What evidence points toward later Martian epochs when surface water was likely highly saline?

Answer

The abundance of hydrated sulfate salts

Sulfate salts are left behind when water evaporates. Their widespread presence suggests that later surface water often had a high salt content (brine), which lowers the freezing point, allowing liquid to persist briefly under colder conditions.

What evidence points toward later Martian epochs when surface water was likely highly saline?
MarsGeologywaterevidencehypothesis