In kenya, the valley is deepest to the north of nairobi. Areas with the most recent rvf outbreaks include somalia 20067, kenya 20067, tanzania 2007, sudan 20078, mayotte 20078, madagascar 2008, swaziland 2008. Geology, geochemistry, and stratigraphy of the lemudongo formation, kenya rift valley article pdf available january 2007 with 650 reads how we measure reads. Pdf mechanistic interpretation of rift valley formation. History of the development of the east african rift system. From its inception, rift valley has focused on six objectives. A rift valley can be defined as a valley that is created by the splitting of the earths crust. A rift valley is formed on a divergent plate boundary, a crustal extension or. This small rift valley has a typical formationlong, narrow. What is the difference between delta estuary lagoon bay gulf straits peninsula duration. To demonstrate the formation of block mountains and rift. Rift valleys differ from river or glacial valleys in that they are created by tectonic activity. Rift valley fever, enzootic hepatitis, slenkdalkoors afrik. If you continue browsing the site, you agree to the use of cookies on this website.
Eduard suess thoughts on the east african rift system encouraged john gregory to further explore the faulted basins of kenya in 1893, and subsequently expressing the term rift valley. Since all of these are formed at divergent plate boundaries, the. Progressive formation of a rift valley through extension of the lithosphere and continental crust by about 50 km. Rift valley fever an overview sciencedirect topics. Benefits of the rift valley to people of east africa. Nevertheless, the formation of rift valley in kenya is an. Two arms of the triple junction can split to form an entire ocean. The great rift valley is a series of contiguous geographic trenches, approximately 6,000 kilometres 3,700 mi in total length, that runs from the beqaa valley in lebanon which is in asia to mozambique in southeast africa. A rift valley is the long, narrow, flatbottomed trough of land created when a block of earths lithospheric crust drops into the space thats left when two divergent tectonic. Chapter 4 lake water management in three ethiopian rift. It is found in the central rift valley system with altitudes ranging from 16702000m a.
The hypotheses regarding the origin of the rift valleys are generally grouped in two categories. Chris carlson slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Notice how the width taken up by the trapezoidal areas undergoing normal faulting and horst and graben formation increases from top to bottom in the left panel. The great rift valley is a geographical feature running north to south for around 6,400 kilometres from northern syria to central mozambique in east africa. Many rift valleys are part of triple junctions, a type of divergent boundary where three tectonic plates meet at about 120 angles.
Inevitably, this human dynamic impacts ecological factors such as water quality. Rift valley fever is an infectious disease primarily affecting ruminants but to which other species, including humans, are also susceptible. There is a clear age predisposition to clinical disease rendering lambs, goat kids, puppies, and kittens extremely susceptible, with mortality rates between 70% and 100%. Mechanistic interpretation of rift valley formation science. The southern boundary may be traced at latitude 5n, south of the area where the rift is divided into two branches chamo basin to. The upper rhine plain, rhine rift valley or upper rhine graben german. Fold mountains and rift valleys flashcards quizlet. African rift tectonics and sedimentation, an introduction h. Midcontinent rift the midcontinent rift formed when north america began to pull apart about 1 billion years ago. When the plates are pulled apart, the centre block drops down to form a graben. The rift valleys are a system of normal faults bordering a 4060 km wide trough. Building sustainable, longterm businesses in agriculture and energy 2.
Divergence can also cause earthquakes and if it occurs near the continental crust, a rift valley will be created through faulting. The third, failed rift or aulacogen, may become a rift valley. Rift valleys are found both on land and at the bottom of the ocean, where they are created by the process of seafloor spreading. The east african rift system comprises a series of individual graben rift valleys that linkup to form the western and eastern branch. A rift valley is a linearshaped lowland between several highlands or mountain ranges created by the action of a geologic rift or fault. Divergent boundary, the great rift valley african rift. There is also an atlas maps skills homework activity included in the lesson and a separate rift valley homework answer sheet to help give feedback to the students. Pdf the stress distribution on the lithospheric plate due to excess magma pressure is obtained from an exact solution of the. The stress distribution on the lithospheric plate due to excess magma pressure is obtained from an exact solution of the threedimensional theory of elasticity. Threats and opportunities to major rift valley lakes. Some of the groups individual businesses have been in operation since the early 20th century. Block mountains are formed c the middle block stays in the place and a rift valley form.
What is not likely to happen at a divergent boundary. Download fulltext pdf mechanistic interpretation of rift valley formation article pdf available in science 1894205. East african rift valley powerpoint slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Rift valleys differ from river valleys and glacial valleys in that they are created by tectonic activity and not the process of erosion. Winters book describes the inter congolese dialogue icd, which was the programme. Rift valley corporation about us corporate governance. As it spreads apart, the land between two parallel fault lines has sunk. Rifting is the process in which continental crust is extended and thinned, forming extensional sedimentary basins andor mafic dykeswarms. What was once thought to be one giant 6,000mile long rift is now known to be several smaller rifts joined together. A rift valley is a huge fracture on continental and oceanic plates which widens gradually over extensive periods of times. The rift extends from south in mozambique all the way up north in jordan to the southwestern asia. The northwardmigrating spreading center pushed cimmeria in front of it, away from gondwana, replacing the old paleotethys ocean with a neotethys ocean. Rvf was first reported in 1931 by daubney, hudson, and garnham as an outbreak of enzootic hepatitis observed in the rift valley. The great rift valley is filled with hot springs, geysers and has multiple earthquakes each year.
All of the african great lakes were formed as the result of the rift, and most lie within its rift valley. While the name continues in some usages, it is rarely used in geology as it is considered an imprecise merging of separate though related rift and fault systems. A stress analysis of the model shows how the rift valley and its fault pattern are formed on two oppositely inclined boundaries in the stress field. The rift valley and the block mountains are now formed. Rift valley, any elongated trough formed by the subsidence of a segment of the earths crust between dipslip, or normal, faults. Textbook horst and graben formation left compared with actual rift terrain upper right and topography lower right.
Rift valley formation rift valleys are formed on divergent plate boundaries when the plates are moving apart, it leaves a long deep gorge with reasonably flat sides and a flat floor. The country has a number of lakes and rivers with substantial quantity of fish stocks. Olduvai, also known as oldupai, was the site of a large lake 500,000 years ago. A rift valley is a lowland region formed by the interaction of earths tectonic plates. How rift valleys are formed some interesting facts. What was the formation process of the great rift valley. A rift valley is formed on a divergent plate boundary, a.
Rift valleys are thought to have been developed either from the action of tensional forces in the crust or from the action of compressional forces. Bedrock geology of michigan university of michigan. The northernmost part of the rift forms the beqaa valley in lebanon. The great rift valley olduvai gorge, in tanzanias great rift valley, is one of the most important sites for the study of human evolution. T he african rift valley system is one of the tectonic features not only of kenya but also of africa that extends from mozambique in the south through eastern africa to jordan in southwestern asia. Rift valley has a long history of operating in subsaharan africa.
Lake water management in three ethiopian rift valley watersheds by katie graichen introduction across geographic and temporal scales, humans are drawn to water for both the concrete and intangible resources it provides. Rifts commence as intracratonic, downthrown blocks dominated by normal or obliqueextensional transtensional faults e. The eastern rift valley which is more commonly referred to as the great rift valley is a zone of tectonic subsidence that extends the full length of the ears. The great rift valley central bucks school district. The atlantic ocean, for instance, is a result of a triple junction that started in what is now the gulf of guinea on the. Scientists sometimes argue whether both block mountains horsts and rift valleys grabens move, or if only one part moves. The main phenomenon is formation of domes related to plume e.
Such a fault is a fracture in the terrestrial surface in which the rock material on the upper side of the fault plane has been displaced downward relative to the rock. With total area of 90 km2, it is the smallest lake in the rift valley system. Tectonics and volcanism of the southern kenya rift valley and its. Introduction to rift valleys excerpt from national geographic education. Oberrheinische tiefebene, oberrheinisches tiefland or oberrheingraben, french. Pdf geology, geochemistry, and stratigraphy of the. Africas great rift valley, 2001, isbn 0810906023 tribesofthegreatriftvalley,2007,isbn9780810994119 east african rift valley lakes, 2006, oclc 76876862 photographic atlas of the midatlantic ridge rift valley,1977,isbn0387902473 riftvalleyfever. A rift formed along the northeastern shelf of gondwana. There are 10 major lakes with a total area of 7400 km2 and 7185 km of major rivers 2. Hence the lakes formed along rift valleys are also deep, narrow and very long. The east african rift, is a divergent plate boundary where the east african plate is being separated into two separate plates. A rift valley is a landform whose formation is triggered by a geologic rift or fault. A rift valley is a lowland region that forms where earths tectonic plates move apart, or rift.
The formation of rift valleys and their zigzag fault patterns. Rift valley fever rvf is an acute, fever causing viral disease most commonly observed in domesticated animals such as cattle, buffalo, sheep, goats, and camels, with the ability to. The analysis indicates that rift valley formation and associated structural and. Rift valley fever virus rvfv, the cause of rift valley fever rvf, is a zoonosis endemic to africa and the arabian peninsula that now represents a looming health threat to europe, asia, and the new world 1,2. Formation of east african rift valley kenya wildlife safaris. The most extensive rift valley is located along the crest of the midocean ridge system and is the result of sea floor spreading. Desta stated that, awassa lake receives its recharge from groundwater through precipitation 2325. The land on both sides of the rift valley remains in place. The analysis indicates that rift valley formation and associated structural and geophysical characteristics can be suitably explained by dikelike intrusions of magma or igneous mush into the lithospheric plate. Tectonics rift valley formation teaching resources. Faulting rift valley and block mountains askmisstan. Farther south, the valley is the home of the jordan river which continues south through the jordan valley into the dead. The ethiopian sector of the east african rift system extends for more than km in a nesw to ns direction from the afar depression, at red seagulf of aden junction, southwards to the turkana depression.
348 1420 1264 1093 937 466 911 715 229 38 1107 196 673 8 573 454 325 159 1536 404 1068 1413 1219 75 390 562 791 957 98 68 1287 1145 987 1391 176