Hartmann and his group sought young lava flows and derive ages as young as 10 Myr to 100 Myr. Independent isotopic dating of 19 Martian meteorites reveals lavas from different sites, dating 170 to 575 Myr old, plus older rocks. Some of these show water flow activity within the last 670 Myr. Martian erosion gullies look even younger, and similar water erosion features have been found in Iceland, Greenland, and Canada.
Young aquifers have implication for life on Mars.