Geological Structure of the Upper Part of Nirgal Vallis, Mars

Photogeological analysis of the upper Nirgal Vallis area, located in the northwestern part of the Noachis Terra highland plain, has shown that there were at least two episodes of fluvial activity in this area: the Noachis, which resulted in the formation of channels on the slopes of the ancient volcano, and the Hesperian, which formed Her Desher and Nirgal Vallis and channels on the southern slope of the northwestern ancient uplift. Similar results for determining the absolute model age of the formation of channels and large craters may indicate that impact activity in this region was the main cause of episodic warming. In addition, glacial activity may have occurred in the study area during early Amazonian times, forming an erosion area near Her Desher Vallis.