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The Sinus Sabaeus quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS) Astrogeology Research Program. It is also referred to as MC-20 (Mars Chart-20).〔Davies, M.E.; Batson, R.M.; Wu, S.S.C. “Geodesy and Cartography” in Kieffer, H.H.; Jakosky, B.M.; Snyder, C.W.; Matthews, M.S., Eds. ''Mars.'' University of Arizona Press: Tucson, 1992.〕 The Sinus Sabaeus quadrangle covers the area from 315° to 360° west longitude and 0° to 30° degrees south latitude on Mars. It contains Schiaparelli, a large, easily visible crater that sits close to the equator. The Sinus Sabaeus quadrangle contains parts of Noachis Terra and Terra Sabaea. == Layers == Wislicenus Crater and the Schiaparelli basin crater contains layers, also called strata. Many places on Mars show rocks arranged in layers.〔Grotzinger, J. and R. Milliken (eds.) 2012. Sedimentary Geology of Mars. SEPM〕 Sometimes the layers are of different colors. Light-toned rocks on Mars have been associated with hydrated minerals like sulfates. The Mars Rover Opportunity examined such layers close-up with several instruments. Some layers are probably made up of fine particles because they seem to break up into fine dust. Other layers break up into large boulders so they are probably much harder. Basalt, a volcanic rock, is thought to in the layers that form boulders. Basalt has been identified on Mars in many places. Instruments on orbiting spacecraft have detected clay (also called phyllosilicates) in some layers. Scientists are excited about finding hydrated minerals such as sulfates and clays on Mars because they are usually formed in the presence of water.〔http://themis.asu.edu/features/nilosyrtis〕 Places that contain clays and/or other hydrated minerals would be good places to look for evidence of life.〔http://hirise.lpl.arizona.edu/PSP_004046_2080〕 Rock can form layers in a variety of ways. Volcanoes, wind, or water can produce layers.〔http://hirise.lpl.arizona.edu?PSP_008437_1750〕 Layers can be hardened by the action of groundwater. Martian ground water probably moved hundreds of kilometers, and in the process it dissolved many minerals from the rock it passed through. When ground water surfaces in low areas containing sediments, water evaporates in the thin atmosphere and leaves behind minerals as deposits and/or cementing agents. Consequently, layers of dust could not later easily erode away since they were cemented together. On Earth, mineral-rich waters often evaporate forming large deposits of various types of salts and other minerals. Sometimes water flows through Earth's aquifers, and then evaporates at the surface just as is hypothesed for Mars. One location this occurs on Earth is the Great Artesian Basin of Australia.〔Habermehl, M. A. (1980) The Great Artesian Basin, Australia. J. Austr. Geol. Geophys. 5, 9–38.〕 On Earth the hardness of many sedimentary rocks, like sandstone, is largely due to the cement that was put in place as water passed through. Image:Schiaparelli basin crater.jpg|Layers in crater found within the Schiaparelli crater basin as seen by Mars Global Surveyor. Image:Wislicenus Crater Floor.JPG|Wislicenus Crater Floor, as seen by HiRISE. Erosion on floor has made layers visible. Image:Schiaparelli Crater Layers.JPG|Layers in Crater within Schiaparelli crater, as seen by HiRISE. Image:Bouguer Crater from CTX.JPG|Bouguer Crater as seen by CTX. Crater rim is at top. Small craters are on floor of the crater. Image:Bouguercraterhirise.jpg|Close up of layers in eroded deposits on the floor of Bouguer Crater, as seen by HiRISE. This image is in a different part of the crater than the previous image. Image:Layers in Monument Valley.jpg|Layers in Monument Valley. These are accepted as being formed, at least in part, by water deposition. Since Mars contains similar layers, water remains as a major cause of layering on Mars. Image:26876whitelayers.jpg|White layers that may be related to the white material in Pollack Crater, as seen by HiRISE under HiWish program. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Sinus Sabaeus quadrangle」の詳細全文を読む スポンサード リンク
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