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Aden Ridge
The Aden Ridge is a part of an active oblique rift system located in the Gulf of Aden, between Somalia and the Arabian Peninsula to the north. The rift system marks the divergent boundary between the Somali and Arabian tectonic plates, extending from the Owen Transform Fault in the Arabian Sea to the Afar Triple Junction or Afar Plume beneath the Gulf of Tadjoura in Djibouti. The Gulf of Aden is divided east to west into three distinct regions by large-scale discontinuities, the Socotra, Alula Fartak, and Shukra-El Shiek transform faults. Located in the central region, bounded by the Alula Fartak fault and Shukra-El Shiek fault, is the Aden spreading ridge. The Aden Ridge connects to the Sheba Ridge in the eastern region and to the Tadjoura Ridge in the western region. Due to oblique nature of the Aden Ridge, it is highly segmented. Along the ridge there are seven transform faults that offset it to the north. Initiation of rifting Extension of the Gulf of Aden rift sy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aden
Aden ( ar, عدن ' Yemeni: ) is a city, and since 2015, the temporary capital of Yemen, near the eastern approach to the Red Sea (the Gulf of Aden), some east of the strait Bab-el-Mandeb. Its population is approximately 800,000 people. Aden's natural harbour lies in the crater of a dormant volcano, which now forms a peninsula joined to the mainland by a low isthmus. This harbour, Front Bay, was first used by the ancient Kingdom of Awsan between the 7th to 5th centuries BC. The modern harbour is on the other side of the peninsula. Aden gets its name from the Gulf of Aden. Aden consists of a number of distinct sub-centres: Crater, the original port city; Ma'alla, the modern port; Tawahi, known as "Steamer Point" in the colonial period; and the resorts of Gold Mohur. Khormaksar, on the isthmus that connects Aden proper with the mainland, includes the city's diplomatic missions, the main offices of Aden University, and Aden International Airport (the former British ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gulf Of Tadjoura
The Gulf of Tadjoura (; ) is a gulf or basin of the Indian Ocean in the Horn of Africa. It lies south of the straits of Bab-el-Mandeb, or the entrance to the Red Sea, at . The gulf has many fishing grounds, extensive coral reefs, and abundant pearl oysters. Most of its coastline is the territory of Djibouti, except for a short stretch on the southern shore, which is part of the territory of Somaliland. The Gulf’s other marine habitats include sea grass beds, salt pans and mangroves. History In August 1840, the conclusion of a treaty of friendship and commerce between the Sultan Mohammed bin Mohammed of Tadjoura and Commander Robert Moresby of the Indian Navy is tracking the sale of Moucha Island to Great Britain for ten sacks of rice. The sale will however follow any occupation. In 1887, Britain cedes sovereignty of the island to France at the same time it recognizes the French sphere of influence in the Gulf of Tadjoura, in exchange for the abandonment by France of any ri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lithosphere
A lithosphere () is the rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust and the portion of the upper mantle that behaves elastically on time scales of up to thousands of years or more. The crust and upper mantle are distinguished on the basis of chemistry and mineralogy. Earth's lithosphere Earth's lithosphere, which constitutes the hard and rigid outer vertical layer of the Earth, includes the crust and the uppermost mantle. The lithosphere is underlain by the asthenosphere which is the weaker, hotter, and deeper part of the upper mantle. The lithosphere–asthenosphere boundary is defined by a difference in response to stress. The lithosphere remains rigid for very long periods of geologic time in which it deforms elastically and through brittle failure, while the asthenosphere deforms viscously and accommodates strain through plastic deformation. The thickness of the lithosphere is thus considered to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mantle (geology)
A mantle is a layer inside a planetary body bounded below by a core and above by a crust. Mantles are made of rock or ices, and are generally the largest and most massive layer of the planetary body. Mantles are characteristic of planetary bodies that have undergone differentiation by density. All terrestrial planets (including Earth), a number of asteroids, and some planetary moons have mantles. Earth's mantle The Earth's mantle is a layer of silicate rock between the crust and the outer core. Its mass of 4.01 × 1024 kg is 67% the mass of the Earth. It has a thickness of making up about 84% of Earth's volume. It is predominantly solid, but in geological time it behaves as a viscous fluid. Partial melting of the mantle at mid-ocean ridges produces oceanic crust, and partial melting of the mantle at subduction zones produces continental crust. Other planetary mantles Mercury has a silicate mantle approximately thick, constituting only 28% ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oligocene
The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the exact dates of the start and end of the epoch are slightly uncertain. The name Oligocene was coined in 1854 by the German paleontologist Heinrich Ernst Beyrich from his studies of marine beds in Belgium and Germany. The name comes from the Ancient Greek (''olígos'', "few") and (''kainós'', "new"), and refers to the sparsity of extant forms of molluscs. The Oligocene is preceded by the Eocene Epoch and is followed by the Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recent" ... Epoch. The Oligocene is the third and final epoch of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eocene
The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', " dawn") and (''kainós'', "new") and refers to the "dawn" of modern ('new') fauna that appeared during the epoch. The Eocene spans the time from the end of the Paleocene Epoch to the beginning of the Oligocene Epoch. The start of the Eocene is marked by a brief period in which the concentration of the carbon isotope 13C in the atmosphere was exceptionally low in comparison with the more common isotope 12C. The end is set at a major extinction event called the ''Grande Coupure'' (the "Great Break" in continuity) or the Eocene–Oligocene extinction event, which may be related to the impact of one or more large bolides in Siberia and in what is now Chesapeake Bay. As with other geologic periods, the strata that define the start and e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transform Fault
A transform fault or transform boundary, is a fault along a plate boundary where the motion is predominantly horizontal. It ends abruptly where it connects to another plate boundary, either another transform, a spreading ridge, or a subduction zone. A transform fault is a special case of a ''strike-slip fault'' that also forms a plate boundary. Most such faults are found in oceanic crust, where they accommodate the lateral offset between segments of divergent boundaries, forming a zigzag pattern. This is a result of oblique seafloor spreading where the direction of motion is not perpendicular to the trend of the overall divergent boundary. A smaller number of such faults are found on land, although these are generally better-known, such as the San Andreas Fault and North Anatolian Fault. Nomenclature Transform boundaries are also known as conservative plate boundaries because they involve no addition or loss of lithosphere at the Earth's surface. Background Geophysi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tadjoura Ridge
Tadjoura ( aa, Tagórri; ar, تاجوراء ''Tağūrah''; so, Tajuura) is one of the oldest towns in Djibouti and the capital of the Tadjourah Region. The town evolved into an early Islamic center with the arrival of Muslims shortly after the Hijra. An important port for many centuries, it was ruled by a succession of polities, including the Ifat Sultanate, Adal Sultanate, the Ottoman Empire, France until Djibouti's independence in 1977. Lying on the Gulf of Tadjoura, it is home to a population of around 45,000 inhabitants. It is the third largest city in the country after Djibouti and Ali Sabieh. Tadjoura has an airstrip and is linked by ferry with Djibouti City. It is also known for its whitewashed buildings and nearby beaches, along with its mosques. Etymology The Afar name ''Tagórri'' derives from the noun ''tágor'' or ''tógor'', (pl. ''tágar'' meaning "outre à puiser" ("goatskin flask for drawing water"). The name ''Tagórri'' is specifically derived from *''t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sheba Ridge
The Aden Ridge is a part of an active oblique rift system located in the Gulf of Aden, between Somalia and the Arabian Peninsula to the north. The rift system marks the divergent boundary between the Somali and Arabian tectonic plates, extending from the Owen Transform Fault in the Arabian Sea to the Afar Triple Junction or Afar Plume beneath the Gulf of Tadjoura in Djibouti. The Gulf of Aden is divided east to west into three distinct regions by large-scale discontinuities, the Socotra, Alula Fartak, and Shukra-El Shiek transform faults. Located in the central region, bounded by the Alula Fartak fault and Shukra-El Shiek fault, is the Aden spreading ridge. The Aden Ridge connects to the Sheba Ridge in the eastern region and to the Tadjoura Ridge in the western region. Due to oblique nature of the Aden Ridge, it is highly segmented. Along the ridge there are seven transform faults that offset it to the north. Initiation of rifting Extension of the Gulf of Aden rift syst ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alula Fartak Fault
The alula , or bastard wing, (plural ''alulae'') is a small projection on the anterior edge of the wing of modern birds and a few non-avian dinosaurs. The word is Latin and means "winglet"; it is the diminutive of ''ala'', meaning "wing". The alula is the freely moving first digit, a bird's "thumb", and typically bears three to five small flight feathers, with the exact number depending on the species. There also are minor covert feathers overlying the flight feathers. Like the larger flight feathers found on the wing's trailing edge, these alula feathers are asymmetrical, with the shaft running closer to anterior edge. Function In most situations, the alula is held flush against the wing; however, it can be manipulated. When flying at slow speeds or landing, the bird moves its alula slightly upwards and forward, which creates a small slot on the wing's leading edge. This functions in the same way as the slats on the wing of an aircraft, allowing the wing to achieve a highe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Djibouti
Djibouti, ar, جيبوتي ', french: link=no, Djibouti, so, Jabuuti officially the Republic of Djibouti, is a country in the Horn of Africa, bordered by Somalia to the south, Ethiopia to the southwest, Eritrea in the north, and the Red Sea and the Gulf of Aden to the east. The country has an area of . In antiquity, the territory, together with Ethiopia, Eritrea and Somaliland, was part of the Land of Punt. Nearby Zeila, now in Somaliland, was the seat of the medieval Adal and Ifat Sultanates. In the late 19th century, the colony of French Somaliland was established following treaties signed by the ruling Dir Somali sultans with the French, and its railroad to Dire Dawa (and later Addis Ababa) allowed it to quickly supersede Zeila as the port for southern Ethiopia and the Ogaden. It was renamed the French Territory of the Afars and the Issas in 1967. A decade later, the Djiboutian people voted for independence. This officially marked the establishment of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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