When the tilt (or obliquity) is low, the poles are the coldest places on the planet, while the sun is located near the equator all the time.

When carbon dioxide moves from the poles, the atmospheric pressure increases, maybe causing a difference in the ability of winds to transport and deposit sand.

This study was done using stereo topographic maps obtained by processing data from the high-resolution camera onboard NASA's Mars Reconnaissance Orbiter.

[4][5] At first, by examining surface materials with Opportunity Rover, scientists discovered that groundwater had repeatedly risen and deposited sulfates.

[6][7][8][9][10] Later studies with instruments on board the Mars Reconnaissance Orbiter showed that the same kinds of materials exist in a large area that included Arabia.