|
Dawa River
The Dawa River ( so, Webiga Daawa) is found in East Africa, covering an area of, 58,961 km2. It flows through three major countries: Kenya, Ethiopia, and Somalia, with 81% falling into Ethiopian territory. It is known for its complex geological environment, evident through its diverse lithology and structural framework, coming from the river's closeness to multiple volcanic-tectonic events. The wide river has gentle slopes either side of its exposed bedrock. The Dawa river flows south east to form part of the Ethiopia - Somalia border and part of Ethiopia - Kenya border. Awata, Digati, and Mormora are the only significant off-flowing rivers to Dawa. Location and physiography The Dawa river has a maximum and minimum elevation of 3098 and 169 metres above sea level, and the inclination of the basin is toward southeast. The exact location is between 3.92°- 6.47° N and 38.02°- 42.08° E. A significant proportion of the area in the northern and north-western highland is dis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jubba River
The Jubba River or Juba River ( so, Wabiga Jubba) is a river in southern Somalia which flows through the autonomous region of Jubaland. It begins at the border with Ethiopia, where the Dawa and Ganale Dorya rivers meet, and flows directly south to the Somali Sea, where it empties at the ''Goobweyn'' juncture. The Jubba basin covers an area of . The Somali regional state of Jubaland, formerly called ''Trans-Juba'', is named after the river. History Ajuran Empire The Jubba River has a rich history of a once-booming sophisticated civilization and trade network conducted by the powerful Somalis that held sway over the Jubba river. During the Middle Ages Jubba river was under the Ajuran Empire of the Horn of Africa which utilized the Jubba River for its plantations and was the only hydraulic empire in Africa. A hydraulic empire that rose in the 13th century AD, Ajuran monopolized the water resources of the Jubba River and Shebelle. Through hydraulic engineering, it also construct ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Groundwater
Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock become completely saturated with water is called the water table. Groundwater is recharged from the surface; it may discharge from the surface naturally at springs and seeps, and can form oases or wetlands. Groundwater is also often withdrawn for agricultural, municipal, and industrial use by constructing and operating extraction wells. The study of the distribution and movement of groundwater is hydrogeology, also called groundwater hydrology. Typically, groundwater is thought of as water flowing through shallow aquifers, but, in the technical sense, it can also contain soil moisture, perma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drilling Stabilizer
{{Short description, Part of a borehole drill string assembly A drilling stabilizer is a piece of downhole equipment used in the bottom hole assembly (BHA) of a drill string. It mechanically stabilizes the BHA in the borehole in order to avoid unintentional sidetracking, vibrations, and ensure the quality of the hole being drilled. It is composed of a hollow cylindrical body and stabilizing blades, both made of high-strength steel. The blades can be either straight or spiralled, and are hardfaced for wear resistance. Several types of drilling stabilizers are used in the oilfield today. While integral stabilizers (fully machined out of a single piece of steel) tend to be the norm, other types can be used, such as : * Replaceable sleeve stabilizer, where the blades are located on a sleeve, which is then screwed on the body. This type can be economical when no repair facilities are available close to the well being drilled and air freight has to be used. * Welded blades stabilizer, w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Field Research
Field research, field studies, or fieldwork is the collection of raw data outside a laboratory, library, or workplace setting. The approaches and methods used in field research vary across disciplines. For example, biologists who conduct field research may simply observe animals interacting with their environments, whereas social scientists conducting field research may interview or observe people in their natural environments to learn their languages, folklore, and social structures. Field research involves a range of well-defined, although variable, methods: informal interviews, direct observation, participation in the life of the group, collective discussions, analyses of personal documents produced within the group, self-analysis, results from activities undertaken off- or on-line, and life-histories. Although the method generally is characterized as qualitative research, it may (and often does) include quantitative dimensions. History Field research has a long history. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of the entire Phanerozoic. The name is derived from the Latin ''creta'', "chalk", which is abundant in the latter half of the period. It is usually abbreviated K, for its German translation ''Kreide''. The Cretaceous was a period with a relatively warm climate, resulting in high eustatic sea levels that created numerous shallow inland seas. These oceans and seas were populated with now- extinct marine reptiles, ammonites, and rudists, while dinosaurs continued to dominate on land. The world was ice free, and forests extended to the poles. During this time, new groups of mammals and birds appeared. During the Early Cretaceous, flowering plants appeared and began to rapidly diversify, becoming the dominant group of plants across the Earth b ... [...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] |
Shale Gas
Shale gas is an unconventional natural gas that is found trapped within shale formations. Since the 1990s a combination of horizontal drilling and hydraulic fracturing has made large volumes of shale gas more economical to produce, and some analysts expect that shale gas will greatly expand worldwide energy supply. Shale gas has become an increasingly important source of natural gas in the United States since the start of this century, and interest has spread to potential gas shales in the rest of the world. China is estimated to have the world's largest shale gas reserves. A 2013 review by the United Kingdom Department of Energy and Climate Change noted that most studies of the subject have estimated that life-cycle greenhouse gas (GHG) emissions from shale gas are similar to those of conventional natural gas, and are much less than those from coal, usually about half the greenhouse gas emissions of coal; the noted exception was a 2011 study by Howarth and others of Co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) because they are the most resistant minerals to weathering processes at the Earth's surface. Like uncemented sand, sandstone may be any color due to impurities within the minerals, but the most common colors are tan, brown, yellow, red, grey, pink, white, and black. Since sandstone beds often form highly visible cliffs and other topographic features, certain colors of sandstone have been strongly identified with certain regions. Rock formations that are primarily composed of sandstone usually allow the percolation of water and other fluids and are porous enough to store large quantities, making them valuable aquifers and petroleum reservoirs. Quartz-bearing sandstone can be changed into quartzite through metamorphism, usually related to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Karoo
The Karoo ( ; from the Afrikaans borrowing of the South Khoekhoe !Orakobab or Khoemana word ''ǃ’Aukarob'' "Hardveld") is a semi-desert natural region of South Africa. No exact definition of what constitutes the Karoo is available, so its extent is also not precisely defined. The Karoo is partly defined by its topography, geology and climate, and above all, its low rainfall, arid air, cloudless skies, and extremes of heat and cold.Potgieter, D.J. & du Plessis, T.C. (1972) ''Standard Encyclopaedia of Southern Africa''. Vol. 6. pp. 306–307. Nasou, Cape Town.''Reader’s Digest Illustrated Guide to Southern Africa''. (5th Ed. 1993). pp. 78–89. Reader’s Digest Association of South Africa Pty. Ltd., Cape Town. The Karoo also hosted a well-preserved ecosystem hundreds of million years ago which is now represented by many fossils. The ǃ’Aukarob formed an almost impenetrable barrier to the interior from Cape Town, and the early adventurers, explorers, hunters, and travelers o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sedimentary 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 Werne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basement (geology)
In geology, basement and crystalline basement are crystalline rocks lying above the mantle and beneath all other rocks and sediments. They are sometimes exposed at the surface, but often they are buried under miles of rock and sediment. The basement rocks lie below a sedimentation, sedimentary platform (geology), platform or cover, or more generally any rock below sedimentary rocks or sedimentary basins that are metamorphic rock, metamorphic or Igneous rock, igneous in origin. In the same way, the sediments or sedimentary rocks on top of the basement can be called a "cover" or "sedimentary cover". Crustal rocks are modified several times before they become basement, and these transitions alter their composition. Continental crust Basement rock is the thick foundation of ancient, and oldest, metamorphic and igneous rock that forms the Crust (geology), crust of continents, often in the form of granite. Basement rock is contrasted to overlying sedimentary rocks which are laid down ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tectonics
Tectonics (; ) are the processes that control the structure and properties of the Earth's crust and its evolution through time. These include the processes of mountain building, the growth and behavior of the strong, old cores of continents known as cratons, and the ways in which the relatively rigid plates that constitute the Earth's outer shell interact with each other. Tectonics also provide a framework for understanding the earthquake and volcanic belts that directly affect much of the global population. Tectonic studies are important as guides for economic geologists searching for fossil fuels and ore deposits of metallic and nonmetallic resources. An understanding of tectonic principles is essential to geomorphologists to explain erosion patterns and other Earth surface features. Main types of tectonic regime Extensional tectonics Extensional tectonics is associated with the stretching and thinning of the crust or the lithosphere. This type of tectonics is found ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.PNG "Click for more on -> Groundwater")
Saunders_Quarry-1.jpg "Click for more on -> Sandstone")
