Abstract:
A description is presented of 18 Martian basins which were newly discovered on Viking photographs. A study of the basins reveals that diameter dependent differences in the morphology of Martian basins are more complex than previously realized. Basins have been classified according to ring morphology, and a diameter dependent sequence apparently exists. The obtained morphology sequence does not conform to the progression observed on the moon, Mercury, and earth. The small Martian basins are 50 to 100 km smaller than any basin on Mercury and the moon, supporting the view that they are unique to Mars. On earth there are significant terrain influences on crater and basin morphology that encourage the speculation that localized unique characteristics of the Martian crust led to basin formation at diameters where craters would normally be formed.
