"These hydrologic oddities illustrate how much we have still to learn about Earth's dynamic surface," researchers said in a new study.

Image caption, Up to 20 million litres of water flows over the Iguazu falls every second South America is also home ... sit on the Argentina-Brazil border. At 2.7 km (1.7 mi) wide, they are ...

The Rio Grande is a natural marvel and one of North America’s five longest ... The river provides water to more than 6 million people across South Texas and the Mexican states of Chihuahua ...