G. Neukum R. Jaumann H. Hiesinger E. Hauber M. H. Carr P. Masson B. Foing H. Hoffmann M. Kreslavsky S. Milkovich S. Van Gasselt J.W. Head 2005 <div id="Abs1-section" class="c-article-section"><div id="Abs1-content" class="c-article-section__content"><p><a href="https://www.nature.com/articles/nature04357" data-mce-href="https://www.nature.com/articles/nature04357">Gillespie<span>&nbsp;</span><i>et al</i>.</a>^{<a id="ref-link-section-d101162e424" title="Gillespie, A. R., Montgomery, D. R. &amp; Mushkin, A. Nature 438, doi: 10.1038/nature04357 (2005)." href="https://www.nature.com/articles/nature04358#ref-CR1" data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" aria-label="Reference 1" data-mce-href="https://www.nature.com/articles/nature04358#ref-CR1">1</a>}<span>&nbsp;</span>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^{<a id="ref-link-section-d101162e428" title="Head, J. W. et al. Nature 434, 346–351 (2005)." href="https://www.nature.com/articles/nature04358#ref-CR2" data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" aria-label="Reference 2" data-mce-href="https://www.nature.com/articles/nature04358#ref-CR2">2</a>}. They suggest that the ‘hourglass’ deposit, dated at more than 40 Myr old^{<a id="ref-link-section-d101162e432" title="Head, J. W. et al. Nature 434, 346–351 (2005)." href="https://www.nature.com/articles/nature04358#ref-CR2" data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" aria-label="Reference 2" data-mce-href="https://www.nature.com/articles/nature04358#ref-CR2">2</a>}, 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<span>&nbsp;</span><i>aufeis</i><span>&nbsp;</span>(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^{<a id="ref-link-section-d101162e439" title="Carr, M. J. Geophys. Res. 100, 7479–7507 (1995)." href="https://www.nature.com/articles/nature04358#ref-CR3" data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" aria-label="Reference 3" data-mce-href="https://www.nature.com/articles/nature04358#ref-CR3">3</a>,<a id="ref-link-section-d101162e442" title="Lucchitta, B. K. J. Geophys. Res. 89, suppl.B 409–418 (1984)." href="https://www.nature.com/articles/nature04358#ref-CR4" data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" aria-label="Reference 4" data-mce-href="https://www.nature.com/articles/nature04358#ref-CR4">4</a>}. We make particular reference to the key relationships in the accumulation zones.</p></div></div> application/pdf 10.1038/nature04358 en Springer Nature Are there active glaciers on Mars? (Reply) article