Below you will find a set a references that give the "dry dust avalanche" interpretation to the low albedo streaks, though some of you may not have access to the JGR-Planets paper published by Sullivan et al. in the October 25, 2001 MGS Special Issue, which gives a more detailed explanation than the various LPSC abstracts. At any rate, almost the entire set of dark streaks (interpreted as dust avalanche
scars) observed by the MOC N/A display acute upslope ends, many at rocky
outcrops (Sullivan et al., 2001; Sullivan et al., 2000; Sullivan et al., 1999; Edgett et al., 2000). Indeed, Sullivan et al. (2001; 2000) noted that the streaks' apexes are almost invariably found below more rugged, slightly steeper terrain
and distinct outcrops or knobs, which they interpreted as single-point
origins for each individual streak. Moreover, the lack of incised
channels with anastomosis and debris aprons argues for a dry downslope
mass movement origin (i.e. avalanche scars revealing a lower albedo
substrate) and against a fluid formation interpretation. Interestingly, Sullivan et al. (2001) found that the location of the dark streaks have a high degree correlation to areas of low thermal inertian (i.e., dusty), which strengthens their interpretation.

References:

Sullivan, Robert ; Thomas, Peter ; Veverka, Joseph ; Malin, Michael ; Edgett, Kenneth S. 2001
Mass movement slope streaks imaged by the Mars Orbiter Camera
J. Geophys. Res. Vol. 106 , No. E10 , p. 23,607 (2000JE001296)

Edgett, K.S., et al., Lunar Planet Sci XXXI, #1058 (2000)
http://www.lpi.usra.edu/meetings/lpsc2000/pdf/1058.pdf

Sullivan, R.J. et al., Lunar Planet Sci XXX, #1809, (1999)
http://www.lpi.usra.edu/meetings/LPSC99/pdf/1809.pdf

Sullivan, R.J. et al., Lunar Planet Sci XXXI, #1911, (2000)
http://www.lpi.usra.edu/meetings/lpsc2000/pdf/1911.pdf

Alex R. Blackwell
University of Hawaii