Geologists Discover New Type of Landform on Mars Called PBRs

Posted on March 22, 2012

University of Washington geologists have discovered a new class of landform on Mars. The geologists are calling the structures periodic bedrock ridges (PBRs). The ridges resemble sand dunes but instead of being made from material piled up by the wind, the ridges form from wind erosion of bedrock. The above images from NASA's Mars Reconnaissance Orbiter show exposed rock strata in periodic bedrock ridges on the floor of the West Candor Chasma on Mars.

David Montgomery, a UW professor of Earth and space sciences, says, "These bedforms look for all the world like sand dunes but they are carved into hard rock by wind. It is something there are not many analogs for on Earth."

Montgomery says the bedrock is a softer, more erodable type of bedrock. He says the ridges were formed by an unusual form of wind erosion that occurs perpendicular to the prevailing wind rather than in the same direction.

Montgomery also says the unique erosion could provide a way to examine the earlier history of Mars' geology. He says, "You could actually go back and look at some earlier eras in Martian history, and the wind would have done us the favor of exposing the layers that would have that history within it. There are some areas of the Martian surface, potentially large areas, that up until now we've thought you couldn't really get very far back into Mars history geologically."

The paper documenting the discovery was published online March 9 in the Journal of Geophysical Research, a journal of the American Geophysical Union.

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