Free Astronomy Magazine November-December 2016

consistent layers of dust, the Murray Buttes region that we know today has seen periods in which the erosive action of wind and water was dominant. The latter flowed in abundance in Gale Crater, as con- firmed by Curiosity shortly after its landing on the red planet. That combined action has resulted in the ero- sion and removal of less bonded material present above and around the buttes (material that, apparent- ly, was transported elsewhere), with the conse- quent exposure to the sunlight of the more hardened layers of the former dunes, which show clear- ly their sedimen- tary rock na- ture. The im- ages on these A bove, close-up view of a typical butte’s wall in the Mur- ray Buttes region. Below, from one of the hills’ slope, Curiosity rover managed to photograph the far edge of Gale Crater, just noticeable in the haze. [NASA/JPL-Caltech/MSSS]