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Mars Global Surveyor
Mars Orbiter Camera

Locations of Layer Outcrops

MGS MOC Release No. MOC2-265I, 4 December 2000



On Earth, sedimentary bedrock is best exposed in arid regions where there is little vegetation or soil to cover them up. For example, consider the colorful layered rocks of the Bryce, Zion, Arches, Canyonlands, Painted Desert, and Grand Canyon areas of southern Utah and northern Arizona. A similar relationship appears to hold on Mars. Instead of vegetation and soil, much of the martian bedrock is obscured by mantles of dust (and in some places, sand) that can be up to several meters (several yards) thick. However, there are a few places where erosion (and faults, in the case of the Valles Marineris) has exposed layered and massive sedimentary rock at the surface so that they can be seen by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) from orbit.

The dots on this map of Mars indicate all of the places identified from more than 65,000 MOC images acquired through October 2000 as having sedimentary rock outcrops. Most of them occur in six specific regions that are within 25° of latitude of the martian equator---Valles Marineris, Mawrth Vallis, Western Arabia Terra, Terra Meridiani, northern Hellas, and part of the Aeolis region south of Elysium Planitia.

The MOC scientists that have been photographing these outcrops suspect, however, that similar rocks must occur all over Mars, but are usually covered-up by dust and sand. The reason they suspect that these outcrops are common everywhere on Mars is that some exposures are found far outside the ±25° latitude zone--for example, there are layered rocks exposed within Galle Crater at 52.2°S, 30°W (see MOC image M04-00129 for example), and Spallanzani Crater at 58.3°S 273.3°W (see MOC image M02-03385 for example).

Most outcrops of martian sedimentary rock occur in impact craters. Others are found where both faulting and erosion have exposed them, as in the Valles Marineris and along the north-south boundary escarpment in the Aeolis region. Other layered outcrops, such as those in Terra Meridiani and northeastern Hellas, are found in the plains between impact craters.

The map shown here has 90°N at the top, 90°S at the bottom, the Prime Meridian (0° longitude) runs down the center, the equator across the center, and the sides are both at 180°W longitude.

Image Credit: NASA/JPL/Malin Space Science Systems

Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

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