Martian Geological Features

High-resolution images of Mars showing various geological formations, including craters, ridges, and the notable Valles Marineris canyon system.

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$During periods in Mars' history when the planet had greater axial tilt, shifts in atmospheric circulation may have favored the extensive accumulation of snow in some locations. Protonilus Mensae is just such a site of extensive glaciation. We can see a flow of material through the valleys between a complex of small mesas. Streamlines and flow fronts appear as subtle ridges. Some ridges appear perpendicular to the mesas indicating flow direction. Others appear concentric to the mesas and parallel to the valleys, where debris and now-underlying ice bunched up and moved down valley. Deflation of the ice has led to a rich collection of small-scale features. Polygonal patterns of fractures and fissures may be related to a combination of thermal contraction cycles and overall subsidence of the surface. Larger fractures may be glacial crevasses, caused by differential flow rates in the underlying ice. Other more complex patterns of swirled pits and hummocks may result from the continual loss$

$Granicus Valles form a low-lying complex of channel systems located west of the volcano Elysium Mons. They are one of several larger systems known as outflow channels because the water source is from the subsurface. In this case, Granicus Valles emanate from a series of fractures on the western flank of Elysium Mons. In this image, large, streamlined features and grooves have been carved by enormous water volumes into the floor of Granicus and point to the direction of flow towards the northwest. The floods of Granicus Valles are thought to have formed later in Mars history during the Amazonian epoch, several billion years ago.$