Seasonal flows on warm Martian slopes (also called recurring slope lineae, recurrent slope lineae and RSL) are thought to be either salty water flows occurring during the warmest months on Mars, or dry grains that "flow" downslope of at least 27 degrees.

The flows are narrow (0.5 to 5 meters) and exhibit relatively dark markings on steep (25° to 40°) slopes, appear and incrementally grow during warm seasons