GEOMORPHOLOGICAL DIFFERENCES IN SLOPE STREAKS AND RSL

RSL and Slope Streaks have both been suggested to be formed via dry debris flows removing some of the surface dust cover. However, these features have vastly differing characteristics. We compare measured starting, stopping, and mean slopes; seasonality; fading rates; and wind strength and direction modeled via mesoscale modeling. RSL start and stop on slopes that are above the angle of repose. Combined with observations that show no movement of material, this suggests that RSL debris flows must be thin. In contrast, Slope Streaks start on fairly shallow slopes that appear to be below the angle of repose and stop at shallow slopes. The seasonality of RSL is linked to warmer periods and dusty conditions. Conversely, Slope Streaks appear to rapidly increase in number due to unknown one-time events, such as rock falls, Marsquakes, or nearby meteor impacts. One might envision that Slope Streaks that occur on the dustiest parts of Mars would fade more quickly than RSL (which occur in areas with the least dust). However, RSL fade much more quickly than Slope Streaks. This may be due to the fact that Slope Streaks are rougher than RSL, thus more dust is required to make them visually fade. Mesoscale simulations of near-surface wind strength and direction have, to date, shown little correlation to RSL or Slope Streak seasonality or orientation. In conclusion, many questions remain, such as: One-time trigger events must also occur in RSL regions, do they cause an enhancement of RSL activity? RSL and Slope Streaks are both consistent with dust-cleaning debris flows, although the trigger mechanisms between the two features must be vastly different and much more energetic for Slope Streaks. We continue to investigate more sites to further distinguish the differences between these two classes of features.