Why Iguazu Falls Is Moving Upstream 🇦🇷🤯 Iguazu Falls

Did you know Iguazu Falls is slowly moving upstream, and that it started where Argentina, Brazil and Paraguay meet? Argentina's Iguazu Falls is walking upstream. So what's pushing it 👣? Here, at the Devil's Throat, about half the river plunges into a single horseshoe on Brazil's border. But follow the water downstream. It races through a narrow canyon about 20 kilometers long, and the falls carved all of it. How? Centimeter by centimeter, the water saws back through stacked sheets of lava over 100,000,000 years old 🪚. How hard does it hit? In 1542, Spanish explorer Cabeza de Vaca took canoes down this river, which the Guarani called Big Water. The current hurled them toward the drop 🛶. Except no canoe could pass. His men dragged them out and carried them by hand for over half a league, under spray two lances high 💪. Yet that cliff wasn't born here. It began at the canyon's far end, where Argentina 🇦🇷, Brazil 🇧🇷 and Paraguay 🇵🇾 now meet. So what pushed it? A bigger river. The Parana carries over six times more water, and it carved its valley far deeper 🌊. Geologists think that left the Iguazu hanging above it, spilling over a ledge it has been sawing backward ever since 🔍. But it isn't finished. Upstream, rapids mark where older falls may once have stood, and one day Iguazu will fade into rapids too. And Cabeza de Vaca? A small fall at Iguazu now carries his name, Alvar Nunez, and it's walking upstream too. 📚 Sources: Ardolino & Miranda (2008), Las Cataratas del Iguazú. El agua grande, SEGEMAR Anales 46: 275 falls, 2,700 m front, canyon from the Paraná, upstream retreat begun at the triple frontier, Paraná vs Iguazú flow; IUGS Geoheritage: Iguazú / Iguaçu waterfalls; Álvar Núñez Cabeza de Vaca / Pero Hernández, Comentarios (1555), ch. XI (Madrid 1922 ed., via Internet Archive); Encyclopaedia Britannica: Iguazu Falls (Devil's Throat takes about half the flow); OpenStreetMap contributors: Río Iguazú and waterfall geometry (ODbL)