past the area was a tropical swamp, today the area has sparse desert vegetation with cacti. The fauna now includes Andean condor, puma, guanaco, mara and viscacha and numerous passerine birds. Before the Spanish conquest, the area was inhabited by several groups of indigenous tribes, semi-nomadic hunters and gatherers. Their evidence lies in rock art, artefacts and archaeological sites. At Talampaya, many sites have been unearthed and are easily accessible. At Ischigualasto, six sites of rock art have been discovered plus cave and rock overhang habitation sites, as well as burial sites, campgrounds and tool-making areas. The whole area is a World Heritage Site.