Early Mars was covered in ice sheets, not flowing rivers, researchers say

Source: Science Daily

A large number of the valley networks scarring Mars’s surface were carved by water melting beneath glacial ice, not by free-flowing rivers as previously thought, according to new research. The findings effectively throw cold water on the dominant ‘warm and wet ancient Mars’ hypothesis, which postulates that rivers, rainfall and oceans once existed on the red planet.

https://www.sciencedaily.com/releases/2020/08/200803120154.htm