Abstract
Although the nature of the early Martian climate is a matter of
considerable debate, the presence of valley networks (VN) provides
unambiguous evidence for the presence of liquid water on Mars’ surface.
A subaerial fluvial origin of VN is at odds with the expected phase
instability of near-surface water in the cold, dry Late Noachian
climate. Furthermore, many observed geomorphometric properties of VN are
inconsistent with surface water flow. Conversely, subglacial channels
exhibit many of these characteristics and could have persisted beneath
ice sheets even in a cold climate. Here we model basal melting beneath a
Late Noachian Icy Highlands ice sheet and map subglacial hydrological
flow paths to investigate the distribution and geomorphometry of
subglacial channels. We show that subglacial processes produce enough
melt water to carve Mars’ VN; that predicted channel distribution is
consistent with observations; and corroborate geomorphometric
measurements of VN consistent with subglacial formation mechanisms. We
suggest that subglacial hydrology may have played a key role in the
surface modification of Mars.