Signs of water exist in this quadrangle, with ancient river valleys and networks of stream channels showing up as inverted terrain and lakes inside of Valles Marineris.

The word Chasma has been designated by the International Astronomical Union to refer to an elongate, steep-sided depression.

[9] In a study published in the journal Geology in August 2009, a group of scientists led by John Adams of the University of Washington in Seattle proposed that Valles Marineris may have formed from a giant collapse when salts were heated up, thereby releasing water which rushed out carrying mud through underground plumbing.

[3] High-resolution structural and geologic mapping in west Candor Chasma, presented in March 2015, showed that the deposits on the floor of the Candor chasma are basin filling sediments that were deposited in a wet playa like setting; hence water was involved in their formation.

The European Space Agency's Mars Express found possible evidence of the sulfates epsomite and kieserite.

Some cliffs on Mars show a few darker layers standing out and often breaking into large pieces; these are thought to be hard volcanic rock instead of soft ash deposits.

Probably having been formed in water, sulfate deposits are of great interest to scientists because they may contain traces of ancient life.

[19] Because Iron sulfates were sometimes found near the opaline silica, it is thought that the two deposits were formed with an acid fluid.

At a certain point the stored water broke through the rim of Holden and created a lake 200–250 m deep.

[25][26][27][28] Terraces and the presence of large rocks (tens of meters across) support these high discharge rates.

Other ways of making inverted relief might be lava flowing down a stream bed or materials being cemented by minerals dissolved in water.

On Earth, materials cemented by silica are highly resistant to all kinds of erosional forces.

Inverted relief in the shape of streams are further evidence of water flowing on the Martian surface in past times.

The Viking Orbiters caused a revolution in our ideas about water on Mars; huge river valleys were found in many areas.

Space craft cameras showed that floods of water broke through dams, carved deep valleys, eroded grooves into bedrock, and traveled thousands of kilometers.

[37][38][39] Deposits of water ice have been found in Candor Chaos in the middle area of Valles Marineris.

The neutron telescope on EXoMars found that up to 40.3 wt% of the top meter of soil is probably water ice.