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Moss

Mosses are small, non-vascular flowerless plants in the taxonomic division Bryophyta sensu stricto. Bryophyta (sensu lato, Schimp. 1879 ) may also refer to the parent group bryophytes, which comprise liverworts, mosses, and hornworts. Mosses typically form dense green clumps or mats, often in damp or shady locations. The individual plants are usually composed of simple leaves that are generally only one cell thick, attached to a stem that may be branched or unbranched and has only a limited role in conducting water and nutrients. Although some species have conducting tissues, these are generally poorly developed and structurally different from similar tissue found in vascular plants. Mosses do not have seeds and after fertilisation develop sporophytes with unbranched stalks topped with single capsules containing spores. They are typically 0.2-10 cm tall, though some species are much larger. Dawsonia, the tallest moss in the world, can grow to 50 cm in height. There are approximately 12,000 species.

Mosses are commonly confused with liverworts, hornworts and lichens. Although often described as non-vascular plants, many mosses have advanced vascular systems. Like liverworts and hornworts, the haploid gametophyte generation of mosses is the dominant phase of the life cycle. This contrasts with the pattern in all vascular plants (seed plants and pteridophytes), where the diploid sporophyte generation is dominant. Lichens may superficially resemble mosses, and sometimes have common names that include the word "moss" (e.g., "reindeer moss" or "Iceland moss"), but they are fungal symbioses and not related to mosses.

The main commercial significance of mosses is as the main constituent of peat (mostly the genus Sphagnum), although they are also used for decorative purposes, such as in gardens and in the florist trade. Traditional uses of mosses included as insulation and for the ability to absorb liquids up to 20 times their weight. Moss is a keystone genus and benefits habitat restoration and reforestation.

Description

Botanically, mosses are non-vascular plants in the land plant division Bryophyta. They are usually small (a few centimeters tall) herbaceous (non-woody) plants that absorb water and nutrients mainly through their leaves and harvest carbon dioxide and sunlight to create food by photosynthesis. With the exception of the ancient group Takakiopsida, no known mosses form mycorrhiza, but bryophilous fungi is widespread in moss and other bryophytes, where they live as saprotrophs, parasites, pathogens and mutualists, some of them endophytes. Mosses differ from vascular plants in lacking water-bearing xylem tracheids or vessels. As in liverworts and hornworts, the haploid gametophyte generation is the dominant phase of the life cycle. This contrasts with the pattern in all vascular plants (seed plants and pteridophytes), where the diploid sporophyte generation is dominant. Mosses reproduce using spores, not seeds, and have no flowers. Moss gametophytes have stems which may be simple or branched and upright (acrocarp) or prostrate (pleurocarp). The early divergent classes Takakiopsida, Sphagnopsida, Andreaeopsida and Andreaeobryopsida either lack stomata or have pseudostomata that do not form pores. In the remaining classes, stomata have been lost more than 60 times. Their leaves are simple, usually only a single layer of cells with no internal air spaces, often with thicker midribs (nerves). The nerve can run beyond the edge of the leaf tip, termed excurrent. The tip of the leaf blade can be extended as a hair point, made of colourless cells. These appear white against the dark green of the leaves. The edge of the leaf can be smooth or it may have teeth. There may be a distinct type of cell defining the edge of the leaf, distinct in shape and/or colour from the other leaf cells. Moss has threadlike rhizoids that anchor them to their substrate, comparable to root hairs rather than the more substantial root structures of spermatophytes. Mosses do not absorb water or nutrients from their substrate through their rhizoids. They can be distinguished from liverworts (Marchantiophyta or Hepaticae) by their multi-cellular rhizoids. Spore-bearing capsules or sporangia of mosses are borne singly on long, unbranched stems, thereby distinguishing them from the polysporangiophytes, which include all vascular plants. The spore-producing sporophytes (i.e. the diploid multicellular generation) are short-lived and usually capable of photosynthesis, but are dependent on the gametophyte for water supply and most or all of its nutrients. Also, in the majority of mosses, the spore-bearing capsule enlarges and matures after its stalk elongates, while in liverworts the capsule enlarges and matures before its stalk elongates. Other differences are not universal for all mosses and all liverworts, but the presence of a clearly differentiated stem with simple-shaped, non-vascular leaves that are not arranged in three ranks, all point to the plant being a moss.

Life cycle
Vascular plants have two sets of chromosomes in their vegetative cells and are said to be diploid, i.e. each chromosome has a partner that contains the same, or similar, genetic information. By contrast, mosses and other bryophytes have only a single set of chromosomes and so are haploid (i.e. each chromosome exists in a unique copy within the cell). There is a period in the moss life cycle when they do have a double set of paired chromosomes, but this happens only during the sporophyte stage.

The moss life-cycle starts with a haploid spore that germinates to produce a protonema (pl. protonemata), which is either a mass of thread-like filaments or thalloid (flat and thallus-like). Massed moss protonemata typically look like a thin green felt, and may grow on damp soil, tree bark, rocks, concrete, or almost any other reasonably stable surface. This is a transitory stage in the life of a moss, but from the protonema grows the gametophore ("gamete-bearer") that is structurally differentiated into stems and leaves. A single mat of protonemata may develop several gametophore shoots, resulting in a clump of moss.

From the tips of the gametophore stems or branches develop the sex organs of the mosses. The female organs are known as archegonia (sing. archegonium) and are protected by a group of modified leaves known as the perichaetum (plural, perichaeta). The archegonia are small flask-shaped clumps of cells with an open neck (venter) down which the male sperm swim. The male organs are known as antheridia (sing. antheridium) and are enclosed by modified leaves called the perigonium (pl. perigonia). The surrounding leaves in some mosses form a splash cup, allowing the sperm contained in the cup to be splashed to neighboring stalks by falling water droplets.

Gametophore tip growth is disrupted by fungal chitin. Galotto et al., 2020 applied chitooctaose and found that tips detected and responded to this chitin derivative by changing gene expression. They concluded that this defense response was probably conserved from the most recent common ancestor of bryophytes and tracheophytes. Orr et al., 2020 found that the microtubules of growing tip cells were structurally similar to F-actin and served a similar purpose.

Mosses can be either dioicous (compare dioecious in seed plants) or monoicous (compare monoecious). In dioicous mosses, male and female sex organs are borne on different gametophyte plants. In monoicous (also called autoicous) mosses, both are borne on the same plant. In the presence of water, sperm from the antheridia swim to the archegonia and fertilisation occurs, leading to the production of a diploid sporophyte. The sperm of mosses is biflagellate, i.e. they have two flagellae that aid in propulsion. Since the sperm must swim to the archegonium, fertilisation cannot occur without water. Some species (for example Mnium hornum or several species of Polytrichum) keep their antheridia in so called 'splash cups', bowl-like structures on the shoot tips that propel the sperm several decimeters when water droplets hit it, increasing the fertilization distance.

After fertilisation, the immature sporophyte pushes its way out of the archegonial venter. It takes several months for the sporophyte to mature. The sporophyte body comprises a long stalk, called a seta, and a capsule capped by a cap called the operculum. The capsule and operculum are in turn sheathed by a haploid calyptra which is the remains of the archegonial venter. The calyptra usually falls off when the capsule is mature. Within the capsule, spore-producing cells undergo meiosis to form haploid spores, upon which the cycle can start again. The mouth of the capsule is usually ringed by a set of teeth called peristome. This may be absent in some mosses.

Most mosses rely on the wind to disperse the spores. In the genus Sphagnum the spores are projected about 10-20 cm off the ground by compressed air contained in the capsules; the spores are accelerated to about 36,000 times the earth's gravitational acceleration g.

It has recently been found that microarthropods, such as springtails and mites, can effect moss fertilization and that this process is mediated by moss-emitted scents. Male and female fire moss, for example emit different and complex volatile organic scents. Female plants emit more compounds than male plants. Springtails were found to choose female plants preferentially, and one study found that springtails enhance moss fertilization, suggesting a scent-mediated relationship analogous to the plant-pollinator relationship found in many seed plants. The stinkmoss species Splachnum sphaericum develops insect pollination further by attracting flies to its sporangia with a strong smell of carrion, and providing a strong visual cue in the form of red-coloured swollen collars beneath each spore capsule. Flies attracted to the moss carry its spores to fresh herbivore dung, which is the favoured habitat of the species of this genus.

In many mosses, e.g., Ulota phyllantha, green vegetative structures called gemmae are produced on leaves or branches, which can break off and form new plants without the need to go through the cycle of fertilization. This is a means of asexual reproduction, and the genetically identical units can lead to the formation of clonal populations.

Dwarf males
Moss dwarf males (also known as nannandry or phyllodioicy) originate from wind-dispersed male spores that settle and germinate on the female shoot where their growth is restricted to a few millimeters. In some species, dwarfness is genetically determined, in that all male spores become dwarf. More often, it is environmentally determined in that male spores that land on a female become dwarf, while those that land elsewhere develop into large, female-sized males. In the latter case, dwarf males that are transplanted from females to another substrate develop into large shoots, suggesting that the females emit a substance which inhibits the growth of germinating males and possibly also quickens their onset of sexual maturation. The nature of such a substance is unknown, but the phytohormone auxin may be involved

Having the males growing as dwarfs on the female is expected to increase the fertilization efficiency by minimizing the distance between male and female reproductive organs. Accordingly, it has been observed that fertilization frequency is positively associated with the presence of dwarf males in several phyllodioicous species.

Dwarf males occur in several unrelated lineages and may be more common than previously thought. For example, it is estimated that between one quarter and half of all dioicous pleurocarps have dwarf males.

DNA repair
The moss Physcomitrium patens has been used as a model organism to study how plants repair damage to their DNA, especially the repair mechanism known as homologous recombination. If the plant cannot repair DNA damage, e.g., double-strand breaks, in their somatic cells, the cells can lose normal functions or die. If this occurs during meiosis (part of sexual reproduction), they could become infertile. The genome of P. patens has been sequenced, which has allowed several genes involved in DNA repair to be identified. P. patens mutants that are defective in key steps of homologous recombination have been used to work out how the repair mechanism functions in plants. For example, a study of P. patens mutants defective in RpRAD51, a gene that encodes a protein at the core of the recombinational repair reaction, indicated that homologous recombination is essential for repairing DNA double-strand breaks in this plant. Similarly, studies of mutants defective in Ppmre11 or Pprad50 (that encode key proteins of the MRN complex, the principal sensor of DNA double-strand breaks) showed that these genes are necessary for repair of DNA damage as well as for normal growth and development.

Classification
More recently, mosses have been grouped with the liverworts and hornworts in the division Bryophyta (bryophytes, or Bryophyta sensu lato). The bryophyte division itself contains three (former) divisions: Bryophyta (mosses), Marchantiophyta (liverworts) and Anthocerotophyta (hornworts); it has been proposed that these latter divisions are de-ranked to the classes Bryopsida, Marchantiopsida, and Anthocerotopsida, respectively. The mosses and liverworts are now considered to belong to a clade called Setaphyta.

The mosses, (Bryophyta sensu stricto), are divided into eight classes:

Six of the eight classes contain only one or two genera each. Polytrichopsida includes 23 genera, and Bryopsida includes the majority of moss diversity with over 95% of moss species belonging to this class.

The Sphagnopsida, the peat-mosses, comprise the two living genera Ambuchanania and Sphagnum, as well as fossil taxa. Sphagnum is a diverse, widespread, and economically important one. These large mosses form extensive acidic bogs in peat swamps. The leaves of Sphagnum have large dead cells alternating with living photosynthetic cells. The dead cells help to store water. Aside from this character, the unique branching, thallose (flat and expanded) protonema, and explosively rupturing sporangium place it apart from other mosses.

Andreaeopsida and Andreaeobryopsida are distinguished by the biseriate (two rows of cells) rhizoids, multiseriate (many rows of cells) protonema, and sporangium that splits along longitudinal lines. Most mosses have capsules that open at the top.

Polytrichopsida have leaves with sets of parallel lamellae, flaps of chloroplast-containing cells that look like the fins on a heat sink. These carry out photosynthesis and may help to conserve moisture by partially enclosing the gas exchange surfaces. The Polytrichopsida differ from other mosses in other details of their development and anatomy too, and can also become larger than most other mosses, with e.g., Polytrichum commune forming cushions up to 40 cm high. The tallest land moss, a member of the Polytrichidae is probably Dawsonia superba, a native to New Zealand and other parts of Australasia.

Geological history
The fossil record of moss is sparse, due to their soft-walled and fragile nature. Unambiguous moss fossils have been recovered from as early as the Permian of Antarctica and Russia, and a case has been made for Carboniferous mosses. It has further been claimed that tube-like fossils from the Silurian are the macerated remains of moss calyptræ. Mosses also appear to evolve 2–3 times slower than ferns, gymnosperms and angiosperms.

Recent research shows that ancient moss could explain why the Ordovician ice ages occurred. When the ancestors of today's moss started to spread on land 470 million years ago, they absorbed CO2 from the atmosphere and extracted minerals by secreting organic acids that dissolved the rocks they were growing on. These chemically altered rocks in turn reacted with the atmospheric CO2 and formed new carbonate rocks in the ocean through the weathering of calcium and magnesium ions from silicate rocks. The weathered rocks also released significant amounts of phosphorus and iron which ended up in the oceans, where it caused massive algal blooms, resulting in organic carbon burial, extracting more carbon dioxide from the atmosphere. Small organisms feeding on the nutrients created large areas without oxygen, which caused a mass extinction of marine species, while the levels of CO2 dropped all over the world, allowing the formation of ice caps on the poles.

Habitat
Moss gametophytes are autotrophic and require sunlight to perform photosynthesis. Shade tolerance varies by species, just as it does with higher plants. In most areas, mosses grow chiefly in moist, shaded areas, such as wooded areas and at the edges of streams, but they can grow anywhere in cool, humid, cloudy climates, and some species are adapted to sunny, seasonally dry areas like alpine rocks or stabilized sand dunes.

Choice of substrate varies by species as well. Moss species can be classed as growing on: rocks, exposed mineral soil, disturbed soils, acid soil, calcareous soil, cliff seeps and waterfall spray areas, streamsides, shaded humusy soil, downed logs, burnt stumps, tree trunk bases, upper tree trunks, and tree branches or in bogs. Moss species growing on or under trees are often specific about the species of trees they grow on, such as preferring conifers over broadleaf trees, oaks over alders, or vice versa. While mosses often grow on trees as epiphytes, they are never parasitic on the tree.

Mosses are also found in cracks between paving stones in damp city streets, and on roofs. Some species adapted to disturbed, sunny areas are well adapted to urban conditions and are commonly found in cities. Examples would be Rhytidiadelphus squarrosus, a garden weed in Vancouver and Seattle areas; Bryum argenteum, the cosmopolitan sidewalk moss, and Ceratodon purpureus, red roof moss, another cosmopolitan species. A few species are wholly aquatic, such as Fontinalis antipyretica, common water moss; and others such as Sphagnum inhabit bogs, marshes and very slow-moving waterways. Such aquatic or semi-aquatic mosses can greatly exceed the normal range of lengths seen in terrestrial mosses. Individual plants 20-30 cm or more long are common in Sphagnum species for example. But even aquatic species of moss and other bryophytes needs their mature capsules to be exposed to air by seta elongation or seasonal lowering of water level to be able to reproduce.

Wherever they occur, mosses require liquid water for at least part of the year to complete fertilisation. Many mosses can survive desiccation, sometimes for months, returning to life within a few hours of rehydration.

It is generally believed that in the Northern Hemisphere, the north side of trees and rocks will generally have more luxuriant moss growth on average than other sides. The reason is assumed to be because sunshine on the south side causes a dry environment. The reverse would be true in the Southern Hemisphere. Some naturalists feel that mosses grow on the damper side of trees and rocks. In some cases, such as sunny climates in temperate northern latitudes, this will be the shaded north side of the tree or rock. On steep slopes, it may be the uphill side. For mosses that grow on tree branches, this is generally the upper side of the branch on horizontally growing sections or near the crotch. In cool, humid, cloudy climates, all sides of tree trunks and rocks may be equally moist enough for moss growth. Each species of moss requires certain amounts of moisture and sunlight and thus will grow on certain sections of the same tree or rock.

Some mosses grow underwater, or completely waterlogged. Many prefer well-drained locations. There are mosses that preferentially grow on rocks and tree trunks of various chemistries.

Relationship with cyanobacteria
In boreal forests, some species of moss play an important role in providing nitrogen for the ecosystem due to their relationship with nitrogen-fixing cyanobacteria. Cyanobacteria colonize moss and receive shelter in return for providing fixed nitrogen. Moss releases the fixed nitrogen, along with other nutrients, into the soil "upon disturbances like drying-rewetting and fire events", making it available throughout the ecosystem.

Cultivation

Moss is often considered a weed in grass lawns, but is deliberately encouraged to grow under aesthetic principles exemplified by Japanese gardening. In old temple gardens, moss can carpet a forest scene. Moss is thought to add a sense of calm, age, and stillness to a garden scene. Moss is also used in bonsai to cover the soil and enhance the impression of age. Rules of cultivation are not widely established. Moss collections are quite often begun using samples transplanted from the wild in a water-retaining bag. Some species of moss can be extremely difficult to maintain away from their natural sites with their unique requirements of combinations of light, humidity, substrate chemistry, shelter from wind, etc.

Growing moss from spores is even less controlled. Moss spores fall in a constant rain on exposed surfaces; those surfaces which are hospitable to a certain species of moss will typically be colonised by that moss within a few years of exposure to wind and rain. Materials which are porous and moisture retentive, such as brick, wood, and certain coarse concrete mixtures, are hospitable to moss. Surfaces can also be prepared with acidic substances, including buttermilk, yogurt, urine, and gently puréed mixtures of moss samples, water and ericaceous compost.

In the cool, humid, cloudy Pacific Northwest, moss is sometimes allowed to grow naturally as a moss lawn, one that needs little or no mowing, fertilizing or watering. In this case, grass is considered to be the weed. Landscapers in the Seattle area sometimes collect boulders and downed logs growing mosses for installation in gardens and landscapes. Woodland gardens in many parts of the world can include a carpet of natural mosses. The Bloedel Reserve on Bainbridge Island, Washington State, is famous for its moss garden. The moss garden was created by removing shrubby underbrush and herbaceous groundcovers, thinning trees, and allowing mosses to fill in naturally.

Green roofs and walls
Mosses are sometimes used in green roofs. Advantages of mosses over higher plants in green roofs include reduced weight loads, increased water absorption, no fertilizer requirements, and high drought tolerance. Since mosses do not have true roots, they require less planting medium than higher plants with extensive root systems. With proper species selection for the local climate, mosses in green roofs require no irrigation once established and are low maintenance. Mosses are also used on green walls.

Mossery
A passing fad for moss-collecting in the late 19th century led to the establishment of mosseries in many British and American gardens. The mossery is typically constructed out of slatted wood, with a flat roof, open to the north side (maintaining shade). Samples of moss were installed in the cracks between wood slats. The whole mossery would then be regularly moistened to maintain growth.

Aquascaping
Aquascaping uses many aquatic mosses. They do best at low nutrient, light, and heat levels, and propagate fairly readily. They help maintain a water chemistry suitable for aquarium fish. They grow more slowly than many aquarium plants, and are fairly hardy.

Growth inhibition
Moss can be a troublesome weed in containerized nursery operations and greenhouses. Vigorous moss growth can inhibit seedling emergence and penetration of water and fertilizer to the plant roots.

Moss growth can be inhibited by a number of methods:
 * Decreasing availability of water through drainage.
 * Increasing direct sunlight.
 * Increasing number and resources available for competitive plants like grasses.
 * Increasing the soil pH with the application of lime.
 * Heavy traffic or manually disturbing the moss bed with a rake
 * Application of chemicals such as ferrous sulfate (e.g., in lawns) or bleach (e.g., on solid surfaces).
 * In containerized nursery operations, coarse mineral materials such as sand, gravel, and rock chips are used as a fast-draining top dressing in plant containers to discourage moss growth.

The application of products containing ferrous sulfate or ferrous ammonium sulfate will kill moss; these ingredients are typically in commercial moss control products and fertilizers. Sulfur and iron are essential nutrients for some competing plants like grasses. Killing moss will not prevent regrowth unless conditions favorable to their growth are changed.

Traditional
Preindustrial societies made use of the mosses growing in their areas.

Sámi people, North American tribes, and other circumpolar peoples used mosses for bedding. Mosses have also been used as insulation both for dwellings and in clothing. Traditionally, dried moss was used in some Nordic countries and Russia as an insulator between logs in log cabins, and tribes of the northeastern United States and southeastern Canada used moss to fill chinks in wooden longhouses. Circumpolar and alpine peoples have used mosses for insulation in boots and mittens. Ötzi the Iceman had moss-packed boots.

The capacity of dried mosses to absorb fluids has made their use practical in both medical and culinary uses. North American tribal people used mosses for diapers, wound dressing, and menstrual fluid absorption. Tribes of the Pacific Northwest in the United States and Canada used mosses to clean salmon prior to drying it, and packed wet moss into pit ovens for steaming camas bulbs. Food storage baskets and boiling baskets were also packed with mosses.

Recent research investigating the Neanderthals remains recovered from El Sidrón have provided evidence that their diet would have consisted primarily of pine nuts, moss and mushrooms. This is contrasted by evidence from other European locations, which point to a more carnivorous diet.

In Finland, peat mosses have been used to make bread during famines.

Commercial

There is a substantial market in mosses gathered from the wild. The uses for intact moss are principally in the florist trade and for home decoration. Decaying moss in the genus Sphagnum is also the major component of peat, which is "mined" for use as a fuel, as a horticultural soil additive, and in smoking malt in the production of Scotch whisky.

Sphagnum moss, generally the species S. cristatum and S. subnitens, is harvested while still growing and is dried out to be used in nurseries and horticulture as a plant growing medium.

Some Sphagnum mosses can absorb up to 20 times their own weight in water. In World War I, Sphagnum mosses were used as first-aid dressings on soldiers' wounds, as these mosses said to absorb liquids three times faster than cotton, retain liquids better, better distribute liquids uniformly throughout themselves, and are cooler, softer, and be less irritating. It is also claimed to have antibacterial properties. Native Americans were one of the peoples to use Sphagnum for diapers and menstrual pads, which is still done in Canada.

In rural UK, Fontinalis antipyretica was traditionally used to extinguish fires as it could be found in substantial quantities in slow-moving rivers and the moss retained large volumes of water which helped extinguish the flames. This historical use is reflected in its specific Latin/Greek name, the approximate meaning of which is "against fire".

In Mexico, moss is used as a Christmas decoration.

Physcomitrium patens is increasingly used in biotechnology. Prominent examples are the identification of moss genes with implications for crop improvement or human health and the safe production of complex biopharmaceuticals in the moss bioreactor, developed by Ralf Reski and his co-workers.

London installed several structures called "City Trees": moss-filled walls, each of which is claimed to have "the air-cleaning capability of 275 regular trees" by consuming nitrogen oxides and other types of air pollution and producing oxygen.

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Talk:1868

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"Queen Isabella II of Spain derrocated": what is meant? (there doesn't seem to be a word "derrocated"). S.
 * I can't believe someone asked this in Febuary 2003 and no one who has touched the page since addressed the matter. She was deposed by a liberal revolution. -- Jmabel | Talk 21:01, Oct 25, 2004 (UTC)

I have made some year layout proposals which would not affect this page (this page is conform) on my talk page. If no-one flags where I have put the discussion on my talk page that they object in a month I will start making everything consistent. It may take some time... --BozMo 19:01, 6 May 2004 (UTC)(talk)

Semi-protected edit request on 7 June 2019
141.217.172.8 (talk) 18:14, 7 June 2019 (UTC)there was a hanging in 1968 the last public one
 * Red question icon with gradient background.svg Not done: it's not clear what changes you want to be made. Please mention the specific changes in a "change X to Y" format and provide a reliable source if appropriate. Saucy[talk – contribs] 03:14, 8 June 2019 (UTC)

Semi-protected edit request on 23 June 2020
Please add this event to the list of days in 1868.

On this day (23 June 2020) in 1868, American inventor Christopher Latham Sholes (along with Carlos Glidden and Samuel W. Soulé) was granted the first typewriter patent ahead of other competing inventors in the same field. Monsoonlei (talk) 12:21, 23 June 2020 (UTC)
 * Red information icon with gradient background.svg Not done: please provide reliable sources that support the change you want to be made. Dawnseeker2000  12:22, 23 June 2020 (UTC)

Thomas Spence
In the May 31 entry, "Thomas Spence declares himself president of Manitobah", the Thomas Spence link goes to the wrong person. It should point to a (nonexistent) page for the Thomas Spence mentioned on the Republic of Manitobah page. https://en.wikipedia.org/wiki/Republic_of_Manitobah 24.78.190.118 (talk) 00:49, 22 February 2023 (UTC)

nicholas II of russia
Why is nicholas II of russia listed under the may 6th birthdays if by modern standards his birthday was may 18? 142.127.176.100 (talk) 03:08, 15 November 2023 (UTC)

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Molly dance

Molly dancing is a form of English Morris dance, traditionally done by out-of-work ploughboys in midwinter in the 19th century. It was largely ignored by folk dance collectors, who recorded only a handful of dances before the practice died out in the 1930s. The practice was revived in the 1970s.

History
Molly dancing is a dance tradition from East Anglia, first attested in the 1820s. The first recorded use of the word "Molly" in relation to this tradition was in 1866. The dance was performed on Boxing Day (26 December) and Plough Monday (the Monday after 6 January). It died out during the early 1930s, the last dancers seen dancing in Little Downham near Ely, Cambridgeshire, in 1933. The term molly itself was used since at least 1754 for 'a milksop, an effeminate man'; see also Molly house.

In 1911 Cecil Sharp interviewed a man from Little Downham about Plough Monday dancing, but he did not consider it worthy of further study, and the practice was largely ignored by collectors of folk dances until the 1930s. In 1930, Joseph Needham and Arthur Peck collected four molly dances from a dancer from Girton and a concertina player from Histon, near Cambridge; they continued to collect information about molly dancing over the following three years. William Palmer recorded a broom dance performed by the Little Downham dancers in 1933. In 1978, Russell Wortley and Cyril Papworth published four dances collected from the Comberton molly dancers.

Traditions
Molly dancing is most associated with Plough Monday, the first Monday after Epiphany. Tradition has it that as a way of filling the gap between Christmas and the start of the spring ploughing season, the ploughboys would tour around the village landowners, offering to dance for money. Those who refused would be penalised in various ways (see Trick or treat) including having a furrow ploughed across the offender's lawn.

The dancers, wishing to gain employment from those same landowners shortly afterwards, would attempt to conceal their identities by blacking their faces with soot and dressing up in a modified version of their Sunday best, typically black garments adorned with coloured scarves and other fripperies. It was originally an all-male tradition but with one of the members—the Molly—dressed up as a woman. The Molly team seen by William Palmer at Little Downham in 1933 consisted of six men, one dressed as a woman; of the remaining five, one carried a broom and money box, and one played the accordion. The musician wore ordinary clothes, while the other men wore frock coats and top hats; all five had blackened faces and wore ribbons on their clothes.

The modern tradition
Molly dancing was revived in the late 1970s, when teams began to once again perform the preserved dances. In 1977 the Cambridge Morris Men resumed molly dancing to coincide with the revival of the Balsham Ploughboys. The Cambridge Men still dance Molly during the day on Plough Monday. The Morris dance revival of the 1970s led to the creation of many new sides, which nowadays usually involve both men and women.

In recent years, Molly dancing has enjoyed a popular revival both in East Anglia and the East Midlands, one of the best-known teams being the Ouse Washes Molly Dancers. The largest regular assemblage of Molly dancers is at the Whittlesea Straw Bear Festival, established 1980, which is held in Whittlesey, Cambridgeshire, every January.

Modern Molly dancing demonstrates the clearest distinction between "re-enactment of tradition" and "modern interpretation of tradition" of modern morris dancing. Elaine Bradtke wrote a PhD thesis on the inherent post-modernism of the Seven Champions, one of the first and best examples of modern Molly dance. Many other teams have developed Molly, inspired by the unhistorical but very effective military formations of Seven Champions (e.g. Ouse Washes, Gog Magog, Handsome Molly in New Jersey, Countess Isabella's Automata) whilst others have taken it in new directions, equally unhistorical but at their best equally effective in very different ways; e.g. Norwich Shitwitches (now renamed Kit Witches) and Pig Dyke Molly.

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Snowy Mountains Scheme

The Snowy Mountains Scheme, also known as the Snowy Hydro or the Snowy scheme, is a hydroelectricity and irrigation complex in south-east Australia. Near the border of New South Wales and Victoria, the scheme consists of sixteen major dams; nine power stations; two pumping stations; and 225 km of tunnels, pipelines and aqueducts that were constructed between 1949 and 1974. The Scheme was completed under the supervision of Chief Engineer, Sir William Hudson. It is the largest engineering project undertaken in Australia.

The water of the Snowy River and some of its tributaries, much of which formerly flowed southeast onto the river flats of East Gippsland, and into Bass Strait of the Tasman sea, is captured at high elevations and diverted inland to the Murray and Murrumbidgee Rivers irrigation areas. The Scheme includes two major tunnel systems constructed through the continental divide of the Snowy Mountains, known in Australia as the Great Dividing Range. The water falls 800 m and travels through large hydro-electric power stations which generate peak-load power for the Australian Capital Territory, New South Wales and Victoria. The Scheme also provides some security of water flows to the Murray-Darling basin, providing approximately 2100 Gl of water a year to the basin for use in Australia's irrigated agriculture industry.

In 2016, the Snowy Mountains Scheme was added to the Australian National Heritage List.

Background
Since the 1800s, both the Murray and Murrumbidgee rivers have been subject to development and control to meet water supply and irrigation needs. By contrast, the Snowy River, that rises in the Australian Alps and flows through mountainous and practically uninhabited country until debouching onto the river flats of East Gippsland, had never been controlled in any way, neither for the production of power nor for irrigation. A great proportion of its waters flowed eastwards into the South Pacific Ocean (the Tasman Sea). The Snowy River has the highest headwater source of any in Australia and draws away a large proportion of the waters from the south-eastern New South Wales snowfields. The construction of the Snowy Mountains Scheme was seen as a means of supplementing the flow of the great inland rivers, a means for developing hydro-electric power, and also a way to increase agricultural production in the Murray and Murrumbidgee valleys.

Following World War II, the Government of New South Wales proposed that the flow of the Snowy River be diverted into the Murrumbidgee River for irrigation and agricultural purposes. There was little emphasis placed on the generation of power. A counter proposal by the Government of Victoria involved a greater generation of power, and involved diversion of the Snowy River to the Murray River. Additionally, the Government of South Australia was concerned that downstream flows on the Murray River would be severely jeopardised.

The Commonwealth Government, looking at the national implications of the two proposals, initiated a meeting to discuss the use of the waters of the Snowy River, and a Committee was set up in 1946 to examine the question on the broadest possible basis. This Committee, in a report submitted in November 1948, suggested consideration of a far greater scheme than any previously put forward. It involved not only the simple question of use of the waters of the Snowy River, but consideration of the possible diversion of a number of rivers in the area, tributaries, not only of the Snowy, but of the Murray and Murrumbidgee. The recommendations of the Committee were generally agreed to by a conference of Ministers representing the Commonwealth, New South Wales, and Victoria, and it was also agreed that the Committee should continue its investigations.

However, limitations in the Australian Constitution meant that the Commonwealth Government was limited in the powers it could exercise, without the agreement of the States. Subsequently, the Commonwealth Government introduced legislation into the Federal Parliament under its defence power; and enacted the that enabled the formation of the Snowy Mountains Hydroelectric Authority. Ten years later, the relevant States and Territories introduced their own corresponding legislation and in January 1959 the Snowy Mountains Agreement was reached between the Commonwealth and the States.

The legislation created the Snowy Mountains Hydroelectric Authority that was given responsibility for the final evaluation, design and construction of the Snowy Mountains Scheme. The final agreed plan was to divert the waters of the Snowy Mountains region to provide increased electricity generating capacity and to provide irrigation water for the dry west. It was "greeted with enthusiasm by the people of Australia" and was seen to be "a milestone towards full national development".

The chief engineer, New Zealand-born William Hudson (knighted 1955), was chosen to head the scheme as Chairman of the Snowy Mountains Hydroelectric Authority, and was instructed to seek workers from overseas. Hudson's employment of workers from 32 (mostly European) countries, many of whom had been at war with each other only a few years earlier, had a significant effect on the cultural mix of Australia.

Construction
Construction of the Snowy Scheme was managed by the Snowy Mountains Hydroelectric Authority. It officially began on 17 October 1949 and took 25 years, being officially completed in 1974.

An agreement between the United States Bureau of Reclamation and Snowy Mountains Hydro to provide technical assistance and training of engineers was agreed between the United States and Australia in Washington, D.C., on 16 November 1951. A loan for $100 million was obtained from the World Bank in 1962.

Tunneling records were set in the construction of the Scheme and it was completed on time and on budget in 1974, at a cost of A$820 million; a dollar value equivalent in 1999 and 2004 to A$6 billion. Around two thirds of the workforce employed in the construction of the scheme were immigrant workers, originating from over thirty countries. The official death toll of workers on the Scheme stands at 121 people. Some 1600 km of roads and tracks were constructed, seven townships and over 100 camps were built to enable construction of the 16 major dams, seven hydroelectric power stations, two pumping stations, 145 km of tunnel and 80 km of pipelines and aqueducts. Just 2% of the construction work is visible from above ground.

Two of the towns constructed for the scheme are now permanent; Cabramurra, the highest town in Australia; and Khancoban. Cooma flourished during construction of the Scheme and remains the headquarters of the operating company of the Scheme. Townships at Adaminaby, Jindabyne and Talbingo were inundated by the flooded waters from Lake Eucumbene, Lake Jindabyne and Jounama Reservoir. Improved vehicular access to the high country enabled ski-resort villages to be constructed at Thredbo and Guthega in the 1950s by former Snowy Scheme workers who realised the potential for expansion of the Australian ski industry.

The Scheme is in an area of 5124 km2, almost entirely within the Kosciuszko National Park. The design of the scheme was modelled on that of the Tennessee Valley Authority. Over 100,000 people from over 30 countries were employed during its construction, providing employment for many recently arrived immigrants, and was important in Australia's post-war economic and social development. Seventy percent of all the workers were migrants. During construction of the tunnels, a number of railways were employed to convey spoil from worksites and to deliver personnel, concrete and equipment throughout.

The project used Australia's first transistorised computer; one of the first in the world. Called 'Snowcom', the computer was used from 1960 to 1967.

At the completion of the project, the Australian Government maintained much of the diverse workforce and established the Snowy Mountains Engineering Corporation (SMEC), which is now an international engineering consultancy company. The Scheme is the largest renewable energy generator in mainland Australia and plays an important role in the operation of the National Electricity Market, generating approximately 67% of all renewable energy in the mainland National Electricity Market. The Snowy Scheme's primary function is as a water manager, however under the corporatised model must deliver dollar dividends to the three shareholder governments - the NSW, Commonwealth and Victorian Governments.

The Scheme also has a significant role in providing security of water flows to the Murray-Darling Basin. The Scheme provides approximately 2100 GL of water a year to the Basin, providing additional water for an irrigated agriculture industry worth about A$3 bn per annum, representing more than 40% of the gross value of the nation's agricultural production.

The Snowy Mountains Hydro-electric Scheme, is one of the most complex integrated water and hydro-electric power schemes in the world and is listed as a "world-class civil engineering project" by the American Society of Civil Engineers. The scheme interlocks seven power stations and 16 major dams through 145 km of trans-mountain tunnels and 80 km of aqueducts. The history of the Snowy Scheme reveals its important role in building post World War II Australia.

Sir William Hudson was appointed the first commissioner of the Snowy Mountains Hydroelectric Authority, serving between 1949 and 1967. The Commissioner's role was the overall management of the Scheme. He represented the Scheme at the highest levels of government, welcomed international scientists and engineers, encouraged scientific and engineering research, as well as attending many social and civic activities. Sir William's management style 'stressed cooperation between management and labour and scientific knowledge (facts) over opinion'.

The Scheme was completed with the official opening of the Tumut 3 Power Station project by the Governor-General of Australia, Sir Paul Hasluck on 21 October 1972.

Safety
The Scheme used a number of innovative approaches to all sorts of things during its construction. For example all vehicles driven on all parts of the scheme were required to be fitted with seatbelts for driver and front seat passenger; and that these seatbelts were required to be used.

On 16 April 1958, an elevator at a dam near Cabramurra fell about 400 feet when the cable broke, killing 4 Italian employees of a French construction firm.

Personal stories and memoirs of work on the Snowy Scheme
Various stories and memoirs have been written about work on the Snowy Mountains Scheme. Siobhan McHugh's social history, The Snowy: The People Behind the Power is the most prominent, having been awarded the NSW Premier's Literary Award for Non-Fiction and being the source of an ABC radio documentary series (1987) and a Film Australia documentary, Snowy, A Dream of Growing Up (1989). Her book is based on about 90 oral histories with former Snowy workers and residents, with original recordings archived as a research collection at the State Library of New South Wales. An updated 70th anniversary edition of her book was published by New South in 2019 and its content showcased by Richard Fidler in an interview with McHugh for his popular ABC podcast, Conversations. Most recently, Snowy Hydro, Woden Community Service, Gen S Stories and PhotoAccess partnered for a Digital Storytelling project to present a diverse collection of stories told from the point of view of seven ex-workers, two lifelong employees and a child of a Snowy worker.

As part of the project, participants created short films about their experience on the Snowy Scheme, each story offering a unique perspective into what life was like building the Scheme between 1949 and 1974. The project's artistic director Jenni Savigny assisted participants to make the short films; enabling them to put together the scripts, record voice overs and edit the short films. In an interview with Andrew Brown (The Canberra Times), Savigny said it was important to create a history of the Snowy Hydro using the participant's own words, "You just get a personal sense of what it was like to be there, and what it meant to people's lives."

The films premiered 7 June 2018 at the Palace Electric Cinema in New Acton in Canberra and can be viewed on the Woden Community Service YouTube Channel.

Current operations
The Scheme is operated by Snowy Hydro Limited, an unlisted public company incorporated pursuant to the, owned by the Australian Federal government.

There is currently further work ongoing for the expansion of the snowy scheme under the Snowy scheme 2.0 announced in 2017. Despite government support it has received many criticisms and concerns over the logistical and financial feasibility of the operation.

Environmental concerns
The original plan was for 99% of the water of the Snowy River's natural flow to be diverted by the Scheme below Lake Jindabyne. Releases from the Scheme were based on the needs of riparian users only and took no account of the ecosystem's needs. It soon became clear that there were major environmental problems in the lower reaches of the Snowy river. An extensive public campaign led to the Snowy Water Inquiry being established in January 1998. The Inquiry reported to the New South Wales and Victorian Governments in October of that year, recommending an increase to 15% of natural flows. The two governments were equivocal about this target. Aside from economic considerations, there was a view that the health of the Murray was more important than that of the Snowy and that any extra environmental flows were better used there instead.

In the 1999 Victorian state election, the seat of Gippsland East was won by Craig Ingram, an independent and member of the Snowy River Alliance, based in large part on his campaign to improve Snowy flows. In 2000, Victoria and NSW agreed to a long-term target of 28%, requiring A$156 million of investment to offset losses to inland irrigators. In August 2002 flows were increased to 6%, with a target of 21% within 10 years. However, by October 2008 it was evident that the return of environmental flows to the Snowy River in 2009 would be no more than 4% of natural flow with governments arguing the Snowy River needs to "pay back" the "Mowamba Borrowings". At the 2010 state election, Ingram lost the seat of Gippsland East to the Nationals.

In 2017, it was announced that the 21% target would be reached for the first time.

Some concerned water managers, conservationists, politicians and farmers continue to advocate for the return of environmental flows to the Snowy River. The Snowy River Alliance formed in 1996 to address the lack of environmental flow commemorates Snowy River Day annually, towards the end of August, to mark the 2002 anniversary of when the governments of Victoria, NSW and the Commonwealth first released water into the Snowy River over the Mowamba Weir. The Dalgety District and Community Association started in response to dirty drinking water for the town of Dalgety, the loss of fishing and looming closure of the caravan park. A weir was constructed at Dalgety and the caravan park stayed as a result of their efforts. In accordance with the Snowy Water Licence, Snowy Hydro Limited has 're-commissioned' the Mowamba Aqueduct. Seasonal variable flows are essential to river ecology including flushing flows to support vital ecosystems for the Australian platypus and native Australian Bass, the species over which Ingram initially fought for flows into the Snowy River. A major spillway upgrade now facilitates these flows.

Components
Construction of the Scheme began in 1949 and was completed in 1974. Guthega power station commenced power production on 21 February 1955.

Power stations
The total installed capacity is 4.073 GW.

Major dams and reservoirs
The Scheme's largest dam is Talbingo Dam with an embankment volume of 14 488 000 m3 and a wall height of 161.5 metres. Khancoban Dam is the longest dam in the scheme with a crest length of 1067 m. A variety of dam and spillway types were used in the construction.

With a capacity of 4798400 ML, Lake Eucumbene is the largest reservoir in the Scheme. At the other end of the scale, Deep Creek Reservoir is the smallest reservoir with just 11 ML.

Pumping Stations
The Snowy Mountains Scheme has two pumping stations. The 600 MW pump storage facility at Tumut 3 Power Station returns water to Talbingo Reservoir. The 1 MW Jindabyne Pumping Station pumps water from Lake Jindabyne through to the Snowy-Geehi Tunnel at Island Bend.

Expansion plans
In March 2017, the Australian government then headed by Malcolm Turnbull suggested a $2 billion project expanding the 4.1 GW Snowy Mountains Scheme by 2 GW of pump storage for a week, building new tunnels and power stations, but no new dams. The 80% efficiency of such storage can be sufficient in leveling differences between supply and demand. Dubbed Snowy 2.0, the expansion has been under construction since 2019 and was expected to be complete by 2026. Delays have meant the project will not be fully operational until 2029.

Tourism
The Snowy Scheme is a major tourist destination. Sightseeing driving tours to the key locations of the Scheme are popular out of regional centres like Cooma, Adaminaby and Jindabyne along roads built for the Scheme like the Snowy Mountains Highway and Alpine Way and towards sights like Cabramurra, as Australia's highest town, spectacular dam walls, and scenic lakes. Trout fishing is popular in the lakes of the Scheme, notably Lake Jindabyne and Lake Eucumbene.

The Snowy Scheme Museum opened at Adaminaby in 2011 to profile the history of the Scheme.

Though skiing in Australia began in the northern Snowy Mountains in the 1860s, it was the construction of the vast Snowy Scheme from 1949, with its improvements to infrastructure and influx of experienced European skiers among the workers on the Scheme, that really opened up the mountains for the large scale development of a ski industry, and led to the establishment of Thredbo and Perisher as leading Australian resorts. The construction of Guthega Dam brought skiers to the isolated Guthega district and a rope tow was installed there in 1957. Charles Anton, a snowy worker identified the potential of the Thredbo Valley.

Engineering heritage award
The scheme is listed as a National Engineering Landmark by Engineers Australia as part of its Engineering Heritage Recognition Program.

title: Snowy Mountains Scheme


text:
Talk:Lime kiln

Wood Ash
The traditional process of burning lime would leave a lot of wood ash mixed in with the lime, but its presence is ignored in the discussion. Is this ash a contaminant? Is its presence negligible?
 * Although wood is, indeed, added to a lime kiln or limepit, the limestone is usually of a coarser consistency, sometimes even chunks or blocks of limestone are used. The wood ash is removed from the kiln, and the limestone chunks/blocks are also removed and only then crushed.Davidbena (talk) 03:30, 24 July 2019 (UTC)

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This entry could do with expansion and probably correction

--

My dictionary says the process here is "carbonation", but my dictionary of science says "carbonation" is "treatment with CO2 usually giving a carbonate". But here a carbonate is the raw material. could someone clear this up? -- Tarquin

Clear-up carbonation...
Either the article has been edited since Tarquin remarked 'carbonation is treatment with CO2', or an easy error was made - seing one word where a different one was actually present. The article says 'calcination', not 'carbonation'. Tarquin's understanding of Carbonation is correct.

UK Focus
This article is very focused on lime kilns in the UK/Europe, and does not provide any historical references to the many lime kilns in the United States or other countries around the world. —Preceding unsigned comment added by Thefox226G (talk • contribs) 20:38, 11 February 2010 (UTC)
 * Broken down "Early kilns" to add geographic specific subsections. I also organised the photos into galleries as they were all over the place. Feel free to add sections for other countries or to expand poor lonely Belgium there. Citizen D (talk) 01:29, 11 July 2012 (UTC)

Coal as fuel
Once coal became available it was used as a fuel. George Stephenson built the limeworks at Ambergate to use the slack from his coal mines at Clay Cross.This lime would be useful to farmers but how would be affected as a building material since the coal ash would be a pozzolan?2.28.217.186 (talk)

Strange claim
" The manufacture of one tonne of calcium oxide involves decomposing calcium carbonate, with the formation of 785 kg of CO2 in some applications, such as when used as mortar; this CO2 is later re-adsorbed as the mortar goes off. "

So if you mix up a large batch of lime mortar, and build a brick wall with it,   how does it absorb hundreds of kilograms of carbon dioxide from the atmosphere ? This seems highly implausible. How does the carbon dioxide get into the mortar which is nowhere near the surfaces exposed to the air ? Tallewang (talk) 08:55, 22 October 2013 (UTC)
 * It takes a very long time to do this. Very long. I remember reading (a few years back) that some of the WWII German fortifications still weren't thought to be fully cured, as they were so thick and originally poured so quickly.
 * Lime and cement mortars have two curing phases. Firstly they "set", mostly from hydration by, and by losing through evaporation, the mixture water. This is quick: hours and days. However they're not at full strength yet. Then they "cure" by absorbing CO2. This takes longer: months or years, and it's how they achieve full strength. Sometimes heavily stressed foundations, such as bridge piers, have to wait for this. The atmosphere is full of CO2 and mortar, especially lime, is fairly permeable so it's the reaction speed that's the limit, not the availability of the reagent.
 * Note also that mortars are mostly an inert sand filler and there's only a smaller proportion of the active cement binder. Andy Dingley (talk) 09:57, 22 October 2013 (UTC)

Old lime kilns
Add to references: https://au.news.yahoo.com/thewest/wa/a/30494628/family-keep-old-lime-ways-burning/ Which is a currently working commercial old kiln. Oaec 60.230.194.64 (talk) 22:55, 6 January 2016 (UTC)

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Math error in section "CO2 Emissions"
"If the heat supplied to form the lime (3.75 MJ/kg in an efficient kiln) is obtained by burning fossil fuel it will release CO2: in the case of coal fuel 295 kg/t; in the case of natural gas fuel 206 kg/t. The electric power consumption of an efficient plant is around 20 kWh per tonne of lime. This additional input is the equivalent of around 20 kg CO2 per ton if the electricity is coal-generated."

Obviously this is wrong: turning coal into electricity into heat is not more efficient than turning coal directly into heat.

Using the value of 0.9 Joules / (grams*degC) as the heat capacity of CaCO3, I calculate that heating one tonne of CaCO3 to 1000 degC requires 250kWh, not 20kWh. 2601:98A:4400:2E50:F563:2062:9BAD:7358 (talk) 20:53, 11 March 2023 (UTC)

title: Talk:Lime kiln


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Great Zimbabwe

Great Zimbabwe is a medieval city in the south-eastern hills of the modern country of Zimbabwe, near Lake Mutirikwe and the town of Masvingo. It was the capital of the Kingdom of Zimbabwe from the 13th century, having been settled in the 4th century AD. Construction on the city began in the 11th century and continued until it was abandoned in the 15th century. The edifices were erected by ancestors of the Shona people, currently located in Zimbabwe and nearby countries. The stone city spans an area of 7.22 km2 and could have housed up to 18,000 people at its peak, giving it a population density of approximately 2500 PD/km2. It is recognised as a World Heritage Site by UNESCO.

Great Zimbabwe is believed to have served as a royal palace for the local monarch. As such, it would have been used as the seat of political power. Among the edifice's most prominent features were its walls, some of which are 11 m high. They were constructed of "dry stone" (that is, without mortar). Eventually, the city was abandoned and fell into ruin.

The earliest document mentioning the Great Zimbabwe ruins was in 1531 by Vicente Pegado, captain of the Portuguese garrison of Sofala on the coast of modern-day Mozambique, who recorded it as Symbaoe. The first confirmed visits by Europeans were in the late 19th century, with investigations of the site starting in 1871. Some later studies of the monument were controversial, as the white government of Rhodesia pressured archeologists to deny its construction by black Africans. Great Zimbabwe has since been adopted as a national monument by the Zimbabwean government, and the modern independent state was named after it.

The word great distinguishes the site from the many smaller ruins, now known as "zimbabwes", spread across the Zimbabwe Highveld. There are 200 such sites in southern Africa, such as Bumbusi in Zimbabwe and Manyikeni in Mozambique, with monumental, mortarless walls.

Name
Zimbabwe is the Shona name of the ruins, first recorded in 1531 by Vicente Pegado, captain of the Portuguese garrison of Sofala. Pegado noted that "The natives of the country call these edifices Symbaoe, which according to their language signifies 'court.

The name contains dzimba, the Shona term for "houses". There are two theories for the etymology of the name. The first proposes that the word is derived from Dzimba-dza-mabwe, translated from Shona as "large houses of stone" (dzimba = plural of imba, "house"; mabwe = plural of bwe, "stone"). A second suggests that Zimbabwe is a contracted form of dzimba-hwe, which means "venerated houses" in the Zezuru dialect of Shona, as usually applied to the houses or graves of chiefs.

Settlement
The majority of scholars believe that it was built by members of the Gokomere culture, who were the ancestors of the modern Shona in Zimbabwe.

The Great Zimbabwe area was settled by the 4th century AD. Between the 4th and the 7th centuries, communities of the Gokomere or Ziwa cultures farmed the valley, and mined and worked iron, but built no stone structures. These are the earliest Iron Age settlements in the area identified from archaeological diggings.

Construction and growth
Construction of the stone buildings started in the 11th century and continued for over 300 years. The ruins at Great Zimbabwe are some of the oldest and largest structures located in Southern Africa, and are the second oldest after nearby Mapungubwe in South Africa. Its most formidable edifice, commonly referred to as the Great Enclosure, has walls as high as 36 ft extending approximately 820 ft. David Beach believes that the city and its proposed state, the Kingdom of Zimbabwe, flourished from 1200 to 1500, although a somewhat earlier date for its demise is implied by a description transmitted in the early 16th century to João de Barros. Its growth has been linked to the decline of Mapungubwe from around 1300, due to climatic change or the greater availability of gold in the hinterland of Great Zimbabwe.

Traditional estimates are that Great Zimbabwe had as many as 18,000 inhabitants at its peak. However, a more recent survey concluded that the population likely never exceeded 10,000. The ruins that survive are built entirely of stone; they span 1800 acre.

Features of the ruins
In 1531, Vicente Pegado, Captain of the Portuguese Garrison of Sofala, described Zimbabwe thus: "Among the gold mines of the inland plains between the Limpopo and Zambezi rivers there is a fortress built of stones of marvelous size, and there appears to be no mortar joining them ... This edifice is almost surrounded by hills, upon which are others resembling it in the fashioning of stone and the absence of mortar, and one of them is a tower more than 12 fathoms [22 m] high. The natives of the country call these edifices Symbaoe, which according to their language signifies court." The ruins form three distinct architectural groups. They are known as the Hill Complex, the Valley Complex and the Great Enclosure. The Hill Complex is the oldest, and was occupied from the 11th to 13th centuries. The Great Enclosure was occupied from the 13th to 15th centuries, and the Valley Complex from the 14th to 16th centuries. Notable features of the Hill Complex include the Eastern Enclosure, in which it is thought the Zimbabwe Birds stood, a high balcony enclosure overlooking the Eastern Enclosure, and a huge boulder in a shape similar to that of the Zimbabwe Bird. The Great Enclosure is composed of an inner wall, encircling a series of structures and a younger outer wall. The Conical Tower, 18 ft in diameter and 30 ft high, was constructed between the two walls. The Valley Complex is divided into the Upper and Lower Valley Ruins, with different periods of occupation. There are different archaeological interpretations of these groupings. It has been suggested that the complexes represent the work of successive kings: some of the new rulers founded a new residence. The focus of power moved from the Hill Complex in the 12th century, to the Great Enclosure, the Upper Valley and finally the Lower Valley in the early 16th century. The alternative "structuralist" interpretation holds that the different complexes had different functions: the Hill Complex as an area for rituals, perhaps related to rain making, the Valley complex was for the citizens, and the Great Enclosure was used by the king. Structures that were more elaborate were probably built for the kings, although it has been argued that the dating of finds in the complexes does not support this interpretation.

Notable artefacts
The most important artefacts recovered from the Monument are the eight Zimbabwe Birds. These were carved from a micaceous schist (soapstone) on the tops of monoliths the height of a person. Slots in a platform in the Eastern Enclosure of the Hill Complex appear designed to hold the monoliths with the Zimbabwe birds, but as they were not found in situ, the original location of each monolith and bird within the enclosure cannot be determined. Other artefacts include soapstone figurines (one of which is in the British Museum ), pottery, iron gongs, elaborately worked ivory, iron and copper wire, iron hoes, bronze spearheads, copper ingots and crucibles, and gold beads, bracelets, pendants and sheaths. Glass beads and porcelain from China and Persia among other foreign artefacts were also found, attesting the international trade linkages of the Kingdom. In the extensive stone ruins of the great city, which still remain today, include eight, monolithic birds carved in soapstone. It is thought that they represent the bateleur eagle – a good omen, protective spirit and messenger of the gods in Shona culture.

Trade
Archaeological evidence suggests that Great Zimbabwe became a centre for trading, with artefacts suggesting that the city formed part of a trade network linked to Kilwa and extending as far as China. Copper coins found at Kilwa Kisiwani appear to be of the same pure ore found on the Swahili coast. This international trade was mainly in gold and ivory. That international commerce was in addition to the local agricultural trade, in which cattle were especially important. The large cattle herd that supplied the city moved seasonally and was managed by the court. Chinese pottery shards, coins from Arabia, glass beads and other non-local items have been excavated at Zimbabwe. Despite these strong international trade links, there is no evidence to suggest exchange of architectural concepts between Great Zimbabwe and centres such as Kilwa.

Decline
The causes for the decline and ultimate abandonment of the site around 1450 have been suggested as due to a decline in trade compared to sites further north, the exhaustion of the gold mines, political instability and famine and water shortages induced by climatic change. The Mutapa state arose in the 15th century from the northward expansion of the Great Zimbabwe tradition, having been founded by Nyatsimba Mutota from Great Zimbabwe after he was sent to find new sources of salt in the north; (this supports the belief that Great Zimbabwe's decline was due to a shortage of resources). Great Zimbabwe also predates the Khami and Nyanga cultures.

From Portuguese traders to Karl Mauch
The first European visit may have been made by the Portuguese traveler António Fernandes in 1513–1515, who crossed twice and reported in detail the region of present-day Zimbabwe (including the Shona kingdoms) and also fortified centers in stone without mortar. However, passing en route a few kilometres north and about 35 mi south of the site, he did not make a reference to Great Zimbabwe. Portuguese traders heard about the remains of the medieval city in the early 16th century, and records survive of interviews and notes made by some of them, linking Great Zimbabwe to gold production and long-distance trade. Two of those accounts mention an inscription above the entrance to Great Zimbabwe, written in characters not known to the Arab merchants who had seen it.

In 1506, the explorer Diogo de Alcáçova described the edifices in a letter to Manuel I of Portugal, writing that they were part of the larger kingdom of Ucalanga (presumably Karanga, a dialect of the Shona people spoken mainly in Masvingo and Midlands provinces of Zimbabwe). João de Barros left another such description of Great Zimbabwe in 1538, as recounted to him by Moorish traders who had visited the area and possessed knowledge of the hinterland. He indicates that the edifices were locally known as Symbaoe, which meant "royal court" in the vernacular. As to the actual identity of the builders of Great Zimbabwe, de Barros writes: "When and by whom, these edifices were raised, as the people of the land are ignorant of the art of writing, there is no record, but they say they are the work of the devil, for in comparison with their power and knowledge it does not seem possible to them that they should be the work of man."

Additionally, with regard to the purpose of the Great Zimbabwe ruins, de Barros asserted that: "in the opinion of the Moors who saw it [Great Zimbabwe] it is very ancient and was built to keep possessions of the mines, which are very old, and no gold has been extracted from them for years, because of the wars ... it would seem that some prince who has possession of these mines ordered it to be built as a sign thereof, which he afterwards lost in the course of time and through their being so remote from his kingdom".

De Barros further remarked that Symbaoe "is guarded by a nobleman, who has charge of it, after the manner of a chief alcaide, and they call this officer Symbacayo ... and there are always some of Benomotapa's wives therein of whom Symbacayo takes care." Thus, Great Zimbabwe appears to have still been inhabited as recently as the early 16th century.

Karl Mauch and the Queen of Sheba
The ruins were rediscovered during a hunting trip in 1867 by Adam Render, a German-American hunter, prospector and trader in southern Africa, who in 1871 showed the ruins to Karl Mauch, a German explorer and geographer of Africa. Karl Mauch recorded the ruins 3 September 1871, and immediately speculated about a possible Biblical association with King Solomon and the Queen of Sheba, an explanation which had been suggested by earlier writers such as the Portuguese João dos Santos. Mauch went so far as to favour a legend that the structures were built to replicate the palace of the Queen of Sheba in Jerusalem, and claimed a wooden lintel at the site must be Lebanese cedar, brought by Phoenicians. The Sheba legend, as promoted by Mauch, became so pervasive in the white settler community as to cause the later scholar James Theodore Bent to say, "The names of King Solomon and the Queen of Sheba were on everybody's lips, and have become so distasteful to us that we never expect to hear them again without an involuntary shudder."

Carl Peters and Theodore Bent
Carl Peters collected a ceramic ushabti in 1905. Flinders Petrie examined it and identified a cartouche on its chest as belonging to the 18th Dynasty Egyptian Pharaoh Thutmose III and suggested that it was a statuette of the king and cited it as proof of commercial ties between rulers in the area and the ancient Egyptians during the New Kingdom (c. 1550–1077 BC), if not a relic of an old Egyptian station near the local gold mines. Johann Heinrich Schäfer later appraised the statuette, and argued that it belonged to a well-known group of forgeries. After having received the ushabti, Felix von Luschan suggested that it was of more recent origin than the New Kingdom. He asserted that the figurine instead appeared to date to the subsequent Ptolemaic era (c. 323–30 BC), when Alexandria-based Greek merchants would export Egyptian antiquities and pseudo-antiquities to southern Africa.

J. Theodore Bent undertook a season at Zimbabwe with Cecil Rhodes's patronage and funding from the Royal Geographical Society and the British Association for the Advancement of Science. This, and other excavations undertaken for Rhodes, resulted in a book publication that introduced the ruins to English readers. Bent had no formal archaeological training, but had travelled very widely in Arabia, Greece and Asia Minor. He was aided by the expert cartographer and surveyor Robert M. W. Swan (1858–1904), who also visited and surveyed a host of related stone ruins nearby. Bent stated in the first edition of his book The Ruined Cities of Mashonaland (1892) that the ruins revealed either the Phoenicians or the Arabs as builders, and he favoured the possibility of great antiquity for the fortress. By the third edition of his book (1902) he was more specific, with his primary theory being "a Semitic race and of Arabian origin" of "strongly commercial" traders living within a client African city.

The Lemba
The construction of Great Zimbabwe is also claimed by the Lemba, as documented by William Bolts in 1777 (to the Austrian Habsburg authorities), and by an A.A. Anderson (writing about his travels north of the Limpopo River in the 19th century). Lemba speak the Bantu languages spoken by their geographic neighbours and resemble them physically, but they have some religious practices and beliefs similar to those in Judaism and Islam, which they claim were transmitted by oral tradition.

David Randall-MacIver and medieval origin
The first scientific archaeological excavations at the site were undertaken by David Randall-MacIver for the British Association in 1905–1906. In Medieval Rhodesia, he rejected the claims made by Adam Render, Carl Peters and Karl Mauch, and instead wrote of the existence in the site of objects that were of Bantu origin. Randall-MacIver concluded that all available evidence led him to believe that the Zimbabwe structures were constructed by the ancestors of the Shona people. More importantly he suggested a wholly medieval date for the walled fortifications and temple. This claim was not immediately accepted, partly due to the relatively short and undermanned period of excavation he was able to undertake.

Gertrude Caton Thompson
In mid-1929 Gertrude Caton Thompson concluded, after a twelve-day visit of a three-person team and the digging of several trenches, that the site was indeed created by Bantu. She had first sunk three test pits into what had been refuse heaps on the upper terraces of the hill complex, producing a mix of unremarkable pottery and ironwork. She then moved to the Conical Tower and tried to dig under the tower, arguing that the ground there would be undisturbed, but nothing was revealed. Some further test trenches were then put down outside the lower Great Enclosure and in the Valley Ruins, which unearthed domestic ironwork, glass beads, and a gold bracelet. Caton Thompson immediately announced her Bantu origin theory to a meeting of the British Association in Johannesburg. "Examination of all the existing evidence, gathered from every quarter, still can produce not one single item that is not in accordance with the claim of Bantu origin and medieval date" Caton Thompson's claim was not immediately favoured, although it had strong support among some scientific archaeologists due to her modern methods. Her most important contribution was in helping to confirm the theory of a medieval origin for the masonry work of the 14th and 15th centuries. By 1931, she had modified her Bantu theory somewhat, allowing for a possible Arabian influence for the towers through the imitation of buildings or art seen at coastal Arabian trading cities.

Post-1945 research
Since the 1950s, there has been consensus among archaeologists as to the African origins of Great Zimbabwe. Artefacts and radiocarbon dating indicate settlement in at least the 5th century, with continuous settlement of Great Zimbabwe between the 12th and 15th centuries and the bulk of the finds from the 15th century. The radiocarbon evidence is a suite of 28 measurements, for which all but the first four, from the early days of the use of that method and now viewed as inaccurate, support the 12th-to-15th-centuries chronology. In the 1970s, a beam that produced some of the anomalous dates in 1952 was reanalysed and gave a 14th-century date. Dated finds such as Chinese, Persian and Syrian artefacts also support the 12th- and 15th-century dates.

Gokomere
Archaeologists generally agree that the builders probably spoke one of the Shona languages, based upon evidence of pottery,  oral traditions and anthropology and recent scholarship supports the construction of Great Zimbabwe (and the origin of its culture) by Shona and Venda peoples,    who were probably descended from the Gokomere culture. The Gokomere culture, an eastern Bantu subgroup, existed in the area from around 200 AD and flourished from 500 AD to about 800 AD. Archaeological evidence indicates that it constitutes an early phase of the Great Zimbabwe culture. The Gokomere culture likely gave rise to both the modern Mashona people, an ethnic cluster comprising distinct sub-ethnic groups such as the local Karanga clan and the Rozwi culture, which originated as several Shona states. Gokomere peoples were probably also related to certain nearby early Bantu groups like the Mapungubwe civilisation of neighbouring North eastern South Africa, which is believed to have been an early Venda-speaking culture, and to the nearby Sotho.

Recent research
More recent archaeological work has been carried out by Peter Garlake, who has produced the comprehensive descriptions of the site, David Beach  and Thomas Huffman, who have worked on the chronology and development of Great Zimbabwe and Gilbert Pwiti, who has published extensively on trade links. Today, the most recent consensus appears to attribute the construction of Great Zimbabwe to the Shona people. Some evidence also suggests an early influence from the probably Venda-speaking peoples of the Mapungubwe civilization.

Damage to the ruins
Damage to the ruins has taken place throughout the last century. The removal of gold and artefacts in amateurist diggings by early colonial antiquarians caused widespread damage, notably diggings by Richard Nicklin Hall. More extensive damage was caused by the mining of some of the ruins for gold. Reconstruction attempts since 1980 caused further damage, leading to alienation of the local communities from the site. Another source of damage to the ruins has been due to the site being open to visitors with many cases of people climbing the walls, walking over archaeological deposits, and the over-use of certain paths all have had major impacts on the structures at the site. These are in conjunction with damages due to the natural weathering that occurs over time due to vegetation growth, the foundations settling, and erosion from the weather.

Political implications
Martin Hall writes that the history of Iron Age research south of the Zambezi shows the prevalent influence of colonial ideologies, both in the earliest speculations about the nature of the African past and in the adaptations that have been made to contemporary archaeological methodologies. Preben Kaarsholm writes that both colonial and black nationalist groups invoked Great Zimbabwe's past to support their vision of the country's present, through the media of popular history and of fiction. Examples of such popular history include Alexander Wilmot's Monomotapa (Rhodesia) and Ken Mufuka's Dzimbahwe: Life and Politics in the Golden Age; examples from fiction include Wilbur Smith's The Sunbird and Stanlake Samkange's Year of the Uprising.

When white colonialists like Cecil Rhodes first saw the ruins, they saw them as a sign of the great riches that the area would yield to its new masters. Pikirayi and Kaarsholm suggest that this presentation of Great Zimbabwe was partly intended to encourage settlement and investment in the area. Gertrude Caton-Thompson recognised that the builders were indigenous Africans, but she characterised the site as the "product of an infantile mind" built by a subjugated society. The official line in Rhodesia during the 1960s and 1970s was that the structures were built by non-blacks. Archaeologists who disputed the official statement were censored by the government. According to Paul Sinclair, interviewed for None But Ourselves:

This suppression of archaeology culminated in the departure from the country of prominent archaeologists of Great Zimbabwe, including Peter Garlake, Senior Inspector of Monuments for Rhodesia, and Roger Summers of the National Museum.

To black nationalist groups, Great Zimbabwe became an important symbol of achievement by Africans: reclaiming its history was a major aim for those seeking majority rule. In 1980 the new internationally recognised independent country was renamed for the site, and its famous soapstone bird carvings were retained from the Rhodesian flag and Coat of Arms as a national symbol and depicted in the new Zimbabwean flag. After the creation of the modern state of Zimbabwe in 1980, Great Zimbabwe has been employed to mirror and legitimise shifting policies of the ruling regime. At first it was argued that it represented a form of pre-colonial "African socialism" and later the focus shifted to stressing the natural evolution of an accumulation of wealth and power within a ruling elite. An example of the former is Ken Mufuka's booklet, although the work has been heavily criticised. A tower of the Great Zimbabwe is also depicted on the coat of arms of Zimbabwe.

Some of the carvings had been taken from Great Zimbabwe around 1890 and sold to Cecil Rhodes, who was intrigued and had copies made which he gave to friends. Most of the carvings have now been returned to Zimbabwe, but one remains at Rhodes' old home, Groote Schuur, in Cape Town.

The Great Zimbabwe University
In the early 21st century, the government of Zimbabwe endorsed the creation of a university in the vicinity of the ruins. This university is an arts and culture based university which draws from the rich history of the monuments. The university main site is near the monuments with other campuses in the City centre and Mashava. The campuses include Herbet Chitepo Law School, Robert Mugabe School of Education, Gary Magadzire School of Agriculture and Natural Science, Simon Muzenda School of Arts, and Munhumutapa School of Commerce.

title: Great Zimbabwe