Slope Lineae, Recurrent
Recurring slope lineae (RSL) are seasonal dark markings on steep slopes (25–40°) that appear and progressively grow throughout the warm season and subsequently fade in the cold season (McEwen et al. 2011). RSL generally originate at rocky bedrock outcrops on slopes and are frequently associated with small channels. RSL have been found between 50 and 30°S latitude on slopes facing the equator and reaching surface temperatures during summer of up to 300 K. At these temperatures, liquid brines could develop close to the surface and percolate downhill through the subsurface pore space resulting in dark surficial “water tracks” that are know from Antarctic environments (Levy 2012). However, the origin of these seasonal features on Mars remains debated.