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94-781: The Pensacola Dam , also known as the Grand River Dam , is a multiple- arch buttress dam located between the towns of Disney and Langley on the Grand River in Mayes County , Oklahoma . The dam is operated by the Grand River Dam Authority and creates Grand Lake o' the Cherokees . After decades of vision and planning, it was constructed between 1938 and 1940 for the purposes of hydroelectric power generation, flood control and recreation. It

188-455: A Mohs hardness of 2 to 4, dense limestone can have a crushing strength of up to 180 MPa . For comparison, concrete typically has a crushing strength of about 40 MPa. Although limestones show little variability in mineral composition, they show great diversity in texture. However, most limestone consists of sand-sized grains in a carbonate mud matrix. Because limestones are often of biological origin and are usually composed of sediment that

282-463: A bloom of cyanobacteria or microalgae . However, stable isotope ratios in modern carbonate mud appear to be inconsistent with either of these mechanisms, and abrasion of carbonate grains in high-energy environments has been put forward as a third possibility. Formation of limestone has likely been dominated by biological processes throughout the Phanerozoic , the last 540 million years of

376-582: A better regulation of releases has been proposed while the GRDA is contemplating the installation of aeration devices and conducting studies along with other measures. The 1992 FERC license had addressed problematic DO levels and required the GRDA to plan methods to monitor and improve DO levels to a consistency with state water quality standards. In 2019-2020, residents of the town of Miami and neighboring Native American groups have objected to proposals to increase high water levels at Pensacola Dam and Grand Lake , on

470-434: A carbonate rock outcrop can be estimated in the field by etching the surface with dilute hydrochloric acid. This etches away the calcite and aragonite, leaving behind any silica or dolomite grains. The latter can be identified by their rhombohedral shape. Crystals of calcite, quartz , dolomite or barite may line small cavities ( vugs ) in the rock. Vugs are a form of secondary porosity, formed in existing limestone by

564-616: A central quartz grain or carbonate mineral fragment. These likely form by direct precipitation of calcium carbonate onto the ooid. Pisoliths are similar to ooids, but they are larger than 2 mm in diameter and tend to be more irregular in shape. Limestone composed mostly of ooids is called an oolite or sometimes an oolitic limestone . Ooids form in high-energy environments, such as the Bahama platform, and oolites typically show crossbedding and other features associated with deposition in strong currents. Oncoliths resemble ooids but show

658-449: A change in environment that increases the solubility of calcite. Dense, massive limestone is sometimes described as "marble". For example, the famous Portoro "marble" of Italy is actually a dense black limestone. True marble is produced by recrystallization of limestone during regional metamorphism that accompanies the mountain building process ( orogeny ). It is distinguished from dense limestone by its coarse crystalline texture and

752-949: A composition reflecting the organisms that produced them and the environment in which they were produced. Low-magnesium calcite skeletal grains are typical of articulate brachiopods , planktonic (free-floating) foraminifera, and coccoliths . High-magnesium calcite skeletal grains are typical of benthic (bottom-dwelling) foraminifera, echinoderms , and coralline algae . Aragonite skeletal grains are typical of molluscs , calcareous green algae , stromatoporoids , corals , and tube worms . The skeletal grains also reflect specific geological periods and environments. For example, coral grains are more common in high-energy environments (characterized by strong currents and turbulence) while bryozoan grains are more common in low-energy environments (characterized by quiet water). Ooids (sometimes called ooliths) are sand-sized grains (less than 2mm in diameter) consisting of one or more layers of calcite or aragonite around

846-412: A considerable fraction of the limestone bed. At depths greater than 1 km (0.62 miles), burial cementation completes the lithification process. Burial cementation does not produce stylolites. When overlying beds are eroded, bringing limestone closer to the surface, the final stage of diagenesis takes place. This produces secondary porosity as some of the cement is dissolved by rainwater infiltrating

940-473: A dam at the "Pensacola site" for flood control. The name "Pensacola" was derived from the only available means of identifying the site at the time: an old store on a Cherokee plantation. Because of limited state funding and a limited water supply on the Grand River, the project was not proposed at first for federal funding under the scope of hydroelectric power but instead for flood control. Oklahoma set up

1034-483: A drop of dilute hydrochloric acid is dropped on it. Dolomite is also soft but reacts only feebly with dilute hydrochloric acid, and it usually weathers to a characteristic dull yellow-brown color due to the presence of ferrous iron. This is released and oxidized as the dolomite weathers. Impurities (such as clay , sand, organic remains, iron oxide , and other materials) will cause limestones to exhibit different colors, especially with weathered surfaces. The makeup of

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1128-637: A few million years, as this is the most stable form of calcium carbonate. Ancient carbonate formations of the Precambrian and Paleozoic contain abundant dolomite, but limestone dominates the carbonate beds of the Mesozoic and Cenozoic . Modern dolomite is quite rare. There is evidence that, while the modern ocean favors precipitation of aragonite, the oceans of the Paleozoic and middle to late Cenozoic favored precipitation of calcite. This may indicate

1222-455: A few thousand years. As rainwater mixes with groundwater, aragonite and high-magnesium calcite are converted to low-calcium calcite. Cementing of thick carbonate deposits by rainwater may commence even before the retreat of the sea, as rainwater can infiltrate over 100 km (60 miles) into sediments beneath the continental shelf. As carbonate sediments are increasingly deeply buried under younger sediments, chemical and mechanical compaction of

1316-463: A generator was taken out of service, upgraded and returned to service by spring of the next year. The sixth and final generator upgrade was completed in May 2003. Among the components principally upgraded were the turbine shafts and runners . Pensacola Dam is a multiple-arch buttress type consisting of 51 arches and one main spillway , two auxiliary. It has a maximum height of 150 ft (46 m) above

1410-490: A high percentage of the mineral dolomite , CaMg(CO 3 ) 2 . Magnesian limestone is an obsolete and poorly-defined term used variously for dolomite, for limestone containing significant dolomite ( dolomitic limestone ), or for any other limestone containing a significant percentage of magnesium . Most limestone was formed in shallow marine environments, such as continental shelves or platforms , though smaller amounts were formed in many other environments. Much dolomite

1504-435: A limestone sample except in thin section and are less common in ancient limestones, possibly because compaction of carbonate sediments disrupts them. Limeclasts are fragments of existing limestone or partially lithified carbonate sediments. Intraclasts are limeclasts that originate close to where they are deposited in limestone, while extraclasts come from outside the depositional area. Intraclasts include grapestone , which

1598-471: A lower Mg/Ca ratio in the ocean water of those times. This magnesium depletion may be a consequence of more rapid sea floor spreading , which removes magnesium from ocean water. The modern ocean and the ocean of the Mesozoic have been described as "aragonite seas". Most limestone was formed in shallow marine environments, such as continental shelves or platforms . Such environments form only about 5% of

1692-525: A lower diversity of organisms and a greater fraction of silica and clay minerals characteristic of marls . The Green River Formation is an example of a prominent freshwater sedimentary formation containing numerous limestone beds. Freshwater limestone is typically micritic. Fossils of charophyte (stonewort), a form of freshwater green algae, are characteristic of these environments, where the charophytes produce and trap carbonates. Limestones may also form in evaporite depositional environments . Calcite

1786-523: A mechanism for dolomitization, with one 2004 review paper describing it bluntly as "a myth". Ordinary seawater is capable of converting calcite to dolomite, if the seawater is regularly flushed through the rock, as by the ebb and flow of tides (tidal pumping). Once dolomitization begins, it proceeds rapidly, so that there is very little carbonate rock containing mixed calcite and dolomite. Carbonate rock tends to be either almost all calcite/aragonite or almost all dolomite. About 20% to 25% of sedimentary rock

1880-448: A plausible source of mud. Another possibility is direct precipitation from the water. A phenomenon known as whitings occurs in shallow waters, in which white streaks containing dispersed micrite appear on the surface of the water. It is uncertain whether this is freshly precipitated aragonite or simply material stirred up from the bottom, but there is some evidence that whitings are caused by biological precipitation of aragonite as part of

1974-449: A radial rather than layered internal structure, indicating that they were formed by algae in a normal marine environment. Peloids are structureless grains of microcrystalline carbonate likely produced by a variety of processes. Many are thought to be fecal pellets produced by marine organisms. Others may be produced by endolithic (boring) algae or other microorganisms or through breakdown of mollusc shells. They are difficult to see in

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2068-484: A radius of 35 m (115 ft). Their second dam was built around 1350 and is called the Kurit Dam . After 4 m (13 ft) was added to the dam in 1850, it became 64 m (210 ft) tall and remained the tallest dam in the world until the early 20th century. The Kurit Dam was of masonry design and built in a very narrow canyon. The canyon was so narrow that its crest length is only 44% of its height. The dam

2162-462: A week. Initial construction began in February 1938 and included the excavation of over 1,600,000 cu yd (1,200,000 m) of earth and rock. Workers also constructed the first cofferdam on the east side of the river and left it in place until the arches were above the normal water level. Once this was achieved, workers removed the east cofferdam and constructed another on the west side of

2256-617: Is double-curved in both its horizontal and vertical planes may be called a dome dam . Arch dams with more than one contiguous arch or plane are described as multiple-arch dams . Early examples include the Roman Esparragalejo Dam with later examples such as the Daniel-Johnson Dam (1968) and Itaipu Dam (1982). However, as a result of the failure of the Gleno Dam shortly after it was constructed in 1923,

2350-502: Is 214 meters (702 ft) high and 1,314 meters (4,311 ft) long across its crest. It was completed in 1968 and put in service in 1970. Pensacola Dam was one of the last multiple arch types built in the United States. Its NRHP application states that this was because three dams of this type failed: (1) Gem Lake Dam, St. Francis Dam (California), Lake Hodges Dam (California). None of these failures were inherently caused by

2444-402: Is 742 ft (226 m) above sea level. The dam's power station is located at the base of the dam's western end and its building is 279 ft (85 m) long, 72 ft (22 m) wide and 60 ft (18 m) tall. The building houses six 20 MW Francis turbine generators that generate 335 million kWh annually and are each fed with their own individual penstock . The power plant

2538-509: Is Oklahoma's first hydroelectric power plant and is referred to as the longest multiple-arch dam in the world. The idea to construct a dam on the Grand River originated in the late 1800s with Henry C. Holderman, a Cherokee Nation citizen, who wanted to provide electric power to the Cherokee Nation. Holderman and a few colleagues soon conducted the first survey of the river in 1895 on their own handmade houseboat. Holderman later left

2632-560: Is also favored on the seaward margin of shelves and platforms, where there is upwelling deep ocean water rich in nutrients that increase organic productivity. Reefs are common here, but when lacking, ooid shoals are found instead. Finer sediments are deposited close to shore. The lack of deep sea limestones is due in part to rapid subduction of oceanic crust, but is more a result of dissolution of calcium carbonate at depth. The solubility of calcium carbonate increases with pressure and even more with higher concentrations of carbon dioxide, which

2726-482: Is an uncommon mineral in limestone, and siderite or other carbonate minerals are rare. However, the calcite in limestone often contains a few percent of magnesium . Calcite in limestone is divided into low-magnesium and high-magnesium calcite, with the dividing line placed at a composition of 4% magnesium. High-magnesium calcite retains the calcite mineral structure, which is distinct from dolomite. Aragonite does not usually contain significant magnesium. Most limestone

2820-402: Is carbonate rock, and most of this is limestone. Limestone is found in sedimentary sequences as old as 2.7 billion years. However, the compositions of carbonate rocks show an uneven distribution in time in the geologic record. About 95% of modern carbonates are composed of high-magnesium calcite and aragonite. The aragonite needles in carbonate mud are converted to low-magnesium calcite within

2914-474: Is clusters of peloids cemented together by organic material or mineral cement. Extraclasts are uncommon, are usually accompanied by other clastic sediments, and indicate deposition in a tectonically active area or as part of a turbidity current . The grains of most limestones are embedded in a matrix of carbonate mud. This is typically the largest fraction of an ancient carbonate rock. Mud consisting of individual crystals less than 5 μm (0.20 mils) in length

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3008-416: Is commonly white to gray in color. Limestone that is unusually rich in organic matter can be almost black in color, while traces of iron or manganese can give limestone an off-white to yellow to red color. The density of limestone depends on its porosity, which varies from 0.1% for the densest limestone to 40% for chalk. The density correspondingly ranges from 1.5 to 2.7 g/cm . Although relatively soft, with

3102-420: Is controlled largely by the amount of dissolved carbon dioxide ( CO 2 ) in the water. This is summarized in the reaction: Increases in temperature or decreases in pressure tend to reduce the amount of dissolved CO 2 and precipitate CaCO 3 . Reduction in salinity also reduces the solubility of CaCO 3 , by several orders of magnitude for fresh water versus seawater. Near-surface water of

3196-545: Is converted to low-magnesium calcite. Diagenesis is the likely origin of pisoliths , concentrically layered particles ranging from 1 to 10 mm (0.039 to 0.394 inches) in diameter found in some limestones. Pisoliths superficially resemble ooids but have no nucleus of foreign matter, fit together tightly, and show other signs that they formed after the original deposition of the sediments. Silicification occurs early in diagenesis, at low pH and temperature, and contributes to fossil preservation. Silicification takes place through

3290-503: Is deposited close to where it formed, classification of limestone is usually based on its grain type and mud content. Most grains in limestone are skeletal fragments of marine organisms such as coral or foraminifera . These organisms secrete structures made of aragonite or calcite, and leave these structures behind when they die. Other carbonate grains composing limestones are ooids , peloids , and limeclasts ( intraclasts and extraclasts  [ ca ] ). Skeletal grains have

3384-460: Is described as coquinite . Chalk is a soft, earthy, fine-textured limestone composed of the tests of planktonic microorganisms such as foraminifera, while marl is an earthy mixture of carbonates and silicate sediments. Limestone forms when calcite or aragonite precipitate out of water containing dissolved calcium, which can take place through both biological and nonbiological processes. The solubility of calcium carbonate ( CaCO 3 )

3478-617: Is described as micrite . In fresh carbonate mud, micrite is mostly small aragonite needles, which may precipitate directly from seawater, be secreted by algae, or be produced by abrasion of carbonate grains in a high-energy environment. This is converted to calcite within a few million years of deposition. Further recrystallization of micrite produces microspar , with grains from 5 to 15 μm (0.20 to 0.59 mils) in diameter. Limestone often contains larger crystals of calcite, ranging in size from 0.02 to 0.1 mm (0.79 to 3.94 mils), that are described as sparry calcite or sparite . Sparite

3572-586: Is designed to accommodate four additional generators. It operates at its highest generation levels during the summer and lowest during the winter. Just west of the power station is its substation and an observation house. The power station is regulated by the Federal Energy Regulatory Commission (FERC), under the Federal Power Act , with the current license issued in 1992 and set to expire in 2022. The first license

3666-462: Is distinguished from micrite by a grain size of over 20 μm (0.79 mils) and because sparite stands out under a hand lens or in thin section as white or transparent crystals. Sparite is distinguished from carbonate grains by its lack of internal structure and its characteristic crystal shapes. Geologists are careful to distinguish between sparite deposited as cement and sparite formed by recrystallization of micrite or carbonate grains. Sparite cement

3760-403: Is made of concrete and placed in a V-shaped valley. The foundation or abutments for an arch dam must be very stable and proportionate to the concrete. There are two basic designs for an arch dam: constant-radius dams , which have constant radius of curvature, and variable-radius dams , which have both upstream and downstream curves that systematically decrease in radius below the crest. A dam that

3854-560: Is one of the first minerals to precipitate in marine evaporites. Most limestone is formed by the activities of living organisms near reefs, but the organisms responsible for reef formation have changed over geologic time. For example, stromatolites are mound-shaped structures in ancient limestones, interpreted as colonies of cyanobacteria that accumulated carbonate sediments, but stromatolites are rare in younger limestones. Organisms precipitate limestone both directly as part of their skeletons, and indirectly by removing carbon dioxide from

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3948-473: Is otherwise chemically fairly pure, with clastic sediments (mainly fine-grained quartz and clay minerals ) making up less than 5% to 10% of the composition. Organic matter typically makes up around 0.2% of a limestone and rarely exceeds 1%. Limestone often contains variable amounts of silica in the form of chert or siliceous skeletal fragments (such as sponge spicules, diatoms , or radiolarians ). Fossils are also common in limestone. Limestone

4042-472: Is produced by decaying organic matter settling into the deep ocean that is not removed by photosynthesis in the dark depths. As a result, there is a fairly sharp transition from water saturated with calcium carbonate to water unsaturated with calcium carbonate, the lysocline , which occurs at the calcite compensation depth of 4,000 to 7,000 m (13,000 to 23,000 feet). Below this depth, foraminifera tests and other skeletal particles rapidly dissolve, and

4136-518: Is secondary dolomite, formed by chemical alteration of limestone. Limestone is exposed over large regions of the Earth's surface, and because limestone is slightly soluble in rainwater, these exposures often are eroded to become karst landscapes. Most cave systems are found in limestone bedrock. Limestone has numerous uses: as a chemical feedstock for the production of lime used for cement (an essential component of concrete ), as aggregate for

4230-557: Is still erect, even though part of its lower downstream face fell off. The Tibi Dam in Tibi , Spain was a post-medieval arch dam built between 1579 and 1594 and the first in Europe since the Romans. The dam was 42.7 metres (140 ft) high and 65 metres (213 ft) long. This arch dam rests on the mountains sides. In the early 20th century, the world's first variable-radius arch dam

4324-743: The World War II effort and returned it to the GRDA in 1946. The construction of the Pensacola Dam resulted in the loss of 1,285 acres (520 ha) of Cherokee land and 802 acres (325 ha) of the Quapaw Indian Agency , most of which belonged to the Seneca-Cayuga Tribe . This land was condemned and later flooded by the reservoir in 1940. Half of the Seneca-Cayuga Elk River ceremonial area

4418-588: The 143-meter double-curved Morrow Point Dam in Colorado, completed in 1968. By the late 20th century, arch dam design reached a relative uniformity in design around the world. Currently, the tallest arch dam in the world is the 305 metres (1,001 ft) Jingpin-I Dam in China , which was completed in 2013. The longest multiple arch with buttress dam in the world is the Daniel-Johnson Dam in Quebec , Canada . It

4512-496: The Earth's history. Limestone may have been deposited by microorganisms in the Precambrian , prior to 540 million years ago, but inorganic processes were probably more important and likely took place in an ocean more highly oversaturated in calcium carbonate than the modern ocean. Diagenesis is the process in which sediments are compacted and turned into solid rock . During diagenesis of carbonate sediments, significant chemical and textural changes take place. For example, aragonite

4606-534: The Grand River Dam Authority (GRDA) on January 10, 1935. Eventually, on September 18, 1937, with the help of Oklahoma Representative Wesley E. Disney , Senator Elmer Thomas and engineer W. R. Holway , President Franklin D. Roosevelt approved $ 20 million in funding through the New Deal 's Public Works Administration for the dam. The higher cost for the dam was attributed to a project that

4700-434: The Romans in 300 AD. It was 5.7 metres (19 ft) high and 52 m long (171 ft), with a radius of 19 m (62 ft). The curved ends of the dam met with two winged walls that were later supported by two buttresses. The dam also contained two water outlets to drive mills downstream. The Dara Dam was another arch dam built by the Romans in which the historian Procopius would write of its design: "This barrier

4794-457: The United States at the age of 16 and worked on dam projects in India and Africa before returning to Oklahoma. He sold his land holdings and borrowed money from friends in order to purchase rights to the dam sites he had prospected. Over several decades, Holderman and a group known as the "Rainbow Chasers" tried to secure funding to construct the dam; making several trips to Washington DC . The dam

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4888-616: The Vallon de Baume Dam, was built by the Romans in France and it dates back to the 1st century BC. The dam was about 12 metres (39 ft) high and 18 metres (59 ft) in length. Its radius was about 14 m (46 ft), and it consisted of two masonry walls. The Romans built it to supply nearby Glanum with water. The Monte Novo Dam in Portugal was another early arch dam built by

4982-430: The accumulation of corals and shells in the sea, have likely been more important for the last 540 million years. Limestone often contains fossils which provide scientists with information on ancient environments and on the evolution of life. About 20% to 25% of sedimentary rock is carbonate rock, and most of this is limestone. The remaining carbonate rock is mostly dolomite , a closely related rock, which contains

5076-434: The base of roads, as white pigment or filler in products such as toothpaste or paint, as a soil conditioner , and as a popular decorative addition to rock gardens . Limestone formations contain about 30% of the world's petroleum reservoirs . Limestone is composed mostly of the minerals calcite and aragonite , which are different crystal forms of calcium carbonate ( CaCO 3 ). Dolomite , CaMg(CO 3 ) 2 ,

5170-616: The base to 2.2 ft (0.67 m) at the crest. Inside of each buttress are 18 in (460 mm) thick transverse walls that act as "stiffeners". The buttresses were the widest of their type prior to 1938 and are designed to withstand 500 lbf/in (3,400 kPa; 35 kgf/cm). The main spillway, part of the eastern end of the dam, is a 861 ft (262 m) long Ogee-type and utilizes twenty-one 25 ft (7.6 m) tall and 36 ft (11 m) wide tainter gates that are operated by two 60-ton hoists . The auxiliary spillways are located about 1 mi (1.6 km) northeast of

5264-657: The beds. This may include the formation of vugs , which are crystal-lined cavities within the limestone. Diagenesis may include conversion of limestone to dolomite by magnesium-rich fluids. There is considerable evidence of replacement of limestone by dolomite, including sharp replacement boundaries that cut across bedding. The process of dolomitization remains an area of active research, but possible mechanisms include exposure to concentrated brines in hot environments ( evaporative reflux ) or exposure to diluted seawater in delta or estuary environments ( Dorag dolomitization ). However, Dorag dolomitization has fallen into disfavor as

5358-694: The construction of new multiple arch dams has become less popular. Contraction joints are normally placed every 20 m in the arch dam and are later filled with grout after the control cools and cures. Limestone Limestone ( calcium carbonate CaCO 3 ) is a type of carbonate sedimentary rock which is the main source of the material lime . It is composed mostly of the minerals calcite and aragonite , which are different crystal forms of CaCO 3 . Limestone forms when these minerals precipitate out of water containing dissolved calcium. This can take place through both biological and nonbiological processes, though biological processes, such as

5452-480: The dam and are controlled by another twenty-one 37 ft (11 m) wide and 15 ft (4.6 m) high tainter gates stretched over their combined 860 ft (260 m) length. The lip of the spillways lie at an elevation of 730 ft (220 m) above sea level while the tops of the gates are 755 ft (230 m). All three spillways have a combined maximum discharge of 525,000 cu ft/s (14,900 m/s). The two-lane State Highway 28 crosses over

5546-415: The dam has a clear span of 60 ft (18 m) and each buttress is 24 ft (7.3 m) wide. Arch dam designs would continue to test new limits and designs such as the double- and multiple-curve. Alfred Stucky and the U.S. Bureau of Reclamation developed a method of weight and stress distribution in the 1960s, and arch dam construction in the United States would see its last surge then with dams like

5640-414: The dam have been the center of controversy in recent years. Since the dam is a multi-purpose project, there are conflicting interests between flood control, environmental conservation, recreation and hydroelectric power production. The USACE may request minimal releases to prevent flooding in areas downstream and in hot mid-summer periods, releases can be minimal. This reduces dissolved oxygen (DO) levels in

5734-485: The dam while also being instrumental in its legislation. Once approved and funded, Holway, the main engineer on the project and previous engineer of the nearby Spavinaw Dam , began survey and engineering work on October 25, 1937. The multiple-arch buttress design was adopted because materials were expensive at the time of the Great Depression and the limestone and chert foundation was considered "ideal" for

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5828-466: The depositional fabric of carbonate rocks. Dunham divides the rocks into four main groups based on relative proportions of coarser clastic particles, based on criteria such as whether the grains were originally in mutual contact, and therefore self-supporting, or whether the rock is characterized by the presence of frame builders and algal mats. Unlike the Folk scheme, Dunham deals with the original porosity of

5922-469: The deposits are highly porous, so that they have a spongelike texture, they are typically described as tufa . Secondary calcite deposited by supersaturated meteoric waters ( groundwater ) in caves is also sometimes described as travertine. This produces speleothems , such as stalagmites and stalactites . Coquina is a poorly consolidated limestone composed of abraded pieces of coral , shells , or other fossil debris. When better consolidated, it

6016-406: The design. John Duncan Forsyth served as the architect for the dam and applied an Art Deco -style to it and the power house. Massman Construction Company out of Kansas City, Missouri was selected to construct the major superstructures , including the dam and power plant. Thousands of workers moved to the area to work on the dam before construction began and 3,000 eventually did, earning about $ 16

6110-406: The earth's oceans are oversaturated with CaCO 3 by a factor of more than six. The failure of CaCO 3 to rapidly precipitate out of these waters is likely due to interference by dissolved magnesium ions with nucleation of calcite crystals, the necessary first step in precipitation. Precipitation of aragonite may be suppressed by the presence of naturally occurring organic phosphates in

6204-399: The first refers to the grains and the second to the cement. For example, a limestone consisting mainly of ooids, with a crystalline matrix, would be termed an oosparite. It is helpful to have a petrographic microscope when using the Folk scheme, because it is easier to determine the components present in each sample. Robert J. Dunham published his system for limestone in 1962. It focuses on

6298-572: The formation of distinctive minerals from the silica and clay present in the original limestone. Two major classification schemes, the Folk and Dunham, are used for identifying the types of carbonate rocks collectively known as limestone. Robert L. Folk developed a classification system that places primary emphasis on the detailed composition of grains and interstitial material in carbonate rocks . Based on composition, there are three main components: allochems (grains), matrix (mostly micrite), and cement (sparite). The Folk system uses two-part names;

6392-429: The geologic record are called bioherms . Many are rich in fossils, but most lack any connected organic framework like that seen in modern reefs. The fossil remains are present as separate fragments embedded in ample mud matrix. Much of the sedimentation shows indications of occurring in the intertidal or supratidal zones, suggesting sediments rapidly fill available accommodation space in the shelf or platform. Deposition

6486-649: The grounds that when water backs up downstream, it can increase Miami's flooding problems. Between Memorial Day and Labor Day , the GRDA offers free tours of the dam. In 2010, there were over 9,000 visitors; a number which has been steadily growing in recent years. Additionally in 2010, the Ecosystems and Education Center was completed and has become part of the tour. The center serves as a water and fish monitoring research lab while offering visitors information about hydropower and water/electrical safety. Arch dam In general, arch dams are classified based on

6580-401: The multiple arch design. The design of an arch dam is a very complex process. It starts with an initial dam layout, that is continually improved until the design objectives are achieved within the design criteria. The main loads for which an arch dam is designed are: Other miscellaneous loads that affect a dam include: ice and silt loads, and uplift pressure. Most often, the arch dam

6674-410: The ocean basins, but limestone is rarely preserved in continental slope and deep sea environments. The best environments for deposition are warm waters, which have both a high organic productivity and increased saturation of calcium carbonate due to lower concentrations of dissolved carbon dioxide. Modern limestone deposits are almost always in areas with very little silica-rich sedimentation, reflected in

6768-459: The ratio of the base thickness to the structural height (b/h) as: Arch dams classified with respect to their structural height are: The development of arch dams throughout history began with the Romans in the 1st century BC and after several designs and techniques were developed, relative uniformity was achieved in the 20th century. The first known arch dam, the Glanum Dam , also known as

6862-426: The reaction: Fossils are often preserved in exquisite detail as chert. Cementing takes place rapidly in carbonate sediments, typically within less than a million years of deposition. Some cementing occurs while the sediments are still under water, forming hardgrounds . Cementing accelerates after the retreat of the sea from the depositional environment, as rainwater infiltrates the sediment beds, often within just

6956-482: The relative purity of most limestones. Reef organisms are destroyed by muddy, brackish river water, and carbonate grains are ground down by much harder silicate grains. Unlike clastic sedimentary rock, limestone is produced almost entirely from sediments originating at or near the place of deposition. Limestone formations tend to show abrupt changes in thickness. Large moundlike features in a limestone formation are interpreted as ancient reefs , which when they appear in

7050-438: The river bed. The total length of the dam and its sections is 6,565 ft (2,001 m) while the multiple-arch section is 4,284 ft (1,306 m) long and its combination with the spillway sections measure 5,145 ft (1,568 m). Each arch in the dam has a clear span of 60 ft (18 m) and each buttress is 24 ft (7.3 m) wide. The thickness of the buttress sidewalls ranges from 5 ft (1.5 m) at

7144-460: The river downstream. Such reductions resulted in the death of at least 5,000 fish downstream in July 2007. Significant releases from the dam have drawn opposition from people such as Oklahoma State Representative Doug Cox. He argues that the large releases effect the state's economy as an off-road recreational rock park is flooded downstream. Inconsistent releases are blamed for the overall problem and

7238-405: The river to divert water from the location of the future power plant. On December 30, 1938, Massman began the first concrete pour. Pouring was conducted 24-hours a day for 20 months, totaling 510,000 cu yd (390,000 m). A total of 23.9 million pounds of steel and iron were placed into the dam's structure to reinforce it. Major works on the dam were complete on March 21, 1940 and the lake

7332-460: The rock. The Dunham scheme is more useful for hand samples because it is based on texture, not the grains in the sample. A revised classification was proposed by Wright (1992). It adds some diagenetic patterns to the classification scheme. Travertine is a term applied to calcium carbonate deposits formed in freshwater environments, particularly waterfalls , cascades and hot springs . Such deposits are typically massive, dense, and banded. When

7426-479: The sediments increases. Chemical compaction takes place by pressure solution of the sediments. This process dissolves minerals from points of contact between grains and redeposits it in pore space, reducing the porosity of the limestone from an initial high value of 40% to 80% to less than 10%. Pressure solution produces distinctive stylolites , irregular surfaces within the limestone at which silica-rich sediments accumulate. These may reflect dissolution and loss of

7520-662: The sediments of the ocean floor abruptly transition from carbonate ooze rich in foraminifera and coccolith remains ( Globigerina ooze) to silicic mud lacking carbonates. In rare cases, turbidites or other silica-rich sediments bury and preserve benthic (deep ocean) carbonate deposits. Ancient benthic limestones are microcrystalline and are identified by their tectonic setting. Fossils typically are foraminifera and coccoliths. No pre-Jurassic benthic limestones are known, probably because carbonate-shelled plankton had not yet evolved. Limestones also form in freshwater environments. These limestones are not unlike marine limestone, but have

7614-459: The state of Oklahoma in 1940, was considered the longest multiple arch dam in the United States. Designed by W. R. Holway , it has 51 arches. and a maximum height of 150 ft (46 m) above the river bed. The total length of the dam and its sections is 6,565 ft (2,001 m) while the multiple-arch section is 4,284 ft (1,306 m) long and its combination with the spillway sections measure 5,145 ft (1,568 m). Each arch in

7708-507: The state's economy but local energy providers opposed the possibility of a state-run electric utility . The onset of the Great Depression would revive and accelerate plans to construct the dam. Just prior in 1928, Oklahoma Representative Everette B. Howard secured $ 5,000 in funding for the U.S. Army Corps of Engineers to survey the Grand River. The results of the study concluded that it would cost over $ 6.2 million to construct

7802-589: The top of the dam and a bridge that stretches over the main spillway. It is accessible by cars and trucks within weight. The dam's reservoir , Grand Lake o' the Cherokees (Grand Lake over the Cherokees), has a storage capacity of 1,672,000 acre⋅ft (2.062 × 10 m) of which 540,000 acre⋅ft (670,000,000 m) is flood storage. The reservoir's surface area is 46,500 acres (188 km) and it extends 66 mi (106 km) upstream, creating 1,300 mi (2,100 km) of shoreline. Normal surface elevation

7896-533: The water by photosynthesis and thereby decreasing the solubility of calcium carbonate. Limestone shows the same range of sedimentary structures found in other sedimentary rocks. However, finer structures, such as lamination , are often destroyed by the burrowing activities of organisms ( bioturbation ). Fine lamination is characteristic of limestone formed in playa lakes , which lack the burrowing organisms. Limestones also show distinctive features such as geopetal structures , which form when curved shells settle to

7990-553: The water. Although ooids likely form through purely inorganic processes, the bulk of CaCO 3 precipitation in the oceans is the result of biological activity. Much of this takes place on carbonate platforms . The origin of carbonate mud, and the processes by which it is converted to micrite, continue to be a subject of research. Modern carbonate mud is composed mostly of aragonite needles around 5 μm (0.20 mils) in length. Needles of this shape and composition are produced by calcareous algae such as Penicillus , making this

8084-614: The world, in particular by the U.S. Bureau of Reclamation . In 1920, the Swiss engineer and dam designer Alfred Stucky developed new calculation methods for arch dams, introducing the concept of elasticity during the construction of the Montsalvens arch dam in Switzerland, thereby improving the dam profile in the vertical direction by using a parabolic arch shape instead of a circular arch shape. Pensacola Dam , completed in

8178-508: Was almost built in 1914 by British capitalists but plans were halted due to World War I . In 1920, Holderman refused an offer given by Chicago businessmen and in 1929, the Wall Street Crash ended the hopes of Canadian engineers and investors building the dam for Holderman. In DC, supporters of the dam, which later included state and federal officials, argued for the dam as a source of hydroelectric power and that it could stimulate

8272-507: Was approved for additional purposes, including hydroelectric power generation and recreation. Additional costs for the dam were covered by the state government and by GRDA municipal bond auctions which appropriated or raised $ 11 million. Disney had pushed much of the legislation for the dam, comparing the higher electric utility rates in Oklahoma compared to other states. Senator Thomas helped appropriate additional state and public funding for

8366-629: Was built on the Salmon Creek near Juneau , Alaska . The Salmon Creek Dam's upstream face bulged upstream, which relieved pressure on the stronger, curved lower arches near the abutments. The dam also had a larger toe, which off-set pressure on the upstream heel of the dam, which now curved more downstream. The technology and economical benefits of the Salmon Creek Dam allowed for larger and taller dam designs. The dam was, therefore, revolutionary, and similar designs were soon adopted around

8460-480: Was filled by the end of that year's summer. The dam's power plant, with four original hydroelectric generators, began commercial operation in 1941. The dam was finished in 26 months, ahead of schedule. Much of this was attributed to eastern Oklahoma having its 18 driest months on record during construction which alleviated obstacles from flooding. The federal government took control of the dam in November 1941 to aid in

8554-429: Was flooded as well. Although losing significant portions of land, some tribe members were forced to find work on the dam project. In the 1950s, two additional generators were added to the power station, bringing the total to six. Between 1995 and 2003, the dam's six hydroelectric generators were upgraded, bringing the installed capacity of the power plant from 92 MW to 120 MW and increasing its generation 20%. Each autumn,

8648-623: Was granted by the FERC's predecessor, the Federal Power Commission in 1939. When the reservoir's elevation exceeds 745 ft (227 m), control of the dam's discharges are transferred to the U.S. Army Corps of Engineers (USACE) who manage flood control in the larger basin. By federal regulation, the GRDA and the Corps of Engineers often coordinate discharges and reservoir levels. FERC and USACE regulated releases downstream from

8742-416: Was likely deposited in pore space between grains, suggesting a high-energy depositional environment that removed carbonate mud. Recrystallized sparite is not diagnostic of depositional environment. Limestone outcrops are recognized in the field by their softness (calcite and aragonite both have a Mohs hardness of less than 4, well below common silicate minerals) and because limestone bubbles vigorously when

8836-460: Was not built in a straight line, but was bent into the shape of a crescent, so that the curve, by lying against the current of the river, might be able to offer still more resistance to the force of the stream." The Mongols also built arch dams in modern-day Iran. Their earliest was the Kebar Dam built around 1300, which was 26 m (85 ft) high and 55 m (180 ft) long, and had

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