Editor's Summary
14 June 2007
A stranger shore
The question of whether there were oceans on Mars is a compelling topic. All seemed clear when a set of surface features that ring the martian plains for thousands of kilometres were interpreted as relics of former shorelines. But topographic profiles along the putative shorelines revealed long-wavelength trends in elevation, with amplitudes of up to several kilometres. This argued against the shoreline hypothesis. Now, though, the ocean is back with a bang. Perron et al. show that polar wander — a change in the orientation of the planet's surface with respect to its pole of rotation — can explain the shoreline deformation. Moreover, the track of polar wander that would have caused the observed deformation seems consistent with the planet's rotational dynamics.
News and Views: Planetary science: Mars at the tipping point
There's a big problem with the idea of ancient oceans on Mars: if they were contained within the 'shoreline' visible today, sea level would not have been level. Could it be that Mars has since tipped over?
Maria T. Zuber
doi:10.1038/447785a
Letter: Evidence for an ancient martian ocean in the topography of deformed shorelines
J. Taylor Perron, Jerry X. Mitrovica, Michael Manga, Isamu Matsuyama & Mark A. Richards
doi:10.1038/nature05873
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