A maze-like system of deep valleys in Mars called Noctis Labyrinthus ("the labyrinth of the night") may just be Martian life's last stand on the Red Planet:
Scientists have found water-bearing deposits on Mars that are out of step with what was happening elsewhere on the planet, raising the prospect that the sites could have hosted Martian life's last stand.
The deposits are a type of clay called smectites, which contain a blend of silica with aluminum, iron or magnesium. They form in the presence of water. [...] The Noctis Labyrinthus smectites are believed to have formed around 2 to 3 billion years ago, possibly providing a haven for life when the rest of the planet dried out.
"It was a surprise to see such young clays that must have formed in a persistent water under neutral conditions," Weitz said. "If there's life on Mars, if it had persisted, this would be a nice place for it, because it does indicate that there was water in this location on the surface at that relatively young age."
Read the rest at Discovery News: Link