These geologic maps of the north and south polar regions of Mars, extending to 55 north and south latitudes, overlap by 2 the geologic maps of the western and eastern regions, which extend to lat 57 . In contrast, the south polar region is nearly completely covered by images at medium resolution but is not imaged at high resolution.
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. Information has been obtained from sources believed to be reliable, but its accuracy and completeness and the opinions based thereon, are not guaranteed.