Distribution and timing of thick transient air-fall deposits in Electris: Implications for the nature of the upland plains

A large area in the Electris region of Mars is (or once was) covered by an unconformable and etched deposit. Although interpreted as lava filling volcano-tectonic depressions or fluvial deposits filling large degraded craters, more recent work has shown the deposit is more likely the result of air-fall deposition. Crater densities on both the surface of the deposit and on exhumed, underlying ridged plains indicate that the deposit was emplaced and eroded over a relatively short time. These crater statistics also demonstate that the relative age of the Electris deposit is similar to those obtained for other unconformable deposits, thereby suggesting they may be related.