The map area is in the Mangala-Memnonia region, which contains remarkably diverse geologic features and terrain types. Studies of the Mariner 9 images revealed the wide range of ages of the major rock units in this region; age assignments were based on the density of impact craters preserved on the various surfaces (Mutch and others, 1976, p. 56-60; Scott and Carr, 1978; Mutch and Morris, 1979). The region includes ancient cratered highlands, more sparsely cratered smooth plains, young volcanic plains, and the Mangala Valles channel system. The sinuousity of the streamlined landforms within the Mangala Valles, combined with braided channels evident throughout the lower reaches of the valley system, were recognized...
