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Amba Aradam Formation
The Amba Aradam Formation is a Cretaceous sandstone formation in Ethiopia. It is up to 200 metres thick, for instance in the Degua Tembien district. As fossils are absent, the age of the Amba Aradam Formation was interpreted based on the age of assumed corresponding sandstones elsewhere in Ethiopia: the Debre Libanos Sandstones in the Blue Nile Basin, and the Upper Sandstone near Harrar in southeast Ethiopia, both of Late Cretaceous age (100–66 million years ago). The lithology of the Amba Aradam Formation makes it less suitable for rock church excavation; caves have however been blasted in this formation to serve as headquarters for the TPLF during the Ethiopian Civil War of the 1980s. Name and definition The name “Amba Aradam Sandstone” was coined by geologist William Thomas Blanford, who accompanied the British invading army in 1868. The formation is named after the Amba Aradam mountain, where the formation widely outcrops. So far the nomenclature was not proposed for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geological Formation
A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exposed in a geographical region (the stratigraphic column). It is the fundamental unit of lithostratigraphy, the study of strata or rock layers. A formation must be large enough that it can be mapped at the surface or traced in the subsurface. Formations are otherwise not defined by the thickness of their rock strata, which can vary widely. They are usually, but not universally, tabular in form. They may consist of a single lithology (rock type), or of alternating beds of two or more lithologies, or even a heterogeneous mixture of lithologies, so long as this distinguishes them from adjacent bodies of rock. The concept of a geologic formation goes back to the beginnings of modern scientific geology. The term was used by Abraham Gottlob Wer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Degua Tembien
Dogu'a Tembien (, "Upper Tembien", sometimes transliterated as Degua Tembien) is a woreda in Tigray Region, Ethiopia. It is named in part after the former province of Tembien. Nowadays, the mountainous district is part of the Southeastern Tigray Zone. The administrative centre of this woreda is Hagere Selam. History Dogu’a Tembien holds numerous prehistoric sites, which have been dated to the Middle Stone Age in Ayninbirkekin, or Pastoral Neolithic in Aregen and Menachek. Geography Topography and landscapes Major mountains :* Tsatsen, 2815 metres, a wide mesa between Hagere Selam and Inda Maryam Qorar () :* Ekli Imba, 2799 metres, summit of the Arebay massif in Arebay ''tabia'' or district () :* Imba Zuw’ala, 2710 metres, near Hagere Selam () :* Aregen, 2660 metres, in Aregen ''tabia'' () :* Dabba Selama, 2630 metres, in Haddinnet ''tabia'' () (not to be confused with the homonymous monastery) :* Imba Dogu’a, 2610 metres, in Mizane Birhan ''tabia'' () :* Imb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cross-bedding
In geology, cross-bedding, also known as cross-stratification, is layering within a stratum and at an angle to the main bedding plane. The sedimentary structures which result are roughly horizontal units composed of inclined layers. The original depositional layering is tilted, such tilting not being the result of post-depositional deformation. Cross-beds or "sets" are the groups of inclined layers, which are known as cross-strata. Cross-bedding forms during deposition on the inclined surfaces of bedforms such as ripples and dunes; it indicates that the depositional environment contained a flowing medium (typically water or wind). Examples of these bedforms are ripples, dunes, anti-dunes, sand waves, hummocks, bars, and delta slopes.Collinson, J.D., Thompson, D.B., 1989, Sedimentary Structures (2nd ed): Academic Division of Unwin Hyman Ltd, Winchester, MA, XXX p. Environments in which water movement is fast enough and deep enough to develop large-scale bed forms fall into thre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trap Rock
Trap rock, also known as either trapp or trap, is any dark-colored, fine-grained, non-granitic intrusive or extrusive igneous rock. Types of trap rock include basalt, peridotite, diabase, and gabbro.Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, J.A., eds. (2005) ''Glossary of Geology'' (5th ed.) American Geological Institute, Alexandria, Virginia. 779 pp. Trapp (trap) is also used to refer to flood (plateau) basalts, e.g. the Deccan Traps and Siberian Traps.Le Maitre, R. W., ed. (2002) ''Igneous Rocks: A Classification and Glossary of Terminology''. Cambridge University Press, New York. 236 pp. The erosion of trap rock created by the stacking of successive lava flows often created a distinct stairstep landscape from which the term ''trap'' was derived from the Swedish word ''trappa'', which means "stairway". The slow cooling of magma either as a sill or as a thick lava flow sometimes creates systematic vertical fractures within the resulting layer of trap rock. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tertiary
Tertiary ( ) is a widely used but obsolete term for the geologic period from 66 million to 2.6 million years ago. The period began with the demise of the non-avian dinosaurs in the Cretaceous–Paleogene extinction event, at the start of the Cenozoic Era, and extended to the beginning of the Quaternary glaciation at the end of the Pliocene Epoch. The time span covered by the Tertiary has no exact equivalent in the current geologic time system, but it is essentially the merged Paleogene and Neogene periods, which are informally called the Early Tertiary and the Late Tertiary, respectively. The Tertiary established the Antarctic as an icy island continent. Historical use of the term The term Tertiary was first used by Giovanni Arduino during the mid-18th century. He classified geologic time into primitive (or primary), secondary, and tertiary periods based on observations of geology in Northern Italy. Later a fourth period, the Quaternary, was applied. In the early d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adigrat Sandstone
The Adigrat Sandstone formation in north Ethiopia, in a wide array of reddish colours, comprises sandstones with coarse to fine grains, and locally conglomerates, silt- and claystones. Given the many lateritic palaeosols and locally fossil wood fragments, the formation is interpreted as a deposit in estuarine, lacustrine-deltaic or continental environments. The upper limit of Adigrat Sandstone is of Middle-Late Jurassic age (around 160 million years or Ma ago) whereas the lower boundary is Triassic (200 Ma). There are numerous rock-hewn churches in this formation. Name and definition The name “Adigrat Sandstone” was coined by geologist William Thomas Blanford, who accompanied the British Expedition to Abyssinia in 1868. The formation is named after the town of Adigrat, on the route of the invading British army. So far the nomenclature was not proposed for recognition to the International Commission on Stratigraphy. Stratigraphic context The Adigrat Sandstone has been depos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antalo Limestone
The Antalo Limestone, also known as the Antalo Sequence, is a geological formation in Ethiopia. It is between 300 and 800 metres thick and comprises fossiliferous limestones and marls that were deposited in a reef. Marine microfossils have shown an age between 165 and 150 million years. Name and definition The Antalo Supersequence includes two main stratigraphic units: the Antalo Sequence and the Agula Group. The Antalo Sequence, or Antalo Limestone has been named after the town of Hintalo in Tigray, Ethiopia. The name of the formation was coined by geologist William Thomas Blanford, who accompanied the British Expedition to Abyssinia in 1868. At that time, Hintalo was a major town on the route of the invading British army. So far the nomenclature has not been proposed for recognition to the International Commission on Stratigraphy. Geographical extent The sedimentary succession is found in Ethiopia, in the Mekelle Outlier, in the Blue Nile gorge, in the Harrar Plateau and a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Commission On Stratigraphy
The International Commission on Stratigraphy (ICS), sometimes referred to unofficially as the "International Stratigraphic Commission", is a daughter or major subcommittee grade scientific daughter organization that concerns itself with stratigraphy, stratigraphical, geology, geological, and chronology, geochronological matters on a global scale. It is the largest subordinate body of the International Union of Geological Sciences (IUGS). The ICS is essentially a permanent working committee, working subcommittee, which meets far more regularly than the quadrennial meetings scheduled by the IUGS, when it meets as a congress or committee, membership of the whole. Aims One of its main aims, a project begun in 1974, is to establish a multidisciplinary standard and global geologic time scale that will ease paleontology, paleontological and geobiology, geobiological comparisons region to region by benchmarks with stringent and rigorous strata criteria called Global Boundary Stratotype ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
British Expedition To Abyssinia
The British Expedition to Abyssinia was a rescue mission and punitive expedition carried out in 1868 by the armed forces of the British Empire against the Ethiopian Empire (also known at the time as Abyssinia). Emperor Tewodros II of Ethiopia, then often referred to by the anglicized name Theodore, imprisoned several missionaries and two representatives of the British government in an attempt to force the British government to comply with his requests for military assistance. The punitive expedition launched by the British in response required the transportation of a sizeable military force hundreds of kilometres across mountainous terrain lacking any road system. The formidable obstacles to the action were overcome by the commander of the expedition, General Robert Napier, who was victorious in every battle against the troops of Tewodros, captured the Ethiopian capital, and rescued all the hostages. The expedition was widely hailed on its return for achieving all its objectives ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethiopian Civil War
The Ethiopian Civil War was a civil war in Ethiopia and present-day Eritrea, fought between the Ethiopian military junta known as the Derg and Ethiopian-Eritrean anti-government rebels from 12 September 1974 to 28 May 1991. The Derg overthrew the Ethiopian Empire and Emperor Haile Selassie in a coup d'état on 12 September 1974, establishing Ethiopia as a Marxist-Leninist state under a military junta and provisional government. Various opposition groups of ideological affiliations ranging from Communist to anti-Communist, often drawn from ethnic background, began armed resistance to the Soviet-backed Derg, in addition to the Eritrean separatists already fighting in the Eritrean War of Independence. The Derg used military campaigns and the Qey Shibir (Ethiopian Red Terror) to repress the rebels. By the mid-1980s, various issues such as the 1983–1985 famine, economic decline, and other after-effects of Derg policies ravaged Ethiopia, increasing popular support for the rebels ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tigray People's Liberation Front
The Tigray People's Liberation Front (TPLF; ti, ህዝባዊ ወያነ ሓርነት ትግራይ, lit=Popular Struggle for the Freedom of Tigray), also called the Tigrayan People's Liberation Front, is a left-wing ethnic nationalist paramilitary group, a banned political party, and the former ruling party of Ethiopia. It is designated as a terrorist organization by the Ethiopian government. It is widely known as Woyane ( ti, ወያነ), or Wayane ( am, ወያኔ) in older texts and Amharic publications. The TPLF was established on 18 February 1975 in Dedebit, northwestern Tigray, according to official records. Within 16 years, it had grown from about a dozen men into the most powerful armed “liberation” movement in Ethiopia. It led a political coalition called the Ethiopian People's Revolutionary Democratic Front (EPRDF) from 1989 to 2018. It fought a 15-year-long war against the Derg regime which was overthrown in 1991. Due largely to its war fighting capabilities, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monolithic Church
A monolithic church or rock-hewn church is a church made from a single block of stone. Because freestanding rocks of sufficient size are rare, such edifices are usually hewn into the ground or into the side of a hill or mountain. They can be of comparable architectural complexity to constructed buildings. The term ''monolithic church'' is used of churches in various countries, not least the complex of eleven churches in Lalibela, Ethiopia, believed to have been created in the 12th century. Ethiopia The eleven monolithic churches in Lalibela are: * Church of the Redeemer * Saint Mary * Mount Sinai * Golgotha * House of the Cross * House of the Virgins * Saint Gabriel * Abba Matta * Saint Mercurius * Immanuel * Church of St. George (Bete Giyorgis) The most famous of the edifices is the cross-shaped Church of St. George. Tradition credits its construction to the Zagwe dynasty King Gebre Mesqel Lalibela, who was a devout Orthodox Tewahedo Christian. The medieval monolith ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
