Viking 1 landed on volcanic terrain in the plains of Chryse. Stereo pictures reveal an undulating topography. Bedrock is exposed along several ridge crests. Blocks are more numerous than can be attributed to impact ejecta. The presence of an apparent variety of rock types suggests in situ weathering of extrusive and near-surface basaltic igneous rocks along a linear volcanic vent. Fine-grained sediment is present in drift complexes and isolated drifts. During the course of the Viking mission a small patch of fine-grained sediment slumped down one of the drift faces. Otherwise, no morphological changes unrelated to spacecraft activity have been observed.