Upper Plains Unit

The Upper Plains Unit is the remnants of a 50-100 meter thick mantling that has been discovered in the mid-latitudes of the planet Mars. It was first investigated in the Deuteronilus Mensae (Ismenius Lacus quadrangle) region, but it occurs in other places as well. The remnants consist of sets of dipping layers in impact craters, in depressions, and along mesas. Sets of dipping layers may be of various sizes and shapes—some look like Aztec pyramids from Central America.

Layered structure in crater that is probably what is left of a layered unit that once covered a much larger area. Material for this unit fell from the sky as ice-coated dust. The picture was taken by HiRISE, under the HiWish program. Picture is from Hellas quadrangle.

Dipping layers, as seen by HiRISE under HiWish program

Close view of dipping layers along a mesa wall, as seen by HiRISE under HiWish program Location is Ismenius Lacus quadrangle.

Dipping layers in a crater, as seen by HiRISE under HiWish program

Layered features in crater, as seen by HiRISE under HiWish program

Layered feature in crater, as seen by HiRISE under the HiWish program

Layered feature in Red Rocks Park, Colorado. This has a different origin than ones on Mars, but it has a similar shape. Features in Red Rocks region were caused by uplift of mountains.

Dipping layers, as seen by HiRISE under HiWish program

Layered structures, as seen by HiRISE under HiWish program

Dipping layers, as seen by HiRISE under HiWish program

This unit also degrades into brain terrain. Brain terrain is a region of maze-like ridges 3–5 meters high. Some ridges may consist of an ice core, so they may be sources of water for future colonists.

Small, layered structure, as seen by HiRISE under the HiWish program Picture also shows brain terrain forming. Brain terrain seems to start with pits that get longer and more complicated. Picture is from Hellas quadrangle.

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Wikipedia