rocks in the plains may have occurred when rocks were buried and interacted with thin films of water and dust. One sign that they were altered was that it was easier to grind these rocks compared to the same types of rocks found on Earth. See also Aeolis quadrangle Composition of Mars List of rocks on Mars Scientific information from the Mars Exploration Rover mission References External links Official Mars Rovers site January 19, 2004 JPL press release Rocks on Mars