Scientists have discovered a process that could explain the long-debated mystery of how land features on Mars are formed in the absence of significant amounts of water. Experiments reveal that Mars' thin atmosphere (about 7 mbar -- compared to 1,000 mbar on Earth) combined with periods of relatively warm surface temperatures causes water flowing on the surface to violently boil. This process can then move large amounts of sand and other sediment, which effectively 'levitates' on the boiling water.