Initial mapping was compiled on uncontrolled mosaics prepared during Viking mission operations. Although these mosaics were produced at a wide range of scales, were not uniform in format, and did not cover the entire area of interest, this preliminary mapping provided insight into local geologic relations. The map portrays inferred rock units, stratigraphic relations, and other features such as faults. From this mapping, the major impact, tectonic, and volcanic events that have shaped the surface of Mars are interpreted, as are modifications produced by wind, water, and other agents of gradation. Definition of possible rock units is based on assessment of their geomorphology, albedo, spectral properties, and thermal characteristics.
Line geometry is topologically clean.
During shaded relief portrayal, features on these bases were used to position details taken from Viking Orbiter pictures. The shading is not generalized and accurately represents the character of surface features. Shaded relief analysis and portrayal were made by Barbara J. Hall. Information has been obtained from sources believed to be reliable, but its accuracy and completeness and the opinions based thereon, are not guaranteed.