<collapse brought about by winds

I see this as working hand-in-hand with item 1, simple dust buildup and collapse. Merely a breeze to topple the buildup, so it would not need to follow a specific wind direction.

collapse associated with moisture seepage weighting dust/sand particles to collapse

This one was to explain the apparent uniform altitude of the streaks' sources, however, this would only apply to craters. I see that the streaks are at varying levels along natural ridges. Also, the crater idea kills itself with the fact that they are steepest toward the rim, therefore the slippage would be expected to originate there anyway.

Wondering, though. What about craters? Are the streaks shown to be all around the bowl, or are they heavily concentrated in one section, possibly due to prevailing winds dropping additional particles, or knocking the grains loose?

Dan