NASA's Mars Global Surveyor shows Sinus Meridiani, the site of the largest outcropping of light-toned, layered sedimentary rocks on Mars. Sedimentary rocks are covered by a regolith of windblown sand and granules.

27 November 2004
Sinus Meridiani is the site of the largest outcropping of light-toned, layered sedimentary rocks on Mars. Last January, the Mars Exploration Rover (MER-B), Opportunity, landed in a portion of central Sinus Meridiani and has since that time been exploring the local outcrops of light-toned, sedimentary rock. Where Opportunity landed, most of the sedimentary rocks are covered by a regolith of windblown sand and granules. At the rover site, rock outcrops are found mostly in crater walls. Further to the north, the outcrops are not covered with sediment. Vast plains of exposed sedimentary rock, covering an area several times larger than all the sedimentary rock exposures of northern Arizona, New Mexico, and eastern Utah, combined, are found in northern and eastern Sinus Meridiani. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the northern Sinus Meridiani sedimentary rock outcrops. It also shows the locations of several meteor impact craters that have been degraded as the sedimentary rocks have been eroded away. The large, dark, circular area near the top of the picture may mark the location of a crater that is still mostly filled and buried beneath dark, windblown debris. The sedimentary rocks of northern Sinus Meridiani have been known to occur there for at least the past seven years. They were initially described in a paper in Science describing MOC results about sedimentary rocks on Mars, published in December 2000 (see "Sedimentary rocks of early Mars"). This image is located near 2.3°N, 2.0°W, and covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the upper left.

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