26. Fractures

Craters can be used to constrain the timing of tectonic activity by using the principle of superposition. The highly degraded 53-km-diameter crater shows extensive deformation by the fractures, but the fresher craters exhibiting pristine ejecta blankets appear undeformed. Therefore, the sequence of events for this region can be summarized as follows: (1) formation of the large impact crater, (2) partial burial of crater and its surroundings, (3) fracturing of the region, and (4) formation of smaller impact craters.

53-km-diameter crater at 53.83° N, 97.38° W; Viking Orbiter frame 701B82

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