Yer, some salt flat with an area of ~80,000 km^3 and several km of relief! Slowly the "oodles of water" trickles away and we have an episodically altered environment. The papers in the Science Dec 3 issue showed how the altered rocks had suffered from a sequence of events i.e. diagenesis. Even formation of authigenic minerals, which have been redissolved and we now see only the casts. But how do we get episodic fluids? Mars has a long history of volcanism which produce acid volatiles - ready source of SO4, Cl and Br and H2O. Volumes involved are easily shown to be adequate for the extent of alteration seen. Any model for understanding what is seen on Mars must be holistic and cover where the fluids originate, how they remain stable, where the acidity arises, how Fe(II) becomes oxidised, how minerals crystallize and redissove, how some rocks are harder than others in a non-uniform distribution, why the spherules have a more uniform than random distribution, why the spherules are hematite, why jarosite has remained stable through the diagenesis, just to set out a few. Waving terms around such as playa or sabkha or salt-flat to me gets us nowhere.