Robert Clark wrote:
Again it is not clear to me with dust depostion all over Mars as well as high albedo areas you would expect these dust landslides to be concentrated in Tharsis and Arabia.

[snip]

A report given at the 1991 LPSC conference that references Lucchitta and Ferguson suggests their nearness to the equator is due to Viking orbiter images having better resolution at the equator:

[snip

However, this would still not explain their concentration in Tharsis and Arabia.

Alex writes:
Important points to be sure, but one should bear in mind that not all areas of Mars are "equally dusty"; the important point is to note where aeolian sinks exist that permit *active* accumulation of dust, not just those that serve as repositories for existing dust deposits. Moreover, a correlation of these areas to areas with local slopes/angles of repose that match model predictions for accumulations to overcome the values of angles of internal friction for low cohesion particles would have to be factored in. FWIW, both Tharsis and Arabia correspond, to first order, to these requirements. 'Nuff said, as I cannot really disclose the details on the still-embaroged JGR-Planets paper. At any rate, take care as I'm off to Europe tomorrow or thereabouts, assuming of course I can get a plane out ;-)

Alex R. Blackwell
University of Hawaii