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Arabia Mountain National Heritage Area
Arabia Mountain, a part of Arabia Mountain National Heritage Area, is the northern of two peaks in the Davidson-Arabia Mountain Nature Preserve, in DeKalb County, Georgia, United States. A low saddle separates it from Bradley Mountain, several hundred feet to its south. The two form a monadnock. The peak is 955 feet (290 m) above sea level, rising 172 feet (52 m) above Arabia Lake reservoir. Bradley Mountain is closer to the visitor trails than Arabia Mountain and is often misidentified by visitors as Arabia Mountain. The mountain is also in a namesake National Heritage Area in the U.S. state of Georgia that encompasses natural, cultural, and historical elements to form a cohesive, nationally significant landscape. The area is due east of Atlanta and spans reaching from the historic commercial center of Lithonia to the Monastery of the Holy Spirit in Conyers, including a number of sites in between, including Panola Mountain State Park, Davidson-Arabia Mountain Nat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DeKalb County, Georgia
DeKalb County (, , ) is located in the north central portion of the U.S. state of Georgia. As of the 2020 census, the population was 764,382, making it Georgia's fourth-most populous county. Its county seat is Decatur. DeKalb County is included in the Atlanta-Sandy Springs-Roswell, GA Metropolitan Statistical Area. It contains roughly 10% of the city of Atlanta (the other 90% lies in Fulton County). DeKalb is primarily a suburban county. In 2009, DeKalb earned the Atlanta Regional Commission's "Green Communities" designation for its efforts in conserving energy, water and fuel, investing in renewable energy, reducing waste, and protecting and restoring natural resources. In 2021, the non-profit American Rivers named DeKalb's South River the fourth-most endangered river in the United States, citing "the egregious threat that ongoing sewage pollution poses to clean water and public health." In recent years, some communities in North DeKalb have incorporated, following a t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brooklyn Bridge
The Brooklyn Bridge is a hybrid cable-stayed/ suspension bridge in New York City, spanning the East River between the boroughs of Manhattan and Brooklyn. Opened on May 24, 1883, the Brooklyn Bridge was the first fixed crossing of the East River. It was also the longest suspension bridge in the world at the time of its opening, with a main span of and a deck above mean high water. The span was originally called the New York and Brooklyn Bridge or the East River Bridge but was officially renamed the Brooklyn Bridge in 1915. Proposals for a bridge connecting Manhattan and Brooklyn were first made in the early 19th century, which eventually led to the construction of the current span, designed by John A. Roebling. The project's chief engineer, his son Washington Roebling, contributed further design work, assisted by the latter's wife, Emily Warren Roebling. Construction started in 1870, with the Tammany Hall-controlled New York Bridge Company overseeing construction, although ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gratiola Amphiantha
''Gratiola amphiantha'' is a rare species of flowering plant known by the common names little amphianthus, pool sprite and snorkelwort. It was previously the only species in the monotypic genus ''Amphianthus'', but it was moved to genus '' Gratiola'' after genetic analysis in 2008.Estes, D. and R. L. Small. (2008)Phylogenetic relationships of the monotypic genus ''Amphianthus'' (Plantaginaceae Tribe Gratioleae) inferred from chloroplast DNA sequences. ''Systematic Botany'' 33:1 176. It is native to the Piedmont region of the southeastern United States, with a center of distribution in Georgia. It occurs in Alabama and South Carolina as well. It is limited to granite outcrops, a high-biodiversity habitat type that is threatened by activities such as quarrying, off-road vehicles, and trash and debris dumping.USFWSEndangered or Threatened Status for Three Granite Outcrop Plants.''Federal Register'' February 5, 1988. It is a federally listed threatened species. ''Gratiola amphiantha'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isoetes Melanospora
''Isoetes melanospora'', commonly known as black-spored quillwort or black-spored Merlin's grass, is a rare and endangered aquatic lycophyte endemic to the U.S. states of Georgia and South Carolina. It grows exclusively in shallow, temporary pools on granite outcrops, often with only 2 cm of soil. 11 populations are known to exist in Georgia, while only one has been recorded in South Carolina, though this population is believed to be extirpated. The number of sites has dropped from 18 following its discovery due to habitat destruction caused by quarrying, trash dumping and trampling. New leaves quickly sprout after fall and winter rains, but during the dry summer months these typically shrivel. ''Isoetes melanospora'' is a small plant growing in mud or shallow water but becoming terrestrial as the ground dries. Rootstock is nearly spherical. Leaves are up to 7 cm (2.8 inches) long, spirally arranged, tapering to the tip. Megaspores are gray or black, 350-480 μm in dia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quarry
A quarry is a type of open-pit mine in which dimension stone, rock, construction aggregate, riprap, sand, gravel, or slate is excavated from the ground. The operation of quarries is regulated in some jurisdictions to reduce their environmental impact. The word ''quarry'' can also include the underground quarrying for stone, such as Bath stone. Types of rock Types of rock extracted from quarries include: *Chalk * China clay * Cinder *Clay *Coal *Construction aggregate (sand and gravel) *Coquina *Diabase *Gabbro *Granite *Gritstone *Gypsum *Limestone *Marble * Ores *Phosphate rock *Quartz *Sandstone *Slate *Travertine Stone quarry Stone quarry is an outdated term for mining construction rocks (limestone, marble, granite, sandstone, etc.). There are open types (called quarries, or open-pit mines) and closed types ( mines and caves). For thousands of years, only hand tools had been used in quarries. In the 18th century, the use of drilling and blasting operations w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gneiss
Gneiss ( ) is a common and widely distributed type of metamorphic rock. It is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. Gneiss forms at higher temperatures and pressures than schist. Gneiss nearly always shows a banded texture characterized by alternating darker and lighter colored bands and without a distinct cleavage. Gneisses are common in the ancient crust of continental shields. Some of the oldest rocks on Earth are gneisses, such as the Acasta Gneiss. Description Orthogneiss from the Czech Republic In traditional English and North American usage, a gneiss is a coarse-grained metamorphic rock showing compositional banding ( gneissic banding) but poorly developed schistosity and indistinct cleavage. In other words, it is a metamorphic rock composed of mineral grains easily seen with the unaided eye, which form obvious compositional layers, but which has only a weak tendency to fract ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Migmatite
Migmatite is a composite rock found in medium and high-grade metamorphic environments, commonly within Precambrian cratonic blocks. It consists of two or more constituents often layered repetitively: one layer is an older metamorphic rock that was reconstituted subsequently by partial melting ("paleosome"), while the alternate layer has a pegmatitic, aplitic, granitic or generally plutonic appearance ("neosome"). Commonly, migmatites occur below deformed metamorphic rocks that represent the base of eroded mountain chains. Migmatites form under extreme temperature and pressure conditions during prograde metamorphism, when partial melting occurs in metamorphic paleosome. Components exsolved by partial melting are called neosome (meaning ‘new body’), which may or may not be heterogeneous at the microscopic to macroscopic scale. Migmatites often appear as tightly, incoherently folded veins (ptygmatic folds).Recommendations by the IUGS Subcommission on the Systematics of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metamorphic Rock
Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causing profound physical or chemical changes. During this process, the rock remains mostly in the solid state, but gradually recrystallizes to a new texture or mineral composition. The protolith may be an igneous, sedimentary, or existing metamorphic rock. Metamorphic rocks make up a large part of the Earth's crust and form 12% of the Earth's land surface. They are classified by their protolith, their chemical and mineral makeup, and their texture. They may be formed simply by being deeply buried beneath the Earth's surface, where they are subject to high temperatures and the great pressure of the rock layers above. They can also form from tectonic processes such as continental collisions, which cause horizontal pressure, friction, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Granite
Granite () is a coarse-grained ( phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies underground. It is common in the continental crust of Earth, where it is found in igneous intrusions. These range in size from dikes only a few centimeters across to batholiths exposed over hundreds of square kilometers. Granite is typical of a larger family of ''granitic rocks'', or '' granitoids'', that are composed mostly of coarse-grained quartz and feldspars in varying proportions. These rocks are classified by the relative percentages of quartz, alkali feldspar, and plagioclase (the QAPF classification), with true granite representing granitic rocks rich in quartz and alkali feldspar. Most granitic rocks also contain mica or amphibole minerals, though a few (known as leucogranites) contain almost no dark minerals. Granite is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Panola Mountain
Panola Mountain is a granite monadnock near Stockbridge, Georgia, Stockbridge on the boundary between Henry County, Georgia, Henry County and Rockdale County, Georgia. The peak is above sea level, rising above the South River (Ocmulgee River), South River. The South River marks the boundary between Henry, Rockdale, and DeKalb County, Georgia, DeKalb counties. Due to its delicate ecological features, Panola Mountain was designated a National Natural Landmark in 1980. References External links * Panola Mountain State Park {{authority control State parks of Georgia (U.S. state) Mountains of Georgia (U.S. state) Inselbergs of North America National Natural Landmarks in Georgia (U.S. state) Protected areas of Rockdale County, Georgia Protected areas of Henry County, Georgia Nature centers in Georgia (U.S. state) Landforms of Rockdale County, Georgia Landforms of Henry County, Georgia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stone Mountain
Stone Mountain is a quartz monzonite dome Inselberg, monadnock and the site of Stone Mountain Park, east of Atlanta, Georgia. Outside the park is the small city of Stone Mountain, Georgia. The park is the most visited tourist site in the state of Georgia. The park is owned by the state of Georgia (U.S. state), Georgia and is currently managed by Herschend Family Entertainment. At its summit, the elevation is AMSL, above sea level and above the surrounding area. Stone Mountain is well known for not only its geology, but also the enormous rock relief on its north face, the largest bas-relief artwork in the world.Stone Mountain ." ''georgia.gov,'' retrieved February 2007. The carving, completed in 1972, depicts three Confederate States of America, Confederate leaders, Jefferson Davis, Rob ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monadnocks
An inselberg or monadnock () is an isolated rock hill, knob, ridge, or small mountain that rises abruptly from a gently sloping or virtually level surrounding plain. In Southern Africa a similar formation of granite is known as a koppie, an Afrikaans word ("little head") from the Dutch diminutive word ''kopje''. If the inselberg is dome-shaped and formed from granite or gneiss, it can also be called a bornhardt, though not all bornhardts are inselbergs. An inselberg results when a body of rock resistant to erosion, such as granite, occurring within a body of softer rocks, is exposed by differential erosion and lowering of the surrounding landscape. Etymology Inselberg The word ''inselberg'' is a loan word from German, and means "island mountain". The term was coined in 1900 by geologist Wilhelm Bornhardt (1864–1946) to describe the abundance of such features found in eastern Africa. At that time, the term applied only to arid landscape features. However, it has ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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