Morphology of Yardangs Within Nicholson Crater, Mars: Records of Past Fluvial and Aeolian Activities

Large scale landform modifications on varying temporal and spatial scales in response to past active processes are still evident on Mars providing important clues on the past climatic and environmental conditions. Nicholson crater on Mars is a ~100 km impact crater located near the dichotomy boundary. Based on a detailed morphological analysis using high resolution data, particularly from the Context Camera (CTX) onboard Mars Reconnaissance Orbiter, the present study attempts to bring out potential evidences of ancient fluvial processes and their subsequent modifications within this crater. This is manifested through the presence of inverted channel network, valley network, possible presence of a canyon/deep valley, presence of fluvially carved lobate features as well as fan/deltaic deposits observed at various locations throughout the crater. The yardang landform morphologies discussed here show prominent fluvial signatures on the intra-crater sedimentary mound, that are features shaped over millions of years. We recognise three distinct types of yardangs, for all of which, mostly wind direction and strength have played a major role in sculpting their distinct morphology. Although wind flow in different directions have played a role in sculpting varied yardang patterns, unidirectional wind strength seems to have played a common and predominant role in all the cases.