Giant Landform on Mars
Sandy landforms formed by the wind, or aeolian bedforms, are classified by
the wavelength--or length--between crests. On Mars, we can observe four classes
of bedforms (in order of increasing wavelengths): ripples, transverse aeolian
ridges (known as TARs), dunes, and what are called “draa.” All of these are
visible in this Juventae Chasma image.
Ripples are the smallest bedforms (less than 20 meters) and can only be
observed in high-resolution images commonly superposed on many surfaces. TARs
are slightly larger bedforms (wavelengths approximately 20 to 70 meters), which
are often light in tone relative to their surroundings. Dark-toned dunes
(wavelengths 100 meters to 1 kilometer) are a common landform and many are
active today. What geologists call “draa” is the highest-order bedform with
largest wavelengths (greater than 1 kilometer), and is relatively uncommon on
Mars.
Here, this giant draa possesses steep faces or slip faces several hundreds of
meters tall and has lower-order superposed bedforms, such as ripples and dunes.
A bedform this size likely formed over thousands of Mars years, probably
longer.
This image was acquired by the HiRISE camera aboard NASA's Mars
Reconnaissance Orbiter on Jan. 6, 2014. The University of Arizona, Tucson,
operates the HiRISE camera, which was built by Ball Aerospace & Technologies
Corp., Boulder, Colo. NASA's Jet Propulsion Laboratory, a division of the
California Institute of Technology in Pasadena, manages the Mars Reconnaissance
Orbiter Project for the NASA Science Mission Directorate, Washington.
Image Credit: NASA/JPL/University of Arizona
Caption: Matthew Chojnacki
Caption: Matthew Chojnacki
NASA
Guillermo Gonzalo Sánchez Achutegui
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