The importance of lake breach floods for valley incision on early Mars.

The surface environment of early Mars had an active hydrologic cycle, including flowing liquid water that carved river valleys and filled lake basins. Over 200 of these lake basins filled with sufficient water to breach the confining topography, causing catastrophic flooding and incision of outlet canyons. Much past work has recognized the local importance of lake breach floods on Mars for rapidly incising large valleys; however, on a global scale, valley systems have often been interpreted as recording more persistent fluvial erosion linked to a distributed Martian hydrologic cycle.

Surface boulder banding indicates Martian debris-covered glaciers formed over multiple glaciations.

Glacial landforms, including lobate debris aprons, are a global water ice reservoir on Mars preserving ice from past periods when high orbital obliquity permitted nonpolar ice accumulation. Numerous studies have noted morphological similarities between lobate debris aprons and terrestrial debris-covered glaciers, an interpretation supported by radar observations. On Earth and Mars, these landforms consist of a core of flowing ice covered by a rocky lag.

Flood volcanism in the northern high latitudes of Mercury revealed by MESSENGER.

MESSENGER observations from Mercury orbit reveal that a large contiguous expanse of smooth plains covers much of Mercury's high northern latitudes and occupies more than 6% of the planet's surface area. These plains are smooth, embay other landforms, are distinct in color, show several flow features, and partially or completely bury impact craters, the sizes of which indicate plains thicknesses of more than 1 kilometer and multiple phases of emplacement. These characteristics, as well as associated features, interpreted to have formed by thermal erosion, indicate emplacement in a flood-basalt style, consistent with x-ray spectrometric data indicating surface compositions intermediate between those of basalts and komatiites.