Nasa’s Perseverance rover has detected underground remains of an ancient river delta on Mars, offering some of the strongest evidence that water once flowed on the planet’s surface. The discovery was ...

Undisturbed river deltas are diverse ecosystems that encompass tidal wetlands and floodplains. Because of their rich soils and convenient positions for trade and transport, many deltas have also ...

The Colorado River once flowed with so much water that steamboats sailed on its wide, meandering stretches near the U.S.-Mexico border. When the environmentalist Aldo Leopold paddled the river’s delta ...