1.
Rift zone
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For example, in the currently ongoing eruption of Kilauea in Hawaii, lava is emitted continuously from the Puʻu ʻŌʻō vent located in Kilaueas East Rift Zone roughly 15 km east of Kilauea Crater. Rift zones tend to extend for tens of kilometers radially outward from the volcanic summit, the accumulated lava of repeated eruptions from rift zones causes these volcanoes to have an elongated shape. Perhaps the best example of this is Mauna Loa, which in Hawaiian means long mountain, the origin of the fractures that comprise the rift zones is the spreading of the volcano. The more material a shield volcano accumulates, the heavier it gets and these systems of fissures that make up a rift zone allow this to happen more easily. Hawaii, Most Hawaiian volcanoes have two or sometimes three rift zones
2.
African Rift Valley
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The East African Rift is an active continental rift zone in East Africa. The EAR began developing around the onset of the Miocene, 22–25 million years ago, in the past, it was considered to be part of a larger Great Rift Valley that extended north to Asia Minor. As extension continues, lithospheric rupture will occur within 10 million years, the Somalian plate will break off, a series of distinct rift basins, the East African Rift System extends over thousands of kilometers. The EAR consists of two main branches, the Eastern Rift Valley includes the Main Ethiopian Rift, running eastward from the Afar Triple Junction, which continues south as the Kenyan Rift Valley. The Western Rift Valley includes the Albertine Rift, and farther south, to the north of the Afar Triple Junction, the rift follows one of two paths, west to the Red Sea Rift or east to the Aden Ridge in the Gulf of Aden. The EAR runs from the Afar Triple Junction in the Afar Triangle of Ethiopia through eastern Africa, the EAR transects through Ethiopia, Kenya, Uganda, Rwanda, Burundi, Zambia, Tanzania, Malawi and Mozambique. The Davie Ridge ranges between 30–120 km wide, with a west facing scarp along the half of its length that rises up to 2300 m above the sea floor. Its movement is concurrent with the EAR, over time, many theories have tried to clarify the evolution of the East African Rift. In 1972 it was proposed that the EAR was not caused by tectonic activity, others proposed an African superplume causing mantle deformation. However, the varying geochemical signatures of a suite of Ethiopian lavas suggest multiple plume sources, at least one of deep mantle origin, additionally, the subject of deep-rooted mantle plumes is still a matter of controversy, and therefore cannot be confirmed. The most recent and accepted view is the theory put forth in 2009, at that time it was suggested that lithospheric thinning generated volcanic activity, further increasing the magmatic processes at play such as intrusions and numerous small plumes. These processes further thin the lithosphere in saturated areas, forcing the thinning lithosphere to behave like a mid-ocean ridge, prior to rifting, enormous continental flood basalts erupted on the surface and uplift of the Ethiopian, Somalian, and East African plateaus occurred. The first stage of rifting of the EAR is characterized by rift localization, periods of extension alternated with times of relative inactivity. There was also the reactivation of a weakness in the crust, a suture zone of multiple cratons, displacement along large boundary faults. The second stage of rifting is characterized by the deactivation of large boundary faults, the development of internal fault segments, today, the narrow rift segments of the East African Rift system form zones of localized strain. These rifts are the result of the actions of numerous faults which are typical of all tectonic rift zones. The African continental crust is generally cool and strong, many cratons are found throughout the EAR, such as the Tanzania and Kaapvaal cratons. The cratons are thick, and have survived for billions of years with little tectonic activity and they are characterized by greenstone belts, tonalites, and other high-grade metamorphic lithologies
3.
Lake Mweru
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Lake Mweru is a freshwater lake on the longest arm of Africas second-longest river, the Congo. Located on the border between Zambia and Democratic Republic of the Congo, it makes up 110 km of the length of the Congo. Mweru means lake in a number of Bantu languages, so it is referred to as just Mweru. Mweru is mainly fed by the Luapula River, which comes in through swamps from the south, at its north end the lake is drained by the Luvua River, which flows in a northwesterly direction to join the Lualaba River and thence to the Congo. It is the second-largest lake in the Congos drainage basin and is located 150 km west of the end of the largest. The Luapula forms a swampy delta almost as wide as the end of the lake. In a number of respects the lower river and lake can be treated as one entity, for a lake in a region with pronounced wet and dry seasons, Mweru does not change much in level and area. The annual fluctuation in level is 1. 7m, with highs in May. A rise in Mweru is quickly offset by a faster flow down the Luvua, Mwerus average length is 118 km and its average width is 45 km, with its long axis oriented northeast-southwest. Its elevation is 917 m, quite a bit higher than Tanganyika and it is a rift valley lake lying in the Lake Mweru-Luapula graben, which is a branch of the East African Rift. Mweru is shallow in the south and deeper in the north, with two depressions in the section with maximum depths of 20 m and 27 m. A smaller very marshy lake called Mweru Wantipa lies about 50 km to its east and it is mostly endorheic and actually takes water from the Kalungwishi through a dambo most of the time, but in times of high flood it may overflow into the Kalungwishi and Lake Mweru. The lake was known to Arab and Swahili traders who used Kilwa Island on the lake as a base at one time. They used trade routes from Zanzibar on the Indian Ocean to Ujiji on Lake Tanganyika to Mweru and then to the Lunda, Luba, Yeke or Kazembe kingdoms, western trade routes went from those kingdoms to the Atlantic, so Mweru lay on a transcontinental trade route. The Portuguese must have known of the lake, and the visitors only had to walk to higher ground about 5 km north of Kazembes Kanyembo capital to see the lake 10 km distant. However they were interested in trade routes than discovery, they had approached from the south and their movements were restricted by Mwata Kazembe. Explorer and missionary David Livingstone, who referred to it as Moero, is credited with its discovery during his travels of 1867-8. Livingstone witnessed the devastation and suffering caused by the trade in the area to the north and east of Mweru
4.
Lake Tanganyika
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Lake Tanganyika is an African Great Lake. It is the second oldest freshwater lake in the world, second largest by volume, the lake is divided among four countries – Tanzania, Democratic Republic of the Congo, Burundi, and Zambia, with Tanzania and DRC possessing the majority of the lake. The water flows into the Congo River system and ultimately into the Atlantic Ocean, the name apparently refers to Tanganika, the great lake spreading out like a plain, or plain-like lake. Lake Tanganyika is situated within the Albertine Rift, the branch of the East African Rift. It is the largest rift lake in Africa and the second largest lake by volume in the world and it is the deepest lake in Africa and holds the greatest volume of fresh water, accounting for 18% of the worlds available fresh water. It extends for 676 km in a general direction and averages 50 km in width. The lake covers 32,900 km2, with a shoreline of 1,828 km, a depth of 570 m. It holds an estimated 18,900 cubic kilometres and this is equivalent to about 16% of all fresh water on Earth. The catchment area of the lake is 231,000 km2, two main rivers flow into the lake, as well as numerous smaller rivers and streams. There is one major outflow, the Lukuga River, which empties into the Congo River drainage, the major river flowing into the lake is the Ruzizi River, formed about 10,000 years ago, which enters the north of the lake from Lake Kivu. The Malagarasi River, which is Tanzanias second largest river, enters the east side of Lake Tanganyika, the Malagarasi is older than Lake Tanganyika and, before the lake was formed, directly drained into the Congo River. Apparently it has rarely in the past had an outflow to the sea and it has been described as practically endorheic for this reason. The lakes connection to the sea is dependent on a water level allowing water to overflow out of the lake through the Lukunga into the Congo. Due to the tropical location, it has a high rate of evaporation. Thus it depends on a high inflow through the Ruzizi out of Lake Kivu to keep the lake high enough to overflow. Signs of ancient shorelines indicate that at times Tanganyika may have been up to 300 m lower than its present surface level, even its current outlet is intermittent and may not have been operating when first visited by Western explorers in 1858. Lake Tanganyika is an ancient lake and its three basins, which in periods with much lower water levels were separate lakes, are of different ages. The central began to form 9—12 million years ago, the northern 7—8 mya, there are several islands in Lake Tanganyika
5.
Lake Rukwa
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Lake Rukwa is an endorheic lake in the Rukwa Valley of southwestern Tanzania. The alkaline Lake Rukwa lies midway between Lake Tanganyika and Lake Nyasa at an elevation of about 800 metres, in a branch of the rift system. Almost half of the lies in Uwanda Game Reserve. The lake has seen large fluctuations in its size over the years, currently it is about 180 kilometres long and averages about 32 kilometres wide, making it about 5,760 square kilometres in size. In 1929 it was only about 48 kilometres long, but in 1939 it was about 128 kilometres long and 40 kilometres wide. The lake may at times have been higher and linked Lake Tanganyika with Lake Malawi, ancient shorelines suggest a final date of overflow into Tanganyika of 33. In 2016, an estimated 1.53 billion cubic meters volume of Helium Gas was discovered in Lake Rukwa worth $3.5 billion
6.
Quilotoa
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Quilotoa is a water-filled caldera and the most western volcano in the Ecuadorian Andes. This last eruption followed a period of 14,000 years and is known as the 1280 Plinian eruption. The fourth eruptive phase was phreatomagmatic, indicating that a Crater lake was present at that time. The caldera has since accumulated a 250 m deep crater lake, fumaroles are found on the lake floor and hot springs occur on the eastern flank of the volcano. Quilotoa is a tourist site of growing popularity, the route to the summit is generally traveled by hired truck or bus from the town of Zumbahua 17 km to the South, or more commonly by bus from Latacunga. Visitors may have to pay two US dollars each to look from the lip of the caldera, there are a number of simple hostels in the immediate area offering services such as mules and guides. Activities include a four to five-hour hike around the caldera, the caldera rim is highly irregular and reaches its maximum elevations at three lava domes. The 10 km hike is sandy and steep in places and can be quite taxing and its a half-hour hike down from the viewpoint, and very basic lodging down in its bowl. Camping is permitted at the bottom of the crater, but there is no potable water, the lake surface is located at 3,500 m asl. The total volume of water stored in Lake Quilotoa is 0.35 km3, according to local inhabitants, the lake level has been slowly declining over the last 10 years. Travertine deposits occur along the shore up to 10 m above the lake level, Travel information Travel information Jan 2009 Updated travel info Events in Quilotoa
7.
Ecuador
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Ecuador also includes the Galápagos Islands in the Pacific, about 1,000 kilometres west of the mainland. What is now Ecuador was home to a variety of Amerindian groups that were incorporated into the Inca Empire during the 15th century. The territory was colonized by Spain during the 16th century, achieving independence in 1820 as part of Gran Colombia, Spanish is the official language and is spoken by a majority of the population, though 13 Amerindian languages are also recognized, including Quichua and Shuar. The capital city is Quito, while the largest city is Guayaquil, in reflection of the countrys rich cultural heritage, the historical center of Quito was declared a UNESCO World Heritage Site in 1978. Cuenca, the third-largest city, was declared a World Heritage Site in 1999 as an outstanding example of a planned. Ecuador has an economy that is highly dependent on commodities, namely petroleum. The country is classified as a medium-income country, Ecuador is a democratic presidential republic. The new constitution of 2008 is the first in the world to recognize legally enforceable Rights of Nature, Ecuador is also known for its rich ecology, hosting many endemic plants and animals, such as those of the Galápagos Islands. It is one of 17 megadiverse countries in the world, various peoples had settled in the area of the future Ecuador before the arrival of the Incas. They developed different languages while emerging as unique ethnic groups, even though their languages were unrelated, these groups developed similar groups of cultures, each based in different environments. Over time these groups began to interact and intermingle with each other so that groups of families in one area became one community or tribe, with a similar language and culture. Many civilizations arose in Ecuador, such as the Valdivia Culture and Machalilla Culture on the coast, the Quitus, each civilization developed its own distinctive architecture, pottery, and religious interests. Eventually, through wars and marriage alliances of their leaders, a group of nations formed confederations, one region consolidated under a confederation called the Shyris, which exercised organized trading and bartering between the different regions. Its political and military came under the rule of the Duchicela blood-line. The native confederations that gave them the most problems were deported to distant areas of Peru, Bolivia, similarly, a number of loyal Inca subjects from Peru and Bolivia were brought to Ecuador to prevent rebellion. Thus, the region of highland Ecuador became part of the Inca Empire in 1463 sharing the same language, in contrast, when the Incas made incursions into coastal Ecuador and the eastern Amazon jungles of Ecuador, they found both the environment and indigenous people more hostile. Moreover, when the Incas tried to subdue them, these indigenous people withdrew to the interior, as a result, Inca expansion into the Amazon basin and the Pacific coast of Ecuador was hampered. The indigenous people of the Amazon jungle and coastal Ecuador remained relatively autonomous until the Spanish soldiers, the Amazonian people and the Cayapas of Coastal Ecuador were the only groups to resist Inca and Spanish domination, maintaining their language and culture well into the 21st century
8.
Ottawa-Bonnechere Graben
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The Ottawa-Bonnechere Graben is a seismically active structure that coincides with a 55 km wide topographic depression extending from near Montréal through Ottawa. It is part of the St. Lawrence rift system also includes the seismically active Saguenay graben. This rift valley was formed when the Earths crust moved downward about a kilometre between two major fault zones known as the Mattawa and Petawawa faults. These ancient faults are still active and occasionally release stress in the form of earthquakes, such as the 1935 Timiskaming earthquake, the length of the graben is about 700 km. The Ottawa-Bonnechere Graben runs from the Montreal area on the east to near Sudbury, on the east, it joins the Saint Lawrence rift system, a half-graben which extends more than 1000 km along the Saint Lawrence River valley and links the Ottawa and Saguenay Graben. The 200 km segment of the Ottawa-Bonnechere Graben west of Ottawa was the first to be recognized as a graben and this latter branch is the Timiskaming Graben. At the rifts western termini, the main faults split into divergent smaller faults, the graben has been interpreted as a Late Proterozoic to Early Paleozoic failed arm of the Iapetus Ocean, the precursor to the Atlantic Ocean. These graben were reactivated during the breakup of supercontinent Pangaea some 150 mya, since the Late Proterozoic to Early Paleozoic, erosion has removed the volcanic peaks, exposing a number of relic volcanic pipes, such as Callander Bay and the Manitou Islands in Lake Nipissing. These features are subterranean geological structures formed by the violent, supersonic eruption of deep-origin volcanoes, batholiths and dikes were also exposed by erosion, such as the Timber Lake, Mulock, West Arm, Powassan and Bonfield batholiths. The precise age of these volcanics is unknown but they are either early Cambrian and this volcanism was probably coeval with the emplacement of the Grenville dike swarm. This second episode of alkalic volcanism occurred along the part of the graben in the early Cretaceous. The products of this event are the Monteregian Hills in Montérégie, of all these features, Mont Saint-Hilaire is the best known as a source of rare specimens. Along the northern side of the Ottawa-Bonnechere Graben lies a dramatic escarpment that forms the edge of the Gatineau Hills. On or near a branch of the Ottawa-Bonnechere Graben lies the Brent impact crater and it is 3.8 km in diameter and the age is estimated about 400 million years. The impact crater, which was first recognized in 1951 from aerial photographs, geophysical and diamond drilling investigations show that the crater has a present depth of about 425 m but is partly filled with sedimentary rocks with a thickness of about 274 m. The rocks beneath the floor are thoroughly fragmented over a depth of about 610 m. Like the similar Pingualuit crater, the Brent crater is attributed to the high speed impact of a giant meteorite and it is calculated that the impact released energy equaling 250 megatons of TNT and occurred when this area was probably covered by a shallow sea. The depressions formed by the graben across the rugged Canadian Shield were a spillway for the Great Lakes after the last Ice Age, later they became a thoroughfare for exploration and trade
9.
Rift
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In geology, a rift is a linear zone where the Earths crust and lithosphere are being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-graben with normal faulting, where rifts remain above sea level they form a rift valley, which may be filled by water forming a rift lake. The axis of the area may contain volcanic rocks, and active volcanism is a part of many. Major rifts occur along the axis of most mid-ocean ridges. Failed rifts are the result of rifting that failed to continue to the point of break-up. Typically the transition from rifting to spreading develops at a junction where three converging rifts meet over a hotspot. Two of these evolve to the point of spreading, while the third ultimately fails. Most rifts consist of a series of segments that together form the linear zone characteristic of rifts. The individual rift segments have a dominantly half-graben geometry, controlled by a single basin-bounding fault, segment lengths vary between rifts, depending on the elastic thickness of the lithosphere. Areas of thick colder lithosphere, such as the Baikal Rift have segment lengths in excess of 80 km, while in areas of warmer thin lithosphere, segment lengths may be less than 30 km. Along the axis of the rift the position, and in cases the polarity. Segment boundaries often have a complex structure and generally cross the rift axis at a high angle. These segment boundary zones accommodate the differences in fault displacement between the segments and are known as accommodation zones. Accommodation zones may be located where older crustal structures intersect the rift axis, in the Gulf of Suez rift, the Zaafarana accommodation zone is located where a shear zone in the Arabian-Nubian Shield meets the rift. At the onset of rifting, the part of the lithosphere starts to extend on a series of initially unconnected normal faults. In subaerial rifts, drainage at this stage is generally internal, as the rift evolves, some of the individual fault segments grow, eventually becoming linked together to form the larger bounding faults. Subsequent extension becomes concentrated on these faults, the longer faults and wider fault spacing leads to more continuous areas of fault-related subsidence along the rift axis. Significant uplift of the rift shoulders develops at this stage, strongly influencing drainage, during rifting, as the crust is thinned, the Earths surface subsides and the Moho becomes correspondingly raised
10.
Fault (geology)
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In geology, a fault is a planar fracture or discontinuity in a volume of rock, across which there has been significant displacement as a result of rock-mass movement. Large faults within the Earths crust result from the action of tectonic forces. Energy release associated with movement on active faults is the cause of most earthquakes. A fault plane is the plane that represents the surface of a fault. A fault trace or fault line is the intersection of a plane with the ground surface. A fault trace is also the line commonly plotted on maps to represent a fault. Since faults do not usually consist of a single, clean fracture, the two sides of a non-vertical fault are known as the hanging wall and footwall. By definition, the wall occurs above the fault plane. This terminology comes from mining, when working a tabular ore body, because of friction and the rigidity of rocks, they cannot glide or flow past each other easily, and occasionally all movement stops. A fault in ductile rocks can also release instantaneously when the rate is too great. The energy released by instantaneous strain-release causes earthquakes, a common phenomenon along transform boundaries, slip is defined as the relative movement of geological features present on either side of a fault plane, and is a displacement vector. A faults sense of slip is defined as the motion of the rock on each side of the fault with respect to the other side. In practice, it is only possible to find the slip direction of faults. Based on direction of slip, faults can be categorized as, strike-slip. Dip-slip, offset is predominantly vertical and/or perpendicular to the fault trace, oblique-slip, combining significant strike and dip slip. The fault surface is usually vertical and the footwall moves either left or right or laterally with very little vertical motion. Strike-slip faults with left-lateral motion are known as sinistral faults. Those with right-lateral motion are known as dextral faults
11.
East African Rift
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The East African Rift is an active continental rift zone in East Africa. The EAR began developing around the onset of the Miocene, 22–25 million years ago, in the past, it was considered to be part of a larger Great Rift Valley that extended north to Asia Minor. As extension continues, lithospheric rupture will occur within 10 million years, the Somalian plate will break off, a series of distinct rift basins, the East African Rift System extends over thousands of kilometers. The EAR consists of two main branches, the Eastern Rift Valley includes the Main Ethiopian Rift, running eastward from the Afar Triple Junction, which continues south as the Kenyan Rift Valley. The Western Rift Valley includes the Albertine Rift, and farther south, to the north of the Afar Triple Junction, the rift follows one of two paths, west to the Red Sea Rift or east to the Aden Ridge in the Gulf of Aden. The EAR runs from the Afar Triple Junction in the Afar Triangle of Ethiopia through eastern Africa, the EAR transects through Ethiopia, Kenya, Uganda, Rwanda, Burundi, Zambia, Tanzania, Malawi and Mozambique. The Davie Ridge ranges between 30–120 km wide, with a west facing scarp along the half of its length that rises up to 2300 m above the sea floor. Its movement is concurrent with the EAR, over time, many theories have tried to clarify the evolution of the East African Rift. In 1972 it was proposed that the EAR was not caused by tectonic activity, others proposed an African superplume causing mantle deformation. However, the varying geochemical signatures of a suite of Ethiopian lavas suggest multiple plume sources, at least one of deep mantle origin, additionally, the subject of deep-rooted mantle plumes is still a matter of controversy, and therefore cannot be confirmed. The most recent and accepted view is the theory put forth in 2009, at that time it was suggested that lithospheric thinning generated volcanic activity, further increasing the magmatic processes at play such as intrusions and numerous small plumes. These processes further thin the lithosphere in saturated areas, forcing the thinning lithosphere to behave like a mid-ocean ridge, prior to rifting, enormous continental flood basalts erupted on the surface and uplift of the Ethiopian, Somalian, and East African plateaus occurred. The first stage of rifting of the EAR is characterized by rift localization, periods of extension alternated with times of relative inactivity. There was also the reactivation of a weakness in the crust, a suture zone of multiple cratons, displacement along large boundary faults. The second stage of rifting is characterized by the deactivation of large boundary faults, the development of internal fault segments, today, the narrow rift segments of the East African Rift system form zones of localized strain. These rifts are the result of the actions of numerous faults which are typical of all tectonic rift zones. The African continental crust is generally cool and strong, many cratons are found throughout the EAR, such as the Tanzania and Kaapvaal cratons. The cratons are thick, and have survived for billions of years with little tectonic activity and they are characterized by greenstone belts, tonalites, and other high-grade metamorphic lithologies
12.
Continental crust
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The continental crust is the layer of igneous, sedimentary, and metamorphic rocks that forms the continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called sial because its composition is more felsic compared to the oceanic crust. The continental crust consists of layers, with a bulk composition that is intermediate to felsic. The average density of continental crust is about 2.7 g/cm3, less dense than the material that makes up the mantle. Continental crust is less dense than oceanic crust, whose density is about 2.9 g/cm3. At 25 to 70 km, continental crust is thicker than oceanic crust. About 40% of Earths surface is occupied by continental crust. It makes up about 70% of the volume of Earths crust, because the surface of continental crust mainly lies above sea level, its existence allowed land life to evolve from marine life. There is little evidence of continental crust prior to 3.5 Ga, all continental crust ultimately derives from the fractional differentiation of oceanic crust over many eons. This process has been and continues today primarily as a result of the associated with subduction. In contrast to the persistence of continental crust, the size, shape, different tracts rift apart, collide and recoalesce as part of a grand supercontinent cycle. There are currently about 7 billion cubic kilometers of continental crust, the relative permanence of continental crust contrasts with the short life of oceanic crust. Because continental crust is less dense oceanic crust, when active margins of the two meet in subduction zones, the oceanic crust is typically subducted back into the mantle. Continental crust is rarely subducted.01 Ga, whereas the oldest oceanic crust is from the Jurassic, Continental crust and the rock layers that lie on and within it are thus the best archive of Earths history. The height of mountain ranges is usually related to the thickness of crust and this results from the isostasy associated with orogeny. The crust is thickened by the compressive forces related to subduction or continental collision, the buoyancy of the crust forces it upwards, the forces of the collisional stress balanced by gravity and erosion. This forms a keel or mountain root beneath the mountain range, the thinnest continental crust is found in rift zones, where the crust is thinned by detachment faulting and eventually severed, replaced by oceanic crust. The edges of continental fragments formed this way are termed passive margins, igneous rock may also be underplated to the underside of the crust, i. e. adding to the crust by forming a layer immediately beneath it
13.
Oceanic crust
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Oceanic crust is the uppermost layer of the oceanic portion of a tectonic plate. The crust overlies the solidified and uppermost layer of the mantle, the crust and the solid mantle layer together constitute oceanic lithosphere. Oceanic crust is the result of erupted mantle material originating from below the plate, cooled and in most instances and this occurs mostly at mid-ocean ridges, but also at scattered hotspots, and also in rare but powerful occurrences known as flood basalt eruptions. It is primarily composed of rocks, or sima, which is rich in iron. Although a complete section of oceanic crust has not yet been drilled, Oceanic crust is significantly simpler than continental crust and generally can be divided in three layers. Layer 1 is on an average 0.4 km thick and it consists of unconsolidated or semiconsolidated sediments, usually thin or even not present near the mid-ocean ridges but thickens farther away from the ridge. Layer 3 is formed by slow cooling of magma beneath the surface and consists of coarse grained gabbros and it constitutes over two-thirds of oceanic crust volume with almost 5 km thickness. The most voluminous volcanic rocks of the floor are the mid-oceanic ridge basalts. These rocks have low concentrations of large ion lithophile elements, light rare earth elements, volatile elements, there can be found basalts enriched with incompatible elements, but they are rare and associated with mid-ocean ridge hot spots such as surroundings of Galapagos Islands, the Azores and Iceland. Oceanic crust is continuously being created at mid-ocean ridges, as plates diverge at these ridges, magma rises into the upper mantle and crust. As it moves away from the ridge, the lithosphere becomes cooler and denser, the youngest oceanic lithosphere is at the oceanic ridges, and it gets progressively older away from the ridges. As the mantle rises it cools and melts, as the pressure decreases, the amount of melt produced depends only on the temperature of the mantle as it rises. Hence most oceanic crust is the same thickness, an example of this is the Gakkel Ridge under the Arctic Ocean. Thicker than average crust is found above plumes as the mantle is hotter and hence it crosses the solidus and melts at a depth, creating more melt. An example of this is Iceland which has crust of thickness ~20 km, the oceanic lithosphere subducts at what are known as convergent boundaries. These boundaries can exist between oceanic lithosphere on one plate and oceanic lithosphere on another, or between oceanic lithosphere on one plate and continental lithosphere on another, in the second situation, the oceanic lithosphere always subducts because the continental lithosphere is less dense. The subduction process consumes older oceanic lithosphere, so oceanic crust is more than 200 million years old. The process of super-continent formation and destruction via repeated cycles of creation and destruction of oceanic crust is known as the Wilson cycle, the oldest large scale oceanic crust is in the west Pacific and north-west Atlantic - both are about up to 180-200 million years old
14.
Mid-ocean ridge
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A mid-ocean ridge is an underwater mountain system formed by plate tectonics. It consists of various mountains linked in chains, typically having a known as a rift running along its spine. This type of mountain ridge is characteristic of what is known as an oceanic spreading center. The production of new results from mantle upwelling in response to plate spreading. The buoyant melt rises as magma at a linear weakness in the oceanic crust, a mid-ocean ridge demarcates the boundary between two tectonic plates, and consequently is termed a divergent plate boundary. Mid-ocean ridges are geologically active, with new magma constantly emerging onto the floor and into the crust at. The crystallized magma forms new crust of basalt and gabbro and they are formed by two oceanic plates moving away from each other. The rocks making up the crust below the seafloor are youngest along the axis of the ridge and age with increasing distance from that axis, new magma of basalt composition emerges at and near the axis because of decompression melting in the underlying Earths mantle. The oceanic crust is made up of much younger than the Earth itself. Most oceanic crust in the basins is less than 200 million years old. The crust is in a constant state of renewal at the ocean ridges, moving away from the mid-ocean ridge, ocean depth progressively increases, the greatest depths are in ocean trenches. As the oceanic crust moves away from the axis, the peridotite in the underlying mantle cools. The crust and the relatively rigid peridotite below it make up the oceanic lithosphere, by contrast, fast spreading ridges like the East Pacific Rise are narrow, sharp incisions surrounded by generally flat topography that slopes away from the ridge over many hundreds of miles. The overall shape of ridges results from Pratt isostacy, close to the ridge there is hot. As the oceanic plates cool, away from the axes, the oceanic mantle lithosphere thickens. Thus older seafloor is underlain by denser material and sits lower, there are two processes, ridge-push and slab pull, thought to be responsible for the spreading seen at mid-ocean ridges, and there is some uncertainty as to which is dominant. Ridge-push occurs when the bulk of the ridge pushes the rest of the tectonic plate away from the ridge. At the subduction zone, slab-pull comes into effect and this is simply the weight of the tectonic plate being subducted below the overlying plate dragging the rest of the plate along behind it
15.
Sea floor spreading
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Seafloor spreading is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge. Seafloor spreading helps explain continental drift in the theory of plate tectonics, basaltic magma rises up the fractures and cools on the ocean floor to form new seabed. Older rocks will be farther away from the spreading zone while younger rocks will be found nearer to the spreading zone. Additionally spreading rates determine if the ridge is a fast, intermediate, as a general rule, fast ridges see spreading rate of more than 9 cm/year. Intermediate ridges have a rate of 4-9 cm/year while slow spreading ridges have a rate less than 4 cm/year. Earlier theories of continental drift were that continents ploughed through the sea, the idea that the seafloor itself moves as it expands from a central axis was proposed by Harry Hess from Princeton University in the 1960s. The theory is accepted now, and the phenomenon is known to be caused by convection currents in the asthenosphere, which is ductile, or plastic. In the general case, sea floor spreading starts as a rift in a land mass. The process starts with heating at the base of the continental crust which causes it to become more plastic, because less dense objects rise in relation to denser objects, the area being heated becomes a broad dome. As the crust bows upward, fractures occur that gradually grow into rifts, the typical rift system consists of three rift arms at approximately 120 degree angles. These areas are named triple junctions and can be found in places across the world today. The separated margins of the continents evolve to form passive margins, Hess theory was that new seafloor is formed when magma is forced upward toward the surface at a mid-ocean ridge. If spreading continues past the incipient stage described above, two of the arms will open while the third arm stops opening and becomes a failed rift. As the two active rifts continue to open, eventually the continental crust is attenuated as far as it will stretch, at this point basaltic oceanic crust begins to form between the separating continental fragments. When one of the rifts opens into the ocean, the rift system is flooded with seawater. The Red Sea is an example of a new arm of the sea, during this period of initial flooding the new sea is sensitive to changes in climate and eustasy. As a result, the new sea will evaporate several times before the elevation of the valley has been lowered to the point that the sea becomes stable. During this period of evaporation large evaporite deposits will be made in the rift valley, later these deposits have the potential to become hydrocarbon seals and are of particular interest to petroleum geologists
16.
Mid-Atlantic Ridge
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In the North Atlantic, it separates the Eurasian and North American Plates, whereas in the South Atlantic it separates the African and South American Plates. The ridge extends from a junction with the Gakkel Ridge northeast of Greenland southward to the Bouvet Triple Junction in the South Atlantic, although the Mid-Atlantic Ridge is mostly an underwater feature, portions of it have enough elevation to extend above sea level. The section of the ridge that includes the island of Iceland is also known as the Reykjanes Ridge, the ridge has an average spreading rate of about 2.5 cm per year. A ridge under the Atlantic Ocean was first inferred by Matthew Fontaine Maury in 1850, the ridge was discovered during the expedition of HMS Challenger in 1872. A team of scientists on board, led by Charles Wyville Thomson, the existence of such a ridge was confirmed by sonar in 1925 and was found to extend around the Cape of Good Hope into the Indian Ocean by the German Meteor expedition. Ewing, Heezen and Tharp discovered that the ridge is part of a 40, the ridge is central to the breakup of the hypothetical supercontinent of Pangaea that began some 180 million years ago. The Mid-Atlantic Ridge includes a deep valley that runs along the axis of the ridge along nearly its entire length. This rift marks the boundary between adjacent tectonic plates, where magma from the mantle reaches the seafloor, erupting as lava. This trench, however, is not regarded as the boundary between the North and South American Plates, nor the Eurasian and African Plates and this bulge is thought to be caused by upward convective forces in the asthenosphere pushing the oceanic crust and lithosphere. This divergent boundary first formed in the Triassic period, when a series of three-armed grabens coalesced on the supercontinent Pangaea to form the ridge, usually, only two arms of any given three-armed graben become part of a divergent plate boundary. The failed arms are called aulacogens, and the aulacogens of the Mid-Atlantic Ridge eventually became many of the river valleys seen along the Americas. The Fundy Basin on the Atlantic coast of North America between New Brunswick and Nova Scotia in Canada is evidence of the ancestral Mid-Atlantic Ridge, atlantis Massif Central Atlantic Magmatic Province Fifteen-Twenty Fracture Zone Evans, Rachel. Plumbing Depths to Reach New Heights, Marie Tharp Explains Marine Geological Maps, the Library of Congress Information Bulletin. MAR-ECO, a Census of Marine Life project on life along the Mid-Atlantic Ridge
17.
East Pacific Rise
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The East Pacific Rise is a mid-oceanic ridge, a divergent tectonic plate boundary located along the floor of the Pacific Ocean. It separates the Pacific Plate to the west from the North American Plate, the Rivera Plate, the Cocos Plate, the Nazca Plate, and the Antarctic Plate. Much of the lies about 3200 km off the South American coast and rises about 1. The oceanic crust is moving away from the East Pacific Rise to either side, near Easter Island the rate is over 15 cm per year which is the fastest in the world but it is lower at about 6 cm at the north end. On the eastern side of the rise the eastward moving Cocos and Nazca plates meet the westward moving South American Plate, the belt of volcanoes along the Andes and the arc of volcanoes through Central America and Mexico are the direct results of this collision. Due east of the Baja California Peninsula, the Rise is sometimes referred to as the Gulf of California Rift Zone, in this area, newly formed oceanic crust is intermingled with rifted continental crust originating from the North American Plate. The southern extension of the East Pacific Rise merges with the Southeast Indian Ridge at the Macquarie Triple Junction south of New Zealand, along the East Pacific Rise the hydrothermal vents called black smokers were first discovered and have been extensively studied. These vents are forming volcanogenic massive sulfide ore deposits on the ocean floor, many strange deep-water creatures have been found here. The southern stretch of the East Pacific Rise is one of the sections of the Earths mid-ocean ridge system. East Pacific Rise 2004 – Scripps Institution of Oceanography Columbia University Researchers Find Key to the Formation of New Seafloor Spreading Centers – Columbia University
18.
Triple junction
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A triple junction is the point where the boundaries of three tectonic plates meet. Of the many types of triple junction only a few are stable through time. The first scientific paper detailing the triple junction concept was published in 1969 by W. Jason Morgan, Dan McKenzie, the term had traditionally been used for the intersection of three divergent boundaries or spreading ridges. These three divergent boundaries ideally meet at near 120° angles, in plate tectonics theory during the breakup of a continent, three divergent boundaries form, radiating out from a central point. One of these divergent plate boundaries fails and the two continue spreading to form an ocean. The NE-trending Benue Trough is the arm of this junction. In the years since, the term triple-junction has come to refer to any point where three tectonic plates meet, the junction of the Red Sea, the Gulf of Aden and the East African Rift centered in the Afar Triangle is the only Ridge-Ridge-Ridge triple junction above sea level. The Rodrigues Triple Point is a R-R-R triple junction in the southern Indian Ocean, where the African, the Indo-Australian, the Galapagos Triple Junction is an R-R-R triple junction where the Nazca, the Cocos, and the Pacific Plates meet. The East Pacific Rise extends north and south from this junction and this example is made more complex by the Galapagos Microplate which is a small separate plate on the rise just to the southeast of the triple junction. Chiapas coast off Tapachula where Guatemala, North America and Pacific join and this is pushed eastward by the Cocos plate. On the west coast of North America is another triple junction offshore of Cape Mendocino. To the south, the San Andreas Fault, a fault and transform plate boundary, separates the Pacific Plate. To the north lies the Cascadia subduction zone, where a section of the Juan de Fuca Plate called the Gorda Plate is being subducted under the North American Plate, another transform fault, the Mendocino Fault, runs along the boundary between the Pacific Plate and the Gorda Plate. Where the three intersect is the active, F-F-T Mendocino Triple Junction. The Amurian Plate, the Okhotsk Plate, and the Philippine Sea Plate meet in Japan near Mt. Fuji. The Azores Triple Junction is a triple junction where the boundaries of three tectonic plates intersect, the North American Plate, the Eurasian Plate and the African Plate. The Boso Triple Junction offshore Japan is a T-T-T triple junction between the Okhotsk Plate, Pacific Plate and Philippine Sea Plate, the North Sea is located at the extinct triple junction of three former continental plates of the Palaeozoic era, Avalonia, Laurentia and Baltica. The properties of triple junctions are most easily understood from the purely kinematic point of view where the plates are rigid, no knowledge of the Earths interior or the geological details of the crust are then needed
19.
Baikal Rift Zone
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The Baikal Rift Zone is a series of continental rifts centered beneath Lake Baikal in southeastern Russia. Current strain in the rifts tends to be extending with some shear movement, a series of basins form along the zone for more than 2,000 kilometres, creating a rift valley. The rifts form between the Eurasian Plate to the west and the Amur Plate to the east, to the northwest of the rifts is the Siberian Craton, on the Eurasian Plate. The Sayan-Baikal and Mongolia-Okhotsk mobile belts are formations to the southeast of the rifts, there are three basins in the area, the South Basin, Central Basin, and North Basin. In the North, half-grabens form smaller basins, such as the North Baikal Basin, the Central Basin is the deepest in the rift system. The largest fault it contains is the Morskiy Fault, however, another fault, the basins also display evidence of crustal thinning below the rift zone. The thickness of the crust beneath the rift is disputed, as the structures of the rift deep beneath the surface are unknown. The difference in thickness of the crust, between the crust under the rift and that under the areas, has been bounded to be less than 10 kilometres. They interpret the extension as a pure shear process, Volcanism is generally associated with the rift. Hot springs are present both on land and under Lake Baikal, although thus far, no evidence of volcanism has been found in the immediate vicinity of the lake. Despite this, Cenozoic volcanism has occurred nearby and is associated with the Baikal Rift Zone. Early volcanism has been confirmed to exist from the early Miocene, along the boundary both normal and shear strains have occurred in the rift. Plates are diverging along the boundary at 3 to 4 millimetres per year, in addition to divergent movement, left lateral strike-slip movement also occurs in the fault system, such as along the Sayan Fault. The rate of slip has been estimated at 3.2 ±0.5 millimetres per year in the north by looking at offsets of morphological features, although this estimate does not agree with current models. The total throw that has occurred has been estimated at 7 ±0.5 kilometres in extension and 12 ±1 kilometre in the vertical direction, locally, there may be a mantle up-welling driving the extension. This latter theory is held by most Russian Scientists, the area was originally characterized by Precambrian and Paleozoic northeast-southwest fold and thrust belts. The Primorsky fault zone of the basin was present at this time also. Volcanism began in the late Cretaceous in limited areas, but is limited to the Miocene
20.
West Antarctic Rift
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The West Antarctic Rift is a major, active rift valley lying between East and West Antarctica. It encompasses the Ross Sea, the area under the Ross Ice Shelf and its evolution is due to lithospheric thinning of the non-cratonic area of West Antarctica. Thus, the rift is less known than other major rift valleys. It is known, however, that like the East African Rift, there is also a sharp division between older, broader Paleogene rifts including the Ross Sea Basin and the younger, narrower Terror Rift. There are also a number of failed rifts extending as far as Berkner Island. The West Antarctic Rift is the source of all the active volcanoes within Antarctica. Map of the West Antarctic Rift System and Transantarctic Mountains Winberry, J. P. and S. Anandakrishnan,2004, Crustal structure of the West Antarctic rift system and Marie Byrd Land hotspot
21.
Tectonic plate
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The theoretical model builds on the concept of continental drift developed during the first few decades of the 20th century. The geoscientific community accepted plate-tectonic theory after seafloor spreading was validated in the late 1950s, the lithosphere, which is the rigid outermost shell of a planet, is broken up into tectonic plates. The Earths lithosphere is composed of seven or eight major plates, where the plates meet, their relative motion determines the type of boundary, convergent, divergent, or transform. Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along plate boundaries. The relative movement of the plates typically ranges from zero to 100 mm annually, tectonic plates are composed of oceanic lithosphere and thicker continental lithosphere, each topped by its own kind of crust. Along convergent boundaries, subduction carries plates into the mantle, the material lost is balanced by the formation of new crust along divergent margins by seafloor spreading. In this way, the surface of the lithosphere remains the same. This prediction of plate tectonics is also referred to as the conveyor belt principle, earlier theories, since disproven, proposed gradual shrinking or gradual expansion of the globe. Tectonic plates are able to move because the Earths lithosphere has greater strength than the underlying asthenosphere. Lateral density variations in the result in convection. Plate movement is thought to be driven by a combination of the motion of the seafloor away from the ridge and drag, with downward suction. Another explanation lies in the different forces generated by forces of the Sun. The relative importance of each of these factors and their relationship to other is unclear. The outer layers of the Earth are divided into the lithosphere and asthenosphere and this is based on differences in mechanical properties and in the method for the transfer of heat. Mechanically, the lithosphere is cooler and more rigid, while the asthenosphere is hotter, in terms of heat transfer, the lithosphere loses heat by conduction, whereas the asthenosphere also transfers heat by convection and has a nearly adiabatic temperature gradient. The key principle of plate tectonics is that the lithosphere exists as separate and distinct tectonic plates, Plate motions range up to a typical 10–40 mm/year, to about 160 mm/year. The driving mechanism behind this movement is described below, tectonic lithosphere plates consist of lithospheric mantle overlain by either or both of two types of crustal material, oceanic crust and continental crust. Average oceanic lithosphere is typically 100 km thick, its thickness is a function of its age, as passes, it conductively cools
22.
Dead Sea
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The Dead Sea, is a salt lake bordered by Jordan to the east and Israel and Palestine to the west. Its surface and shores are 430.5 metres below sea level, the Dead Sea is 304 m deep, the deepest hypersaline lake in the world. With 34. 2% salinity, it is 9.6 times as salty as the ocean and this salinity makes for a harsh environment in which plants and animals cannot flourish, hence its name. The Dead Sea is 50 kilometres long and 15 kilometres wide at its widest point and it lies in the Jordan Rift Valley and its main tributary is the Jordan River. The Dead Sea has attracted visitors from around the Mediterranean basin for thousands of years and it was one of the worlds first health resorts, and it has been the supplier of a wide variety of products, from asphalt for Egyptian mummification to potash for fertilizers. People also use the salt and the minerals from the Dead Sea to create cosmetics, the Dead Sea water has a density of 1.24 kg/litre, which makes swimming similar to floating. The Dead Sea is receding at an alarming rate, multiple canals and pipelines were proposed to reduce its recession, which had begun causing many problems. The Red Sea–Dead Sea Water Conveyance project, carried out by Jordan, will provide water to neighboring countries, the first phase of the project is scheduled to begin in 2018 and be completed in 2021. In Hebrew, the Dead Sea is Yām ha-Melaḥ, meaning sea of salt, the Bible uses this term alongside two others, the Sea of the Arabah, and the Eastern Sea. The designation Dead Sea never appears in the Bible, in prose sometimes the term Yām ha-Māvet is used, due to the scarcity of aquatic life there. In Arabic the Dead Sea is called al-Bahr al-Mayyit, or less commonly baḥrᵘ lūṭᵃ, another historic name in Arabic was the Sea of Zoʼar, after a nearby town in biblical times. The Greeks called it Lake Asphaltites, the Dead Sea is an endorheic lake located in the Jordan Rift Valley, a geographic feature formed by the Dead Sea Transform. This left lateral-moving transform fault lies along the plate boundary between the African Plate and the Arabian Plate. It runs between the East Anatolian Fault zone in Turkey and the end of the Red Sea Rift offshore of the southern tip of Sinai. It is here that the Upper Jordan River/Sea of Galilee/Lower Jordan River water system comes to an end. The Jordan River is the major water source flowing into the Dead Sea, although there are small perennial springs under and around the Dead Sea, forming pools. The Mujib River, biblical Arnon, is one the larger sources of the Dead Sea other than the Jordan. The Wadi Mujib valley,420 m below the sea level in the southern of Jordan valley, is a biosphere reserve, other more substantial sources are Wadi Darajeh /Nahal Dragot, and Nahal Arugot
23.
Dead Sea Transform
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The Dead Sea Transform fault system, also sometimes referred to as the Dead Sea Rift, is a series of faults that run from the Maras Triple Junction to the northern end of the Red Sea Rift. The fault system forms the boundary between the African Plate to the west and the Arabian Plate to the east. It is a zone of left lateral displacement, signifying the relative motions of the two plates, both plates are moving in a general north-northeast direction, but the Arabian Plate is moving faster, resulting in the observed left lateral motions along the fault of approximately 107 km. The DST fault system is considered to be a transform fault that has accommodated a 105 km northwards displacement of the Arabian Plate. GPS data give similar rates of movement of the Arabian Plate relative to the Africa Plate. It has also proposed that the fault zone is a rift system that is an incipient oceanic spreading center. The Dead Sea Transform began to form during the early to mid-Miocene, a total displacement of 64 km has been estimated for this early phase of motion. In the Pliocene the DST propagated northwards once more through Lebanon into northwestern Syria before reaching the East Anatolian Fault. The southern section of the DST is about 400 km long, extending from the center in the Red Sea at southern end of the Gulf of Aqaba to just north of the Hula basin in southernmost Lebanon. The Gulf of Aqaba was created by movement on four left-stepping strike-slip fault segments in a diagonal stepwise sequence known as echelon formation. In the areas where these segments overlap, pull-apart basins have developed, parts of three of these faults ruptured during the 1995 Gulf of Aqaba earthquake. The Wadi Arabah segment of the DST extends for about 160 km from the Gulf of Aqaba to the end of the Dead Sea. Some researchers have further broken down this segment, recognising two separate segments, Avrona and Arava, the Avrona fault extends from the northern part of the Gulf of Aqaba for about 50 km along the Arava Valley. The Arava fault runs from just north of the Avrona fault segment for about 100 km, a slip rate of 4 ±2 mm per year has been estimated from the offset of gullies across the fault. Four major earthquakes are thought to have occurred due to movement on this fault in the last 1,000 years, the Dead Sea is formed in a pull-apart basin due to the left-stepping offset between the Wadi Arabah and Jordan Valley segments. The part of the basin with a fill of more than 2 km is 150 km long. In the north, the fill reaches its maximum thickness of about 10 km. The Jordan valley segment of the DST, the Jordan Rift Valley, a slip rate of between 4.7 and 5.1 mm per year has been estimated over the last 47,500 years
24.
Landslide
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A landslide, also known as a landslip, is a form of mass wasting that includes a wide range of ground movements, such as rockfalls, deep failure of slopes, and shallow debris flows. Landslides can occur underwater, called a submarine landslide, coastal, although the action of gravity is the primary driving force for a landslide to occur, there are other contributing factors affecting the original slope stability. Typically, pre-conditional factors build up specific sub-surface conditions that make the prone to failure. Landslides occur when the changes from a stable to an unstable condition. A change in the stability of a slope can be caused by a number of factors, slope material that becomes saturated with water may develop into a debris flow or mud flow. The resulting slurry of rock and mud may pick up trees, houses and cars, debris flow is often mistaken for flash flood, but they are entirely different processes. Muddy-debris flows in alpine areas cause severe damage to structures and infrastructure, muddy-debris flows can start as a result of slope-related factors and shallow landslides can dam stream beds, resulting in temporary water blockage. As the impoundments fail, an effect may be created, with a remarkable growth in the volume of the flowing mass. The solid–liquid mixture can reach densities of up to 2,000 kg/m3, for a small basin in the Italian Alps affected by a debris flow, estimated a peak discharge of 750 m3/s for a section located in the middle stretch of the main channel. At the same section, the maximum foreseeable water discharge, was 19 m3/s. Earthflows are downslope, viscous flows of saturated, fine-grained materials, typically, they can move at speeds from 0.17 to 20 km/h. Though these are a lot like mudflows, overall they are slow moving and are covered with solid material carried along by flow from within. They are different from fluid flows which are more rapid, clay, fine sand and silt, and fine-grained, pyroclastic material are all susceptible to earthflows. The velocity of the earthflow is all dependent on how much content is in the flow itself, if there is more water content in the flow. This thereby creates a bulging lobe which advances with a slow, as these lobes spread out, drainage of the mass increases and the margins dry out, thereby lowering the overall velocity of the flow. This process causes the flow to thicken, the bulbous variety of earthflows are not that spectacular, but they are much more common than their rapid counterparts. They develop a sag at their heads and are derived from the slumping at the source. Earthflows occur much more during periods of precipitation, which saturates the ground
25.
Rift lake
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The Rift Valley lakes are a group of lakes in the East African Rift that runs north-south through the eastern side of the African continent, from Ethiopia in the north to Malawi in the south. These lakes include some of the oldest, largest, and deepest lakes in the world, many are freshwater ecoregions of great biodiversity, while others are alkaline soda lakes supporting highly specialised organisms. The Rift Valley lakes are known for the evolution of at least 800 cichlid fish species that live in their waters. More species are expected to be discovered, the World Wildlife Fund has designated these lakes as one of its Global 200 priority ecoregions for conservation. In this article, the lakes are listed, generally in order from north to south. Lakes such as Lake Malawi and Lake Tanganyika have formed in the valleys of the East African Rift zone. Hide another face, dissolved within are billions of cubic meters of methane and more still of carbon dioxide. The Ethiopian Rift Valley lakes are the northernmost of the African Rift Valley lakes, most of the Ethiopian Rift Valley lakes do not have an outlet, and most are alkaline. South of the Ethiopian highlands, the valley splits into two major troughs. The Eastern Rift is home to the Kenyan Rift Valley lakes, the Kenyan section of the Rift Valley is home to eight lakes, of which three are freshwater and the rest alkaline. Of the latter, the soda lakes of the Eastern Rift Valley have crystallised salt turning the shores white and are famous for the large flocks of flamingo that feed on crustaceans. Lake Baringo, second largest of the Kenyan Rift Valley lakes,80 square miles, elevation 1,000 metres, freshwater Lake Bogoria, shallow soda lake, a national preserve. 34 square kilometres, elevation 990 metres Lake Elmenteita, shallow soda lake, Lake Logipi, a shallow hot-spring fed soda lake in the Suguta Valley just south of Lake Turkana. Lake Magadi, shallow soda lake near the border with Tanzania. Lake Naivasha,160 square kilometres although it varies somewhat with rainfall, elevation 1,890 metres, freshwater Lake Nakuru,40 square kilometres, elevation 1,759 metres Lake Turkana, the largest of the Kenyan lakes, on the border of Kenya and Ethiopia. The lakes of the Western or Albertine Rift, with Lake Victoria, include the largest, deepest and they are also referred to as the Central African lakes. Lakes Albert, Victoria, and Edward are part of the Nile River basin, Lake Victoria, with an area of 68,800 square kilometres, is the largest lake in Africa. It is not in the valley, instead occupying a depression between the eastern and western rifts formed by the uplift of the rifts to either side
26.
Lake Baikal
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Lake Baikal is a rift lake in Russia, located in southern Siberia, between Irkutsk Oblast to the northwest and the Buryat Republic to the southeast. Lake Baikal is the largest freshwater lake by volume in the world, with 23,615.39 km3 of fresh water, it contains more water than the North American Great Lakes combined. With a maximum depth of 1,642 m, Baikal is the worlds deepest lake and it is considered among the worlds clearest lakes and is considered the worlds oldest lake — at 25 million years. It is the seventh-largest lake in the world by surface area, like Lake Tanganyika, Lake Baikal was formed as an ancient rift valley, having the typical long crescent shape with a surface area of 31,722 km2. Baikal is home to thousands of species of plants and animals, the lake was declared a UNESCO World Heritage Site in 1996. The region to the east of Lake Baikal is referred to as Transbaikalia, Lake Baikal is in a rift valley, created by the Baikal Rift Zone, where the Earths crust is slowly pulling apart. At 636 km long and 79 km wide, Lake Baikal has the largest surface area of any lake in Asia, at 31,722 km2. The bottom of the lake is 1,186.5 m below sea level, but below this lies some 7 km of sediment, placing the rift floor some 8–11 km below the surface, the deepest continental rift on Earth. In geological terms, the rift is young and active—it widens about 2 cm per year, the fault zone is also seismically active, hot springs occur in the area and notable earthquakes happen every few years. The lake is divided into three basins, North, Central, and South, with depths about 900 m,1,600 m, fault-controlled accommodation zones rising to depths about 300 m separate the basins. The North and Central basins are separated by Academician Ridge, while the area around the Selenga Delta, the lake drains into the Angara tributary of the Yenisei. Notable landforms include Cape Ryty on Baikals northwest coast, Baikals age is estimated at 25 million years, making it the most ancient lake in geological history. It is unique among large, high-latitude lakes, as its sediments have not been scoured by overriding continental ice sheets. Russian, U. S. and Japanese cooperative studies of deep-drilling core sediments in the 1990s provide a record of climatic variation over the past 6.7 million years. Longer and deeper sediment cores are expected in the near future, Lake Baikal is the only confined freshwater lake in which direct and indirect evidence of gas hydrates exists. The lake is surrounded by mountains. The Baikal Mountains on the shore and the taiga are technically protected as a national park. It contains 27 islands, the largest, Olkhon, is 72 km long and is the third-largest lake-bound island in the world, the lake is fed by as many as 330 inflowing rivers
27.
Siberia
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Siberia is an extensive geographical region, and by the broadest definition is also known as North Asia. Siberia has historically been a part of Russia since the 17th century, the territory of Siberia extends eastwards from the Ural Mountains to the watershed between the Pacific and Arctic drainage basins. It stretches southwards from the Arctic Ocean to the hills of north-central Kazakhstan and to the borders of Mongolia. With an area of 13.1 million square kilometres, Siberia accounts for 77% of Russias land area and this is equivalent to an average population density of about 3 inhabitants per square kilometre, making Siberia one of the most sparsely populated regions on Earth. If it were a country by itself, it would still be the largest country in area, the origin of the name is unknown. Some sources say that Siberia originates from the Siberian Tatar word for sleeping land, another account sees the name as the ancient tribal ethnonym of the Sirtya, a folk, which spoke a language that later evolved into the Ugric languages. This ethnic group was assimilated to the Siberian Tatar people. The modern usage of the name was recorded in the Russian language after the Empires conquest of the Siberian Khanate, a further variant claims that the region was named after the Xibe people. The Polish historian Chycliczkowski has proposed that the name derives from the word for north. He said that the neighbouring Chinese, Arabs and Mongolians would not have known Russian and he suggests that the name is a combination of two words, su and bir. The region is of significance, as it contains bodies of prehistoric animals from the Pleistocene Epoch. Specimens of Goldfuss cave lion cubs, Yuka and another woolly mammoth from Oymyakon, a rhinoceros from the Kolyma River. The Siberian Traps were formed by one of the largest known volcanic events of the last 500 million years of Earths geological history. They continued for a million years and are considered a cause of the Great Dying about 250 million years ago. At least three species of human lived in Southern Siberia around 40,000 years ago, H. sapiens, H. neanderthalensis, the last was determined in 2010, by DNA evidence, to be a new species. Siberia was inhabited by different groups of such as the Enets, the Nenets, the Huns, the Scythians. The Khan of Sibir in the vicinity of modern Tobolsk was known as a prominent figure who endorsed Kubrat as Khagan of Old Great Bulgaria in 630, the Mongols conquered a large part of this area early in the 13th century. With the breakup of the Golden Horde, the autonomous Khanate of Sibir was established in the late 15th century, turkic-speaking Yakut migrated north from the Lake Baikal region under pressure from the Mongol tribes during the 13th to 15th century
28.
World Heritage Site
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A World Heritage Site is a landmark which has been officially recognized by the United Nations, specifically by the United Nations Educational, Scientific and Cultural Organization. Sites are selected on the basis of having cultural, historical, scientific or some form of significance. UNESCO regards these sites as being important to the interests of humanity. The programme catalogues, names, and conserves sites of outstanding cultural or natural importance to the common culture, under certain conditions, listed sites can obtain funds from the World Heritage Fund. The program was founded with the Convention Concerning the Protection of the Worlds Cultural and Natural Heritage, since then,192 state parties have ratified the convention, making it one of the most adhered to international instruments. As of July 2016,1052 sites are listed,814 cultural,203 natural, in 1959, the governments of Egypt and Sudan requested UNESCO to assist their countries to protect and rescue the endangered monuments and sites. In 1960, the Director-General of UNESCO launched an appeal to the Member States for an International Campaign to Save the Monuments of Nubia, the campaign, which ended in 1980, was considered a success. The project cost $80 million, about $40 million of which was collected from 50 countries, the projects success led to other safeguarding campaigns, saving Venice and its lagoon in Italy, the ruins of Mohenjo-daro in Pakistan, and the Borobodur Temple Compounds in Indonesia. UNESCO then initiated, with the International Council on Monuments and Sites, the United States initiated the idea of cultural conservation with nature conservation. The International Union for Conservation of Nature developed similar proposals in 1968, the Convention came into force on 17 December 1975. As of June 2016, it has been ratified by 192 states, including 188 UN member states plus the Cook Islands, the Holy See, Niue, a country must first list its significant cultural and natural sites, the result is called the Tentative List. A country may not nominate sites that have not been first included on the Tentative List, next, it can place sites selected from that list into a Nomination File. The Nomination File is evaluated by the International Council on Monuments and Sites and these bodies then make their recommendations to the World Heritage Committee. There are ten selection criteria – a site must meet at least one of them to be included on the list, up to 2004, there were six criteria for cultural heritage and four criteria for natural heritage. In 2005, this was modified so there is now only one set of ten criteria. Nominated sites must be of outstanding value and meet at least one of the ten criteria. Thus, the Geneva Convention treaty promulgates, Article 53, PROTECTION OF CULTURAL OBJECTS AND OF PLACES OF WORSHIP. There are 1,052 World Heritage Sites located in 165 States Party, of these,814 are cultural,203 are natural and 35 are mixed properties
29.
Albertine Rift
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The Albertine Rift is the western branch of the East African Rift, covering parts of Uganda, the Democratic Republic of the Congo, Rwanda, Burundi and Tanzania. It extends from the end of Lake Albert to the southern end of Lake Tanganyika. The geographical term includes the valley and the surrounding mountains, the Albertine Rift and the mountains are the result of tectonic movements that are gradually splitting the Somali Plate away from the rest of the African continent. The mountains surrounding the rift are composed of uplifted Pre-Cambrian basement rocks, the northern part of the rift is crossed by two large mountain ranges, the Rwenzori Mountains between Lake Albert and Lake Rutanzige and the Virunga Mountains between Lake Rutanziga and Lake Kivu. The Virungas form a barrier between the Nile Basin to the north and east and the Congo Basin to the west, Lake Rutenzige is fed by several large rivers, the Rutshuru River being one, and drains to the north through the Semliki River into Lake Albert. The Victoria Nile flows from Lake Victoria into the end of Lake Albert and exits as the White Nile from a point slightly to the west. South of the Virungu, Lake Kivu drains to the south into Lake Tanganyika through the Ruzizi River, Lake Tanganyika then drains into the Congo River via the Lukuga River. Before that Lake Tanganyika, or separate sub-basins in what is now the lake, the Lukuga has formed relatively recently, providing a route through which aquatic species of the Congo Basin could colonize Lake Tanganyika, which formerly had distinct fauna. From north to south the mountains include the Lendu Plateau, Rwenzori Mountains, Virunga Mountains, the Ruwenzori mountains have been identified with Ptolemys Mountains of the Moon. The range covers an area 120 kilometres long and 65 kilometres wide and this range includes Mount Stanley at 5,119 metres, Mount Speke at 4,890 metres and Mount Baker at 4,843 metres. The Virunga Massif along the border between Rwanda and the DRC consists of eight volcanoes, two of these, Nyamuragira and Nyiragongo, are still highly active. Most of the rise to between 2,000 metres and 3,500 metres. The Albertine Rift montane forests are important eco-regions, transitional forests, intermediate between lowland and montane forest, are found at elevations from around 1,000 metres to 1,750 metres. Montane forest covers the slopes from around 1,600 metres to 3,500 metres, above 2,400 metres there are areas of bamboo and elfin forest. Heather and grasses predominate above 3,500 metres, the ecology is threatened by deforestation as a growing population seeks new farmland. Illegal timber extraction is another problem, and artisanal gold mining causes some local damage
30.
Lake Superior
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Lake Superior is the largest of the Great Lakes of North America. The lake is shared by the Canadian province of Ontario to the north, the US state of Minnesota to the west and it is generally considered the largest freshwater lake in the world by surface area. It is the worlds third-largest freshwater lake by volume and the largest by volume in North America, the Ojibwe call the lake gichi-gami, meaning be a great sea. Henry Wadsworth Longfellow wrote the name as Gitche Gumee in The Song of Hiawatha, as did Gordon Lightfoot in his song, according to other sources the actual Ojibwe name is Ojibwe Gichigami or Anishinaabe Gichigami. The 1878 dictionary by Father Frederic Baraga, the first one written for the Ojibway language, the first French explorers approaching the great inland sea by way of the Ottawa River and Lake Huron during the 17th century referred to their discovery as le lac supérieur. Properly translated, the expression means Upper Lake, that is, the lake was also called Lac Tracy by 17th century Jesuit missionaries. Lake Superior empties into Lake Huron via the St. Marys River, Lake Superior is the largest freshwater lake in the world in area, and the third largest in volume, behind Lake Baikal in Siberia and Lake Tanganyika in East Africa. Lake Superior has an area of 31,700 square miles. It has a length of 350 statute miles and maximum breadth of 160 statute miles. Its average depth is 80.5 fathoms with a depth of 222.17 fathoms. Lake Superior contains 2,900 cubic miles of water, there is enough water in Lake Superior to cover the entire land mass of North and South America to a depth of 30 centimetres. The shoreline of the lake stretches 2,726 miles, while the temperature of the surface of Lake Superior varies seasonally, the temperature below 110 fathoms is an almost constant 39 °F. This variation in temperature makes the lake seasonally stratigraphic, twice per year, however, the water column reaches a uniform temperature of 39 °F from top to bottom, and the lake waters thoroughly mix. This feature makes the lake dimictic, because of its volume, Lake Superior has a retention time of 191 years. Annual storms on Lake Superior regularly feature wave heights of over 20 feet, waves well over 30 feet have been recorded. The lake is fed by over 200 rivers, the largest include the Nipigon River, the St. Louis River, the Pigeon River, the Pic River, the White River, the Michipicoten River, the Bois Brule River and the Kaministiquia River. Lake Superior drains into Lake Huron via the St. Marys River, there are rapids at the rivers upper end where the river bed has a relatively steep gradient. The Soo Locks were built to enable ships to bypass the rapids, the lakes average surface elevation is 600 feet above sea level
31.
North America
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North America is a continent entirely within the Northern Hemisphere and almost all within the Western Hemisphere. It can also be considered a subcontinent of the Americas. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the west and south by the Pacific Ocean, and to the southeast by South America and the Caribbean Sea. North America covers an area of about 24,709,000 square kilometers, about 16. 5% of the land area. North America is the third largest continent by area, following Asia and Africa, and the fourth by population after Asia, Africa, and Europe. In 2013, its population was estimated at nearly 565 million people in 23 independent states, or about 7. 5% of the worlds population, North America was reached by its first human populations during the last glacial period, via crossing the Bering land bridge. The so-called Paleo-Indian period is taken to have lasted until about 10,000 years ago, the Classic stage spans roughly the 6th to 13th centuries. The Pre-Columbian era ended with the migrations and the arrival of European settlers during the Age of Discovery. Present-day cultural and ethnic patterns reflect different kind of interactions between European colonists, indigenous peoples, African slaves and their descendants, European influences are strongest in the northern parts of the continent while indigenous and African influences are relatively stronger in the south. Because of the history of colonialism, most North Americans speak English, Spanish or French, the Americas are usually accepted as having been named after the Italian explorer Amerigo Vespucci by the German cartographers Martin Waldseemüller and Matthias Ringmann. Vespucci, who explored South America between 1497 and 1502, was the first European to suggest that the Americas were not the East Indies, but a different landmass previously unknown by Europeans. In 1507, Waldseemüller produced a map, in which he placed the word America on the continent of South America. He explained the rationale for the name in the accompanying book Cosmographiae Introductio, for Waldseemüller, no one should object to the naming of the land after its discoverer. He used the Latinized version of Vespuccis name, but in its feminine form America, following the examples of Europa, Asia and Africa. Later, other mapmakers extended the name America to the continent, In 1538. Some argue that the convention is to use the surname for naming discoveries except in the case of royalty, a minutely explored belief that has been advanced is that America was named for a Spanish sailor bearing the ancient Visigothic name of Amairick. Another is that the name is rooted in a Native American language, the term North America maintains various definitions in accordance with location and context. In Canadian English, North America may be used to refer to the United States, alternatively, usage sometimes includes Greenland and Mexico, as well as offshore islands
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Freshwater
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Fresh water is generally characterized by having low concentrations of dissolved salts and other total dissolved solids. The term specifically excludes seawater and brackish water although it does include mineral-rich waters such as chalybeate springs, the term sweet water has been used to describe fresh water in contrast to salt water. The term fresh water does not have the meaning as potable water. Much of the fresh water and ground water is unsuitable for drinking without some form of purification because of the presence of chemical or biological contaminants. It may also be in contact with the underlying underground water. The majority of water on Earth is in ice caps. The source of almost all water is precipitation from the atmosphere, in the form of mist, rain. Fresh water falling as mist, rain or snow contains materials dissolved from the atmosphere and material from the sea, in some cases this acid rain results in pollution of lakes and rivers. In coastal areas fresh water may contain significant concentrations of salts derived from the sea if windy conditions have lifted drops of seawater into the rain-bearing clouds. This can give rise to elevated concentrations of sodium, chloride, magnesium, significant quantities of iron may be transported in this way including the well-documented transfer of iron-rich rainfall falling in Brazil derived from sand-storms in the Sahara in north Africa. Water is an issue for the survival of all living organisms. Some can use water but many organisms including the great majority of higher plants. Out of all the water on Earth, saline water in oceans, seas and saline groundwater make up about 97% of it. Freshwater lakes contain about 87% of this surface water, including 29% in the African Great Lakes, 20% in Lake Baikal in Russia, 21% in the North American Great Lakes. Swamps have most of the balance only a small amount in rivers. In areas with no water on the ground surface, fresh water derived from precipitation may, because of its lower density. Most of the fresh water is frozen in ice sheets. Many areas suffer from lack of distribution of water, such as deserts
33.
Lake
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A lake is an area of variable size filled with water, localized in a basin, that is surrounded by land, apart from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, and therefore are distinct from lagoons, Lakes can be contrasted with rivers or streams, which are usually flowing. Most lakes are fed and drained by rivers and streams, natural lakes are generally found in mountainous areas, rift zones, and areas with ongoing glaciation. Other lakes are found in endorheic basins or along the courses of mature rivers, in some parts of the world there are many lakes because of chaotic drainage patterns left over from the last Ice Age. All lakes are temporary over geologic time scales, as they will fill in with sediments or spill out of the basin containing them. The word lake comes from Middle English lake, from Old English lacu, from Proto-Germanic *lakō, cognates include Dutch laak, Middle Low German lāke as in, de, Moorlake, de, Wolfslake, de, Butterlake, German Lache, and Icelandic lækur. Also related are the English words leak and leach, none of these definitions completely excludes ponds and all are difficult to measure. For this reason, simple size-based definitions are used to separate ponds. One definition of lake is a body of water of 2 hectares or more in area, however, others have defined lakes as waterbodies of 5 hectares and above, or 8 hectares and above. Charles Elton, one of the founders of ecology, regarded lakes as waterbodies of 40 hectares or more. The term lake is used to describe a feature such as Lake Eyre. In common usage, many bear names ending with the word pond. One textbook illustrates this point with the following, In Newfoundland, for example, almost every lake is called a pond, whereas in Wisconsin, the majority of lakes on Earth are fresh water, and most lie in the Northern Hemisphere at higher latitudes. Canada, with a drainage system has an estimated 31,752 lakes larger than 3 square kilometres and an unknown total number of lakes. Finland has 187,888 lakes 500 square metres or larger, most lakes have at least one natural outflow in the form of a river or stream, which maintain a lakes average level by allowing the drainage of excess water. Some lakes do not have an outflow and lose water solely by evaporation or underground seepage or both. Many lakes are artificial and are constructed for power generation, aesthetic purposes, recreational purposes, industrial use. Globally, lakes are greatly outnumbered by ponds, of an estimated 304 million standing water bodies worldwide, 91% are 1 hectare or less in area
34.
Midcontinent Rift
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The Midcontinent Rift System or Keweenawan Rift is a 2,000 km long geological rift in the center of the North American continent and south-central part of the North American plate. It formed when the core, the North American craton, began to split apart during the Mesoproterozoic era of the Precambrian. The rift failed, leaving thick layers of rock that are exposed in its northern reaches. Those arms meet at Lake Superior, which is contained within the rift valley, the lakes north shore in Ontario and Minnesota defines the northern arc of the rift. From the lake, the eastern arm trends south to central lower Michigan. The western arm runs from Lake Superior southwest through portions of Wisconsin, Minnesota, Iowa, the rock formations created by the rift included gabbro and granites from magma and basalts from lava. In the Lake Superior region, the upwelling of molten rock may have been the result of a hotspot which produced a triple junction. The hotspot made a dome covered the Lake Superior area. Voluminous basaltic lava erupted from the central axis of the rift. The southwest and southeast extensions represent two arms of the junction while a third failed arm extends north into Ontario as the Nipigon Embayment. This failed arm includes Lake Nipigon, Ontario and it is possible that the rift was the result of extensional forces behind the continental collision of the Grenville Orogeny to the east which in part overlaps the timing of the rift development. Later compressive forces from the Grenville Orogeny likely played a role in the rifts failure and closure. Had the rifting continued, the eventual result would have been sundering of the North American craton and creation of a sea. The Midcontinent Rift appears to have progressed almost to the point where the ocean intruded, but after about 15–22 million years the rift failed. The Midcontinent Rift is the deepest closed or healed rift yet discovered, Lake Superior occupies a basin created by the rift. Similar rocks are exposed as far south as Interstate Park near Saint Paul, Minnesota, where buried, the rift has been mapped by gravity anomalies, aeromagnetic surveys, and seismic data. The Proterozoic Nonesuch Shale formation in the Keweenawan Rift contains enough carbon to be considered a potential source rock for petroleum. Oil identified as Precambrian has been found seeping out of the Nonesuch Shale in the White Pine mine in Michigan, a few deep wells were drilled to explore for oil and gas in rift rocks as far southwest as Kansas
35.
Lake Vostok
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Lake Vostok is the largest of Antarcticas almost 400 known subglacial lakes. Lake Vostok is located at the southern Pole of Cold, beneath Russias Vostok Station under the surface of the central East Antarctic Ice Sheet, which is at 3,488 m above mean sea level. The surface of fresh water lake is approximately 4,000 m under the surface of the ice. Measuring 250 km long by 50 km wide at its widest point, and covering an area of 12,500 km2, the lake is divided into two deep basins by a ridge. The liquid water over the ridge is about 200 m, compared to roughly 400 m deep in the basin and 800 m deep in the southern. The lake is named after Vostok Station, which in turn is named after the Vostok, a sloop-of-war ship, which means East in Russian. The continued research by Russian and British scientists led by 1993 to the confirmation of the existence of the lake by J. P. Ridley using ERS-1 laser altimetry. The overlying ice provides a continuous record of 400,000 years. On 5 February 2012, a team of Russian scientists completed the longest ever ice core of 3,768 m, the first core of freshly frozen lake ice was obtained on 10 January 2013 at a depth of 3,406 m. However, as soon as the ice was pierced, water from the underlying lake gushed up the borehole, mixing it with the Freon, a new borehole was drilled and an allegedly pristine water sample was obtained in January 2015. The Russian team plans to lower a probe into the lake to collect water samples. It is hypothesized that unusual forms of life could be found in the liquid layer. Russian scientist Peter Kropotkin first proposed the idea of water under Antarctic ice sheets at the end of the 19th century. Kropotkins theory was developed by Russian glaciologist I. A. Zotikov. Russian geographer Andrey Kapitsa used seismic soundings in the region of Vostok Station made during the Soviet Antarctic Expedition in 1959 and 1964 to measure the thickness of the ice sheet. Kapitsa was the first to suggest the existence of a lake in the region. The data from ERS-1 confirmed the findings from the 1973 British surveys, space-based radar revealed that this subglacial body of fresh water is one of the largest lakes in the world, and one of some 140 subglacial lakes in Antarctica. Russian and British scientists delineated the lake in 1996 by integrating a variety of data, including airborne ice-penetrating radar imaging observations and it has been confirmed that the lake contains large amounts of liquid water under the more than 3-kilometer-thick ice cap
36.
Lake Nipissing
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Lake Nipissing is a lake in the Canadian province of Ontario. It has an area of 873.3 km2, a mean elevation of 196 m above sea level. Excluding the Great Lakes, Lake Nipissing is the third-largest lake in Ontario and it is relatively shallow for a large lake, with an average depth of only 4.5 m. The shallowness of the lake makes for many sandbars along the lakes irregular shoreline, the lake has many islands most of which are protected under the Protection of Significant Wetlands scheme, controlled by the Ministry of Natural Resources and Forestry. The largest population centre on the shoreline is the city of North Bay. North Bay sits along the northeastern shoreline. The larger towns toward the end of the lake are Sturgeon Falls, Garden Village, Cache Bay. Lake Nipissing drains into Georgian Bay, which is a part of Lake Huron, Lake Nipissing lies about 25 km northwest of Algonquin Provincial Park. The French fur trader Étienne Brûlé was the first European to visit the lake in 1610, the first permanent European settlement on the lake dates from around 1874 with a trading post of the Hudsons Bay Company on the northwest corner in what is now Sturgeon Falls. In 1882 the North-West Mounted Police established their presence on the north east shore, the lake contains over 40 different species of fish. Numerous sport fishing lodges dot the shoreline and can also be found on several of Nipissings many islands. Most anglers target walleye, smallmouth bass, muskie, and northern pike, for various reasons, largely social, numerous stocking associations are engaged in attempts to manage the lakes walleye population. The lakes name means big water in the Algonquin language, the name Nipissing was also given to many places in the area, notably the Township of Nipissing, Nipissing District, and Nipissing University. In the days of fur trade, coureur des bois and later travelled through the lake by canoe via the Mattawa. When the fur trade started to decline in the 1880s, logging became the economic activity. After World War I, the economic activity became tourism and recreation. Unlike most lakes in Ontario, Lake Nipissing contains two volcanic pipes, which are the Manitou Islands and Callander Bay, the volcanic pipes formed by the violent, supersonic eruption of deep-origin volcanoes. Lake Nipissing lies in the Ottawa-Bonnechere Graben, a Mesozoic era rift valley that formed 175 million years ago
37.
Lake Timiskaming
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Lake Timiskaming or Lake Temiskaming is a large freshwater lake on the provincial boundary between Ontario and Quebec, Canada. The lake, which part of the Ottawa River, is 110 kilometres in length. Its water level ranges between 175 m and 179 m above sea-level, with an annual average of 178.4 m. The lake is in places up to 216 m deep, there are several islands on the lake, notably Mann and du Collège Islands. The name is from the Algonquin Temikami or Temikaming, meaning deep waters, there are 30 species of fish in Lake Timiskaming, the best known are northern pike, sturgeon, lake trout, walleye, smallmouth bass, bullhead, carp, burbot, perch and whitefish. The lake was shaped during the last ice age when glaciers carved into the rock and it is also the remnants of a huge basin called Lake Ojibway, which existed about 9,500 years ago. Between 1976 and 1981 the DuPagne Classic fishing tourney took place at Wells Rock, for the trading post and some history see Fort Témiscamingue. Lake Timiskaming is centered on a rift valley that extends several hundred miles to the north-east called the Timiskaming Graben. It is the extension of the Ottawa-Bonnechere Graben, which is part of the Saint Lawrence rift system. There have been recent earthquakes along the valley, the most recent being in 2000. There are numerous faults in the area and has produced such as Devils Rock. There are known kimberlite pipes within the valley that are considered to be diamondiferous
38.
Ontario
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Ontario, one of the 13 provinces and territories of Canada, is located in east-central Canada. It is Canadas most populous province by a margin, accounting for nearly 40 percent of all Canadians. Ontario is fourth-largest in total area when the territories of the Northwest Territories and it is home to the nations capital city, Ottawa, and the nations most populous city, Toronto. There is only about 1 km of land made up of portages including Height of Land Portage on the Minnesota border. Ontario is sometimes divided into two regions, Northern Ontario and Southern Ontario. The great majority of Ontarios population and arable land is located in the south, in contrast, the larger, northern part of Ontario is sparsely populated with cold winters and is heavily forested. The province is named after Lake Ontario, a thought to be derived from Ontarí, io, a Huron word meaning great lake, or possibly skanadario. Ontario has about 250,000 freshwater lakes, the province consists of three main geographical regions, The thinly populated Canadian Shield in the northwestern and central portions, which comprises over half the land area of Ontario. Although this area mostly does not support agriculture, it is rich in minerals and in part covered by the Central and Midwestern Canadian Shield forests, studded with lakes, Northern Ontario is subdivided into two sub-regions, Northwestern Ontario and Northeastern Ontario. The virtually unpopulated Hudson Bay Lowlands in the north and northeast, mainly swampy. Southern Ontario which is further sub-divided into four regions, Central Ontario, Eastern Ontario, Golden Horseshoe, the highest point is Ishpatina Ridge at 693 metres above sea level located in Temagami, Northeastern Ontario. In the south, elevations of over 500 m are surpassed near Collingwood, above the Blue Mountains in the Dundalk Highlands, the Carolinian forest zone covers most of the southwestern region of the province. A well-known geographic feature is Niagara Falls, part of the Niagara Escarpment, the Saint Lawrence Seaway allows navigation to and from the Atlantic Ocean as far inland as Thunder Bay in Northwestern Ontario. Northern Ontario occupies roughly 87 percent of the area of the province. Point Pelee is a peninsula of Lake Erie in southwestern Ontario that is the southernmost extent of Canadas mainland, Pelee Island and Middle Island in Lake Erie extend slightly farther. All are south of 42°N – slightly farther south than the border of California. The climate of Ontario varies by season and location, the effects of these major air masses on temperature and precipitation depend mainly on latitude, proximity to major bodies of water and to a small extent, terrain relief. In general, most of Ontarios climate is classified as humid continental, Ontario has three main climatic regions
39.
Quebec
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Quebec is the second-most populous province of Canada and the only one to have a predominantly French-speaking population, with French as the sole provincial official language. Quebec is Canadas largest province by area and its second-largest administrative division and it also shares maritime borders with Nunavut, Prince Edward Island, and Nova Scotia. Quebec is Canadas second-most populous province, after Ontario, most inhabitants live in urban areas near the Saint Lawrence River between Montreal and Quebec City, the capital. Approximately half of Quebec residents live in the Greater Montreal Area, the Nord-du-Québec region, occupying the northern half of the province, is sparsely populated and inhabited primarily by Aboriginal peoples. Even in central Quebec at comparatively southerly latitudes winters are severe in inland areas, Quebec independence debates have played a large role in the politics of the province. Parti Québécois governments held referendums on sovereignty in 1980 and 1995, in 2006, the House of Commons of Canada passed a symbolic motion recognizing the Québécois as a nation within a united Canada. These many industries have all contributed to helping Quebec become an economically influential province within Canada, early variations in the spelling of the name included Québecq and Kébec. French explorer Samuel de Champlain chose the name Québec in 1608 for the colonial outpost he would use as the seat for the French colony of New France. The province is sometimes referred to as La belle province, the Province of Quebec was founded in the Royal Proclamation of 1763 after the Treaty of Paris formally transferred the French colony of Canada to Britain after the Seven Years War. The proclamation restricted the province to an area along the banks of the Saint Lawrence River, the Treaty of Versailles ceded territories south of the Great Lakes to the United States. After the Constitutional Act of 1791, the territory was divided between Lower Canada and Upper Canada, with each being granted an elected legislative assembly, in 1840, these become Canada East and Canada West after the British Parliament unified Upper and Lower Canada into the Province of Canada. This territory was redivided into the Provinces of Quebec and Ontario at Confederation in 1867, each became one of the first four provinces. In 1898, the Canadian Parliament passed the first Quebec Boundary Extension Act that expanded the provincial boundaries northward to include the lands of the aboriginal peoples. This was followed by the addition of the District of Ungava through the Quebec Boundaries Extension Act of 1912 that added the northernmost lands of the Inuit to create the modern Province of Quebec. In 1927, the border between Quebec and Newfoundland and Labrador was established by the British Judicial Committee of the Privy Council. Located in the part of Canada, and part of Central Canada. Its topography is very different from one region to another due to the composition of the ground, the climate. The Saint Lawrence Lowland and the Canadian Shield are the two main regions, and are radically different
40.
Iceland
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Iceland is a Nordic island country in the North Atlantic Ocean. It has a population of 332,529 and an area of 103,000 km2, the capital and largest city is Reykjavík. Reykjavík and the areas in the southwest of the country are home to over two-thirds of the population. Iceland is volcanically and geologically active, the interior consists of a plateau characterised by sand and lava fields, mountains and glaciers, while many glacial rivers flow to the sea through the lowlands. Iceland is warmed by the Gulf Stream and has a climate, despite a high latitude just outside the Arctic Circle. Its high latitude and marine influence still keeps summers chilly, with most of the archipelago having a tundra climate. According to the ancient manuscript Landnámabók, the settlement of Iceland began in the year 874 AD when the Norwegian chieftain Ingólfr Arnarson became the first permanent settler on the island. In the following centuries, Norwegians, and to a lesser extent other Scandinavians, emigrated to Iceland, the island was governed as an independent commonwealth under the Althing, one of the worlds oldest functioning legislative assemblies. Following a period of strife, Iceland acceded to Norwegian rule in the 13th century. The establishment of the Kalmar Union in 1397 united the kingdoms of Norway, Denmark, Iceland thus followed Norways integration to that Union and came under Danish rule after Swedens secession from that union in 1523. In the wake of the French revolution and the Napoleonic wars, Icelands struggle for independence took form and culminated in independence in 1918, until the 20th century, Iceland relied largely on subsistence fishing and agriculture, and was among the poorest in Europe. Industrialisation of the fisheries and Marshall Plan aid following World War II brought prosperity, in 1994, it became a part of the European Economic Area, which further diversified the economy into sectors such as finance, biotechnology, and manufacturing. Iceland has an economy with relatively low taxes compared to other OECD countries. It maintains a Nordic social welfare system that provides health care. Iceland ranks high in economic, political and social stability and equality, in 2013, it was ranked as the 13th most-developed country in the world by the United Nations Human Development Index. Iceland runs almost completely on renewable energy, some bankers were jailed, and the economy has made a significant recovery, in large part due to a surge in tourism. Icelandic culture is founded upon the nations Scandinavian heritage, most Icelanders are descendants of Germanic and Gaelic settlers. Icelandic, a North Germanic language, is descended from Old Norse and is related to Faroese
41.
Valles Marineris
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Valles Marineris is a system of canyons that runs along the Martian surface east of the Tharsis region. At more than 4,000 km long,200 km wide and up to 7 km deep, Valles Marineris is one of the largest canyons of the Solar System, surpassed in length only by the rift valleys of Earth. Valles Marineris is located along the equator of Mars, on the east side of the Tharsis Bulge and it has been recently suggested that Valles Marineris is a large tectonic crack in the Martian crust. Most researchers agree that this formed as the crust thickened in the Tharsis region to the west, near the eastern flanks of the rift, there appear to be channels that may have been formed by water or carbon dioxide. It has also proposed that Valles Marineris is a large channel formed by the erosion of lava flowing from the flank of Pavonis Mons. There have been many different theories about the formation of Valles Marineris that have changed over the years, ideas in the 1970s were erosion by water or thermokarst activity, which is the melting of permafrost in glacial climes. Many scientists agree that there was liquid water flowing on the Martian surface in the past, Valles Marineris may have been enlarged by flowing water at this time. Another hypothesis by McCauley in 1972 was that the canyons formed by withdrawal of subsurface magma, around 1989 Tanaka and Golombek proposed a theory of formation by tensional fracturing. The most agreed upon theory today is that Valles Marineris was formed by rift faults like the East African Rift, later made bigger by erosion and it has also been proposed that Valles Marineris was formed by flowing lava. The formation of Valles Marineris is thought to be tied with the formation of the Tharsis Bulge. The Tharsis Bulge was formed from the Noachian to Late Hesperian period of Mars, stage two consisted of more volcanism and a loss of isostatic equilibrium, the source regions of the volcanism no longer resided underneath Tharsis, creating a very large load. Finally, the crust failed to hold up Tharsis and radial fractures formed, stage three mainly consisted of more volcanism and asteroid impacts. The crust, having reached its failure point, just stayed in place. Landslides have left numerous deposits on the floor of Valles Marineris, possible triggers of landslides are quakes caused by tectonic activity or impact events. Both types of events release seismic waves that accelerate the ground at, Mars is much less tectonically active than Earth, and Mars-quakes are unlikely to have provided seismic waves of the required magnitude. Most sizable craters on Mars date to the Late Heavy Bombardment,4.1 to 3.8 billion years ago, and are older than the landslide deposits in Valles Marineris. However, three craters have been identified, on the basis of their proximity and later dates, as ones whose formation may have caused some of the landslides, also it contains canyons that run in different directions surrounding large blocks of older terrain. Most of the parts of the blocks are composed of younger fractured material thought to be of volcanic origin associated with the Tharsis bulge
42.
Devana Chasma
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Devana Chasma is a weak extensional rift zone on Venus, with a length of 4000 km, a width of 150–250 km, and a depth reaching 5 km. Most of the faults are facing north-south, the rift is located in Beta Regio, a 3000 km rise created by volcanic activity. Mantle plumes rising from the bottom are the reason behind the formation of the rift zone, the slow extension rates in the rift may be driven by the same reason. Formation of Theia Mons Volcano and Devana Chasma, The lava escapes through the crust forming Theia Mons volcano, repeated eruptions causes more lava to come and activate the rift zone which causes the extension of the crust. The Devana Chasma formed along the Beta Regio and Phoebe Regio volcanic rises and these extensional faults are 4000 km long and can be divided to two main parts, the northern part which covers around 700 km between Theia Mons and Rhea Mons which formed via Beta Regio mantle plume. The southern part cover the rest and formed due Phoebe Regio mantle plume, arecibo radar images and Magellan spacecraft helped in studying the Beta Regio region and shading the light on the Devana Chasma rift system. The lack of erosion and deformation processes record the history and development of Venus, the Devana Chasma rift system were also constructed by the uplift, and became active due the Theia Mons volcano. Furthermore, these evidences proposed several aspects concerning the development and history of the rift zone, nowadays, the rift zone is still active but the rifting is much slower because of the relative cold mantle plume. In previous centuries, the plumes were hotter and the rifting rate were faster, but the mantle got colder. Due to the similarities between Earth and Venus, it is suggested that they have a similar lithospheric elastic thickness of ~30 km, East African Rift is the only rift that can be compared to Devana Chasma. Both rifts have fault segments length around ~100 km, which makes them stronger than any extensional system on Earth, however, they differ in their half grabens, East African Rifts half grabens are around 50 km wide while on Venus it is around 150 km. In East African Rift, the elastic thickness can explain the wide half grabens. However, on Venus the main force is the shear stress due to the cold lithosphere. As a result, it has a wider half grabens than the one on Earth, studying and comparing these two rift systems help us to understand how volcanism and tectonic activities affected the development and formation of the Beta Regio region on Venus
43.
Ithaca Chasma
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Ithaca Chasma is a valley on Saturns moon Tethys, named after the island of Ithaca, in Greece. It is up to 100 km wide,3 to 5 km deep and 2,000 km long, running approximately three-quarters of the way around Tethys circumference, Ithaca Chasma is approximately concentric with Odysseus crater. Ithaca Chasma may have originated when the ocean inside Tethys froze. This would have caused the surface to crack in order to accommodate the increase in volume. Another hypothesis is that Ithaca Chasma is the outermost ring of the Odysseus impact basin, the Chasma is 4 to 0.4 billion years old, and slightly older than Odysseus. Ithaca Chasma was discovered by Voyager 1 spacecraft on 12 November 1980 during its flyby of Saturn, however its full extent was realized only in 1981 after the Voyager 2 flyby. It was named after the island of Ithaca, in Greece, Ithaca Chasma is a giant trough system about 3 km deep and approximately confined to a great circle running through the poles of Tethys. It is approximately concentric with Odysseus impact crater—a pole of Ithaca Chasma lies only approximately 20° from it, the chasma has a rather complex structure consisting of two narrow branches towards the south. Its exterior walls are made of multiple sub-parallel scarps and terraces, at some places the chasma has a rim standing as high as 0.5 km about the surrounding cratered planes. Its width varies from only a few kilometers at some places to more than 100 km, the age of Ithaca Chasma is estimated to be either 4.0 or 0. 4–3.3 billion years depending on chosen impact chronology. The crater counts indicate that the chasma is slightly older than Odysseus crater, there are two basic hypothesis as to how Ithaca Chasma formed. One of them is that it formed as Tethys internal liquid water solidified, causing the moon to expand. Earlier craters made before Tethys solidified were probably all erased by geological activity before then, Tethys subsurface ocean may have resulted from a 2,3 orbital resonance between Dione and Tethys early in the solar systems history. The resonance would have led to orbital eccentricity and tidal heating that may have warmed Tethys interior enough to form the ocean, subsequent freezing of the ocean after the moons escaped from the resonance may have generated the extensional stresses that created Ithaca Chasma. An alternative hypothesis is that it was formed at the time as the large crater Odysseus which lies near a pole of the Ithaca Chasma. When the impact that created Odysseus occurred, the shockwave may have traveled through Tethys, however, age determination based on crater counts in high resolution Cassini images showed that Ithaca Chasma is older than Odysseus, making the impact hypothesis unlikely
