Planetary science: Are there active glaciers on Mars? (Reply)
Jaumann, R.; Head, J. W.; Neukum, G.; Hiesinger, H.; Hauber, E.; Carr, M.; Masson, P.; Foing, B.; Hoffmann, H.; Kreslavsky, M.; Werner, S.; Milkovich, S.; van Gasselt, S.; HRSC Co-Investigator Team
United States
Abstract
Gillespie et al. concur with our interpretation that certain lobate equatorial and mid-latitude features on Mars are due to debris-covered glaciers formed largely during past periods of increased spin-axis obliquity, when climate regimes favoured snow and ice accumulation and glacial flow. They suggest that the `hourglass' deposit, dated at more than 40 Myr old, could be active today owing to an additional mechanism that supports ``local augmentation of accumulation from snowfall'' without climate change on Mars. This mechanism requires the present, or very recent, release of groundwater to the surface to form aufeis (groundwater-fed `glaciers') where the groundwater is generated by dewatering of hydrous compounds or melting by magmatic or impact-generated heat. We assess whether this suggestion applies to the deposits in question - it was previously proposed for much older deposits in other areas of Mars. We make particular reference to the key relationships in the accumulation zones.