Limestone
Limestone is a carbonate sedimentary rock, composed of the skeletal fragments of marine organisms such as coral and molluscs. Its major materials are the minerals calcite and aragonite, which are different crystal forms of calcium carbonate. A related rock is dolostone, which contains a high percentage of the mineral dolomite, CaMg2. In fact, in old USGS publications, dolostone was referred to as magnesian limestone, a term now reserved for magnesium-deficient dolostones or magnesium-rich limestones. About 10% of sedimentary rocks are limestones; the solubility of limestone in water and weak acid solutions leads to karst landscapes, in which water erodes the limestone over thousands to millions of years. Most cave systems are through limestone bedrock. Limestone has numerous uses: as a building material, an essential component of concrete, as aggregate for the base of roads, as white pigment or filler in products such as toothpaste or paints, as a chemical feedstock for the production of lime, as a soil conditioner, or as a popular decorative addition to rock gardens.
Like most other sedimentary rocks, most limestone is composed of grains. Most grains in limestone are skeletal fragments of marine organisms such as foraminifera; these organisms secrete shells made of aragonite or calcite, leave these shells behind when they die. Other carbonate grains composing limestones are ooids, peloids and extraclasts. Limestone contains variable amounts of silica in the form of chert or siliceous skeletal fragment, varying amounts of clay and sand carried in by rivers; some limestones do not consist of grains, are formed by the chemical precipitation of calcite or aragonite, i.e. travertine. Secondary calcite may be deposited by supersaturated meteoric waters; this produces speleothems, such as stalactites. Another form taken by calcite is oolitic limestone, which can be recognized by its granular appearance; the primary source of the calcite in limestone is most marine organisms. Some of these organisms can construct mounds of rock building upon past generations. Below about 3,000 meters, water pressure and temperature conditions cause the dissolution of calcite to increase nonlinearly, so limestone does not form in deeper waters.
Limestones may form in lacustrine and evaporite depositional environments. Calcite can be dissolved or precipitated by groundwater, depending on several factors, including the water temperature, pH, dissolved ion concentrations. Calcite exhibits an unusual characteristic called retrograde solubility, in which it becomes less soluble in water as the temperature increases. Impurities will cause limestones to exhibit different colors with weathered surfaces. Limestone may be crystalline, granular, or massive, depending on the method of formation. Crystals of calcite, dolomite or barite may line small cavities in the rock; when conditions are right for precipitation, calcite forms mineral coatings that cement the existing rock grains together, or it can fill fractures. Travertine is a banded, compact variety of limestone formed along streams where there are waterfalls and around hot or cold springs. Calcium carbonate is deposited where evaporation of the water leaves a solution supersaturated with the chemical constituents of calcite.
Tufa, a porous or cellular variety of travertine, is found near waterfalls. Coquina is a poorly consolidated limestone composed of pieces of coral or shells. During regional metamorphism that occurs during the mountain building process, limestone recrystallizes into marble. Limestone is a parent material of Mollisol soil group. Two major classification schemes, the Folk and the Dunham, are used for identifying the types of carbonate rocks collectively known as limestone. Robert L. Folk developed a classification system that places primary emphasis on the detailed composition of grains and interstitial material in carbonate rocks. Based on composition, there are three main components: allochems and cement; the Folk system uses two-part names. It is helpful to have a petrographic microscope when using the Folk scheme, because it is easier to determine the components present in each sample; the Dunham scheme focuses on depositional textures. Each name is based upon the texture of the grains. Robert J. Dunham published his system for limestone in 1962.
Dunham divides the rocks into four main groups based on relative proportions of coarser clastic particles. Dunham names are for rock families, his efforts deal with the question of whether or not the grains were in mutual contact, therefore self-supporting, or whether the rock is characterized by the presence of frame builders and algal mats. Unlike the Folk scheme, Dunham deals with the original porosity of the rock; the Dunham scheme is more useful for hand samples because it is based on texture, not the grains in the sample. A revised classification was proposed by Wright, it adds some diagenetic patterns and can be summarized as follows: See: Carbonate platform About 10% of all sedimentary rocks are limestones. Limestone is soluble in acid, therefore forms many erosional landforms; these include limestone pavements, pot holes, cenotes and gorges. Such erosion landscapes are known
Mediterranean climate
A Mediterranean climate or dry summer climate is characterized by rainy winters and dry summers, with less than 40 mm of precipitation for at least three summer months. While the climate receives its name from the Mediterranean Basin, these are located on the western coasts of continents, between 30 and 45 degrees north and south of the equator between oceanic climates towards the poles, semi-arid and arid climates towards the equator. In essence, due to the seasonal shift of the subtropical high-pressure belts with the apparent movement of the Sun, a Mediterranean climate is an intermediate type between these other climates, with winters warmer and drier than oceanic climates and summers imitating sunny weather in semi-arid and arid climates; the resulting vegetation of Mediterranean climates are the garrigue or maquis in the Mediterranean Basin, the chaparral in California, the fynbos in South Africa, the mallee in Australia, the matorral in Chile. Areas with this climate are where the so-called "Mediterranean trinity" of agricultural products have traditionally developed: wheat and olive.
Most large, historic cities of the Mediterranean basin lie within Mediterranean climatic zones, including Algiers, Beirut, İzmir, Marseille, Rome and Valencia. Examples of major cities with Mediterranean climates that lie outside of the historic Mediterranean basin include major examples as Adelaide, Cape Town, Dushanbe, Los Angeles, Perth, San Francisco and Victoria. Under the Köppen climate classification, "hot dry-summer" climates and "cool dry-summer" climates are referred to as "Mediterranean". Under the Köppen climate system, the first letter indicates the climate group. Temperate climates or "C" zones have an average temperature above 0 °C, but below 18 °C, in their coolest months; the second letter indicates the precipitation pattern. Köppen has defined a dry summer month as a month with less than 30 mm of precipitation and with less than one-third that of the wettest winter month. Some, use a 40 mm level; the third letter indicates the degree of summer heat: "a" represents an average temperature in the warmest month above 22 °C, while "b" indicates the average temperature in the warmest month below 22 °C.
Under the Köppen classification, dry-summer climates occur on the western sides of continents. Csb zones in the Köppen system include areas not associated with Mediterranean climates but with Oceanic climates, such as much of the Pacific Northwest, much of southern Chile, parts of west-central Argentina, parts of New Zealand. Additional highland areas in the subtropics meet Cs requirements, though they, are not associated with Mediterranean climates, as do a number of oceanic islands such as Madeira, the Juan Fernández Islands, the western part of the Canary Islands, the eastern part of the Azores. Under Trewartha's modified Köppen climate classification, the two major requirements for a Cs climate are revised. Under Trewartha's system, at least eight months must have average temperatures of 10 °C or higher, the average annual precipitation must not exceed 900 mm. Thus, under this system, many Csb zones in the Köppen system become Do, the rare Csc zones become Eo, with only the classic dry-summer to warm winter, low annual rainfall locations included in the Mediterranean type climate.
During summer, regions of Mediterranean climate are influenced by cold ocean currents which keep the weather in the region dry and pleasant. Similar to desert climates, in many Mediterranean climates there is a strong diurnal character to daily temperatures in the warm summer months due to strong heating during the day from sunlight and rapid cooling at night. In winter, Mediterranean climate zones are no longer influenced by the cold ocean currents and therefore warmer water settles near land and causes clouds to form and rainfall becomes much more likely; as a result, areas with this climate receive all of their precipitation during their winter and spring seasons, may go anywhere from 3 to 6 months during the summer without having any significant precipitation. In the lower latitudes, precipitation decreases in both the winter and summer because they are closer to the Horse latitudes, thus bringing smaller amounts of rain. Toward the polar latitudes, total moisture increases; the rainfall tends to be more evenly distributed throughout the year in Southern Europe, while in the Eastern Mediterranean and in Southern California the summer is nearly or dry.
In places where evapotranspiration is higher, steppe climates tend to prevail, but still follow the weather pattern of the Mediterranean climate. The majority of the regions with Mediterranean climates have mild winters and warm summers; however winter and summer temperatures can vary between different regions with a Mediterranean climate. For instance, in the case of winters and Los Angeles experience mild temperatures in the winter, with frost and snowfall unknown, whereas Tashkent has colder winters with annual frosts and snowfall. Or to consider summer, Athens experiences rather high temperatures in that season. In contrast, San Francisco has cool summers with daily highs around 21 °C due to
Karst
Karst is a topography formed from the dissolution of soluble rocks such as limestone and gypsum. It is characterized by underground drainage systems with caves, it has been documented for more weathering-resistant rocks, such as quartzite, given the right conditions. Subterranean drainage may limit surface water, with few to no lakes. However, in regions where the dissolved bedrock is covered or confined by one or more superimposed non-soluble rock strata, distinctive karst features may occur only at subsurface levels and be missing above ground; the study of karst is considered of prime importance in petroleum geology because as much as 50% of the world's hydrocarbon reserves are hosted in porous karst systems. The English word karst was borrowed from German Karst in the late 19th century, which entered German much earlier. According to one interpretation the term is derived from the German name for a number of geological and hydrological features found within the range of the Dinaric Alps, stretching from the northeastern corner of Italy above the city of Trieste, across the Balkan peninsula along the coast of the eastern Adriatic to Kosovo and North Macedonia, where the massif of the Šar Mountains begins, more the karst zone at the northwestern-most section, described in early topographical research as a plateau, between Italy and Slovenia.
In the local South Slavic languages, all variations of the word are derived from a Romanized Illyrian base metathesized from the reconstructed form *korsъ into forms such as Bosnian: krš, Croatian: krš, kraš, Serbian: kras, Slovene: kras. Languages preserving the older, non-metathesized form include Italian: Carso, German: Karst, Albanian: karsti; the Slovene common noun kras was first attested in the 18th century, the adjective form kraški in the 16th century. As a proper noun, the Slovene form Grast was first attested in 1177; the word is of Mediterranean origin. It has been suggested that the word may derive from the Proto-Indo-European root karra-'rock'; the name may be connected to the oronym Karsádios oros cited by Ptolemy, also to Latin Carusardius. Johann Weikhard von Valvasor, a pioneer of the study of karst in Slovenia and a fellow of the Royal Society for Improving Natural Knowledge, introduced the word karst to European scholars in 1689, describing the phenomenon of underground flows of rivers in his account of Lake Cerknica.
Jovan Cvijić advanced the knowledge of karst regions, so much that he became known as the "father of karst geomorphology". Discussing the karstic regions of the Balkans, Cvijić's 1893 publication Das Karstphänomen describes landforms such as karren and poljes. In a 1918 publication, Cvijić proposed a cyclical model for karstic landscape development. Karst hydrology emerged as a discipline in early 1960s in France; the activities of cave explorers, called speleologists, had been dismissed as more of a sport than a science, meaning that underground karstic caves and their associated watercourses were, from a scientific perspective, understudied. The development of karst occurs whenever acidic water starts to break down the surface of bedrock near its cracks, or bedding planes; as the bedrock continues to degrade, its cracks tend to get bigger. As time goes on, these fractures will become wider, a drainage system of some sort may start to form underneath. If this underground drainage system does form, it will speed up the development of karst formations there because more water will be able to flow through the region, giving it more erosive power.
The carbonic acid that causes karstic features is formed as rain passes through Earth's atmosphere picking up carbon dioxide, which dissolves in the water. Once the rain reaches the ground, it may pass through soil that can provide much more CO2 to form a weak carbonic acid solution, which dissolves calcium carbonate; the primary reaction sequence in limestone dissolution is the following: In particular and rare conditions such as encountered in the past in Lechuguilla Cave in New Mexico, other mechanisms may play a role. The oxidation of sulfides leading to the formation of sulfuric acid can be one of the corrosion factors in karst formation; as oxygen -rich surface waters seep into deep anoxic karst systems, they bring oxygen, which reacts with sulfide present in the system to form sulfuric acid. Sulfuric acid reacts with calcium carbonate, causing increased erosion within the limestone formation; this chain of reactions is: This reaction chain forms gypsum. The karstification of a landscape may result in a variety of large- or small-scale features both on the surface and beneath.
On exposed surfaces, small features may include solution flutes, limestone pavement, collectively called karren or lapiez. Medium-sized surface features may include sinkholes or cenotes, vertical shafts, disappearing streams, reappearing springs. Large-scale features may include limestone pavements and karst valleys. Mature karst landscapes, where more bedrock has been removed than remains, may result in karst towers, or haystack/eggbox landscapes. Beneath the surface, complex underground drainage systems and extensive caves and cavern systems may form. Erosion along limes
Carboniferous
The Carboniferous is a geologic period and system that spans 60 million years from the end of the Devonian Period 358.9 million years ago, to the beginning of the Permian Period, 298.9 Mya. The name Carboniferous means "coal-bearing" and derives from the Latin words carbō and ferō, was coined by geologists William Conybeare and William Phillips in 1822. Based on a study of the British rock succession, it was the first of the modern'system' names to be employed, reflects the fact that many coal beds were formed globally during that time; the Carboniferous is treated in North America as two geological periods, the earlier Mississippian and the Pennsylvanian. Terrestrial animal life was well established by the Carboniferous period. Amphibians were the dominant land vertebrates, of which one branch would evolve into amniotes, the first terrestrial vertebrates. Arthropods were very common, many were much larger than those of today. Vast swaths of forest covered the land, which would be laid down and become the coal beds characteristic of the Carboniferous stratigraphy evident today.
The atmospheric content of oxygen reached its highest levels in geological history during the period, 35% compared with 21% today, allowing terrestrial invertebrates to evolve to great size. The half of the period experienced glaciations, low sea level, mountain building as the continents collided to form Pangaea. A minor marine and terrestrial extinction event, the Carboniferous rainforest collapse, occurred at the end of the period, caused by climate change. In the United States the Carboniferous is broken into Mississippian and Pennsylvanian subperiods; the Mississippian is about twice as long as the Pennsylvanian, but due to the large thickness of coal-bearing deposits with Pennsylvanian ages in Europe and North America, the two subperiods were long thought to have been more or less equal in duration. In Europe the Lower Carboniferous sub-system is known as the Dinantian, comprising the Tournaisian and Visean Series, dated at 362.5-332.9 Ma, the Upper Carboniferous sub-system is known as the Silesian, comprising the Namurian and Stephanian Series, dated at 332.9-298.9 Ma.
The Silesian is contemporaneous with the late Mississippian Serpukhovian plus the Pennsylvanian. In Britain the Dinantian is traditionally known as the Carboniferous Limestone, the Namurian as the Millstone Grit, the Westphalian as the Coal Measures and Pennant Sandstone; the International Commission on Stratigraphy faunal stages from youngest to oldest, together with some of their regional subdivisions, are: A global drop in sea level at the end of the Devonian reversed early in the Carboniferous. There was a drop in south polar temperatures; these conditions had little effect in the deep tropics, where lush swamps to become coal, flourished to within 30 degrees of the northernmost glaciers. Mid-Carboniferous, a drop in sea level precipitated a major marine extinction, one that hit crinoids and ammonites hard; this sea level drop and the associated unconformity in North America separate the Mississippian subperiod from the Pennsylvanian subperiod. This happened about 323 million years ago, at the onset of the Permo-Carboniferous Glaciation.
The Carboniferous was a time of active mountain-building as the supercontinent Pangaea came together. The southern continents remained tied together in the supercontinent Gondwana, which collided with North America–Europe along the present line of eastern North America; this continental collision resulted in the Hercynian orogeny in Europe, the Alleghenian orogeny in North America. In the same time frame, much of present eastern Eurasian plate welded itself to Europe along the line of the Ural Mountains. Most of the Mesozoic supercontinent of Pangea was now assembled, although North China, South China continents were still separated from Laurasia; the Late Carboniferous Pangaea was shaped like an "O." There were two major oceans in the Carboniferous—Panthalassa and Paleo-Tethys, inside the "O" in the Carboniferous Pangaea. Other minor oceans were shrinking and closed - Rheic Ocean, the small, shallow Ural Ocean and Proto-Tethys Ocean. Average global temperatures in the Early Carboniferous Period were high: 20 °C.
However, cooling during the Middle Carboniferous reduced average global temperatures to about 12 °C. Lack of growth rings of fossilized trees suggest a lack of seasons of a tropical climate. Glaciations in Gondwana, triggered by Gondwana's southward movement, continued into the Permian and because of the lack of clear markers and breaks, the deposits of this glacial period are referred to as Permo-Carboniferous in age; the cooling and drying of the climate led to the Carboniferous Rainforest Collapse during the late Carboniferous. Tropical rainforests fragmented and were devastated by climate change. Carboniferous rocks in Europe and eastern North America consist of a repeated sequence of limestone, sandstone and coal beds. In North America, the early Carboniferous is marine
Cantabria
Cantabria is an autonomous community in northern Spain with Santander as its capital city. It is recognized as a historic community and is bordered on the east by the Basque Autonomous Community, on the south by Castile and León, on the west by the Principality of Asturias, on the north by the Cantabrian Sea. Cantabria belongs to Green Spain, the name given to the strip of land between the Bay of Biscay and the Cantabrian Mountains, so called because of its lush vegetation, due to the wet and moderate oceanic climate; the climate is influenced by Atlantic Ocean winds trapped by the mountains. The most significant site for cave paintings is that in the cave of Altamira, dating from about 37,000 BC and declared, along with nine other Cantabrian caves, as World Heritage Sites by UNESCO; the modern Province of Cantabria was constituted on 28 July 1778 at Reocín. The Organic Law of the Autonomy Statute of Cantabria was approved on 30 December 1981, giving the region its own institutions of self-government.
Numerous authors, including Isidore of Seville, Julio Caro Baroja, Aureliano Fernández Guerra and Adolf Schulten, have explored the etymology of the name Cantabria, yet its origins remain uncertain. It is claimed that the root cant- comes from Celtic for "rock" or "stone", while -abr was a common suffix used in Celtic regions. Thus, Cantabrian could mean "people who live in the rocks" or "highlanders", a reference to the steep and mountainous territory of Cantabria; the name Cantabria could be related to the Celtic root "kant" or "cant" meaning edge or rim thus "coastal district," or "corner-land", "land on the edge" thus having the same probable derivation as the name of the English county of Kent. Cantabria is coastal region, with important natural resources, it has two distinct areas: Coast. A coastal strip of low and rolling valleys some 10 kilometres in width, the altitude of which does not rise above 500 metres, which meets the ocean in a line of abrupt cliffs broken by river estuaries, forming rias and beaches.
Santander Bay is the most prominent indentation in the coastline. To the south, the coastal strip rises to meet the mountains. Mountains; this is a long barrier made up of abruptly rising mountains parallel to the sea, which are part of the Cantabrian Mountains. The mountains are made of limestone with karst topography, occupy most of Cantabria's area, they form deep valleys running north-south. The torrential rivers are fast flowing and of great eroding power, so the slopes are steep; the valleys define different natural regions, delimited physically by the intervening mountain ranges: Liébana, Saja-Nansa, Pas-Pisueña, Miera, Asón-Gándara, Campoo. To the'mountain' region belongs the Escudo Range, a mountain range of 600 to 1,000 metres high that covers 15 or 20 km in a parallel line to the coast in the West part of Cantabria. Towards the south are higher mountains, the tops of which form the watershed between the drainage basins of the Rivers Ebro and the rivers that flow into the Bay of Biscay.
These peaks exceed 1,500 m from the Pass of San Glorio in the west to the Pass of Los Tornos in the eastern part: Peña Labra, Castro Valnera and the mountain passes of Sejos, El Escudo and La Sía. The great limestone masses of Picos de Europa stand out in the southwest of the region: most of their summits exceed 2,500 m, their topography is shaped by the former presence of glaciers. Due to the gulf stream, Cantabria, as well as the rest of "Green Spain", has a much more temperate climate than might be expected for its latitude, comparable to that of Oregon; the region has a humid oceanic climate, with mild winters. Annual precipitation is higher in the mountains; the mean temperature is about 14 °C. Snow is frequent in higher zones of Cantabria between the months of March; some zones of Picos de Europa, over 2,500 metres high, have an alpine climate with snow persisting year round. The driest months are August; the mountainous relief of Cantabria has a dominant effect on local microclimate in Cantabria.
It is the main cause of the peculiar meteorologic situations like the so-called "suradas", due to the foehn effect: the southerly wind coming down from the mountains blows and dry, increasing the temperature closer to the coast. This causes a decrease in air humidity and rainfall; these conditions are more frequent in autumn and winter, the temperatures are higher than 20 °C. Fires are helped by this type of wind: one example is the fire that destroyed part of the city of Santander in the winter of 1941. In these specific cases in the southern part of the mountain range the dry adiabatic gradient produces different conditions to the rest of the region: the wind there is fresher and more humid, there is more rain; the rivers of Cantabria are short and rapid, descending steeply because the sea is so close to their source in the Cantabrian Mountains. They flow perpendicular except for the Ebro, they generally flow year round due to constant rainfall. The rate of flow is modest compared to the other rivers of the Iberian peninsula.
The rapidness of their waters, caused by their steep descents, gives them great erosive power, creating the narrow V-shaped valleys characteristic of Green Spain. Th
Oceanic climate
An oceanic climate known as a marine climate or maritime climate, is the Köppen classification of climate typical of west coasts in higher middle latitudes of continents, features mild summers and mild winters, with a narrow annual temperature range and few extremes of temperature, with the exception for transitional areas to continental and highland climates. Oceanic climates are defined as having a monthly mean temperature below 22 °C in the warmest month, above 0 °C in the coldest month, it lacks a dry season, as precipitation is more evenly dispersed throughout the year. It is the predominant climate type across much of Western Europe including the United Kingdom, the Pacific Northwest region of the United States and Canada, portions of central Mexico, southwestern South America, southeastern Australia including Tasmania, New Zealand, as well as isolated locations elsewhere. Oceanic climates are characterised by a narrower annual range of temperatures than in other places at a comparable latitude, do not have the dry summers of Mediterranean climates or the hot summers of humid subtropical.
Oceanic climates are most dominant in Europe, where they spread much farther inland than in other continents. Oceanic climates can have considerable storm activity as they are located in the belt of the stormy westerlies. Many oceanic climates have frequent cloudy or overcast conditions due to the near constant storms and lows tracking over or near them; the annual range of temperatures is smaller than typical climates at these latitudes due to the constant stable marine air masses that pass through oceanic climates, which lack both warm and cool fronts. Locations with oceanic climates tend to feature cloudy conditions with precipitation, though it can experience clear, sunny days. London is an example of an oceanic climate, it experiences constant precipitation throughout the entire year. Despite this, thunderstorms are quite rare since hot and cold air masses meet infrequently in the region. In most areas with an oceanic climate, precipitation comes in the form of rain for the majority of the year.
However, some areas with this climate see some snowfall annually during winter. Most oceanic climate zones, or at least a part of them, experience at least one snowfall per year. In the poleward locations of the oceanic climate zone, snowfall is more commonplace. Overall temperature characteristics of the oceanic climates feature cool temperatures and infrequent extremes of temperature. In the Köppen climate classification, Oceanic climates have a mean temperature of 0 °C or higher in the coldest month, compared to continental climates where the coldest month has a mean temperature of below 0 °C. Summers are cool, with the warmest month having a mean temperature below 22 °C. Poleward of the latter is a zone of the aforementioned subpolar oceanic climate, with long but mild winters and cool and short summers. Examples of this climate include parts of coastal Iceland, Norway, the Scottish Highlands, the mountains of Vancouver Island, Haida Gwaii in Canada, in the Northern Hemisphere and extreme southern Chile and Argentina in the Southern Hemisphere, the Tasmanian Central Highlands, parts of New Zealand.
Oceanic climates are not always found in coastal locations on the aforementioned parallels. The polar jet stream, which moves in a west to east direction across the middle latitudes, advances low pressure systems and fronts. In coastal areas of the higher middle latitudes, the prevailing onshore flow creates the basic structure of most oceanic climates. Oceanic climates are a reflection of the ocean adjacent to them. In the fall and early spring, when the polar jet stream is most active, the frequent passing of marine weather systems creates the frequent fog, cloudy skies, light drizzle associated with oceanic climates. In summer, high pressure pushes the prevailing westerlies north of many oceanic climates creating a drier summer climate; the North Atlantic Gulf Stream, a tropical oceanic current that passes north of the Caribbean and up the East Coast of the United States to North Carolina heads east-northeast to the Azores, is thought to modify the climate of Northwest Europe. As a result of the Gulf Stream, west-coast areas located in high latitudes like Ireland, the UK, Norway have much milder winters than would otherwise be the case.
The lowland attributes of western Europe help drive marine air masses into continental areas, enabling cities such as Dresden and Vienna to have maritime climates in spite of being located well inland from the ocean. Oceanic climates in Europe occur in Northwest Europe, from Ireland and Great Britain eastward to central Europe. Most of France, the Netherlands, Germany, the north coast of Spain, the western Azores off the coast of Portugal, the south of Kosovo and southern portions of Sweden have oceanic climates. Examples of oceanic climates are found in Glasgow, Bergen, Dublin, Bilbao, Donostia-San Sebastian, Bayonne, Züri
Fagus sylvatica
Fagus sylvatica, the European beech or common beech, is a deciduous tree belonging to the beech family Fagaceae. Fagus sylvatica is a large tree, capable of reaching heights of up to 50 m tall and 3 m trunk diameter, though more 25–35 m tall and up to 1.5 m trunk diameter. A 10-year-old sapling will stand about 4 m tall, it has a typical lifespan of 150–200 years, though sometimes up to 300 years. In cultivated forest stands trees are harvested at 80–120 years of age. 30 years are needed to attain full maturity. Like most trees, its form depends on the location: in forest areas, F. sylvatica grows to over 30 m, with branches being high up on the trunk. In open locations, it will become more massive; the leaves are alternate and entire or with a crenate margin, 5–10 cm long and 3–7 cm broad, with 6–7 veins on each side of the leaf. When crenate, there is one point at each vein tip, never any points between the veins; the buds are long and slender, 15–30 mm long and 2–3 mm thick, but thicker where the buds include flower buds.
The leaves of beech are not abscissed in the autumn and instead remain on the tree until the spring. This process is called marcescence; this occurs when trees are saplings or when plants are clipped as a hedge, but it often continues to occur on the lower branches when the tree is mature. Small quantities of seeds may be produced around 10 years of age, but not a heavy crop until the tree is at least 30 years old. F. sylvatica male flowers are borne in the small catkins. The female flowers produce beechnuts, small triangular nuts 15–20 millimetres long and 7–10 mm wide at the base. Flower and seed production is abundant in years following a hot and dry summer, though for two years in a row; the natural range extends from southern Sweden to northern Sicily, west to France, southern England, northern Portugal, central Spain, east to northwest Turkey, where it intergrades with the oriental beech, which replaces it further east. In the Balkans, it shows some hybridisation with oriental beech. In the southern part of its range around the Mediterranean, it grows only in mountain forests, at 600–1,800 m altitude.
Although regarded as native in southern England, recent evidence suggests that F. sylvatica did not arrive in England until about 4000 BC, or 2,000 years after the English Channel formed after the ice ages. The beech is classified as a native in the south of England and as a non-native in the north where it is removed from'native' woods. Localised pollen records have been recorded in the North of England from the Iron Age by Sir Harry Godwin. Changing climatic conditions may put beech populations in southern England under increased stress and while it may not be possible to maintain the current levels of beech in some sites it is thought that conditions for beech in north-west England will remain favourable or improve, it is planted in Britain. The nature of Norwegian beech populations is subject to debate. If native, they would represent the northern range of the species. However, molecular genetic analyses support the hypothesis that these populations represent intentional introduction from Denmark before and during the Viking Age.
However, the beech in Vestfold and at Seim north of Bergen in Norway is now spreading and regarded as native. Though not demanding of its soil type, the European beech has several significant requirements: a humid atmosphere and well-drained soil, it prefers moderately fertile ground, calcified or acidic, therefore it is found more on the side of a hill than at the bottom of a clayey basin. It is sensitive to spring frost. In Norway's oceanic climate planted trees grow well as far north as Trondheim. In Sweden, beech trees do not grow as far north as in Norway. A beech forest is dark and few species of plant are able to survive there, where the sun reaches the ground. Young beeches may grow poorly in full sunlight. In a clear-cut forest a European beech will germinate and die of excessive dryness. Under oaks with sparse leaf cover it will surpass them in height and, due to the beech's dense foliage, the oaks will die from lack of sunlight; the root system is shallow superficial, with large roots spreading out in all directions.
European beech forms ectomycorrhizas with a range of fungi including members of the genera Amanita, Cantharellus, Hebeloma and with the species Ramaria flavosaponaria. In the woodlands of southern Britain, beech is dominant over oak and elm south of a line from about north Suffolk across to Cardigan. Oak are the dominant forest trees north of this line. One of the most beautiful European beech forests called Sonian Forest is found in the southeast of Brussels, Belgium. Beech is a dominant tree species in France and constitutes about 10% of French fore
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