Morphological analyses of Utopia Planitia, Mars, have led to the hypothesis that the region contains a substantial amount of near‐surface ice. This paper tests this hypothesis using ground‐penetrating radar techniques. We have identified an expansive radar reflective region spanning approximately 375,000 km² in SHAllow RADar (SHARAD) data over western Utopia Planitia. The SHARAD reflective regions coincides with high densities of scalloped depressions and polygonal terrain. The reflectors are associated with layered mesas ∼80–170 m thick. We find a value of 2.8 ± 0.8 for the dielectric constant of the material overlying the reflectors. This work finds that the dielectric constant is consistent with a mixture of ice, air, and dust, containing a water ice volume up to 14,300 km³ in this unit.

Glacial landforms on Mars, including concentric crater fill (CCF), lineated valley fill (LVF), and lobate debris aprons (LDA), were mapped between ~ ±30 and 50° latitude, and geometric constraints were placed on the volume of these deposits based on their topography and relationship with host topography (e.g., massifs, valleys, and craters). LDA deposits were found to have the largest volume (2.63 × 10⁵ km³), followed by CCF deposits (8.75 × 10⁴ km³) and LVF deposits (6.51 × 10⁴ km³), for a total volume of 4.16 × 10⁵ km³. The actual ice sequestered in these deposits is calculated depending on the estimated fraction of ice currently remaining in the deposits. We adopt end-member values of 30% (pore ice only) and 90% (relatively pure, debris-covered glacial ice). These volumes, 1.25 × 10⁵ km³ and 3.74 × 10⁵ km³ respectively, represent an equivalent global ice layer 0.9–2.6 m thick. On the basis of extensive recent local and regional analysis of these deposits indicating a debris-covered glacial origin, we favor the larger estimate. Taken together, these glacial landforms have an average thickness of ~450 m. The glacial deposition responsible for these features occurred or recurred during an extended period of the middle to late Amazonian, which implies that long-term climate conditions were sufficient to produce and preserve debris-covered glacial landforms on Mars.

Water tracks are zones of high soil moisture that route water downslope over the ice table in polar environments. We present physical, hydrological, and geochemical evidence collected in Taylor Valley, McMurdo Dry Valleys, Antarctica, which suggests that previously unexplored water tracks are a significant component of this cold desert land system and constitute the major flow path in a cryptic hydrological system. Geological, geochemical, and hydrological analyses show that the water tracks are generated by a combination of infiltration from melting snowpacks, melting of pore ice at the ice table beneath the water tracks, and melting of buried segregation ice formed during winter freezing. The water tracks are enriched in solutes derived from chemical weathering of sediments as well as from dissolution of soil salts. The water tracks empty into ice-covered lakes, such as Lake Hoare, resulting in the interfingering of shallow groundwater solutions and glacier-derived stream water, adding complexity to the geochemical profile. Approximately four orders of magnitude less water is delivered to Lake Hoare by any given water track than is delivered by surface runoff from stream flow; however, the solute delivery to Lake Hoare by water tracks equals or may exceed the mass of solutes delivered from stream flow, making water tracks significant geochemical pathways. Additionally, solute transport is two orders of magnitude faster in water tracks than in adjacent dry or damp soil, making water tracks “salt superhighways” in the Antarctic cold desert. Accordingly, water tracks represent a new geological pathway that distributes water, energy, and nutrients in Antarctic Dry Valley, cold desert, soil ecosystems, providing hydrological and geochemical connectivity at the hillslope scale.