Martian Geology

Ghost dunes spotted on Mars

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Science  27 Jul 2018:
Vol. 361, Issue 6400, pp. 376-377
DOI: 10.1126/science.361.6400.376-g

Voids in martian surface strata show where sand dunes once existed.

CREDIT: M. D. DAY AND D. C. CATLING, J. GEOPHYS. RES. PLANETS 10.1029/2018JE005613 (2018)

Sand dunes are imposing physical structures, but few signs of them are preserved in the geological record because their grains do not stick together and are moved by wind. Preservation can occur if a dune field is partially buried by lava or mud, which then forms a layer of hard rock. Subsequent erosion of the sand leaves holes where the dunes once were. These features, termed ghost dunes, were only recently identified on Earth. Day and Catling used images from the Mars Reconnaissance Orbiter spacecraft to identify two locations on Mars where there are hundreds of ghost dunes. Revealing long-vanished dunes will enable studies of Mars' ancient winds.

J. Geophys. Res. Planets 10.1029/2018JE005613 (2018).

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