In agriculture, a terrace is a piece of sloped plane, cut into a series of successively receding flat surfaces or platforms, which resemble steps, for the purposes of more effective farming. This type of landscaping is therefore called terracing. Graduated terrace steps are used to farm on hilly or mountainous terrain. Terraced fields decrease both erosion and surface runoff, may be used to support growing crops that require irrigation, such as rice; the Rice Terraces of the Philippine Cordilleras have been designated as a UNESCO World Heritage Site because of the significance of this technique. Terraced paddy fields are used in rice and barley farming in east and southeast Asia, as well as the Mediterranean and South America. Drier-climate terrace farming is common throughout the Mediterranean Basin, where they are used for vineyards, olive trees, cork oak, etc. In the South American Andes, farmers have used terraces, known as andenes, for over a thousand years to farm potatoes and other native crops.
Terraced farming was developed by the Wari culture and other peoples of the south-central Andes before 1000 AD, centuries before they were used by the Inca, who adopted them. The terraces were built to make the most efficient use of shallow soil and to enable irrigation of crops by allowing runoff to occur through the outlet; the Inca built on these, developing a system of canals and puquios to direct water through dry land and increase fertility levels and growth. These terraced farms are found, they provided the food necessary to support the populations of great Inca cities and religious centres such as Machu Picchu. Terracing is used for sloping terrain. At the seaside Villa of the Papyri in Herculaneum, the villa gardens of Julius Caesar's father-in-law were designed in terraces to give pleasant and varied views of the Bay of Naples. Terraced fields are common in islands with steep slopes; the Canary Islands present a complex system of terraces covering the landscape from the coastal irrigated plantations to the dry fields in the highlands.
These terraces, which are named cadenas, are built with stone walls of skillful design, which include attached stairs and channels. In Old English, a terrace was called a "lynch". An example of an ancient Lynch Mill is in Lyme Regis; the water is directed from a river by a duct along a terrace. This set-up was used in steep hilly areas in the UK. In Japan, some of the 100 Selected Terraced Rice Fields, from Iwate in the north to Kagoshima in the south, are disappearing, but volunteers are helping the farmers both to maintain their traditional methods and for sightseeing purposes. Anden Banaue Rice Terraces Rice Terraces of the Philippine Cordilleras Satoyama Terrace garden Terrace Fields around the World
Aşıklı Höyük is a settlement mound located nearly 1 km south of Kızılkaya village on the bank of the Melendiz brook, 25 kilometers southeast of Aksaray, Turkey. Aşıklı Höyük is located in an area covered by the volcanic tuff of central Cappadocia, in Aksaray Province; the archaeological site of Aşıklı Höyük was first settled in the Aceramic Neolithic period, around 9000 B. C, it is situated 1119.5 metres above sea level, a little higher than the region's average of c. 1000 metres. The site itself is about 4 ha smaller than the situated site of Çatalhöyük; the surrounding landscape is formed by erosion of river valleys into tuff deposits. The Melendiz Valley, where the Aşıklı Höyük is located, constitutes a favourable and diverse habitat; the proximity to an obsidian source did become the base of a trade with the material supplying areas as far away as today's Cyprus and Iraq. Aşıklı Höyük was first investigated by Professor Ian A. Todd when he visited the site in the summer of 1964. Todd emphasised the importance of the obsidian in the area, based on over 6000 obsidian pieces collected from the surface layer alone.
The site was classified as a medium sized mound and destroyed by the river situated next to it. On the basis of the lithics and animal bones located in the surface layers the site became known as a contemporary to the Palestine PPNB, reinforced by 14C dates; the first comprehensive excavations took place late: first when the government launched a plan that would result in the rise of the waters of the Mamasın Lake located close to Aşıklı Höyük, Professor Ufuk Esin started the salvage excavations in 1989. Nine excavations have been undertaken up to 2003, uncovering 4200 m2 on the horizontal plain, making it one of the largest scale excavations in the region; the newest dates for Aşıklı Höyük show that the occupational period was from 8200 to 7400 BC, extracted from 3 layers with a total of 13 phases. It is known as one of the earliest Aceramic Neolithic sites on the Anatolian plateau, the prior mentioned extraction of the obsidian source was to be frequented as far back as the Paleolithic nomadic hunter-gatherers.
Due to its date and structural organization Aşıklı Höyük is known to be "a prime example of a first foray into sedentism". After more than 400 rooms had been excavated, the total number of individual found to have been buried within the settlement did not surpass 70. All these burials were under building floors; the dead were placed in pits cut through the floor during the occupation of the building. The buried are people of all ages. There is a variety of skeletal body postures, from burials in a hocker position to extended skeletons facing upwards. Others are lying on one side with the legs bent at the knees; the orientation of the burials varies within the buildings, as does the number of individuals buried inside them. The male population had individuals up to the age of 55–57 years of age, while the majority of females died between the ages of 20 and 25; the skeletal remains of these women show spinal deformities indicating that they had to carry heavy loads. This does not itself prove; the fact that the men seem to have outlived the women might be interpreted as sign that the women were subject to more strenuous physical labour than their male counterparts.
From Natufian Abu Hureyra there are similar osteological signs, such as pathologies in metatarsals, phalanges and shoulder joints, being specific to females resulting from habitual kneeling in the use of saddle querns. The Neolithic evidence show indications of increased physical workload in the osteological material on both genders, where the male skeletons show signs of joint disease and trauma arguably caused by cutting timber and tilling. Children represent 37.8% of the deceased, with 43.7% mortality within a year of birth. The skeletal remains are complete and with articulations intact, indicating that the burials have been primary; the graves contain either double burials. On one occasion two graves were found under the floor of room AB, belonging to an adjacent court with a large domed mudbrick oven paved with blocks of basalt. In one of the graves were the skeletons of a young woman and an elderly man; the young woman had undergone trepanation and survived only a few days after the operation.
All skeletons were buried in the hocker position, a fetal-like positioning were the arms are embracing the lower limbs. From a different grave a woman shows signs of being scalped after her death, according to the cut marks on her skull; as many as 55% of the skeletons show signs of being burned. The burial under the floor AB is accommodated by walls with the interior side were painted in a purplish red colour; the oven in HG indicates that this was indeed "special individuals of an elite class", claiming it can be compared to the "Terrazzo" Building at Çayönü and the "Temple" Building at Nevalı Çori and therefore have been a shrine used for religious ceremonies. Many of the burials contain burial goods consisting of necklaces and bracelets made of beads of various sorts.70 burials in over 400 rooms suggest that some form of selection took place of, buried at the site, implementing that AB indeed could be the residence or resting place of people influential in terms of both economy and political power.
Rooms containing hearths are more to contain burials. It has been argued that the number of burials could be an
Human prehistory is the period between the use of the first stone tools c. 3.3 million years ago by hominins and the invention of writing systems. The earliest writing systems appeared c. 5,300 years ago, but it took thousands of years for writing to be adopted, it was not used in some human cultures until the 19th century or until the present. The end of prehistory therefore came at different dates in different places, the term is less used in discussing societies where prehistory ended recently. Sumer in Mesopotamia, the Indus valley civilization, ancient Egypt were the first civilizations to develop their own scripts and to keep historical records. Neighboring civilizations were the first to follow. Most other civilizations reached the end of prehistory during the Iron Age; the three-age system of division of prehistory into the Stone Age, followed by the Bronze Age and Iron Age, remains in use for much of Eurasia and North Africa, but is not used in those parts of the world where the working of hard metals arrived abruptly with contact with Eurasian cultures, such as the Americas, Oceania and much of Sub-Saharan Africa.
These areas with some exceptions in Pre-Columbian civilizations in the Americas, did not develop complex writing systems before the arrival of Eurasians, their prehistory reaches into recent periods. The period when a culture is written about by others, but has not developed its own writing is known as the protohistory of the culture. By definition, there are no written records from human prehistory, so dating of prehistoric materials is crucial. Clear techniques for dating were not well-developed until the 19th century; this article is concerned with human prehistory, the time since behaviorally and anatomically modern humans first appeared until the beginning of recorded history. Earlier periods are called "prehistoric". Beginning The term "prehistory" can refer to the vast span of time since the beginning of the Universe or the Earth, but more it refers to the period since life appeared on Earth, or more to the time since human-like beings appeared. End The date marking the end of prehistory is defined as the advent of the contemporary written historical record.
The date varies from region to region depending on the date when relevant records become a useful academic resource. For example, in Egypt it is accepted that prehistory ended around 3200 BCE, whereas in New Guinea the end of the prehistoric era is set much more at around 1900 common era. In Europe the well-documented classical cultures of Ancient Greece and Ancient Rome had neighbouring cultures, including the Celts and to a lesser extent the Etruscans, with little or no writing, historians must decide how much weight to give to the highly prejudiced accounts of these "prehistoric" cultures in Greek and Roman literature. Time periods In dividing up human prehistory in Eurasia, historians use the three-age system, whereas scholars of pre-human time periods use the well-defined geologic record and its internationally defined stratum base within the geologic time scale; the three-age system is the periodization of human prehistory into three consecutive time periods, named for their respective predominant tool-making technologies: Stone Age Bronze Age Iron Age The notion of "prehistory" began to surface during the Enlightenment in the work of antiquarians who used the word'primitive' to describe societies that existed before written records.
The first use of the word prehistory in English, occurred in the Foreign Quarterly Review in 1836. The use of the geologic time scale for pre-human time periods, of the three-age system for human prehistory, is a system that emerged during the late nineteenth century in the work of British and Scandinavian archeologists and anthropologists; the main source for prehistory is archaeology, but some scholars are beginning to make more use of evidence from the natural and social sciences. This view has been articulated by advocates of deep history; the primary researchers into human prehistory are archaeologists and physical anthropologists who use excavation and geographic surveys, other scientific analysis to reveal and interpret the nature and behavior of pre-literate and non-literate peoples. Human population geneticists and historical linguists are providing valuable insight for these questions. Cultural anthropologists help provide context for societal interactions, by which objects of human origin pass among people, allowing an analysis of any article that arises in a human prehistoric context.
Therefore, data about prehistory is provided by a wide variety of natural and social sciences, such as paleontology, archaeology, geology, comparative linguistics, molecular genetics and many others. Human prehistory differs from history not only in terms of its chronology but in the way it deals with the activities of archaeological cultures rather than named nations or individuals. Restricted to material processes and artifacts rather than written records, prehistory is anonymous; because of this, reference terms that prehistorians use, such as Neanderthal or Iron Age are modern labels with definitions sometimes subject to debate. The concept of a "Stone Age" is found useful in the archaeology of most of the world, though in the archaeology of the Americas it is called by different names and begins with a Lithic sta
Antlers are extensions of an animal's skull found in members of the deer family. They are a single structure, they are found only on males, with the exception of the caribou. Antlers are shed and regrown each year and function as objects of sexual attraction and as weapons in fights between males for control of harems. In contrast, found on pronghorns and bovids such as sheep, goats and cattle, are two-part structures. An interior of bone is covered by an exterior sheath grown by specialized hair follicles, the same material as human fingernails and toenails. Horns continue to grow throughout the animal's life; the exception to this rule is the Pronghorn which regrows its horn sheath each year. They grow in symmetrical pairs. Antler comes from the Old French antoillier from some form of an unattested Latin word *anteocularis, "before the eye". Antlers are unique to cervids; the ancestors of deer had tusks. In most species, antlers appear to replace tusks. However, two modern species have tusks and no antlers and the muntjac has small antlers and tusks.
Antlers are found only on males. Only reindeer have antlers on the females, these are smaller than those of the males. Fertile does from other species of deer have the capacity to produce antlers on occasion due to increased testosterone levels; the "horns" of a pronghorn meet some of the criteria of antlers, but are not considered true antlers because they contain keratin. Each antler grows from an attachment point on the skull called a pedicle. While an antler is growing, it is covered with vascular skin called velvet, which supplies oxygen and nutrients to the growing bone. Antlers are considered one of the most exaggerated cases of male secondary sexual traits in the animal kingdom, grow faster than any other mammal bone. Growth occurs at the tip, is cartilage, replaced by bone tissue. Once the antler has achieved its full size, the velvet is lost and the antler's bone dies; this dead bone structure is the mature antler. In most cases, the bone at the base is destroyed by osteoclasts and the antlers fall off at some point.
As a result of their fast growth rate, antlers are considered a handicap since there is an immense nutritional demand on deer to re-grow antlers annually, thus can be honest signals of metabolic efficiency and food gathering capability. In most arctic and temperate-zone species, antler growth and shedding is annual, is controlled by the length of daylight. Although the antlers are regrown each year, their size varies with the age of the animal in many species, increasing annually over several years before reaching maximum size. In tropical species, antlers may be shed at any time of year, in some species such as the sambar, antlers are shed at different times in the year depending on multiple factors; some equatorial deer never shed their antlers. Antlers function as weapons in combats between males, which sometimes cause serious wounds, as dominance and sexual displays; the principal means of evolution of antlers is sexual selection, which operates via two mechanisms: male-to-male competition and female mate choice.
Male-male competition can take place in two forms. First, they can compete behaviorally where males use their antlers as weapons to compete for access to mates. Males with the largest antlers are more to obtain mates and achieve the highest fertilization success due to their competitiveness and high phenotypic quality. Whether this is a result of male-male fighting or display, or of female choosiness differs depending on the species as the shape and function of antlers vary between species. There is evidence to support that antler size influences mate selection in the red deer, has a heritable component. Despite this, a 30-year study showed no shift in the median size of antlers in a population of red deer; the lack of response could be explained by environmental covariance, meaning that lifetime breeding success is determined by an unmeasured trait, phenotypically correlated with antler size but for which there is no genetic correlation of antler growth. Alternatively, the lack of response could be explained by the relationship between heterozygosity and antler size, which states that males heterozygous at multiple loci, including MHC loci, have larger antlers.
The evolutionary response of traits that depend on heterozygosity is slower than traits that are dependent on additive genetic components and thus the evolutionary change is slower than expected. A third possibility is that the costs of having larger antlers exert enough selective pressure to offset the benefit of attracting mates. If antlers functioned only in male–male competition for mates, the best evolutionary strategy would be to shed them after the rutting season, both to free the male from a heavy encumbrance and to give him more time to regrow a larger new pair, yet antlers are retained through the winter and into the spring, suggesting that they have another use. Wolves in Yellowstone National Park are 3.6 times more to
The Netherlands is a country located in Northwestern Europe. The European portion of the Netherlands consists of twelve separate provinces that border Germany to the east, Belgium to the south, the North Sea to the northwest, with maritime borders in the North Sea with Belgium and the United Kingdom. Together with three island territories in the Caribbean Sea—Bonaire, Sint Eustatius and Saba— it forms a constituent country of the Kingdom of the Netherlands; the official language is Dutch, but a secondary official language in the province of Friesland is West Frisian. The six largest cities in the Netherlands are Amsterdam, The Hague, Utrecht and Tilburg. Amsterdam is the country's capital, while The Hague holds the seat of the States General and Supreme Court; the Port of Rotterdam is the largest port in Europe, the largest in any country outside Asia. The country is a founding member of the EU, Eurozone, G10, NATO, OECD and WTO, as well as a part of the Schengen Area and the trilateral Benelux Union.
It hosts several intergovernmental organisations and international courts, many of which are centered in The Hague, dubbed'the world's legal capital'. Netherlands means'lower countries' in reference to its low elevation and flat topography, with only about 50% of its land exceeding 1 metre above sea level, nearly 17% falling below sea level. Most of the areas below sea level, known as polders, are the result of land reclamation that began in the 16th century. With a population of 17.30 million people, all living within a total area of 41,500 square kilometres —of which the land area is 33,700 square kilometres —the Netherlands is one of the most densely populated countries in the world. It is the world's second-largest exporter of food and agricultural products, owing to its fertile soil, mild climate, intensive agriculture; the Netherlands was the third country in the world to have representative government, it has been a parliamentary constitutional monarchy with a unitary structure since 1848.
The country has a tradition of pillarisation and a long record of social tolerance, having legalised abortion and human euthanasia, along with maintaining a progressive drug policy. The Netherlands abolished the death penalty in 1870, allowed women's suffrage in 1917, became the world's first country to legalise same-sex marriage in 2001, its mixed-market advanced economy had the thirteenth-highest per capita income globally. The Netherlands ranks among the highest in international indexes of press freedom, economic freedom, human development, quality of life, as well as happiness; the Netherlands' turbulent history and shifts of power resulted in exceptionally many and varying names in different languages. There is diversity within languages; this holds for English, where Dutch is the adjective form and the misnomer Holland a synonym for the country "Netherlands". Dutch comes from Theodiscus and in the past centuries, the hub of Dutch culture is found in its most populous region, home to the capital city of Amsterdam.
Referring to the Netherlands as Holland in the English language is similar to calling the United Kingdom "Britain" by people outside the UK. The term is so pervasive among potential investors and tourists, that the Dutch government's international websites for tourism and trade are "holland.com" and "hollandtradeandinvest.com". The region of Holland consists of North and South Holland, two of the nation's twelve provinces a single province, earlier still, the County of Holland, a remnant of the dissolved Frisian Kingdom. Following the decline of the Duchy of Brabant and the County of Flanders, Holland became the most economically and politically important county in the Low Countries region; the emphasis on Holland during the formation of the Dutch Republic, the Eighty Years' War and the Anglo-Dutch Wars in the 16th, 17th and 18th century, made Holland serve as a pars pro toto for the entire country, now considered either incorrect, informal, or, depending on context, opprobrious. Nonetheless, Holland is used in reference to the Netherlands national football team.
The region called the Low Countries and the Country of the Netherlands. Place names with Neder, Nieder and Nedre and Bas or Inferior are in use in places all over Europe, they are sometimes used in a deictic relation to a higher ground that consecutively is indicated as Upper, Oben, Superior or Haut. In the case of the Low Countries / Netherlands the geographical location of the lower region has been more or less downstream and near the sea; the geographical location of the upper region, changed tremendously over time, depending on the location of the economic and military power governing the Low Countries area. The Romans made a distinction between the Roman provinces of downstream Germania Inferior and upstream Germania Superior; the designation'Low' to refer to the region returns again in the 10th century Duchy of Lower Lorraine, that covered much of the Low Countries. But this time the corresponding Upper region is Upper Lorraine, in nowadays Northern France; the Dukes of Burgundy, who ruled the Low Countries in the 15th century, used the term les pays de par deçà for the Low Countries as opposed to les pays de par delà for their original
History of archery
The bow and arrow are known to have been invented by the end of the Upper Paleolithic, for at least 10,000 years archery was an important military and hunting skill, features prominently in the mythologies of many cultures. Archers, whether on foot, in chariots or on horseback were a major part of most militaries until about 1500 when they began to be replaced by firearms, first in Europe, progressively elsewhere. Archery continues to be a popular sport. Based on indirect evidence, the bow seems to have been invented near the transition from the Upper Paleolithic to the Mesolithic, some 10,000 years ago; the oldest direct evidence dates to 8,000 years ago. The discovery of stone points that could have been employed successfully as insets for spears or arrows in Sibudu Cave, South Africa, has prompted the proposal that bow and arrow technology could have existed as early as 64,000 years ago. In the Levant, artifacts which may be arrow-shaft straighteners are known from the Natufian culture, onwards.
The Khiamian and PPN A shouldered. The oldest indication for archery in Europe comes from Stellmoor in the Ahrensburg valley north of Hamburg, Germany, they were associated with artifacts of the late Paleolithic. The arrows were made of pine and consisted of a mainshaft and a 15-20 centimetre long foreshaft with a flint point, they had shallow grooves on the base. The oldest definite bows known so far come from the Holmegård swamp in Denmark. In the 1940s, two bows were found there, dated to about 8,000 BP; the Holmegaard bows have flat arms and a D-shaped midsection. The center section is biconvex; the complete bow is 1.50 m long. Bows of Holmegaard-type were in use until the Bronze Age. Mesolithic pointed shafts have been found in England, Germany and Sweden, they were rather long, up to 120 cm and made of European hazel, wayfaring tree and other small woody shoots. Some still have flint arrow-heads preserved; the ends show traces of fletching, fastened on with birch-tar. The oldest depictions of combat, found in Iberian cave art of the Mesolithic, show battles between archers.
A group of three archers encircled by a group of four is found in Cueva del Roure, Morella la Vella, Castellón, Valencia. A depiction of a larger battle, in which eleven archers are attacked by seventeen running archers, is found in Les Dogue, Ares del Maestrat, Castellón, Valencia. At Val del Charco del Agua Amarga, Alcañiz, seven archers with plumes on their heads are fleeing a group of eight archers running in pursuit. Archery seems to have arrived in the Americas via Alaska, as early as 6000 BCE, with the Arctic small tool tradition, about 2,500 BCE, spreading south into the temperate zones as early as 2,000 BCE, was known among the indigenous peoples of North America from about 500 CE; the oldest Neolithic bow known from Europe was found in anaerobic layers dating between 7,400-7,200 BP, the earliest layer of settlement at the lake settlement at La Draga, Girona, Spain. The intact specimen is short at 1.08m, has a D-shaped cross-section, is made of yew wood. Stone wrist-guards, interpreted as display versions of bracers, form a defining part of the Beaker culture and arrowheads are commonly found in Beaker graves.
European Neolithic fortifications, arrow-heads and representations indicate that, in Neolithic and Early Bronze Age Europe, archery was a major form of interpersonal violence. For example, the Neolithic settlement at Carn Brea was occupied between around 3700 and 3400 BC. Chariot-borne archers became a defining feature of Middle Bronze Age warfare, from Europe to Eastern Asia and India. However, in the Middle Bronze Age, with the development of massed infantry tactics, with the use of chariots for shock tactics or as prestigious command vehicles, archery seems to have lessened in importance in European warfare. In the same period, with the Seima-Turbino Phenomenon and the spread of the Andronovo culture, mounted archery became a defining feature of Eurasian nomad cultures and a foundation of their military success, until the massed use of guns. In China, crossbows were developed, Han Dynasty writers attributed Chinese success in battles against nomad invaders to the massed use of crossbows, first attested at the Battle of Ma-Ling in 341 BCE.
Ancient civilizations, notably the Persians, Egyptians, Indians, Koreans and Japanese fielded large numbers of archers in their armies. Arrows were destructive against massed formations, the use of archers proved decisive; the Sanskrit term for archery, came to refer to martial arts in general. Mounted archers were used as the main military force for many of the equestrian nomads, including the Cimmerians and the Mongols; the ancient Egyptian people took to archery as early as 5,000 years ago. Archery was widespread by the time of the earliest pharaohs and was practiced both for hunting and use in warfare. Legendary figures from the tombs of Thebes are depicted giving "lessons in archery"; some Egyptian deities are connected to archery. The "Nine bows" were a conventional representation
A bog or bogland is a wetland that accumulates peat, a deposit of dead plant material—often mosses, in a majority of cases, sphagnum moss. It is one of the four main types of wetlands. Other names for bogs include mire and muskeg, they are covered in ericaceous shrubs rooted in the sphagnum moss and peat. The gradual accumulation of decayed plant material in a bog functions as a carbon sink. Bogs occur where the water at the ground surface is low in nutrients. In some cases, the water is derived from precipitation, in which case they are termed ombrotrophic. Water flowing out of bogs has a characteristic brown colour, which comes from dissolved peat tannins. In general, the low fertility and cool climate result in slow plant growth, but decay is slower owing to the saturated soil. Hence, peat accumulates. Large areas of the landscape can be covered many meters deep in peat. Bogs have distinctive assemblages of animal and plant species, are of high importance for biodiversity in landscapes that are otherwise settled and farmed.
Bogs are distributed in cold, temperate climes in boreal ecosystems in the Northern Hemisphere. The world's largest wetland is the peat bogs of the Western Siberian Lowlands in Russia, which cover more than a million square kilometres. Large peat bogs occur in North America the Hudson Bay Lowland and the Mackenzie River Basin, they are less common in the Southern Hemisphere, with the largest being the Magellanic moorland, comprising some 44,000 square kilometres. Sphagnum bogs were widespread in northern Europe but have been cleared and drained for agriculture. A 2014 expedition leaving from Itanga village, Republic of the Congo, discovered a peat bog "as big as England" which stretches into neighboring Democratic Republic of Congo. There are many specialised animals and plants associated with bog habitat. Most are capable of waterlogging. Sphagnum is abundant, along with ericaceous shrubs; the shrubs are evergreen, understood to assist in conservation of nutrients. In drier locations, evergreen trees can occur, in which case the bog blends into the surrounding expanses of boreal evergreen forest.
Sedges are one of the more common herbaceous species. Carnivorous plants such as sundews and pitcher plants have adapted to the low-nutrient conditions by using invertebrates as a nutrient source. Orchids have adapted to these conditions through the use of mycorrhizal fungi to extract nutrients; some shrubs such as Myrica gale have root nodules in which nitrogen fixation occurs, thereby providing another supplemental source of nitrogen. Bogs are recognized as a significant/specific habitat type by a number of governmental and conservation agencies, they can provide habitat for mammals, such as caribou and beavers, as well as for species of nesting shorebirds, such as Siberian cranes and yellowlegs. The United Kingdom in its Biodiversity Action Plan establishes bog habitats as a priority for conservation. Russia has a large reserve system in the West Siberian Lowland; the highest protected status occurs in Zapovedniks. Bogs have distinctive insects. In Ireland, the viviparous lizard, the only known reptile in the country, dwells in bogland.
Bog habitats may develop depending on the climate and topography. One way of classifying bogs is based upon their location in the landscape, their source of water; these develop in sloping valleys or hollows. A layer of peat fills the deepest part of the valley, a stream may run through the surface of the bog. Valley bogs may develop in dry and warm climates, but because they rely on ground or surface water, they only occur on acidic substrates; these develop over either non-acidic or acidic substrates. Over centuries there is a progression from open lake, to a marsh, to a fen, to a carr, as silt or peat accumulates within the lake. Peat builds up to a level where the land surface is too flat for ground or surface water to reach the center of the wetland; this part, becomes wholly rain-fed, the resulting acidic conditions allow the development of bog. The bog continues to form peat, over time a shallow dome of bog peat develops into a raised bog; the dome is a few meters high in the center and is surrounded by strips of fen or other wetland vegetation at the edges or along streamsides where groundwater can percolate into the wetland.
The various types of raised bog may be divided into: Coastal bog Plateau bog Upland bog Kermi bog String bog Palsa bog Polygonal bog In cool climates with high rainfall, the ground surface may remain waterlogged for much of the time, providing conditions for the development of bog vegetation. In these circumstances, bog develops as a layer "blanketing" much of the land, including hilltops and slopes. Although a blanket bog is more common on acidic substrates, under some conditions it may develop on neutral or alkaline ones, if abundant acidic rainwater predominates over the groundwater. A blanket bog cannot occur in drier or warmer climates, because under those conditions hilltops and sloping ground dry out