Beneath the cascading water lies a geological history that stretches back over 100 million years. The falls sit on the Parana Plateau, a massive layer of basalt rock formed by intense volcanic eruptions during the breakup of the supercontinent Gondwana. As the Iguazu River flowed over this hard volcanic surface, it encountered softer layers of sandstone beneath, causing the riverbed to erode and collapse into the tiered 'staircase' of waterfalls you see today. This is a prime example of what geologists call regressive fluvial erosion, meaning the falls are actually moving backward very slowly over time. Beyond the rocks, this park is a sanctuary for biodiversity. Within these 185,000 hectares of forest, you might spot exotic wildlife like the giant anteater, the rare giant otter, or even the elusive jaguar. Keep your eyes upward too, as over 450 species of birds, including colorful toucans and the Great Dusky Swifts that dive through the falls, call this place home.