The study aims to detail the geologic and stratigraphic character of the martian northern plains, with particular regard to the role that near-surface ice has played in their evolutionary history. It is widely accepted that the uppermost layers of the northern plains are largely sediments that have been shaped  by processes involving water-ice, but no consensus has emerged as to whether the ice accumulated due to surface (freezing of wet sediments of fluvial, lacustrine or marine origin), atmospheric (condensation within the regolith, snow, or niveo-aeolian deposition), or subsurface (shallow groundwater) processes, or combinations of all three. Furthermore, although the spatial distributions of some landform types have been measured and correlated with latitude-controlled climatic processes, broad-scale heterogeneity in surface geomorphology exists within latitude bands, suggesting that regional geology and climate play a dominant role. Improving the geological context of the northern plains will help constrain outstanding questions about martian geological evolution, environmental change and – if ice here was once liquid water – astrobiology. To do this, the spatial distribution of landforms thought to be indicative of ice in the regolith must be assessed in more detail and in a representative way, and the types of materials in which these forms occur must be determined. This requires strategic, targeted geomorphological mapping.

The goal of the proposed work is to produce new geomorphological maps of the northern plains of Mars, and to identify not only the range of geologically recent, ice-related landforms, but also their association with subtly-expressed geological units.  The focus on latitudinal and longitudinal variations in surface geology, and the examination of the surface at high spatial scales, sets this mapping apart from previous work.  Earlier maps of the northern plains have been produced at a scale of 1:15,000,000 (hemisphere scale), but new high-resolution datasets permit increased geological and geomorphological detail to be seen. We will therefore produce geomorphological maps at larger scales, such as 1:1,000,000, by strategically defining latitudinal swaths that cover critical physiographic and geologic boundaries. This approach allows for detailed comparisons at regional scales. We will map a minimum of three long swaths, each covering one of the three main plains regions  (Acidalia, Arcadia and Utopia Planitiae). The main datasets being used, all in the public domain, are medium resolution CTX (5-6 m/pixel) and HRSC (colour and nadir, ~12.5-50 m/pixel) images, supported by higher resolution HiRISE (25 cm/pixel) and MOC (~2 m/pixel) images.

We have brought together experts in planetary geomorphology with experience in studying cold-climate features on Mars and the Earth. We include team members with cross-cutting expertise such as formal planetary mapping techniques and impact crater chronology, and will invite experts in spectral dataset analysis to help us understand surface composition. Our cartographic and topical science results will enhance the community’s understanding of the geologic evolution of this region of Mars. The proposed duration of our project is 18 months, with three meetings to be held at ISSI.