The Warrego Valles are a set of channels in an ancient river valley in the Thaumasia quadrangle of Mars, located at 42.2° south latitude and 93° west longitude.

[1] Mariner 9 and Viking Orbiter images showed a network of branching valleys in Thaumasia called the Warrego Valles.

These networks are evidence that Mars may have once been warmer, wetter, and perhaps had precipitation in the form of rain or snow.

[2] A study with the Mars Orbiter Laser Altimeter, Thermal Emission Imaging System (THEMIS) and the Mars Orbiter Camera (MOC) support the idea that the Warrego Valles were formed from precipitation.

[3] Planetary scans display evidence of rainfall related processes such as fluvial erosion.