Robert Clark writes: [[ Albin and King in their report
"ORIGIN OF DARK SLOPE STREAKS WITHIN THE SCHIAPARELLI IMPACT BASIN, MARS.", http://www.lpi.usra.edu/meetings/lpsc2001/pdf/1395.pdf , proposed a CO2 gas release to support the long flows of the streaks that can extend over a kilometer.
Why again in Arabia then?]]

Yes, the geographical (areographical?) distribution doesn't seem to be accounted for by any variants of the dust slide hypothesis. The clincher for me, though, that these streaks are probably something other than dust slides was the lightening of streaks' color over time that can be inferred by the observation that darker streaks overlay lighter streaks and never the reverse. There are two images Jill or Efrain found showing the color of some of the streaks is even lighter than the background. When I was editing the paper, I made sure to emphasize that point, because it seems to pretty much rule out deposition of airborne light-colored dust as the explanation for the color change.

The paper suggests that the color change is due to some chemical reaction between a flowing liquid and the underlying terrain, or possibly salts left behind after the liquid has sublimated. I realize now that the salt deposition idea doesn't hold water (so to speak), because the color change is a very gradual process, while the sublimation of the liquid must be very rapid, assuming that the streaks are caused by a liquid and that liquid is water.

Another possibility that we didn't think of until after the paper was written is that the color change is produced by exposure to sunlight. This may be the best explanation, actually. If true, then something in the flowing substance has never before been exposed to sunlight, which suggests the substance originated beneath the surface and not on the slopes where the streaks are found.

Perhaps it could be argued in favor of the dust slide theory that the rock surfaces themselves never received much sunlight while buried under the dust layer and become lighter in color when exposed by the dust slides. But if these surfaces are hundeds of millions of years old, I don't see how these surfaces could have avoided exposure to the sun over that length of time.

As for the reference to Hoagland in the paper, I suggested it be removed to avoid trouble. Then I had second thoughts about it since Hoagland was in fact the person who suggested to Efrain doing the plot of the distribution of the streaks. It would have been kind of gutless to deny him the credit he deserved just to avoid giving offense to the delicate sensibilities of some people.