Mars - Evidence for dynamic processes from Mariners 6 and 7.

Detailed study of the evolution of the Martian surface on the basis of an analysis of Mariner 6 and 7 photographs of certain features of the equatorial region of Mars. It is concluded that the planet Mars is characterized by an internal dynamic activity on the scale of the interior of the African plate. Cited as evidence are scarps resembling fault scarps in Meridiani Sinus and on the Hellas-Hellespontus border. Ridges associated with craters on the boundary of Hellas and Hellespontus are most easily explained by volcanic activity, and at least some of the associated craters may themselves be of volcanic origin. Ridges on the Hellas-Hellespontus border and part of the wall of Edom seem to bulge out into cratered swellings or domes. A sequence of events is worked out for different parts of Mars, and an attempt is made to develop a crude threefold geologic time scale. The sequence suggests that dynamic activity was confined neither to the earliest nor the latest periods of Martian history.