Slides 13–17 show craters of similar size (25–27 km in diameter) in various stages of degradation. The amount of detail seen in the crater rim, interior, and ejecta blanket is a good indication of relative crater age.

17. Buried Crater

Overlying sediments have almost completely buried this 27-km-diameter crater. Only the outline of its rim indicates its existence.

64.02° N, 90.74° W; Viking Orbiter frame 701B59

The planetary environment is largely responsible for the appearance of impact craters and their interior and ejecta morphologies. Volcanic, tectonic, aeolian, and fluvial activity have modified the appearance of most martian impact craters.

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