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Hebes Mensa
Hebes Mensa is a large mensa that rises from the floor of Hebes Chasma, one of the chasmata of the Valles Marineris network on Mars. Some researchers have identified this mesa to be an interior layered deposit (ILD), similar to Ganges Mensa, and are named for alternating light-toned and dark-toned layers forming a stair-stepped stratigraphy. The faces of Hebes Mensa are sometimes fluted. It is tall and wide. Observation history Hebes Mensa was first named in 1982. Context Hebes Mensa is located within the Hebes Chasma of Valles Marineris, within the Coprates quadrangle. To its east is Juventae Dorsa and the larger Lunae Planum, and to its south is Perrotin Crater and the main body of Valles Marineris (specifically Ophir Chasma). To its west are Tithoniae Fossae and Echus Chasma, the latter of which continues north of Hebes Mensa into the Lunae Palus quadrangle. Also to the north is Echus Fossae. As Hebes Mensa is part of Valles Marineris, many features which are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hebes Chasma
Hebes Chasma is an isolated chasma just north of the Valles Marineris canyon system of Mars. It is centered at 1 degree southern latitude and 76 degrees western longitude, just between the Martian equator and the Valles Marineris system, just east of the Tharsis region. Geography Hebes Chasma is a completely closed depression in the surface of Mars, with no outflows to the nearby Echus Chasma to the west, Perrotin Crater to the southwest, or Valles Marineris to the south. Its maximum extents are approximately 320 km east to west, 130 km north to south, and 5 to 6 km in depth. At the center of the depression is Hebes Mensa, a large mesa rising some 5 km off the valley floor, nearly as high as the surrounding terrain. This central plateau makes Hebes Chasma a unique valley in Martian geography. In high resolution pictures of Mars Express ( http://spaceinimages.esa.int/Images/2013/10/Hebes_Chasma ) blue areas at the deepest section of the depression show charac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Azas Plateau
Azas Plateau is a volcanic field in Russia. It is also known as East Tuva Plateau, Khamsara-Biykhem Plateau and Northeast Tuva Plateau. It covers a surface area of west of Lake Baikal. Volcanic activity in the area also occurred at the Oka Plateau and the Jom-Bolok volcanic field. The field is formed by a late Pliocene lava plateau. Several volcanoes formed under the influence of ice and are constructed by lava flows and hyaloclastite, these are so-called tuyas which form by eruptions of volcanoes into ice. Ice meltwater floods may have accompanied this activity. The youngest dated volcanic centre was active 48,000 ± 20,000 years ago, but some lava flows may be even younger. Geography The field is located in southern Siberia, between the East Sayan Mountains and the Todzha basin. There it covers a surface area of west of Lake Baikal, at an altitude of . Volcanic landforms include cones, lava fields, tuyas, and other volcanic structures including scoria cones, volcanic dy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wrinkle Ridge
A wrinkle ridge is a type of feature commonly found on lunar maria, or basalt plains. These features are low, sinuous ridges formed on the mare surface that can extend for up to several hundred kilometers. Wrinkle ridges are tectonic features created after the lava cooled and solidified. They frequently outline ring structures buried within the mare, follow circular patterns outlining the mare, or intersect protruding peaks. They are sometimes called ''veins'' due to their resemblance to the veins that protrude from beneath the skin. Wrinkle ridges are named with the Latin designation ''dorsum'' (plural ''dorsa''). The standard IAU nomenclature uses the names of people (generally scientists) to identify wrinkle ridges on the Moon. For example, the Dorsa Burnet are named for Thomas Burnet, and the Dorsum Owen is named after George Owen of Henllys. Wrinkle ridges can also be found on Mars, for example in Chryse Planitia, on several of the asteroids that have been visited by sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hummock
In geology, a hummock is a small knoll or mound above ground.Bates, Robert L. and Julia A. Jackson, ed. (1984). “hummock.” Dictionary of Geological Terms, 3rd Ed. New York: Anchor Books. p. 241. They are typically less than in height and tend to appear in groups or fields. Large landslide avalanches that typically occur in volcanic areas are responsible for formation of hummocks. From the initiation of the landslide to the final formation, hummocks can be characterized by their evolution, spatial distribution, and internal structure. As the movement of landslide begins, the extension faulting results in formation of hummocks with smaller ones at the front of the landslide and larger ones in the back. The size of the hummocks is dependent on their position in the initial mass. As this mass spreads, the hummocks further modify to break up or merger to form larger structures. It is difficult to make generalizations about hummocks because of the diversity in their morphology an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yardang
A yardang is a streamlined protuberance carved from bedrock or any consolidated or semiconsolidated material by the dual action of wind abrasion by dust and sand and deflation (the removal of loose material by wind turbulence.) Yardangs become elongated features typically three or more times longer than wide, and when viewed from above, resemble the hull of a boat. Facing the wind is a steep, blunt face that gradually gets lower and narrower toward the lee end. Yardangs are formed by wind erosion, typically of an originally flat surface formed from areas of harder and softer material. The soft material is eroded and removed by the wind, and the harder material remains. The resulting pattern of yardangs is therefore a combination of the original rock distribution, and the fluid mechanics of the air flow and resulting pattern of erosion. Names The word itself is of Turkic origin, meaning ‘steep bank’, as this type of spectacular landscapes rising are best developed in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ash Fall
Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, created during volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to refer to all explosive eruption products (correctly referred to as ''tephra''), including particles larger than 2 mm. Volcanic ash is formed during explosive volcanic eruptions when dissolved gases in magma expand and escape violently into the atmosphere. The force of the gases shatters the magma and propels it into the atmosphere where it solidifies into fragments of volcanic rock and glass. Ash is also produced when magma comes into contact with water during phreatomagmatic eruptions, causing the water to explosively flash to steam leading to shattering of magma. Once in the air, ash is transported by wind up to thousands of kilometres away. Due to its wide dispersal, ash can have a number of impacts on society, including animal and human ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geological Unit
A stratigraphic unit is a volume of rock of identifiable origin and relative age range that is defined by the distinctive and dominant, easily mapped and recognizable petrographic, lithologic or paleontologic features (facies) that characterize it. Units must be ''mappable'' and ''distinct'' from one another, but the contact need not be particularly distinct. For instance, a unit may be defined by terms such as "when the sandstone component exceeds 75%". Lithostratigraphic units Sequences of sedimentary and volcanic rocks are subdivided the basis of their shared or associated lithology. Formally identified lithostratigraphic units are structured in a hierarchy of lithostratigraphic rank, higher rank units generally comprising two or more units of lower rank. Going from smaller to larger in rank, the main lithostratigraphic ranks are Bed, Member, Formation, Group and Supergroup. Formal names of lithostratigraphic units are assigned by geological surveys. Units of formation or hi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hesperian
The Hesperian is a system (stratigraphy), geologic system and geologic timescale, time period on the planet Mars characterized by widespread Volcanology of Mars, volcanic activity and catastrophic flooding that carved immense outflow channels across the surface. The Hesperian is an intermediate and transitional period of Martian history. During the Hesperian, Mars changed from the wetter and perhaps warmer world of the Noachian (Mars), Noachian to the dry, cold, and dusty planet seen today. The absolute age of the Hesperian Period is uncertain. The beginning of the period followed the end of the Late Heavy Bombardment and probably corresponds to the start of the lunar Late Imbrian period, around 3700 million years ago (Myr, Mya). The end of the Hesperian Period is much more uncertain and could range anywhere from 3200 to 2000 Mya, with 3000 Mya being frequently cited. The Hesperian Period is roughly coincident with the Earth's early Archean Eon. With the decline of heavy impacts a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bishop Tuff
The Bishop Tuff is a welded tuff that formed 764,800 ± 600 years ago as a rhyolitic pyroclastic flow during the approximately six day eruption that created the Long Valley Caldera. Large outcrops of the tuff are located in Inyo and Mono Counties, California, United States. Approximately 200 cubic kilometers of ash and tuff erupted outside the caldera. Modern exposure The Bishop Tuff caps a volcanic plateau in the northern Owens Valley in eastern California. The tableland formation is located east of U.S. Route 395 and west of the Nevada stateline, sitting northwest of Bishop and southeast of Crowley Lake and Mammoth Lakes. Another part of the flow is south of Mono Lake, and surrounding the Mono-Inyo Craters. Deposits of Bishop Tuff in this area cover nearly , and range in thickness from to . The Owens River cuts through the Volcanic Tableland, an ignimbrite plateau that is a principal sector of the Bishop Tuff outflow sheet. Erosion of the plateau by the Owens River has crea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Red Sea
The Red Sea ( ar, البحر الأحمر - بحر القلزم, translit=Modern: al-Baḥr al-ʾAḥmar, Medieval: Baḥr al-Qulzum; or ; Coptic: ⲫⲓⲟⲙ ⲛ̀ϩⲁϩ ''Phiom Enhah'' or ⲫⲓⲟⲙ ⲛ̀ϣⲁⲣⲓ ''Phiom ǹšari''; Tigrinya: ቀይሕ ባሕሪ ''Qeyih Bahri''; ) is a seawater inlet of the Indian Ocean, lying between Africa and Asia. Its connection to the ocean is in the south, through the Bab el Mandeb strait and the Gulf of Aden. To its north lie the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez (leading to the Suez Canal). It is underlain by the Red Sea Rift, which is part of the Great Rift Valley. The Red Sea has a surface area of roughly 438,000 km2 (169,100 mi2), is about 2250 km (1398 mi) long, and — at its widest point — 355 km (220.6 mi) wide. It has an average depth of 490 m (1,608 ft), and in the central ''Suakin Trough'' it reaches its maximum depth of . The Red Sea also has exten ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salt Dome
A salt dome is a type of structural dome formed when salt (or other evaporite minerals) intrudes into overlying rocks in a process known as diapirism. Salt domes can have unique surface and subsurface structures, and they can be discovered using techniques such as seismic reflection. They are important in petroleum geology as they can function as petroleum traps. Formation Stratigraphically, salt basins developed periodically from the Proterozoic to the Neogene. The formation of a salt dome begins with the deposition of salt in a restricted basin. In these basins, the outflow of water exceeds inflow. More concretely, the basin loses water through evaporation, resulting in the precipitation and deposition of salt. While the rate of sedimentation of salt is significantly larger than the rate of sedimentation of clastics, it is recognized that a single evaporation event is rarely enough to produce the vast quantities of salt needed to form a layer thick enough for the formation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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