Martian seeps and their relation to youthful geothermal activity

Gullies found on Martian hillsides by Malin and Edgett (2000) appear in man y cases to be formed by water seeps produced by underground aquifers. It is proposed that these aquifers result from geologically recent melting of pe rmafrost ice by sporadic, localized geothermal activity. This is consistent with evidence from crater counts and Martian meteorites that much higher-t emperature geothermal activity has produced volcanic activity and lava flow s within the last 200 Myr, and perhaps within the last 10 Myr. This hypothe sis explains an aspect initially described as surprising, namely concentrat ion of the gullies at high latitudes and on shadowed slopes. Similar featur es are found on Icelandic basaltic hillsides, which may be ideal analogs fo r further studies that may clarify the Martian phenomena.