Nature Research, Nature, 7069(438), p. E10-E10, 2005
DOI: 10.1038/nature04358
Full text: Unavailable
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.