Letter | Published:

Ancient ocean on Mars supported by global distribution of deltas and valleys

Nature Geoscience volume 3, pages 459463 (2010) | Download Citation



The climate of early Mars could have supported a complex hydrological system and possibly a northern hemispheric ocean covering up to one-third of the planet’s surface1,2,3,4,5. This notion has been repeatedly proposed1,2,3,4,5 and challenged6,7 over the past two decades, and remains one of the largest uncertainties in Mars research. Here, we used global databases of known deltaic deposits, valley networks8 and present-day martian topography to test for the occurrence of an ocean on early Mars. The distribution of ancient martian deltas delineates a planet-wide equipotential surface within and along the margins of the northern lowlands. We suggest that the level reconstructed from the analysis of the deltaic deposits may represent the contact of a vast ocean covering the northern hemisphere of Mars around 3.5 billion years ago. This boundary is broadly consistent with palaeoshorelines suggested by previous geomorphologic, thermophysic and topographic analyses, and with the global distribution and age of ancient valley networks. Our findings lend credence to the hypothesis that an ocean formed on early Mars as part of a global and active hydrosphere.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.


  1. 1.

    , & Transitional morphology in the west Deuteronilus Mensae region of Mars: Implications for modification of the lowland/upland boundary. Icarus 82, 111–145 (1989).

  2. 2.

    , , , & Ancient oceans, ice sheets and the hydrological cycle on Mars. Nature 352, 589–594 (1991).

  3. 3.

    et al. Possible ancient oceans on Mars: Evidence from Mars orbiter laser altimeter data. Science 286, 2134–2137 (1999).

  4. 4.

    & The evolution of the martian hydrosphere: Implications for the fate of a primordial ocean and the current state of the northern plains. Icarus 154, 40–79 (2001).

  5. 5.

    et al. Episodic flood inundations of the northern plains of Mars. Icarus 165, 53–67 (2003).

  6. 6.

    & Oceans or seas in the martian northern lowlands: High resolution imaging tests of proposed coastlines. Geophys. Res. Lett. 26, 3049–3052 (1999).

  7. 7.

    & Paucity of candidate coastal constructional landforms along proposed shorelines on Mars: Implications for a northern lowlands-filling ocean. Icarus 185, 171–196 (2006).

  8. 8.

    , & Updated global map of martian valley networks and implications for climate and hydrologic processes. J. Geophys. Res.10.1029/2009JE003548 (2010, in the press).

  9. 9.

    & Worldwide initiation of Holocene marine deltas by deceleration of sea-level rise. Science 265, 228–231 (1994).

  10. 10.

    & Evidence for persistent flow and aqueous sedimentation on Mars. Science 302, 1931–1934 (2003).

  11. 11.

    , , & An intense terminal epoch of widespread fluvial activity on early Mars: 2. Increased runoff and paleolake development. J. Geophys. Res. 110, E12S15 (2005).

  12. 12.

    , & Positive identification of lake strandlines in Shalbatana Vallis, Mars. Geophys. Res. Lett. 36, L14201 (2009).

  13. 13.

    et al. Mars Orbiter Laser Altimeter: Experiment summary after the first year of global mapping of Mars. J. Geophys. Res. 106, 23689–23722 (2001).

  14. 14.

    et al. Ancient geodynamics and global-scale hydrology on Mars. Science 291, 2587–2591 (2001).

  15. 15.

    Martian cratering 8: Isochron refinement and the chronology of Mars. Icarus 174, 294–320 (2005).

  16. 16.

    , & An intense terminal epoch of widespread fluvial activity on early Mars: 1. Valley network incision and associated deposits. J. Geophys. Res. 110, E12S14 (2005).

  17. 17.

    & The timing of martian valley network activity: Constraints from buffered crater counting. Icarus 195, 61–89 (2008).

  18. 18.

    A cold and wet Mars. Icarus10.1016/j.icarus.2010.01.006 (2010, in the press).

  19. 19.

    et al. Possible ancient giant basin and related water enrichment in the Arabia Terra province, Mars. Icarus 190, 74–92 (2007).

  20. 20.

    & Valley network-fed, open-basin lakes on Mars: Distribution and implications for Noachian surface and subsurface hydrology. Icarus 198, 37–56 (2008).

  21. 21.

    et al. Large-scale spring deposits on Mars? J. Geophys. Res. 113, E08016 (2008).

  22. 22.

    & Sedimentary rocks on Mars. Science 290, 1927–1937 (2000).

  23. 23.

    & Hellas as a possible site of ancient ice-covered lakes on Mars. Icarus 154, 258–276 (2001).

  24. 24.

    , , & Geomorphic and stratigraphic analysis of Crater Terby and layered deposits north of Hellas basin, Mars. J. Geophys. Res. 112, E08009 (2007).

  25. 25.

    , & Styles and timing of volatile-driven activity in the eastern Hellas region of Mars. J. Geophys. Res. 110, E12S22 (2005).

  26. 26.

    & Oceans on Mars: An assessment of the observational evidence and possible fate. J. Geophys. Res. 108, 5042–5070 (2003).

  27. 27.

    & Differential subsidence and rebound in response to changes in water loading on Mars: Possible effects on the geometry of ancient shorelines. J. Geophys. Res. 109, E01005 (2004).

  28. 28.

    , , & Thermal isostasy and deformation of possible paleoshorelines on Mars. Planet. Space Sci. 52, 1297–1301 (2004).

  29. 29.

    , , , & Evidence for an ancient martian ocean in the topography of deformed shorelines. Nature 447, 840–843 (2007).

  30. 30.

    & Geologic Map of the Western Equatorial Region of Mars. (Misc. Invest. Ser. Map, I-1802–A, United States Geological Survey (USGS), 1986).

  31. 31.

    & Geologic Map of the Eastern Equatorial Region of Mars. (Misc. Invest. Ser. Map, I-1802–B, United States Geological Survey (USGS), 1987).

Download references


This research was supported by NASA Mars Data Analysis Program Grant no. NNX06AE08G. Comments of A. Fairen improved earlier versions of this manuscript. Supplementary Fig. S2 was obtained using the Generic Mapping Tools (P. Wessel, and W. H. F. Smith, New version of the Generic Mapping Tools released, EOS Trans. Amer. Geophys. U., vol. 76, pp. 329, 1995).

Author information

Author notes

    • Gaetano Di Achille

    Present address: Research and Scientific Support Department, European Space Agency, ESA-ESTEC, 2200AG Noordwijk, The Netherlands


  1. Laboratory for Atmospheric and Space Physics, University of Colorado, 392 UCB, Boulder, Colorado 80309, United States

    • Gaetano Di Achille
    •  & Brian M. Hynek
  2. Department of Geological Sciences, University of Colorado, 399 UCB, Colorado 80309, United States

    • Brian M. Hynek


  1. Search for Gaetano Di Achille in:

  2. Search for Brian M. Hynek in:


G.D.A. conceived this research study, implemented the deltas’ catalogue and the topographic analyses, and wrote the paper. B.M.H. compiled the valley networks database, discussed the results and contributed to the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Gaetano Di Achille.

Supplementary information

PDF files

  1. 1.

    Supplementary Information

    Supplementary Information

About this article

Publication history






Further reading