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59-744: Lützen is situated in the Leipzig Bay , approximately 10 km (6.2 mi) southwest of the Leipzig city limits and 14 km (8.7 mi) northeast of Weißenfels . The town has access to the Bundesstraße 87 road from Leipzig to Weißenfels as well as to the Bundesautobahn 9 (at the Bad Dürrenberg junction) and the Bundesautobahn 38 . The municipal area comprises the following Ortschaften or municipal divisions: Held by

118-588: A dissected limestone pavement . This process is most effective along the joints, widening and deepening them. In unpolluted environments, the pH of rainwater due to dissolved carbon dioxide is around 5.6. Acid rain occurs when gases such as sulfur dioxide and nitrogen oxides are present in the atmosphere. These oxides react in the rain water to produce stronger acids and can lower the pH to 4.5 or even 3.0. Sulfur dioxide , SO 2 , comes from volcanic eruptions or from fossil fuels, and can become sulfuric acid within rainwater, which can cause solution weathering to

177-691: A mineral crystal exposes ions whose electrical charge attracts water molecules. Some of these molecules break into H+ that bonds to exposed anions (usually oxygen) and OH- that bonds to exposed cations. This further disrupts the surface, making it susceptible to various hydrolysis reactions. Additional protons replace cations exposed on the surface, freeing the cations as solutes. As cations are removed, silicon-oxygen and silicon-aluminium bonds become more susceptible to hydrolysis, freeing silicic acid and aluminium hydroxides to be leached away or to form clay minerals. Laboratory experiments show that weathering of feldspar crystals begins at dislocations or other defects on

236-418: A more humid chemical microenvironment. The attachment of these organisms to the rock surface enhances physical as well as chemical breakdown of the surface microlayer of the rock. Lichens have been observed to pry mineral grains loose from bare shale with their hyphae (rootlike attachment structures), a process described as plucking , and to pull the fragments into their body, where the fragments then undergo

295-403: A process of chemical weathering not unlike digestion. On a larger scale, seedlings sprouting in a crevice and plant roots exert physical pressure as well as providing a pathway for water and chemical infiltration. Most rock forms at elevated temperature and pressure, and the minerals making up the rock are often chemically unstable in the relatively cool, wet, and oxidizing conditions typical of

354-477: A result, thermal stress weathering is sometimes called insolation weathering , but this is misleading. Thermal stress weathering can be caused by any large change of temperature, and not just intense solar heating. It is likely as important in cold climates as in hot, arid climates. Wildfires can also be a significant cause of rapid thermal stress weathering. The importance of thermal stress weathering has long been discounted by geologists, based on experiments in

413-407: A slower reaction kinetics , this process is thermodynamically favored at low temperature, because colder water holds more dissolved carbon dioxide gas (due to the retrograde solubility of gases). Carbonate dissolution is therefore an important feature of glacial weathering. Carbonate dissolution involves the following steps: Carbonate dissolution on the surface of well-jointed limestone produces

472-469: A threat to the environment and occupant safety. Design strategies can moderate the impact of environmental effects, such as using of pressure-moderated rain screening, ensuring that the HVAC system is able to effectively control humidity accumulation and selecting concrete mixes with reduced water content to minimize the impact of freeze-thaw cycles. Granitic rock, the most abundant crystalline rock exposed at

531-426: Is acid hydrolysis , in which protons (hydrogen ions), which are present in acidic water, attack chemical bonds in mineral crystals. The bonds between different cations and oxygen ions in minerals differ in strength, and the weakest will be attacked first. The result is that minerals in igneous rock weather in roughly the same order in which they were originally formed ( Bowen's Reaction Series ). Relative bond strength

590-550: Is 14 megapascals (2,000 psi). This is still much greater than the tensile strength of granite, which is about 4 megapascals (580 psi). This makes frost wedging, in which pore water freezes and its volumetric expansion fractures the enclosing rock, appear to be a plausible mechanism for frost weathering. Ice will simply expand out of a straight open fracture before it can generate significant pressure. Thus, frost wedging can only take place in small tortuous fractures. The rock must also be almost completely saturated with water, or

649-704: Is a crucial part of the rock cycle ; sedimentary rock , the product of weathered rock, covers 66% of the Earth's continents and much of the ocean floor . Physical weathering , also called mechanical weathering or disaggregation , is the class of processes that causes the disintegration of rocks without chemical change. Physical weathering involves the breakdown of rocks into smaller fragments through processes such as expansion and contraction, mainly due to temperature changes. Two types of physical breakdown are freeze-thaw weathering and thermal fracturing. Pressure release can also cause weathering without temperature change. It

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708-403: Is a less well characterized mechanism of physical weathering. It takes place because ice grains always have a surface layer, often just a few molecules thick, that resembles liquid water more than solid ice, even at temperatures well below the freezing point. This premelted liquid layer has unusual properties, including a strong tendency to draw in water by capillary action from warmer parts of

767-671: Is a very flat, originally lakeless and highly fertile plain in Central Germany , in northwestern Saxony and southeastern Saxony-Anhalt , anchored by the foothills of the Harz mountains in the northwest and of the Ore Mountains in the southeast. This region was originally covered with dense forests and meandering rivers. In the course of urbanization and lignite open pit mining , large areas were deforested and many rivers and streams canalised or diverted. The Leipzig Bay

826-440: Is also important, acting to oxidize many minerals, as is carbon dioxide, whose weathering reactions are described as carbonation . The process of mountain block uplift is important in exposing new rock strata to the atmosphere and moisture, enabling important chemical weathering to occur; significant release occurs of Ca and other ions into surface waters. Dissolution (also called simple solution or congruent dissolution )

885-715: Is also known as sheeting . As with thermal weathering, pressure release is most effective in buttressed rock. Here the differential stress directed toward the unbuttressed surface can be as high as 35 megapascals (5,100 psi), easily enough to shatter rock. This mechanism is also responsible for spalling in mines and quarries, and for the formation of joints in rock outcrops. Retreat of an overlying glacier can also lead to exfoliation due to pressure release. This can be enhanced by other physical wearing mechanisms. Salt crystallization (also known as salt weathering , salt wedging or haloclasty ) causes disintegration of rocks when saline solutions seep into cracks and joints in

944-802: Is bounded to the north by the Düben Heath , to the east by the River Elbe , to the south by the Ore Mountain Foreland and the Central Saxon Hills , and by the River Saale to the west. The conurbation formed by the two cities of Leipzig and Halle lies in the centre of the Leipzig Bay. Other important towns are Delitzsch , Eilenburg , Merseburg and Borna . The Leipzig Bay is a Young Drift landscape and

1003-612: Is chemically weathered to iron(II) sulfate and gypsum , which then crystallize as salt lenses. Salt crystallization can take place wherever salts are concentrated by evaporation. It is thus most common in arid climates where strong heating causes strong evaporation and along coasts. Salt weathering is likely important in the formation of tafoni , a class of cavernous rock weathering structures. Living organisms may contribute to mechanical weathering, as well as chemical weathering (see § Biological weathering below). Lichens and mosses grow on essentially bare rock surfaces and create

1062-442: Is distinct from erosion , which involves the transport of rocks and minerals by agents such as water , ice , snow , wind , waves and gravity . Weathering processes are either physical or chemical. The former involves the breakdown of rocks and soils through such mechanical effects as heat, water, ice and wind. The latter covers reactions to water, atmospheric gases and biologically produced chemicals with rocks and soils. Water

1121-577: Is in equilibrium with kaolinite. Soil formation requires between 100 and 1,000 years, a brief interval in geologic time. As a result, some formations show numerous paleosol (fossil soil) beds. For example, the Willwood Formation of Wyoming contains over 1,000 paleosol layers in a 770 meters (2,530 ft) section representing 3.5 million years of geologic time. Paleosols have been identified in formations as old as Archean (over 2.5 billion years in age). They are difficult to recognize in

1180-472: Is likely the more important mechanism in nature. Geomorphologists have begun to reemphasize the importance of thermal stress weathering, particularly in cold climates. Pressure release or unloading is a form of physical weathering seen when deeply buried rock is exhumed . Intrusive igneous rocks, such as granite , are formed deep beneath the Earth's surface. They are under tremendous pressure because of

1239-484: Is relatively poor in potassium, the basalt weathers directly to potassium-poor montmorillonite , then to kaolinite . Where leaching is continuous and intense, as in rain forests, the final weathering product is bauxite , the principal ore of aluminium. Where rainfall is intense but seasonal, as in monsoon climates, the final weathering product is iron- and titanium-rich laterite . Conversion of kaolinite to bauxite occurs only with intense leaching, as ordinary river water

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1298-449: Is shown in the following table: This table is only a rough guide to order of weathering. Some minerals, such as illite , are unusually stable, while silica is unusually unstable given the strength of the silicon–oxygen bond . Carbon dioxide that dissolves in water to form carbonic acid is the most important source of protons, but organic acids are also important natural sources of acidity. Acid hydrolysis from dissolved carbon dioxide

1357-421: Is sometimes described as carbonation , and can result in weathering of the primary minerals to secondary carbonate minerals. For example, weathering of forsterite can produce magnesite instead of brucite via the reaction: Carbonic acid is consumed by silicate weathering, resulting in more alkaline solutions because of the bicarbonate . This is an important reaction in controlling the amount of CO 2 in

1416-427: Is the principal agent behind both kinds, though atmospheric oxygen and carbon dioxide and the activities of biological organisms are also important. Biological chemical weathering is also called biological weathering. The materials left after the rock breaks down combine with organic material to create soil . Many of Earth's landforms and landscapes are the result of weathering, erosion and redeposition. Weathering

1475-417: Is the process in which a mineral dissolves completely without producing any new solid substance. Rainwater easily dissolves soluble minerals, such as halite or gypsum , but can also dissolve highly resistant minerals such as quartz , given sufficient time. Water breaks the bonds between atoms in the crystal: [REDACTED] The overall reaction for dissolution of quartz is The dissolved quartz takes

1534-431: Is usually much less important than chemical weathering, but can be significant in subarctic or alpine environments. Furthermore, chemical and physical weathering often go hand in hand. For example, cracks extended by physical weathering will increase the surface area exposed to chemical action, thus amplifying the rate of disintegration. Frost weathering is the most important form of physical weathering. Next in importance

1593-426: Is wedging by plant roots, which sometimes enter cracks in rocks and pry them apart. The burrowing of worms or other animals may also help disintegrate rock, as can "plucking" by lichens. Frost weathering is the collective name for those forms of physical weathering that are caused by the formation of ice within rock outcrops. It was long believed that the most important of these is frost wedging , which results from

1652-565: The Prince-Bishops of Merseburg , Lützen Castle from the 13th century onwards was the seat of the local administration ( Amt ). After the 1485 Treaty of Leipzig , the town increasingly fell under the Wettin electors of Saxony , until the episcopal lands were finally secularised in 1547; from 1656/57 until 1738 it was held by the secundogeniture of Saxe-Merseburg . The town was the scene of two famous battles: By 1815 resolution of

1711-870: The Vienna Congress , Lützen fell to the Prussian province of Saxony . Part of the Soviet occupation zone after World War II , the town belonged to the East German district of Halle from 1952 to 1990. In 2017 a mass grave with 47 bodies from the Battle of Lützen (1632) were found near the town. Seats in the town's assembly ( Stadtrat ) as of 2019 local elections: [REDACTED] Media related to Lützen at Wikimedia Commons Leipzig Bay The Leipzig Bay ( German : Leipziger Tieflandsbucht ) or Leipzig Basin or Saxon Lowland or Saxon Bay

1770-408: The Earth's surface, begins weathering with the destruction of hornblende . Biotite then weathers to vermiculite , and finally oligoclase and microcline are destroyed. All are converted into a mixture of clay minerals and iron oxides. The resulting soil is depleted in calcium, sodium, and ferrous iron compared with the bedrock, and magnesium is reduced by 40% and silicon by 15%. At the same time,

1829-411: The Earth's surface. Chemical weathering takes place when water, oxygen, carbon dioxide, and other chemical substances react with rock to change its composition. These reactions convert some of the original primary minerals in the rock to secondary minerals, remove other substances as solutes, and leave the most stable minerals as a chemically unchanged resistate . In effect, chemical weathering changes

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1888-409: The affected rocks a reddish-brown coloration on the surface which crumbles easily and weakens the rock. Many other metallic ores and minerals oxidize and hydrate to produce colored deposits, as does sulfur during the weathering of sulfide minerals such as chalcopyrites or CuFeS 2 oxidizing to copper hydroxide and iron oxides . Mineral hydration is a form of chemical weathering that involves

1947-466: The atmosphere and can affect climate. Aluminosilicates containing highly soluble cations, such as sodium or potassium ions, will release the cations as dissolved bicarbonates during acid hydrolysis: Within the weathering environment, chemical oxidation of a variety of metals occurs. The most commonly observed is the oxidation of Fe ( iron ) by oxygen and water to form Fe oxides and hydroxides such as goethite , limonite , and hematite . This gives

2006-819: The carbon dioxide level to 30% of all soil gases, aided by adsorption of CO 2 on clay minerals and the very slow diffusion rate of CO 2 out of the soil. The CO 2 and organic acids help break down aluminium - and iron -containing compounds in the soils beneath them. Roots have a negative electrical charge balanced by protons in the soil next to the roots, and these can be exchanged for essential nutrient cations such as potassium. Decaying remains of dead plants in soil may form organic acids which, when dissolved in water, cause chemical weathering. Chelating compounds, mostly low molecular weight organic acids, are capable of removing metal ions from bare rock surfaces, with aluminium and silicon being particularly susceptible. The ability to break down bare rock allows lichens to be among

2065-530: The early 20th century that seemed to show that its effects were unimportant. These experiments have since been criticized as unrealistic, since the rock samples were small, were polished (which reduces nucleation of fractures), and were not buttressed. These small samples were thus able to expand freely in all directions when heated in experimental ovens, which failed to produce the kinds of stress likely in natural settings. The experiments were also more sensitive to thermal shock than thermal fatigue, but thermal fatigue

2124-427: The expansion of pore water when it freezes. A growing body of theoretical and experimental work suggests that ice segregation, whereby supercooled water migrates to lenses of ice forming within the rock, is the more important mechanism. When water freezes, its volume increases by 9.2%. This expansion can theoretically generate pressures greater than 200 megapascals (29,000 psi), though a more realistic upper limit

2183-404: The expense of silica, titanium, aluminum, ferrous iron, and calcium. Buildings made of any stone, brick or concrete are susceptible to the same weathering agents as any exposed rock surface. Also statues , monuments and ornamental stonework can be badly damaged by natural weathering processes. This is accelerated in areas severely affected by acid rain . Accelerated building weathering may be

2242-488: The first colonizers of dry land. The accumulation of chelating compounds can easily affect surrounding rocks and soils, and may lead to podsolisation of soils. The symbiotic mycorrhizal fungi associated with tree root systems can release inorganic nutrients from minerals such as apatite or biotite and transfer these nutrients to the trees, thus contributing to tree nutrition. It was also recently evidenced that bacterial communities can impact mineral stability leading to

2301-463: The form of silicic acid . A particularly important form of dissolution is carbonate dissolution, in which atmospheric carbon dioxide enhances solution weathering. Carbonate dissolution affects rocks containing calcium carbonate , such as limestone and chalk . It takes place when rainwater combines with carbon dioxide to form carbonic acid , a weak acid , which dissolves calcium carbonate (limestone) and forms soluble calcium bicarbonate . Despite

2360-669: The geologic record. Indications that a sedimentary bed is a paleosol include a gradational lower boundary and sharp upper boundary, the presence of much clay, poor sorting with few sedimentary structures, rip-up clasts in overlying beds, and desiccation cracks containing material from higher beds. The degree of weathering of soil can be expressed as the chemical index of alteration , defined as 100 Al 2 O 3 /(Al 2 O 3 + CaO + Na 2 O + K 2 O) . This varies from 47 for unweathered upper crust rock to 100 for fully weathered material. Wood can be physically and chemically weathered by hydrolysis and other processes relevant to minerals and

2419-439: The ice will simply expand into the air spaces in the unsaturated rock without generating much pressure. These conditions are unusual enough that frost wedging is unlikely to be the dominant process of frost weathering. Frost wedging is most effective where there are daily cycles of melting and freezing of water-saturated rock, so it is unlikely to be significant in the tropics, in polar regions or in arid climates. Ice segregation

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2478-421: The mid 20th century. The Leipzig region is historically, culturally and economically of huge importance to Central Germany . Although open-cast mining continues in the area, it is also being developed from an environmental and tourist perspective, through the reclamation of old lignite pits and mining facilities and their conversion into recreation areas, especially north and south of Leipzig. By flooding some

2537-546: The most effective biological agents of chemical weathering. For example, an experimental study on hornblende granite in New Jersey, US, demonstrated a 3x – 4x increase in weathering rate under lichen covered surfaces compared to recently exposed bare rock surfaces. The most common forms of biological weathering result from the release of chelating compounds (such as certain organic acids and siderophores ) and of carbon dioxide and organic acids by plants. Roots can build up

2596-486: The mountain ranges was deposited. As a result of the creation of bogs and variable flooding , organic material was also deposited in this basin, which in turn was overlaid by sediments . Brown coal or lignite was formed from these deposits, which is covered by layers of sand and loess . The landscape is very well served by communications. A cardioid ring motorway runs around the Leipzig-Halle conurbation,

2655-610: The open-cast mines many new lakes have been and are being created in the Leipzig Basin, which are gradually changing the face of the landscape. 51°00′00″N 13°00′00″E  /  51.0000°N 13.0000°E  / 51.0000; 13.0000 Weathering Weathering is the deterioration of rocks , soils and minerals (as well as wood and artificial materials) through contact with water, atmospheric gases , sunlight , and biological organisms. It occurs in situ (on-site, with little or no movement), and so

2714-551: The original set of minerals in the rock into a new set of minerals that is in closer equilibrium with surface conditions. True equilibrium is rarely reached, because weathering is a slow process, and leaching carries away solutes produced by weathering reactions before they can accumulate to equilibrium levels. This is particularly true in tropical environments. Water is the principal agent of chemical weathering, converting many primary minerals to clay minerals or hydrated oxides via reactions collectively described as hydrolysis . Oxygen

2773-443: The overlying rock material. When erosion removes the overlying rock material, these intrusive rocks are exposed and the pressure on them is released. The outer parts of the rocks then tend to expand. The expansion sets up stresses which cause fractures parallel to the rock surface to form. Over time, sheets of rock break away from the exposed rocks along the fractures, a process known as exfoliation . Exfoliation due to pressure release

2832-402: The production of weathering agents, such as protons, organic acids and chelating molecules. Weathering of basaltic oceanic crust differs in important respects from weathering in the atmosphere. Weathering is relatively slow, with basalt becoming less dense, at a rate of about 15% per 100 million years. The basalt becomes hydrated, and is enriched in total and ferric iron, magnesium, and sodium at

2891-416: The release of inorganic nutrients. A large range of bacterial strains or communities from diverse genera have been reported to be able to colonize mineral surfaces or to weather minerals, and for some of them a plant growth promoting effect has been demonstrated. The demonstrated or hypothesised mechanisms used by bacteria to weather minerals include several oxidoreduction and dissolution reactions as well as

2950-448: The rigid attachment of water molecules or H+ and OH- ions to the atoms and molecules of a mineral. No significant dissolution takes place. For example, iron oxides are converted to iron hydroxides and the hydration of anhydrite forms gypsum . Bulk hydration of minerals is secondary in importance to dissolution, hydrolysis, and oxidation, but hydration of the crystal surface is the crucial first step in hydrolysis. A fresh surface of

3009-455: The rock surface, which gradually pry the rock apart. Thermal stress weathering results from the expansion and contraction of rock due to temperature changes. Thermal stress weathering is most effective when the heated portion of the rock is buttressed by surrounding rock, so that it is free to expand in only one direction. Thermal stress weathering comprises two main types, thermal shock and thermal fatigue . Thermal shock takes place when

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3068-413: The rock. This results in growth of the ice grain that puts considerable pressure on the surrounding rock, up to ten times greater than is likely with frost wedging. This mechanism is most effective in rock whose temperature averages just below the freezing point, −4 to −15 °C (25 to 5 °F). Ice segregation results in growth of ice needles and ice lenses within fractures in the rock and parallel to

3127-408: The rocks and evaporate, leaving salt crystals behind. As with ice segregation, the surfaces of the salt grains draw in additional dissolved salts through capillary action, causing the growth of salt lenses that exert high pressure on the surrounding rock. Sodium and magnesium salts are the most effective at producing salt weathering. Salt weathering can also take place when pyrite in sedimentary rock

3186-425: The rocks on which it falls. Hydrolysis (also called incongruent dissolution ) is a form of chemical weathering in which only part of a mineral is taken into solution. The rest of the mineral is transformed into a new solid material, such as a clay mineral . For example, forsterite (magnesium olivine ) is hydrolyzed into solid brucite and dissolved silicic acid: Most hydrolysis during weathering of minerals

3245-415: The so-called Central German Loop ( Mitteldeutsche Schleife ). Leipzig/Halle Airport is an important transport hub in the eastern German states. Railway lines and Bundesstraßen (federal roads) run in all directions of the compass, linking the Leipzig Bay with other parts of the country. Only inland shipping has no direct access to this region, although work on the unfinished Elster-Saale Canal began in

3304-536: The soil is enriched in aluminium and potassium by at least 50%; by titanium, whose abundance triples, and ferric iron, whose abundance increases by an order of magnitude compared with the bedrock. Basaltic rock is more easily weathered than granitic rock due to its formation at higher temperatures and drier conditions. The fine grain size and presence of volcanic glass also hasten weathering. In tropical settings, it rapidly weathers to clay minerals, aluminium hydroxides, and titanium-enriched iron oxides. Because most basalt

3363-674: The southernmost part of the North German Plain . The landscape is essentially a plain broken only by low eminences such as the Hohburg Hills and dissected by the valleys of the Saale , White Elster , Mulde , and Pleiße rivers. The Leipzig Bay was formed during the Tertiary period. When the Ore Mountains and Vogtland were uplifted, a basin was formed as a compensating movement, into which weathering material from

3422-419: The stresses are so great that the rock cracks immediately, but this is uncommon. More typical is thermal fatigue, in which the stresses are not great enough to cause immediate rock failure, but repeated cycles of stress and release gradually weaken the rock. Thermal stress weathering is an important mechanism in deserts , where there is a large diurnal temperature range, hot in the day and cold at night. As

3481-454: The surface of the crystal, and that the weathering layer is only a few atoms thick. Diffusion within the mineral grain does not appear to be significant. Mineral weathering can also be initiated or accelerated by soil microorganisms. Soil organisms make up about 10 mg/cm of typical soils, and laboratory experiments have demonstrated that albite and muscovite weather twice as fast in live versus sterile soil. Lichens on rocks are among

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