38-836: [REDACTED] Look up amazonian in Wiktionary, the free dictionary. Amazonian may refer to: Amazonian (Mars) , a geologic system and time period on the planet Mars Amazon River , in South America Amazon basin , that river's drainage basin Amazon rainforest , rainforest covering most of the Amazon Basin Relating to the Amazons , female warrior tribe in Greek mythology Amazonian, an employee of
76-612: A bright surface layer of dust to expose a darker substrate. Research, published in January 2012 in Icarus, found that dark streaks were initiated by airblasts from meteorites traveling at supersonic speeds. The team of scientists was led by Kaylan Burleigh, an undergraduate at the University of Arizona. After counting some 65,000 dark streaks around the impact site of a group of five new craters, patterns emerged. The number of streaks
114-434: A central peak. The peak is caused by a rebound of the crater floor following the impact. Sometimes craters will display layers. Since the collision that produces a crater is like a powerful explosion, rocks from deep underground are tossed onto the surface. Hence, craters can show us what lies deep under the surface. A pedestal crater is a crater with its ejecta sitting above the surrounding terrain and thereby forming
152-436: A geologic period represents the time interval over which the strata of a system were deposited, including any unknown amounts of time present in gaps. Periods are measured in years, determined by radioactive dating . On Mars, radiometric ages are not available except from Martian meteorites whose provenance and stratigraphic context are unknown. Instead, absolute ages on Mars are determined by impact crater density, which
190-603: A given system are apt to contain gaps ( unconformities ) analogous to missing pages from a book. In some places, rocks from the system are absent entirely due to nondeposition or later erosion. For example, rocks of the Cretaceous System are absent throughout much of the eastern central interior of the United States. However, the time interval of the Cretaceous (Cretaceous Period) still occurred there. Thus,
228-432: A lattice-like manner. They are hundreds of meters long, tens of meters high, and several meters wide. It is thought that impacts created fractures in the surface, these fractures later acted as channels for fluids. Fluids cemented the structures. With the passage of time, surrounding material was eroded away, thereby leaving hard ridges behind. Since the ridges occur in locations with clay, these formations could serve as
266-525: A marker for clay which requires water for its formation. Water here could have supported past life in these locations. Clay may also preserve fossils or other traces of past life. Dark slope streaks are narrow, avalanche -like features common on dust-covered slopes in the equatorial regions of Mars . They form in relatively steep terrain , such as along escarpments and crater walls. Although first recognized in Viking Orbiter images from
304-501: A raised platform. They form when an impact crater ejects material which forms an erosion resistant layer, thus protecting the immediate area from erosion. As a result of this hard covering, the crater and its ejecta become elevated, as erosion removes the softer material beyond the ejecta. Some pedestals have been accurately measured to be hundreds of meters above the surrounding area. This means that hundreds of meters of material were eroded away. Pedestal craters were first observed during
342-478: A tight group of impact craters resulted. Dark slope streaks have been seen for some time, and many ideas have been advanced to explain them. This research may have finally solved this mystery. When a fluid moves by a feature like a mound, it will become streamlined. Often flowing water makes the shape and later lava flows spread over the region. In the pictures below this has occurred. , Many places on Mars show rocks arranged in layers. Rock can form layers in
380-653: A variety of ways. Volcanoes, wind, or water can produce layers. A detailed discussion of layering with many Martian examples can be found in Sedimentary Geology of Mars. 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 find dust. Other layers break up into large boulders so they are probably much harder. Basalt ,
418-452: 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 phyllosilicate ) in some layers. A detailed discussion of layering with many Martian examples can be found in Sedimentary Geology of Mars. Layers can be hardened by the action of groundwater. Martian ground water probably moved hundreds of kilometers, and in
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#1732757667810456-441: Is a geologic system and time period on the planet Mars characterized by low rates of meteorite and asteroid impacts and by cold, hyperarid conditions broadly similar to those on Mars today. The transition from the preceding Hesperian period is somewhat poorly defined. The Amazonian is thought to have begun around 3 billion years ago, although error bars on this date are extremely large (~500 million years). The period
494-436: Is also referred to as MC-8 (Mars Chart-8). The quadrangle covers the area from 135° to 180° west longitude and 0° to 30° north latitude on Mars . The Amazonis quadrangle contains the region called Amazonis Planitia . This area is thought to be among the youngest parts of Mars because it has a very low density of craters. The Amazonian Epoch is named after this area. This quadrangle contains special, unusual features called
532-613: Is heavily dependent upon models of crater formation over time. Accordingly, the beginning and end dates for Martian periods are uncertain, especially for the Hesperian/Amazonian boundary, which may be in error by a factor of 2 or 3. Amazonis quadrangle The Amazonis quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS) Astrogeology Research Program . The Amazonis quadrangle
570-479: Is shown below. Lava flows sometimes cool to form large groups of more-or-less equally sized columns. The resolution of the HiRISE images is such that the columns were found in various locations in 2009. Impact craters generally have a rim with ejecta around them, in contrast volcanic craters usually do not have a rim or ejecta deposits. As craters get larger (greater than 10 km in diameter) they usually have
608-505: Is sometimes subdivided into the Early, Middle, and Late Amazonian. The Amazonian continues to the present day. The Amazonian period has been dominated by impact crater formation and Aeolian processes with ongoing isolated volcanism occurring in the Tharsis region and Cerberus Fossae , including signs of activity as recently as a tens of thousands of years ago in the latter and within
646-586: Is the youngest of the Martian periods, the chronology of the Amazonian is comparatively well understood through traditional geological laws of superposition coupled to the relative dating technique of crater counting . The scarcity of craters characteristic of the Amazonian also means that unlike the older periods, fine scale (<100 m) surface features are preserved. This enables detailed, process-orientated study of many Amazonian-age surface features of Mars as
684-577: The Mariner missions. Research published in the journal Icarus has found pits in Tooting Crater that are caused by hot ejecta falling on ground containing ice. The pits are formed by heat forming steam that rushes out from groups of pits simultaneously, thereby blowing away from the pit ejecta. Linear ridge networks are found in various places on Mars in and around craters. Ridges often appear as mostly straight segments that intersect in
722-517: The Medusae Fossae Formation and Sulci. The Amazonis quadrangle is of great interest to scientists because it contains a big part of a formation, called the Medusae Fossae Formation . It is a soft, easily eroded deposit that extends for nearly 1,000 km along the equator of Mars. The surface of the formation has been eroded by the wind into a series of linear ridges called yardangs . These ridges generally point in direction of
760-499: The Martian surface; thereby exposing a dark layer. Dust devils on Mars have been photographed both from the ground and high overhead from orbit. They have even blown dust off the solar panels of two Rovers on Mars, thereby greatly extending their useful lifetime. The pattern of the tracks has been shown to change every few months. A study that combined data from the High Resolution Stereo Camera (HRSC) and
798-481: The Medusae Fossae Formation contain water. A very rugged terrain extends from the base of Olympus Mons . It is called Lycus Sulci. Sulci is a Latin term for the furrows on the surface of a brain, so Lycus Sulci has many furrows or grooves. The furrows are huge—up to a full kilometer deep. It would be extremely difficult to walk across it or to land a space ship there. A picture of this area
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#1732757667810836-430: The climate. This has included: Good preservation has also enabled detailed studies of other geological processes on Amazonian Mars, notably volcanic processes , brittle tectonics , and cratering processes . System and Period are not interchangeable terms in formal stratigraphic nomenclature, although they are frequently confused in popular literature. A system is an idealized stratigraphic column based on
874-700: The company Amazon.com Amazonian, a fictional species in the Futurama episode " Amazon Women in the Mood " Amazonians, people who live in the Amazon basin Indigenous peoples in Brazil See also [ edit ] Amazon (disambiguation) All pages with titles containing Amazonian Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with
912-464: The craters were formed. Since the craters were spotted in a HiRISE image from February 2006, but were not present in a Mars Global Surveyor image taken in May 2004, the impact occurred in that time frame. The largest crater in the cluster is about 22 meters (72 feet) in diameter with close to the area of a basketball court. As the meteorite traveled through the Martian atmosphere it probably broke up; hence
950-549: The late 1970s, dark slope streaks were not studied in detail until higher-resolution images from the Mars Global Surveyor (MGS) and Mars Reconnaissance Orbiter (MRO) spacecraft became available in the late 1990s and 2000s. The physical process that produces dark slope streaks is still uncertain. They are most likely caused by the mass movement of loose, fine-grained material on oversteepened slopes (i.e., dust avalanches). The avalanching disturbs and removes
988-470: The necessary details of form of the surface are still visible. Furthermore, the relative youth of this period means that over the past few 100 million years it remains possible to reconstruct the statistics of the orbital mechanics of the Sun , Mars , and Jupiter without the patterns being overwhelmed by chaotic effects, and from this to reconstruct the variation of solar insolation – the amount of heat from
1026-602: The past few million years on Olympus Mons , implying they may still be active but dormant in the present. The Amazonian System and Period is named after Amazonis Planitia , which has a sparse crater density over a wide area. Such densities are representative of many Amazonian-aged surfaces. The type area of the Amazonian System is in the Amazonis quadrangle (MC-8) around 15°N 158°W / 15°N 158°W / 15; -158 . Because it
1064-486: The physical properties, composition, particle size, and/or cementation. Very few impact craters are visible throughout the area so the surface is relatively young. Researchers found that nearly all the dust in that coats everything and is in the atmosphere has its origin in the Medusae Fossae formation. It turns out that the chemical elements (sulfur and chlorine) in this formation, in the atmosphere, and covering
1102-437: The physical rock record of a type area (type section) correlated with rocks sections from many different locations planetwide. A system is bound above and below by strata with distinctly different characteristics (on Earth, usually index fossils ) that indicate dramatic (often abrupt) changes in the dominant fauna or environmental conditions. (See Cretaceous–Paleogene boundary as example.) At any location, rock sections in
1140-447: The prevailing winds that carved them and demonstrate the erosive power of Martian winds. The easily eroded nature of the Medusae Fossae Formation suggests that it is composed of weakly cemented particles, and was most likely formed by the deposition of wind-blown dust or volcanic ash. Using a global climate model, a group of researchers headed by Laura Kerber found that the Medusae Fossae Formation could have easily been formed from ash from
1178-450: 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. Dust devil tracks can be very pretty. They are caused by giant dust devils removing bright colored dust from
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1216-436: The sonic boom of the airblast arrived from the impacts dust started to move down the slope. Using photos from Mars Global Surveyor and HiRISE camera on NASA's Mars Reconnaissance Orbiter, scientists have found about 20 new impacts each year on Mars. Because the spacecraft have been imaging Mars almost continuously for a span of 14 years, newer images with suspected recent craters can be compared to older images to determine when
1254-408: The sun – reaching Mars through time. Climatic variations have been shown to occur in cycles not dissimilar in magnitude and duration to terrestrial Milankovich cycles . Together, these features – good preservation, and an understanding of the imposed solar flux – mean that much research on the Amazonian of Mars has focussed on understanding its climate , and the surface processes that respond to
1292-443: The surface are the same. The amount of dust on Mars is sufficient to form a 2 to 12 meters thick layer over the entire planet. Since there are relatively few depositional features in the Medusae Fossae Formation, most of the materials being eroded are probably small enough to be suspended in the atmosphere and transported long distances. An analysis of data from the 2001 Mars Odyssey Neutron Spectrometer revealed that parts of
1330-468: The title Amazonian . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Amazonian&oldid=1017648252 " Category : Disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Amazonian (Mars) The Amazonian
1368-402: The volcanoes Apollinaris Mons , Arsia Mons , and possibly Pavonis Mons . Another piece of evidence for a fine-grained composition is that the area gives almost no radar return. For this reason it has been called a "stealth" region. Layers are seen in parts of the formation. Images from spacecraft show that they have different degrees of hardness probably because of significant variations in
1406-430: Was greatest closer to the impact site. So, the impact somehow probably caused the streaks. Also, the distribution of the streaks formed a pattern with two wings extending from the impact site. The curved wings resembled scimitars, curved knives. This pattern suggests that an interaction of airblasts from the group of meteorites shook dust loose enough to start dust avalanches that formed the many dark streaks. At first it
1444-528: Was thought that the shaking of the ground from the impact caused the dust avalanches, but if that was the case the dark streaks would have been arranged symmetrically around the impacts, rather than being concentrated into curved shapes. The crater cluster lies near the equator 510 miles) south of Olympus Mons, on a type of terrain called the Medusae Fossae formation. The formation is coated with dust and contains wind-carved ridges called yardangs . These yardangs have steep slopes thickly covered with dust, so when
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