page_title: Mars
section_title: Tectonic sites
hierarchical_section_title: Mars / Physical characteristics / Geography and naming of surface features / Tectonic sites
caption_attribution_description: English: A ragged geological scar crosses the belly of Mars. Long enough to reach from New York City to Los Angeles, this great rift in the martian crust is named Valles Marineris, or Mariner Valley. It was discovered in 1972 by the Mariner 9 spacecraft. Formed out of several parallel, connecting troughs, Valles Marineris dwarfs Earth's Grand Canyon in every respect, being wider, longer, deeper, and older. It easily earns the title of Grandest Canyon of All. This mosaic image of Valles Marineris - colored to resemble the martian surface - comes from the Thermal Emission Imaging System (THEMIS), a visible-light and infrared-sensing camera on NASA's Mars Odyssey orbiter. Mars Odyssey was built by Lockheed Martin and the mission is operated by the Jet Propulsion Laboratory. Built from more than 500 daytime infrared photos, the mosaic shows the whole valley in more detail than any previous composite photo. Despite the valley's huge extent - including its western extension through Noctis Labyrinthus, it reaches some 3,000 kilometers (2,000 miles) long - the smallest details visible in the image are about the size of a football field: 100 meters (328 feet). This is a reduced size (approximately one fourth the linear pixel density) and cropped (at the bottom) version of the original 23,711 x 11,856 pixel THEMIS mosaic, and has also been adjusted in hue and saturation.
context_page_description: Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, being only larger than Mercury. In English, Mars carries the name of the Roman god of war and is often referred to as the "Red Planet". The latter refers to the effect of the iron oxide prevalent on Mars's surface, which gives it a reddish appearance distinctive among the astronomical bodies visible to the naked eye. Mars is a terrestrial planet with a thin atmosphere, with surface features reminiscent of the impact craters of the Moon and the valleys, deserts and polar ice caps of Earth.
  The days and seasons are comparable to those of Earth, because the rotational period as well as the tilt of the rotational axis relative to the ecliptic plane are similar. Mars is the site of Olympus Mons, the largest volcano and highest known mountain on any planet in the Solar System and of Valles Marineris, one of the largest canyons in the Solar System. The smooth Borealis basin in the northern hemisphere covers 40% of the planet and may be a giant impact feature. Mars has two moons, Phobos and Deimos, which are small and irregularly shaped.
context_section_description: The large canyon, Valles Marineris (Latin for "Mariner Valleys", also known as Agathadaemon in the old canal maps), has a length of 4,000 kilometres (2,500 mi) and a depth of up to 7 kilometres (4.3 mi). The length of Valles Marineris is equivalent to the length of Europe and extends across one-fifth the circumference of Mars. By comparison, the Grand Canyon on Earth is only 446 kilometres (277 mi) long and nearly 2 kilometres (1.2 mi) deep. Valles Marineris was formed due to the swelling of the Tharsis area, which caused the crust in the area of Valles Marineris to collapse. In 2012, it was proposed that Valles Marineris is not just a graben, but a plate boundary where 150 kilometres (93 mi) of transverse motion has occurred, making Mars a planet with possibly a two-tectonic plate arrangement.
caption: Valles Marineris (2001 Mars Odyssey)
exif: {"Image Orientation": "Horizontal (normal)", "Image XResolution": "72", "Image YResolution": "72", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop Elements 9.0 Windows", "Image DateTime": "2012:09:15 23:07:27", "Image ExifOffset": "172", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "310", "Thumbnail JPEGInterchangeFormatLength": "4429", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "6000", "EXIF ExifImageLength": "2600"}