The Rockelmann is a mountain in the Ore Mountains in Saxony , southeastern Germany. It is south-southwest of Schwarzenberg . It formerly had two granite quarries, one of which was converted into an open-air theatre in the 1920s, the other into a Nazi arena ( Thingplatz ) in the 1930s, and is also the site of a memorial to soldiers killed in World War I ; all three are within Rockelmann Park, which was laid out in the 1930s.
81-456: The first extant mention of the Rockelmann is in a church document dated 1552. The origin of the name is unknown. The mountain is a source of granite as well as of augen gneiss , and rock was quarried for centuries at two points on the mountain above the town; granite from the Rockelmann was used to build the castle, to build St. George's Church ( St.-Georgen-Kirche ) in the 1690s and to rebuild
162-420: A completely crystalline rock. Granitic rocks mainly consist of feldspar , quartz , mica , and amphibole minerals , which form an interlocking, somewhat equigranular matrix of feldspar and quartz with scattered darker biotite mica and amphibole (often hornblende ) peppering the lighter color minerals. Occasionally some individual crystals ( phenocrysts ) are larger than the groundmass , in which case
243-553: A basaltic magma to a granitic magma, but the quantities produced are small. For example, granitic rock makes up just 4% of the exposures in the South Sandwich Islands . In continental arc settings, granitic rocks are the most common plutonic rocks, and batholiths composed of these rock types extend the entire length of the arc. There are no indication of magma chambers where basaltic magmas differentiate into granites, or of cumulates produced by mafic crystals settling out of
324-520: A diapir it would expend far too much energy in heating wall rocks, thus cooling and solidifying before reaching higher levels within the crust. Fracture propagation is the mechanism preferred by many geologists as it largely eliminates the major problems of moving a huge mass of magma through cold brittle crust. Magma rises instead in small channels along self-propagating dykes which form along new or pre-existing fracture or fault systems and networks of active shear zones. As these narrow conduits open,
405-653: A dry substrate of gravel deposits has formed which breaks the surface in places. The Brandberge was declared a protected natural area on 19 June 1996 and forms part of the Naturpark Unteres Saaletal . It is registered under the European Union Habitats Directive under the name Brandberge in Halle . However, 40 hectares (99 acres) passed into private hands in September 2003. As a botanic habitat,
486-509: A few (known as leucogranites ) contain almost no dark minerals. Granite is nearly always massive (lacking any internal structures), hard (falling between 6 and 7 on the Mohs hardness scale) , and tough. These properties have made granite a widespread construction stone throughout human history. The word "granite" comes from the Latin granum , a grain, in reference to the coarse-grained structure of such
567-610: A granite that is derived from partial melting of metasedimentary rocks may have more alkali feldspar, whereas a granite derived from partial melting of metaigneous rocks may be richer in plagioclase. It is on this basis that the modern "alphabet" classification schemes are based. The letter-based Chappell & White classification system was proposed initially to divide granites into I-type (igneous source) granite and S-type (sedimentary sources). Both types are produced by partial melting of crustal rocks, either metaigneous rocks or metasedimentary rocks. I-type granites are characterized by
648-565: A high content of sodium and calcium, and by a strontium isotope ratio, Sr/ Sr, of less than 0.708. Sr is produced by radioactive decay of Rb, and since rubidium is concentrated in the crust relative to the mantle, a low ratio suggests origin in the mantle. The elevated sodium and calcium favor crystallization of hornblende rather than biotite. I-type granites are known for their porphyry copper deposits. I-type granites are orogenic (associated with mountain building) and usually metaluminous. S-type granites are sodium-poor and aluminum-rich. As
729-608: A moveable stage in front of a rock wall with risers and steps. After renovations, it has a capacity of about 800 and is used for visiting theatrical performances by a troupe from Annaberg-Buchholz and for club events. On 10 October 1926, the Soldiers' Memorial ( Kriegerehrenmal ), a memorial to the men of Schwarzenberg fallen in the First World War , was dedicated by the members of the König Albert (King Albert) military association on
810-820: A much higher proportion of clay with the Cecil soil series a prime example of the consequent Ultisol great soil group. Granite is a natural source of radiation , like most natural stones. Potassium-40 is a radioactive isotope of weak emission, and a constituent of alkali feldspar , which in turn is a common component of granitic rocks, more abundant in alkali feldspar granite and syenites . Some granites contain around 10 to 20 parts per million (ppm) of uranium . By contrast, more mafic rocks, such as tonalite, gabbro and diorite , have 1 to 5 ppm uranium, and limestones and sedimentary rocks usually have equally low amounts. Many large granite plutons are sources for palaeochannel -hosted or roll front uranium ore deposits , where
891-465: A newspaper, a programme from the dedication ceremony and a report on the construction of the monument written by the sculptor's grandfather, Hans Brockhage , also a sculptor. In the early 1930s, the idea arose of converting the upper quarry into an arena for large-scale events. This was done in the context of the Nazi Thing movement, and a large part of the dynamiting, transport and construction work
SECTION 10
#1732872314082972-466: A parabolic amphitheatre (rather than the oval of most of the Nazi arenas). The stage area was on three levels and extended into and was easily reachable from the audience area; the upper stage area was formed by a building, whose rounded rear wall extended into the field like an apse so that it could also serve as a speaker's tribune for gatherings there. Within this building were the dressing rooms and also in
1053-536: A peculiar mineralogy and geochemistry, with particularly high silicon and potassium at the expense of calcium and magnesium and a high content of high field strength cations (cations with a small radius and high electrical charge, such as zirconium , niobium , tantalum , and rare earth elements .) They are not orogenic, forming instead over hot spots and continental rifting, and are metaluminous to mildly peralkaline and iron-rich. These granites are produced by partial melting of refractory lithology such as granulites in
1134-423: A private radio station. Since 1997 it has been leased to Peter Schwenkow 's operating company, then called Concert Concept, now DEAG Deutsche Entertainment , who have also shown films there. Betriebsgesellschaft Waldbühne Schwarzenberg was co-founded by them together with Semmel Concerts Bayreuth, who provide additional events, and renovations have included creating a backstage area at the open-air theatre to serve
1215-568: A range of hills, formed by the metamorphic aureole or hornfels . Granite often occurs as relatively small, less than 100 km stock masses ( stocks ) and in batholiths that are often associated with orogenic mountain ranges. Small dikes of granitic composition called aplites are often associated with the margins of granitic intrusions . In some locations, very coarse-grained pegmatite masses occur with granite. Granite forms from silica-rich ( felsic ) magmas. Felsic magmas are thought to form by addition of heat or water vapor to rock of
1296-415: A result, they contain micas such as biotite and muscovite instead of hornblende. Their strontium isotope ratio is typically greater than 0.708, suggesting a crustal origin. They also commonly contain xenoliths of metamorphosed sedimentary rock, and host tin ores. Their magmas are water-rich, and they readily solidify as the water outgasses from the magma at lower pressure, so they less commonly make it to
1377-472: A smith and an ironworker, and an eternal flame for which a gas line was specially installed. The stage above was also defined by two pillars resembling altars and surmounted by braziers which were ignited during performances. Moshamer's original design, prepared in January 1934, had been for 5,500 seats; this was reduced to 5,050, in the form of benches. Amplification was not installed, but was temporarily added for
1458-466: Is grus , which is often made up of coarse-grained fragments of disintegrated granite. Climatic variations also influence the weathering rate of granites. For about two thousand years, the relief engravings on Cleopatra's Needle obelisk had survived the arid conditions of its origin before its transfer to London. Within two hundred years, the red granite has drastically deteriorated in the damp and polluted air there. Soil development on granite reflects
1539-539: Is microgranite . The extrusive igneous rock equivalent of granite is rhyolite . Granitic rock is widely distributed throughout the continental crust . Much of it was intruded during the Precambrian age; it is the most abundant basement rock that underlies the relatively thin sedimentary veneer of the continents. Outcrops of granite tend to form tors , domes or bornhardts , and rounded massifs . Granites sometimes occur in circular depressions surrounded by
1620-582: Is 15,000, the largest open-air theatre in Saxony and the second largest in Germany; under the GDR it was given as 20,000. In 2010, the town further reduced the number of tickets to a maximum of 12,500 as a safety measure. The entrance is at the stage end of the arena; originally the technical equipment was housed under the stage together with an open space presumably intended for permanent displays, as at Halle . Emergency exits at
1701-517: Is 3–6·10 Pa·s. The melting temperature of dry granite at ambient pressure is 1215–1260 °C (2219–2300 °F); it is strongly reduced in the presence of water, down to 650 °C at a few hundred megapascals of pressure. Granite has poor primary permeability overall, but strong secondary permeability through cracks and fractures if they are present. A worldwide average of the chemical composition of granite, by weight percent, based on 2485 analyses: The medium-grained equivalent of granite
SECTION 20
#17328723140821782-480: 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
1863-410: Is an excess of aluminum beyond what can be taken up in feldspars (Al 2 O 3 > CaO + K 2 O + Na 2 O) are described as peraluminous , and they contain aluminum-rich minerals such as muscovite . The average density of granite is between 2.65 and 2.75 g/cm (165 and 172 lb/cu ft), its compressive strength usually lies above 200 MPa (29,000 psi), and its viscosity near STP
1944-460: Is being encroached upon by bushes, but this process can be kept in check by cutting. The fauna is unusually varied, including the European hare , the European stonechat , the shrike , the diving bell spider and many kinds of amphibians and reptiles , such as the natterjack toad , northern crested newt and grass snake . Waders and songbirds use the area as a brooding site, raptors use
2025-618: Is believed to have a mass of around 81 tonnes. It was the tallest temple in south India. Imperial Roman granite was quarried mainly in Egypt, and also in Turkey, and on the islands of Elba and Giglio . Granite became "an integral part of the Roman language of monumental architecture". The quarrying ceased around the third century AD. Beginning in Late Antiquity the granite was reused, which since at least
2106-434: Is called a binary or two-mica granite. Two-mica granites are typically high in potassium and low in plagioclase, and are usually S-type granites or A-type granites, as described below . Another aspect of granite classification is the ratios of metals that potentially form feldspars. Most granites have a composition such that almost all their aluminum and alkali metals (sodium and potassium) are combined as feldspar. This
2187-433: Is limited by the amount of thermal energy available, which must be replenished by crystallization of higher-melting minerals in the magma. Thus, the magma is melting crustal rock at its roof while simultaneously crystallizing at its base. This results in steady contamination with crustal material as the magma rises. This may not be evident in the major and minor element chemistry, since the minerals most likely to crystallize at
2268-404: Is permeated by sheets and channels of light granitic rock (the leucosome ). The leucosome is interpreted as partial melt of a parent rock that has begun to separate from the remaining solid residue (the melanosome). If enough partial melt is produced, it will separate from the source rock, become more highly evolved through fractional crystallization during its ascent toward the surface, and become
2349-454: Is relieved when overlying material is removed by erosion or other processes. Chemical weathering of granite occurs when dilute carbonic acid , and other acids present in rain and soil waters, alter feldspar in a process called hydrolysis . As demonstrated in the following reaction, this causes potassium feldspar to form kaolinite , with potassium ions, bicarbonate, and silica in solution as byproducts. An end product of granite weathering
2430-411: Is some concern that some granite sold as countertops or building material may be hazardous to health. Dan Steck of St. Johns University has stated that approximately 5% of all granite is of concern, with the caveat that only a tiny percentage of the tens of thousands of granite slab types have been tested. Resources from national geological survey organizations are accessible online to assist in assessing
2511-479: Is that magma will rise through the crust as a single mass through buoyancy . As it rises, it heats the wall rocks , causing them to behave as a power-law fluid and thus flow around the intrusion allowing it to pass without major heat loss. This is entirely feasible in the warm, ductile lower crust where rocks are easily deformed, but runs into problems in the upper crust which is far colder and more brittle. Rocks there do not deform so easily: for magma to rise as
Rockelmann - Misplaced Pages Continue
2592-410: Is the case when K 2 O + Na 2 O + CaO > Al 2 O 3 > K 2 O + Na 2 O. Such granites are described as normal or metaluminous . Granites in which there is not enough aluminum to combine with all the alkali oxides as feldspar (Al 2 O 3 < K 2 O + Na 2 O) are described as peralkaline , and they contain unusual sodium amphiboles such as riebeckite . Granites in which there
2673-485: 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
2754-409: Is typically orthoclase or microcline and is often perthitic . The plagioclase is typically sodium-rich oligoclase . Phenocrysts are usually alkali feldspar. Granitic rocks are classified according to the QAPF diagram for coarse grained plutonic rocks and are named according to the percentage of quartz , alkali feldspar ( orthoclase , sanidine , or microcline ) and plagioclase feldspar on
2835-428: Is uncommon, is classified simply as quartz-rich granitoid or, if composed almost entirely of quartz, as quartzolite . True granites are further classified by the percentage of their total feldspar that is alkali feldspar. Granites whose feldspar is 65% to 90% alkali feldspar are syenogranites , while the feldspar in monzogranite is 35% to 65% alkali feldspar. A granite containing both muscovite and biotite micas
2916-567: The A-Q-P half of the diagram. True granite (according to modern petrologic convention) contains between 20% and 60% quartz by volume, with 35% to 90% of the total feldspar consisting of alkali feldspar . Granitic rocks poorer in quartz are classified as syenites or monzonites , while granitic rocks dominated by plagioclase are classified as granodiorites or tonalites . Granitic rocks with over 90% alkali feldspar are classified as alkali feldspar granites . Granitic rock with more than 60% quartz, which
2997-523: The Brandberge is characterised by arid and semi-arid grassland and heathland vegetation on the porphyry hillocks, in addition to ponds and reedbeds, wet woodland and boggy areas in the central region, semi-bare areas and sparse arable land. The flora includes some worthy of protection such as Polygala vulgaris , Pulsatilla vulgaris , Lychnis flos-cuculi and Ranunculus aquatilis , and also some extremely endangered plant communities . The heathland
3078-462: The Brandberge site.) Financed and built by the German Labour Front , the hall of honour opened onto the assembly field and was intended to symbolise that "art in actuality belongs to the people ". It was made of porphyry and contained six larger than life sculptures by Alfred Vocke in rhyolite from Löbejün depicting different kinds of workers: a labourer, a farmer, a researcher, a miner,
3159-563: The Brandberge which had been used for military exercises had also been an assembly area for Nazis , and that and the Germanic "Thing" site led to its being selected for the first official open-air theatre, or Thingplatz , in association with the Thingspiel movement of nationalistic multi-disciplinary theatre. (In actuality, it turned out to be the Celtic burials that lay above the arena site.) Ground
3240-598: The European Union safety standards (section 4.1.1.1 of the National Health and Engineering study) and radon emission levels well below the average outdoor radon concentrations in the US. Granite and related marble industries are considered one of the oldest industries in the world, existing as far back as Ancient Egypt . Major modern exporters of granite include China, India, Italy, Brazil, Canada, Germany, Sweden, Spain and
3321-504: The United States. The Red Pyramid of Egypt ( c. 2590 BC ), named for the light crimson hue of its exposed limestone surfaces, is the third largest of Egyptian pyramids . Pyramid of Menkaure , likely dating 2510 BC, was constructed of limestone and granite blocks. The Great Pyramid of Giza (c. 2580 BC ) contains a huge granite sarcophagus fashioned of "Red Aswan Granite". The mostly ruined Black Pyramid dating from
Rockelmann - Misplaced Pages Continue
3402-493: The arable land as a source of prey, and the entire area has an extremely varied insect population including the scarce blue-tailed damselfly and small emerald damselfly . Archaeological finds from the Celtic Corded Ware and La Tène cultures and also a former Germanic "Thing" site have been located at the Brandberge. In the 1930s, the area was a popular location for winter sports. After World War II until
3483-465: The arena and constructing an electrical substation . The arena was designed by Ludwig Moshamer , a Berlin architect. It is 102 metres (335 ft) wide at its widest point (to reduce the amount of blasting required, the upper tier of seats was not extended to match the lower), and 30 metres (98 ft) (175 steps) deep. According to a contemporary construction periodical, there were originally 6,500 seats and standing room for 5,600. The current capacity
3564-419: The base of the chamber are the same ones that would crystallize anyway, but crustal assimilation is detectable in isotope ratios. Heat loss to the country rock means that ascent by assimilation is limited to distance similar to the height of the magma chamber. Physical weathering occurs on a large scale in the form of exfoliation joints , which are the result of granite's expanding and fracturing as pressure
3645-418: The big difference in rheology between mafic and felsic magmas makes this process problematic in nature. Granitization is an old, and largely discounted, hypothesis that granite is formed in place through extreme metasomatism . The idea behind granitization was that fluids would supposedly bring in elements such as potassium, and remove others, such as calcium, to transform a metamorphic rock into granite. This
3726-470: The centre a hall of honor for workers (the erste Ehrenmal der Arbeit , first monument to labour; the arena itself was officially the erste Thingstätte des Reiches , first Thing site of the Reich). (In fact the arena at Heringsdorf was begun first, in early February 1934, and also dedicated that May Day, but the official designation of Thingplatz was withheld from it until later, perhaps so as not to overshadow
3807-404: The division between S-type (produced by underplating) and I-type (produced by injection and differentiation) granites, discussed below. The composition and origin of any magma that differentiates into granite leave certain petrological evidence as to what the granite's parental rock was. The final texture and composition of a granite are generally distinctive as to its parental rock. For instance,
3888-467: The early 16th century became known as spolia . Through the process of case-hardening , granite becomes harder with age. The technology required to make tempered metal chisels was largely forgotten during the Middle Ages. As a result, Medieval stoneworkers were forced to use saws or emery to shorten ancient columns or hack them into discs. Giorgio Vasari noted in the 16th century that granite in quarries
3969-567: The edge of the Hercynian strike ; cold south-southwest winds channelled by the area have an important influence on local weather. The area is characterised by multiple groups of porphyry hillocks, with flat areas near the Saale. In the centre of the porphyry is a less hilly area with remnants of early Tertiary kaolin crusts and Tertiary sediments. Between the Saale and its tributary the Hechtgraben,
4050-648: The end of 2007, it was used as a proving ground by the Soviet Red Army , the East German National People's Army and, after German reunification , the Bundeswehr . This was detrimental to plant and animal life but also reduced human interference with the fauna. After the Soviet withdrawal in 1990/91, there was some refuse deposition . The only current commercial use is sheep pasture . A flat area within
4131-579: The first magma to enter solidifies and provides a form of insulation for later magma. These mechanisms can operate in tandem. For example, diapirs may continue to rise through the brittle upper crust through stoping , where the granite cracks the roof rocks, removing blocks of the overlying crust which then sink to the bottom of the diapir while the magma rises to take their place. This can occur as piecemeal stopping (stoping of small blocks of chamber roof), as cauldron subsidence (collapse of large blocks of chamber roof), or as roof foundering (complete collapse of
SECTION 50
#17328723140824212-433: The first performance, of Kurt Heynicke 's Neurode . The slope into which the theatre was built originally had very few trees, but many were planted on both sides to enclose it. Neurode was presented by a cast of 1,000 to about 6,000 spectators. Later the same month, the summer solstice was celebrated using both the arena and the assembly field, with Joseph Goebbels participating and 225,000 people present. Further use
4293-684: The grotto is a highly regarded piece of Buddhist art , and along with the temple complex to which it belongs, Seokguram was added to the UNESCO World Heritage List in 1995. Rajaraja Chola I of the Chola Dynasty in South India built the world's first temple entirely of granite in the 11th century AD in Tanjore , India . The Brihadeeswarar Temple dedicated to Lord Shiva was built in 1010. The massive Gopuram (ornate, upper section of shrine)
4374-474: The lower crust , rather than by decompression of mantle rock, as is the case with basaltic magmas. It has also been suggested that some granites found at convergent boundaries between tectonic plates , where oceanic crust subducts below continental crust, were formed from sediments subducted with the oceanic plate. The melted sediments would have produced magma intermediate in its silica content, which became further enriched in silica as it rose through
4455-697: The lower continental crust at high thermal gradients. This leads to significant extraction of hydrous felsic melts from granulite-facies resitites. A-type granites occur in the Koettlitz Glacier Alkaline Province in the Royal Society Range, Antarctica. The rhyolites of the Yellowstone Caldera are examples of volcanic equivalents of A-type granite. M-type granite was later proposed to cover those granites that were clearly sourced from crystallized mafic magmas, generally sourced from
4536-435: The magma is inevitable once enough magma has accumulated. However, the question of precisely how such large quantities of magma are able to shove aside country rock to make room for themselves (the room problem ) is still a matter of research. Two main mechanisms are thought to be important: Of these two mechanisms, Stokes diapirism has been favoured for many years in the absence of a reasonable alternative. The basic idea
4617-426: The magma. Other processes must produce these great volumes of felsic magma. One such process is injection of basaltic magma into the lower crust, followed by differentiation, which leaves any cumulates in the mantle. Another is heating of the lower crust by underplating basaltic magma, which produces felsic magma directly from crustal rock. The two processes produce different kinds of granites, which may be reflected in
4698-408: The magmatic parent of granitic rock. The residue of the source rock becomes a granulite . The partial melting of solid rocks requires high temperatures and the addition of water or other volatiles which lower the solidus temperature (temperature at which partial melting commences) of these rocks. It was long debated whether crustal thickening in orogens (mountain belts along convergent boundaries )
4779-405: The mantle. Although the fractional crystallisation of basaltic melts can yield small amounts of granites, which are sometimes found in island arcs, such granites must occur together with large amounts of basaltic rocks. H-type granites were suggested for hybrid granites, which were hypothesized to form by mixing between mafic and felsic from different sources, such as M-type and S-type. However,
4860-528: The meadow previously known as the Jahnwiese. It consists of a masonry pillar 8 metres (26 ft) high, originally topped by the figure of a warrior swearing an oath. The statue, the work of Ziegler of Chemnitz , was melted down in the Second World War . In 2008, during renovations of the column made necessary by leaching salts, a welded capsule was discovered under the top; it contained contemporary banknotes,
4941-543: The northwest of Halle . It is part of the Naturpark Unteres Saaletal , a protected landscape area which extends along the River Saale from Halle to Nienburg . In the past it has been used for military exercises and winter sports; during the Nazi era , the first official Thingplatz arena was built there. The Brandberge covers an area of 90.54 hectares (223.7 acres) in the northwest of Halle, between Kröllwitz and Heide Nord, on
SECTION 60
#17328723140825022-441: The overlying crust. Early fractional crystallisation serves to reduce a melt in magnesium and chromium, and enrich the melt in iron, sodium, potassium, aluminum, and silicon. Further fractionation reduces the content of iron, calcium, and titanium. This is reflected in the high content of alkali feldspar and quartz in granite. The presence of granitic rock in island arcs shows that fractional crystallization alone can convert
5103-702: The reign of Amenemhat III once had a polished granite pyramidion or capstone, which is now on display in the main hall of the Egyptian Museum in Cairo (see Dahshur ). Other uses in Ancient Egypt include columns , door lintels , sills , jambs , and wall and floor veneer. How the Egyptians worked the solid granite is still a matter of debate. Tool marks described by the Egyptologist Anna Serotta indicate
5184-551: The risk factors in granite country and design rules relating, in particular, to preventing accumulation of radon gas in enclosed basements and dwellings. A study of granite countertops was done (initiated and paid for by the Marble Institute of America) in November 2008 by National Health and Engineering Inc. of USA. In this test, all of the 39 full-size granite slabs that were measured for the study showed radiation levels well below
5265-418: The rock's high quartz content and dearth of available bases, with the base-poor status predisposing the soil to acidification and podzolization in cool humid climates as the weather-resistant quartz yields much sand. Feldspars also weather slowly in cool climes, allowing sand to dominate the fine-earth fraction. In warm humid regions, the weathering of feldspar as described above is accelerated so as to allow
5346-414: The rocks often bear a close resemblance. Under these conditions, granitic melts can be produced in place through the partial melting of metamorphic rocks by extracting melt-mobile elements such as potassium and silicon into the melts but leaving others such as calcium and iron in granulite residues. This may be the origin of migmatites . A migmatite consists of dark, refractory rock (the melanosome ) that
5427-489: The roof of a shallow magma chamber accompanied by a caldera eruption.) There is evidence for cauldron subsidence at the Mt. Ascutney intrusion in eastern Vermont. Evidence for piecemeal stoping is found in intrusions that are rimmed with igneous breccia containing fragments of country rock. Assimilation is another mechanism of ascent, where the granite melts its way up into the crust and removes overlying material in this way. This
5508-534: The sides have been added, as well as emergency lighting. The entire area surrounding both open-air theatres and the memorial was landscaped as Rockelmann Park, also in 1934–38. A set of bells of Meissen porcelain were previously housed in a tower there, but are now at the old well in the Old Town. 50°32′N 12°47′E / 50.533°N 12.783°E / 50.533; 12.783 Granite Granite ( / ˈ ɡ r æ n ɪ t / GRAN -it )
5589-435: The surface than magmas of I-type granites, which are thus more common as volcanic rock (rhyolite). They are also orogenic but range from metaluminous to strongly peraluminous. Although both I- and S-type granites are orogenic, I-type granites are more common close to the convergent boundary than S-type. This is attributed to thicker crust further from the boundary, which results in more crustal melting. A-type granites show
5670-440: The texture is known as porphyritic . A granitic rock with a porphyritic texture is known as a granite porphyry . Granitoid is a general, descriptive field term for lighter-colored, coarse-grained igneous rocks. Petrographic examination is required for identification of specific types of granitoids. Granites can be predominantly white, pink, or gray in color, depending on their mineralogy . The alkali feldspar in granites
5751-522: The theatre troupe from the open-air theatre at Ehrenfriedersdorf also played there. Under the German Democratic Republic , the arena was renamed in 1950 for President Wilhelm Pieck , who was himself present. In 1993 the town council renamed it the Waldbühne (forest stage or woodland theatre), and since German reunification it has been used for concerts, notably "oldies nights" presented by
5832-553: The town after a disastrous fire in 1709. A section of the town is named after the mountain. In 1908 there were efforts to build a lookout tower on the mountain. The dialect poet Curt Rambach composed a poem entitled "Wos iech erlabt hoo off'n Rokelmaa!" (What I experienced on the Rockelmann) which was printed on postcards in aid of the campaign. In the 1920s the lower quarry on the mountain was converted into an open-air theatre, which opened on 9 July 1924. It originally seated 700 and had
5913-502: The uranium washes into the sediments from the granite uplands and associated, often highly radioactive pegmatites. Cellars and basements built into soils over granite can become a trap for radon gas, which is formed by the decay of uranium. Radon gas poses significant health concerns and is the number two cause of lung cancer in the US behind smoking. Thorium occurs in all granites. Conway granite has been noted for its relatively high thorium concentration of 56±6 ppm. There
5994-599: The use of flint tools on finer work with harder stones, e.g. when producing the hieroglyphic inscriptions. Patrick Hunt has postulated that the Egyptians used emery , which has greater hardness. The Seokguram Grotto in Korea is a Buddhist shrine and part of the Bulguksa temple complex. Completed in 774 AD, it is an artificial grotto constructed entirely of granite. The main Buddha of
6075-461: Was "far softer and easier to work than after it has lain exposed" while ancient columns, because of their "hardness and solidity have nothing to fear from fire or sword, and time itself, that drives everything to ruin, not only has not destroyed them but has not even altered their colour." Brandberge#Nazi arena The Brandberge is a protected natural area in Saxony-Anhalt , Germany , in
6156-436: Was ceremonially broken on 19 February 1934 in front of 110,000 spectators, three times the number expected. Work was hurriedly completed so that the theatre could be dedicated that May 1, on the "National Day of Work" , but the first performance did not take place until 5 June. The theatre was designed by Ludwig Moshamer and placed on a site abutting the existing assembly field, roughly extending its semi-circular shape with
6237-601: Was done by the Workers' Labour Service . A total of 1,300 workers were involved in the project, and according to contemporary accounts, professionals were responsible for 20,000 days of work, Labour Service workers for 60,000. The sod-breaking took place on 7 April 1934, but costs greatly exceeded the estimates, and the project was only completed after the Propaganda Ministry and the State of Saxony provided additional funds. The arena
6318-464: Was inaugurated on 25–26 June 1938 as a Feierstätte der Volksgemeinschaft (ceremonial site for the folk community), the Grenzlandfeierstätte (Borderlands Ceremonial Site). A copper container containing construction plans, a newspaper and coins was sealed into the masonry to the right of the stage. The theatre was operated in cooperation with those at Borna and Kamenz ; in 1938–39,
6399-455: Was made of the theatre for drama, beginning in 1935 in association with other open-air theatres in the Gau . However, by that year the Propaganda Ministry was already withdrawing support for Thingspiel performances in Halle as not worth the cost. Since the Second World War the disused theatre has largely collapsed and been overgrown, although it was made a city monument in 1995. The statues from
6480-405: Was sufficient to produce granite melts by radiogenic heating , but recent work suggests that this is not a viable mechanism. In-situ granitization requires heating by the asthenospheric mantle or by underplating with mantle-derived magmas. Granite magmas have a density of 2.4 Mg/m , much less than the 2.8 Mg/m of high-grade metamorphic rock. This gives them tremendous buoyancy, so that ascent of
6561-564: Was supposed to occur across a migrating front. However, experimental work had established by the 1960s that granites were of igneous origin. The mineralogical and chemical features of granite can be explained only by crystal-liquid phase relations, showing that there must have been at least enough melting to mobilize the magma. However, at sufficiently deep crustal levels, the distinction between metamorphism and crustal melting itself becomes vague. Conditions for crystallization of liquid magma are close enough to those of high-grade metamorphism that
#81918