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Intra-volcanic Sedimentary Rock In North Ethiopia
Between 29 and 27 million years ago, the extrusion of Ethiopia’s flood basalts was interrupted and deposition of continental sediments occurred. Inter-trappean beds outcrop in many places of the Ethiopian highlands. They consist of fluvio-lacustrine deposits, that are generally a few tens of metres thick. Often, these interbedded fluvio-lacustrine deposits are very visible because their bright colours strongly contrast with the basalt environment. Name and definition The formation, also called ''silicified limestone'' and ''interbedded lacustrine deposits'' was first extensively characterised in the 1930s by Merla and Minucci. Stratigraphic context The formation is generally at the interface between the lower Ashangi Basalts, and the upper Alaji Basalts. Environment The sediments were deposited in shallow lakes and marshes in large topographic depressions. The dense vegetation hosted mammals and birds, which found their food between the reeds of the lake shores. The decompos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hagere Selam (Degua Tembien)
Hagere Selam (meaning ''place of peace'') is a town in northern Ethiopia. Located on the Mekelle-Abiy Addi regional road, it is located at an elevation of 2650 metres above sea level. The town is the administrative center of the Dogu'a Tembien woreda. The weekly market is on Saturdays. Hagere Selam is located on the saddle point between two of the higher points in Tigray (Imba Zuw'ala and Tsatsen). The regional road from Mekelle to Abiy Addi climbs towards Hagere Selam, before going down to the Abergele lowlands. The area is categorized as highland or ''dega''. The local economy is dependent on trading, agriculture, with barley being the main crop grown in the area, and on milk production and apiculture. Demographics Based on figures from the census in 2007, Hagere Selam had a total population of 8130, of whom 3702 were men and 4428 were women. The 1994 census reported a total population of 3932. The functional agglomeration of Hagere Selam is larger than its administrative b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lanistes
''Lanistes'' is a genus of freshwater snails which have a gill and an operculum, aquatic gastropod mollusks in the family Ampullariidae, the apple snails.Bouchet, P.; Neubauer, Thomas A. (2015). Lanistes Montfort, 1810. In: MolluscaBase (2015). Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=820447 on 2015-11-11 Distribution The distribution of the genus ''Lanistes'' includes Africa and Madagascar.Brown D. S. (1994). ''Freshwater Snails of Africa and their Medical Importance''. Taylor & Francis. . Description ''Lanistes'' has a unique anatomy among the Ampullariidae: it has a "hyperstrophic" sinistral shell. This means that the body of the snail is dextral (as in all other ampullariids), but the shell appears to be sinistral. However the sinistral appearance stems from the fact that the rotation of the shell as it grows is in an upward direction rather than the usual downward direction. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pila (gastropod)
''Pila'' is a genus of large freshwater snails with an operculum, African and Asian apple snails, aquatic gastropod mollusks in the family Ampullariidae, the apple snails. Distribution Distribution of the genus ''Pila'' include Africa, Madagascar, southern Asia and Indo-Pacific islands. It is amphibious in nature and can undergo summer sleep or aestivation under drought condition. It is generally found in lakes, pools, and sometimes even in the river streams where aquatic vegetation like ''Vallisneria'', '' Pistia'' are found in large amount for food. External Features When viewed from ''ventral'' side facing the collumella towards the ''observer'', the collumella rotates ''clockwise'' or '' Dextral''. Species Species within the genus ''Pila'' include: subgenus ''Pila'' * '' Pila africana'' (v. Martens, 1886)"''Pila''" The apple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mollusc
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is estimated between 60,000 and 100,000 additional species. The proportion of undescribed species is very high. Many taxa remain poorly studied. Molluscs are the largest marine phylum, comprising about 23% of all the named marine organisms. Numerous molluscs also live in freshwater and terrestrial habitats. They are highly diverse, not just in size and anatomical structure, but also in behaviour and habitat. The phylum is typically divided into 7 or 8 taxonomic classes, of which two are entirely extinct. Cephalopod molluscs, such as squid, cuttlefish, and octopuses, are among the most neurologically advanced of all invertebrates—and either the giant squid or the colossal squid is the largest known invertebrate species. The gastropods ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lamination
Lamination is the technique/process of manufacturing a material in multiple layers, so that the composite material achieves improved strength, stability, sound insulation, appearance, or other properties from the use of the differing materials, such as plastic. A laminate is a permanently assembled object created using heat, pressure, welding, or adhesives. Various coating machines, machine presses and calendering equipment are used. Materials There are different lamination processes, depending primarily on the type or types of materials to be laminated. The materials used in laminates can be identical or different, depending on the process and the object to be laminated. Textile Laminated fabric are widely used in different fields of human activity, including medical and military. Woven fabrics (organic and inorganic based) are usually laminated by different chemical polymers to give them useful properties like chemical resistance, dust, grease, windproofness, photolumin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cherty Nodules
Chert () is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz, the mineral form of silicon dioxide (SiO2). Chert is characteristically of biological origin, but may also occur inorganically as a chemical precipitate or a diagenetic replacement, as in petrified wood. Chert is typically composed of the petrified remains of siliceous ooze, the biogenic sediment that covers large areas of the deep ocean floor, and which contains the silicon skeletal remains of diatoms, silicoflagellates, and radiolarians. Precambrian cherts are notable for the presence of fossil cyanobacteria. In addition to microfossils, chert occasionally contains macrofossils. However, some chert is devoid of any fossils. Chert varies greatly in color (from white to black), but most often manifests as gray, brown, grayish brown and light green to rusty redW.L. Roberts, T.J. Campbell, G.R. Rapp Jr., "Encyclopedia of Mineralogy, Second Edition", 1990. R.S. Mitchell, " ... [...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] |
Gastropod
The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. There are many thousands of species of sea snails and slugs, as well as freshwater snails, freshwater limpets, and land snails and slugs. The class Gastropoda contains a vast total of named species, second only to the insects in overall number. The fossil history of this class goes back to the Late Cambrian. , 721 families of gastropods are known, of which 245 are extinct and appear only in the fossil record, while 476 are currently extant with or without a fossil record. Gastropoda (previously known as univalves and sometimes spelled "Gasteropoda") are a major part of the phylum Mollusca, and are the most highly diversified class in the phylum, with 65,000 to 80,000 living snail and slug species. The anatomy, behavior, feeding, and re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molluscs
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant taxon, extant species of molluscs are recognized. The number of fossil species is estimated between 60,000 and 100,000 additional species. The proportion of undescribed species is very high. Many taxa remain poorly studied. Molluscs are the largest marine biology, marine phylum, comprising about 23% of all the named marine organisms. Numerous molluscs also live in freshwater mollusc, freshwater and Terrestrial molluscs, terrestrial habitats. They are highly diverse, not just in size and anatomical structure, but also in behaviour and habitat. The phylum is typically divided into 7 or 8 Taxonomy (biology), taxonomic class (biology), classes, of which two are entirely extinct. Cephalopod molluscs, such as squid, cuttlefish, and octopuses, are among the most neurobiology, neurologically advanced of all inve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isomorphic Substitution
In mathematics, an isomorphism is a structure-preserving mapping between two structures of the same type that can be reversed by an inverse mapping. Two mathematical structures are isomorphic if an isomorphism exists between them. The word isomorphism is derived from the Ancient Greek: ἴσος ''isos'' "equal", and μορφή ''morphe'' "form" or "shape". The interest in isomorphisms lies in the fact that two isomorphic objects have the same properties (excluding further information such as additional structure or names of objects). Thus isomorphic structures cannot be distinguished from the point of view of structure only, and may be identified. In mathematical jargon, one says that two objects are . An automorphism is an isomorphism from a structure to itself. An isomorphism between two structures is a canonical isomorphism (a canonical map that is an isomorphism) if there is only one isomorphism between the two structures (as it is the case for solutions of a universa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silicium
Silicon is a chemical element with the Symbol (chemistry), symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a Tetravalence, tetravalent metalloid and semiconductor. It is a member of carbon group, group 14 in the periodic table: carbon is above it; and germanium, tin, lead, and flerovium are below it. It is relatively unreactive. Because of its high chemical affinity for oxygen, it was not until 1823 that Jöns Jakob Berzelius was first able to prepare it and characterize it in pure form. Its oxides form a family of anions known as silicates. Its melting and boiling points of 1414 °C and 3265 °C, respectively, are the second highest among all the metalloids and nonmetals, being surpassed only by boron. Silicon is the eighth Abundance of the chemical elements, most common element in the universe by mass, but very rarely occurs as the pure element in the Earth's crust. It is widely distributed in space i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
