LAUSR

Abstract Mars has experienced widespread glaciation across the mid-latitudes during the Late Amazonian. Deglaciation has altered these mid-latitude regions, and the characteristics of deglaciation can be useful in determining the variability in environmental response to climate change. The paraglacial period describes the period over which deglaciation occurred, and is characterized by a suite of features that form due to ice loss. Glaciated craters in the martian mid-latitudes were documented for evidence of paraglacial activity to determine how local crater setting affects deglaciation. Five paraglacial features were identified: spatulate depressions, washboard terrain, gullies, polygons, and broad pits, and their occurrence in each glaciated crater was recorded. 71% of glaciated craters (~450 craters) contained some evidence of paraglacial activity. Relatively more southern hemisphere glaciated craters contained paraglacial features (89%) than northern hemisphere glaciated craters (42%). The spatial density of paraglacial features varies with location. Different combinations of paraglacial features were found in each crater, although some features were preferentially associated, including washboard terrain and gullies, and broad pits and polygons, suggesting dependent formation mechanisms. More types of paraglacial features (up to all five features) were found in small craters (~5–10 km) at a range of elevations, and at modest latitudes (~35–45°), which corresponds to a large region of the southern highlands. Few or no paraglacial features were found in craters containing glacial fill exceeding ~70% of their predicted depth. The thickness of crater fill appears to be the dominant control on paraglacial response, which is affected by crater diameter, and partly by latitude. The variation in thickness of crater fill is attributed to variable accumulation and ablation rates during peak glacial periods during the Late Amazonian. The similarity in paraglacial feature morphology across the mid-latitudes of both hemispheres suggests that deglaciation and paraglaciation operate via similar mechanisms, although climatic conditions and geologic setting at each crater will determine the specific pathway for paraglacial activity to occur. These observations can be used to predict where future paraglacial activity will occur, and where it may be inhibited.