Stratigraphic correlation chart of mapped units. Absolute period extents are adopted from G. Neukum & B. A. Ivanov (1994), who modified the stratigraphic scheme originally proposed by D. E. Wilhelms et al. (1987), as described by H. Hiesinger et al. (2023) and H. Hiesinger & K. Tanaka (2020). The range of ages for Shackleton crater were derived by D. A. Kring et al. (2021), P. D. Spudis et al. (2008), A. R. Tye et al. (2015), and M. T. Zuber et al. (2012).