Geology (from Ancient Greek γῆ ( gê ) 'earth' and λoγία ( -logía ) 'study of, discourse') is a branch of natural science concerned with the Earth and other astronomical objects , the rocks of which they are composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth sciences , including hydrology . It is integrated with Earth system science and planetary science .
113-465: Peña Cebollera , Cebollera Vieja or pico de las Tres provincias is a mountain which is part of Sierra de Ayllón mountain range in Sistema Central system of mountain ranges. A tripoint related to the autonomous communities of Madrid , Castilla–La Mancha and Castile and León is located on this elevation. The height of this landform is 2,129 metres. This Spain location article
226-535: A characteristic fabric . All three types may melt again, and when this happens, new magma is formed, from which an igneous rock may once again solidify. Organic matter, such as coal, bitumen, oil, and natural gas, is linked mainly to organic-rich sedimentary rocks. To study all three types of rock, geologists evaluate the minerals of which they are composed and their other physical properties, such as texture and fabric . Geologists also study unlithified materials (referred to as superficial deposits ) that lie above
339-570: A natural area protected within the Natura 2000 network as a Site of Community Importance and Special Protection Area for Birds , located in the northwest of the province of Guadalajara in the autonomous community of Castilla-La Mancha . The natural area of Ayllón occupies the Paleozoic massif of the Sierra de Ayllón, in the province of Guadalajara , including the main core whose highest peak
452-485: A petrographic microscope , where the minerals can be identified through their different properties in plane-polarized and cross-polarized light, including their birefringence , pleochroism , twinning , and interference properties with a conoscopic lens . In the electron microprobe, individual locations are analyzed for their exact chemical compositions and variation in composition within individual crystals. Stable and radioactive isotope studies provide insight into
565-433: A greater extension of oak and beech forests, while the southern slopes are mostly covered with holm oak forests. At the same time, during the second half of the 20th century, numerous reforestations have been carried out, more or less successful in the landscape, with Scotch pines and bog pines . Therefore, oak , beech, birch , pine and, to a lesser extent, holm oak and arar , are the most frequently found trees in
678-437: A land of Royal manor forming its own jurisdiction. Under this seignorial organization would remain the political organization of the area, with its perceptible variables that occur over time, until the abolition of the lordships in the 19th century in favor of the provincialist vision that began to impose itself. Meanwhile, life in the mountains of Ayllón followed the same course as in ancient times. The peace of these lands
791-481: A large number of fungi in the pine forests, with the milk-caps standing out above all others. The holm oak groves occupy the sunny areas of the valleys, highlighting the examples of Tamajón , Valverde and Umbralejo. Also noteworthy is the isolated presence of a juniper in Tamajón , which occupies both Cretaceous dolomites and silurian slates , a very singular fact given the ecology of Juniperus thurifera . On
904-627: A length of less than a meter. Rocks at the depth to be ductilely stretched are often also metamorphosed. These stretched rocks can also pinch into lenses, known as boudins , after the French word for "sausage" because of their visual similarity. Where rock units slide past one another, strike-slip faults develop in shallow regions, and become shear zones at deeper depths where the rocks deform ductilely. The addition of new rock units, both depositionally and intrusively, often occurs during deformation. Faulting and other deformational processes result in
1017-591: A long journey. They are exceptions. The rest of the fluvial currents pour their waters into these two main rivers. Although it does not begin to take shape until it joins the rivers Caslilla and de la Hoz at Sepúlveda, the Duratón river , which rises on the southern slopes on the Madrid side of the Cebollera Vieja , receives water on its right bank from small streams that originate in the Sierra de Ayllón. From
1130-452: A means to provide information about geological history and the timing of geological events. The principle of uniformitarianism states that the geological processes observed in operation that modify the Earth's crust at present have worked in much the same way over geological time. A fundamental principle of geology advanced by the 18th-century Scottish physician and geologist James Hutton
1243-608: A number of fields, laboratory, and numerical modeling methods to decipher Earth history and to understand the processes that occur on and inside the Earth. In typical geological investigations, geologists use primary information related to petrology (the study of rocks), stratigraphy (the study of sedimentary layers), and structural geology (the study of positions of rock units and their deformation). In many cases, geologists also study modern soils, rivers , landscapes , and glaciers ; investigate past and current life and biogeochemical pathways, and use geophysical methods to investigate
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#17327726254491356-499: A single environment and do not necessarily occur in a single order. The Hawaiian Islands , for example, consist almost entirely of layered basaltic lava flows. The sedimentary sequences of the mid-continental United States and the Grand Canyon in the southwestern United States contain almost-undeformed stacks of sedimentary rocks that have remained in place since Cambrian time. Other areas are much more geologically complex. In
1469-496: A valley where Majaelrayo , Robleluengo, Campillo , El Espinar and Roblelacasa are located. The Sorbe River is the natural boundary between the Sierra de Ayllón, on its right bank, and the Sierra de Alto Rey, on its left bank. It is the result of the union of two minor rivers in the area known as Junta de los ríos , between ravines on the slopes of Alto de las Cabras and Peña del Osar, on the Alto Rey side, and Peña de Pinarejo, on
1582-400: A variety of applications. Dating of lava and volcanic ash layers found within a stratigraphic sequence can provide absolute age data for sedimentary rock units that do not contain radioactive isotopes and calibrate relative dating techniques. These methods can also be used to determine ages of pluton emplacement. Thermochemical techniques can be used to determine temperature profiles within
1695-579: A very broken relief, with steep slopes and a complicated and dense hydrographic system . It borders to the west with the Sierra de Somosierra and the Sierra del Rincón, to the east with the Sierra de Pela and Alto Rey mountain, to the north with the Meseta Norte and to the south with the Campiña de Guadalajara. From its mountains rise the Jarama and Sorbe rivers, as well as other minor rivers such as
1808-551: Is a stub . You can help Misplaced Pages by expanding it . Sierra de Ayll%C3%B3n The Sierra de Ayllón (Ayllón mountain chain) or Macizo de Ayllón (Ayllón massif) is a mountain chain of the Iberian Peninsula , belonging to the Sistema Central , of which it constitutes one of its easternmost spurs . It is located between the Spanish provinces of Guadalajara , Segovia and Madrid . The mountain chain consists of
1921-417: Is a good example. The extension of pine in the area corresponds mainly to reforestation policies in the second half of the 20th century due to its rapid growth, the high value of its wood and its great geological amplitude. There are three types of pine trees that repopulate the mountain chain: Scotch pine mainly, and then bog pine and Austrian pine . The autumn humidity also favors the proliferation of
2034-655: Is a major academic discipline , and it is central to geological engineering and plays an important role in geotechnical engineering . The majority of geological data comes from research on solid Earth materials. Meteorites and other extraterrestrial natural materials are also studied by geological methods. Minerals are naturally occurring elements and compounds with a definite homogeneous chemical composition and an ordered atomic arrangement. Each mineral has distinct physical properties, and there are many tests to determine each of them. Minerals are often identified through these tests. The specimens can be tested for: A rock
2147-422: Is accomplished in two primary ways: through faulting and folding . In the shallow crust, where brittle deformation can occur, thrust faults form, which causes the deeper rock to move on top of the shallower rock. Because deeper rock is often older, as noted by the principle of superposition , this can result in older rocks moving on top of younger ones. Movement along faults can result in folding, either because
2260-556: Is an igneous rock . This rock can be weathered and eroded , then redeposited and lithified into a sedimentary rock. Sedimentary rocks are mainly divided into four categories: sandstone, shale, carbonate, and evaporite. This group of classifications focuses partly on the size of sedimentary particles (sandstone and shale), and partly on mineralogy and formation processes (carbonation and evaporation). Igneous and sedimentary rocks can then be turned into metamorphic rocks by heat and pressure that change its mineral content, resulting in
2373-460: Is an intimate coupling between the movement of the plates on the surface and the convection of the mantle (that is, the heat transfer caused by the slow movement of ductile mantle rock). Thus, oceanic parts of plates and the adjoining mantle convection currents always move in the same direction – because the oceanic lithosphere is actually the rigid upper thermal boundary layer of the convecting mantle. This coupling between rigid plates moving on
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#17327726254492486-469: Is any naturally occurring solid mass or aggregate of minerals or mineraloids . Most research in geology is associated with the study of rocks, as they provide the primary record of the majority of the geological history of the Earth. There are three major types of rock: igneous , sedimentary , and metamorphic . The rock cycle illustrates the relationships among them (see diagram). When a rock solidifies or crystallizes from melt ( magma or lava ), it
2599-433: Is horizontal). The principle of superposition states that a sedimentary rock layer in a tectonically undisturbed sequence is younger than the one beneath it and older than the one above it. Logically a younger layer cannot slip beneath a layer previously deposited. This principle allows sedimentary layers to be viewed as a form of the vertical timeline, a partial or complete record of the time elapsed from deposition of
2712-484: Is primarily accomplished through normal faulting and through the ductile stretching and thinning. Normal faults drop rock units that are higher below those that are lower. This typically results in younger units ending up below older units. Stretching of units can result in their thinning. In fact, at one location within the Maria Fold and Thrust Belt , the entire sedimentary sequence of the Grand Canyon appears over
2825-751: Is scrub, due to the effects of human occupation (grazing and firewood cutting). Depending on the ecological conditions, the landscape is dominated by heaths in the more humid and elevated areas and by rockrose in the drier and basal areas. There are many types of vegetation that can be found in the Sierra de Ayllón, although the forests are not very extensive due to the incessant hand of man who for centuries has been obtaining firewood and charcoal and has been opening pastures for livestock, mostly transhumant . Different vegetation can be found established in three bioclimatic levels: one mesomediterranean below 1000m and dominated by holm oak ; another supramediterranean between 1000m and 2000m where oaks and, depending on
2938-568: Is that "the present is the key to the past." In Hutton's words: "the past history of our globe must be explained by what can be seen to be happening now." The principle of intrusive relationships concerns crosscutting intrusions. In geology, when an igneous intrusion cuts across a formation of sedimentary rock , it can be determined that the igneous intrusion is younger than the sedimentary rock. Different types of intrusions include stocks, laccoliths , batholiths , sills and dikes . The principle of cross-cutting relationships pertains to
3051-517: Is the Pico del Lobo (2269 m), and the Sierras de la Concha (1865 m), Pico Ocejón (2048 m) and Alto Rey (1852 m). The Sierra de Ayllón is the eastern end of the Sistema Central , where the bioclimatic level is dominant. Supramediterranean, with notable representations of the oromediterranean level and occasional areas of the cryo-Mediterranean. The massif was raised during the alpine orogeny , having
3164-593: Is the case of Lucanus cervus , Parnassius apollo sp. escalerae, Plebicula nivescens , Ocnogyna tatreillei, Hyphoraia dejeani , Euphydryas aurinia or Nymphalis antiopa , should be highlighted. The Sierra of Ayllón is included in the Carpetano-Ibérico-Leonesa chorological province, in the Guadarrámic sector, forming the Ayllonan subsector with its own chorological identity,
3277-686: Is under the jurisdiction of the Común de Villa y Tierra de Atienza, and later, towards the 14th century, would be included in the newly created County of Galve, in the hands of the Zúñiga and, later, of the Mendoza and the dukes of Alba ; the south of the massif in the districts of Valdepeñas , Tortuero and Valdesotos came under the jurisdiction of the Común de Villa y Tierra de Uceda , controlled since 1249 by Sancho of Castile , archbishop of Toledo and son of king Ferdinand III ; Tamajón would remain as
3390-523: Is used for geologically young materials containing organic carbon . The geology of an area changes through time as rock units are deposited and inserted, and deformational processes alter their shapes and locations. Rock units are first emplaced either by deposition onto the surface or intrusion into the overlying rock . Deposition can occur when sediments settle onto the surface of the Earth and later lithify into sedimentary rock, or when as volcanic material such as volcanic ash or lava flows blanket
3503-640: The Douro Basin , to the north, and the Tagus Basin , to the south. It is the last foothills of the mountain chain which pours water to the northern slope. The rivers and streams pour their waters directly from the mountain to the valley, so they are generally short and not very abundant. Two rivers stand out above the rest, the Duratón river and the Riaza river, both of which flow into the Douro river after
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3616-456: The European otter , with abundant populations. Native fish such as the iberian nase ( Chondrostoma polylepis ), the bermejuela ( Rutilus arcasii ) and the colmilleja ( Cobitis paludica and Cobitis pyrenaicus). Birds such as the kingfisher ( Alcedo atthis ) and mammals such as the desman ( Galemys pyrenaicus ) , which maintains here isolated populations of the main core distribution of
3729-698: The Henares river . Together with the Lillas and the Arroyo de la Dehesa, the Sorbe receives water from the Sierra de Ayllón from three other tributaries with permanent flow, which also follow winding paths and leave deep cuts in their courses. Further north, the Sonsaz river, which gives its name to the extensive hunting reserve that encompasses a large part of the valleys and mountains of the Sierra de Ayllón. It rises under
3842-515: The Silurian period, when mountain ranges are formed throughout western Europe by huge magmatic masses that give rise mainly to granitic rocks , gneisses and slate , and the erosion of seawater that by then occupied a large part of the Iberian Peninsula ; on the other hand, the alpine orogeny from the Cenozoic Era that raised again the mountain ranges of the Sistema Central and when
3955-674: The Visigoths in the 6th century in the Iberian Peninsula , who continued with the feudal structures of the Later Roman Empire , would not affect the way of life or the population settlement in the Sierra de Ayllón, remaining so until the arrival of the Muslims to the Iberian Peninsula in the 8th century. During the first centuries of Muslim rule, the pastoral and livestock practices of the area were maintained until
4068-506: The bedrock . This study is often known as Quaternary geology , after the Quaternary period of geologic history, which is the most recent period of geologic time. Magma is the original unlithified source of all igneous rocks . The active flow of molten rock is closely studied in volcanology , and igneous petrology aims to determine the history of igneous rocks from their original molten source to their final crystallization. In
4181-512: The geochemical evolution of rock units. Petrologists can also use fluid inclusion data and perform high temperature and pressure physical experiments to understand the temperatures and pressures at which different mineral phases appear, and how they change through igneous and metamorphic processes. This research can be extrapolated to the field to understand metamorphic processes and the conditions of crystallization of igneous rocks. This work can also help to explain processes that occur within
4294-414: The low-pressure areas of Atlantic origin bringing with it a greater rainfall on the northern slopes than in the south. This second factor, together with the fact that the northern slopes receive less sunlight and, therefore, maintain a lower temperature, leads to a greater accumulation of snow in winter on the northern slopes than on the southern slopes. The heaviest rainfall occurs in winter, usually in
4407-402: The mantle below (separated within itself by seismic discontinuities at 410 and 660 kilometers), and the outer core and inner core below that. More recently, seismologists have been able to create detailed images of wave speeds inside the earth in the same way a doctor images a body in a CT scan . These images have led to a much more detailed view of the interior of the Earth, and have replaced
4520-427: The massif . The basic lithologys outcrop in certain enclaves to the south of the mountain chain, along a Mesozoic outcrop that borders the mountain chain. In the area where the Jarama river crosses this outcrop there is a well-developed limestone sickle, with isolated basophilic rufic communities, accompanied by a magnificent Portuguese oaks forest with maples ( Cephalanthero rubrae-Quercetum faginae) , which in
4633-434: The relative ages of rocks found at a given location; geochemistry (a branch of geology) determines their absolute ages . By combining various petrological, crystallographic, and paleontological tools, geologists are able to chronicle the geological history of the Earth as a whole. One aspect is to demonstrate the age of the Earth . Geology provides evidence for plate tectonics , the evolutionary history of life , and
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4746-588: The 11th century, when the Christian conquest arrived in the Sistema Central , making the Sierra de Ayllón a frontier between the Christian kingdom of Castile to the north and the Muslim Taifa of Toledo to the south. This fact leads to an increasing instability in the whole Sistema Central which causes the depopulation of the area and the emigration of the population to the Meseta Norte and Meseta Sur of
4859-440: The 1960s, it was discovered that the Earth's lithosphere , which includes the crust and rigid uppermost portion of the upper mantle , is separated into tectonic plates that move across the plastically deforming, solid, upper mantle, which is called the asthenosphere . This theory is supported by several types of observations, including seafloor spreading and the global distribution of mountain terrain and seismicity. There
4972-585: The 3rd or 2nd century B.C. the Romans remained in the area. The crisis of the Empire in the 3rd century provokes that the population of the area is concentrated in the big latifundia villas located in the areas of Riaza , Atienza and Cogolludo in regime of autarchy. However, the settlers of the Macizo de Ayllón, due to the isolation of the area, practically continued with their unchanged life. The settlement of
5085-681: The Arroyo de Vadillo, which after rising in the Pedrosa beech forest under the Mesa Peñota, flows into the left bank of the Aguisejo river, and the Cobos river, which has its source in the Majada de la Sierra, one of the last northern foothills of the Macizo de Ayllón. Thus, the Duratón river and the Aguisejo river border the Macizo de Ayllón from west to east in the north. The southern slope of
5198-746: The Atalaya and follows a winding path between mountains until it flows into the Sorbe river between Peña del Pinarejo and the Loma de las Piquerinas. To the north of the Ocejón rises the Arroyo de la Chorrera, which passes through Valverde and leaves the Chorreras de Despeñalagua on its way before flowing into the river. And under the southern slope of the Ocejón the Seco river or Barranco del Covachón, which passes through Palancares . Hunting has been incessant in
5311-526: The Ayllón side. From the Sierra de Pela, to the north, with springs between Ribalópez and El Portillo, Arroyo de la Dehesa or Sorbe de Galve river, which leaves a wide valley where Cantalojas and Galve de Sorbe settle. From the Tejera Negra beech forest, to the west, flows the Lillas river, which rises under Pico de la Buitrera and which in turn receives water from another tributary with year-round flow,
5424-669: The Berbellido river, which rises in Pico del Lobo and passes through Bocígano; the Jaramilla river, which after rising under Puerto de la Quesera leaves a deep and beautiful gorge to its mouth; the Arroyo de Vallosera, which rises in Pico de la Tornera and after cutting through a gorge in the area of La Vereda flows into the El Vado reservoir, next to the ruins of El Vado, and Arroyo del Soto, union of several minor streams that flow down from Ocejón and leave between it and Cabeza de Ranas
5537-622: The Earth's past climates . Geologists broadly study the properties and processes of Earth and other terrestrial planets. Geologists use a wide variety of methods to understand the Earth's structure and evolution, including fieldwork , rock description , geophysical techniques , chemical analysis , physical experiments , and numerical modelling . In practical terms, geology is important for mineral and hydrocarbon exploration and exploitation, evaluating water resources , understanding natural hazards , remediating environmental problems, and providing insights into past climate change . Geology
5650-424: The Earth, such as subduction and magma chamber evolution. Structural geologists use microscopic analysis of oriented thin sections of geological samples to observe the fabric within the rocks, which gives information about strain within the crystalline structure of the rocks. They also plot and combine measurements of geological structures to better understand the orientations of faults and folds to reconstruct
5763-484: The Grand Canyon in the southwestern United States being a very visible example, the lower rock units were metamorphosed and deformed, and then deformation ended and the upper, undeformed units were deposited. Although any amount of rock emplacement and rock deformation can occur, and they can occur any number of times, these concepts provide a guide to understanding the geological history of an area. Geologists use
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#17327726254495876-452: The Jaramilla river, Berbellido river, Sonsaz river or del Ermito river. In its valleys grow the southernmost beech forests in Europe —Tejera Negra, La Pedrosa and Montejo beech forests—, without missing in its flora the holm oak , oak and Scotch pine . Among its fauna are wolves , vultures and small mammals. The part of the mountain chain in the province of Guadalajara is located within
5989-615: The Loma de la Cebollera to the Sierra del Ocejón . Many of them, including the Jarama itself, erode the rock to create deep ravines, making some of them suitable for the construction of dams such as the El Vado reservoir or the planned but not begun Matallana reservoir. The main tributaries of the Jarama through the Sierra de Ayllón are the Ermito river, which has its source under the Cervunal;
6102-440: The Macizo de Ayllón, the beech forests in the area do represent the unique fact of being among the southernmost in Europe, which has led to their protection. The beech forests of the area are grouped in three sketches: The birch has a certainly small presence in the Sierra de Ayllón. Because of its resistance to cold and because it can grow in poor soils it can be found in the high areas of some rivers. The birch tree of Somosierra
6215-425: The Macizo de Ayllón: the peneplain , areas of undulating surface located at the ends of the massif, mainly to the north and south; the valleys , short in the north and very long and narrow in the south, leaving little room for meadows, and the mountain range itself. The mountain chain is distributed in a main ridge, which runs from west to east to the north of the mountain chain, and three secondary ridges, which leave
6328-596: The Sierra Norte de Guadalajara Natural Park and the Sonsaz Hunting Reserve extends over a large part of its territory. The outcropping materials are mainly slate and quartzites of the Ordovician and Silurian periods, with outcrops in some areas ( El Cardoso , Hiendelaencina , etc.) of Precambrians gneiss . The natural area of Ayllón extends towards the south following the valleys of
6441-429: The Sierra de Ayllón is included in the supramediterranean bioclimatic level, an area where the most extensive of the three relict beech forests of the Sistema Central (Tejera Negra beech forest) is located, which today is a natural park . Within it, the beech forests (Galio rotundifolii-Fagetum) , in remarkable regeneration after the declaration of protected area and the suppression of the exploitation of beech, and
6554-490: The Sierra de Ayllón since ancient times, which has caused the disappearance of several species in the area such as the bear , which was probably present until the 18th century, or the wolf , which was present until the 1960s, and which seems to be present again in the massif in the 2000s. Today the National Hunting Reserve of Sonsaz, which extends its 68,106 ha over a large part of the mountain chain, and
6667-599: The Sierra de Ayllón, which flows into the Tagus Basin, originates in the northern foothills of the massif. It is much more complicated than the northern slope and the rivers and streams, much longer, run tortuously squeezed between mountains, giving rise to ravines and gorges, until they flow into the two main rivers in the area: the Jarama and the Sorbe . It rises at the foot of the Cebollera Vieja and receives its major tributaries on its left bank, extending its basin from
6780-608: The Zarza river or Arroyo de la Hoz, which also crosses Tejera Negra after rising under Alto del Parrejón. After joining the two rivers, the Sorbe, a river with a considerable flow in rainy and thawing periods, flows through deep cliffs to the Beleña reservoir, leaving the Pozo de los Ramos dam between the mountains. The Sorbe flows between Alarilla and Humanes , under the Muela de Alarilla, in
6893-715: The abandonment of traditional activities. In the domain of humid beech and Pyrenean oak forests there are heaths (Erico arboreae-Arctostaphylletum crassifoliae, Halimio ocymoidis-Ericetum aragonensis, Junipero nanae-Vaccinietum myrtilli) , of great importance because they are very scarce in the rest of the Sistema Central . These heaths are a refuge for numerous plant species of Atlantic habit (Genistella tridentata, Genista pilosa , Avenula sulcata, etc.) . They are also accompanied by Portuguese brooms (Genisto floridae-Cytisetum scoparii, Genisto floridae-Adenocarpetum hispanici, Genisto cineracestis-Cytisetum oromediterranei) , communities of Carpathian-Iberian-Leonian optima, which are here at
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#17327726254497006-544: The area between the Sierra del Ocejón and the rivers Jaramilla and Berbedillo reaching south to Almiruete were included within the Común de Villa y Tierra de Ayllón , in the hands of the Marquis of Villena ; Riofrío and Hontanares under the jurisdiction of the Comunidad de Cilla y Tierra de Fresno de Cantespino ; from the Sierra del Ocejón and the Sorbe river eastward, including the term of Valverde de los Arroyos ,
7119-440: The area of El Cardoso de la Sierra to the south until the Jarama river acts as a natural boundary between the Sierra de Ayllón and the Campiña. The slate is the most common rock seen in the Macizo de Ayllón, as well as being the one typically used in the constructions of the villages in the area. Likewise, the slate areas can be classified according to the type of slate that gives shape: There are three relief units that form
7232-598: The area of the Cebollera Vieja and Cebollera Nueva, Somosierra , Santo Tomé del Puerto , Cerezos de Abajo and Cerezos de Arriba came under the jurisdiction of the Común de Villa y Tierra de Sepúlveda , which passed during the 14th century in good part to the Mendoza family, within the Marquisate of Montesclaros since the 15th century, from which fact still remains a House between El Cardoso and Colmenar;
7345-983: The area, beeches predominate, and another oromediterranean above 2000m mainly covered by cytisus , Cornish heath , rockrose , steppes and junipers . The peaks of the Sierra de Ayllón are located in the bioclimatic levels gold and cryo-Mediterranean, with communities characteristic of these high altitudes, very rich in endemic species. Thus, there are psicroxerophilous grasslands at the highest altitudes (Hieracio myriadeni-Festucetum indigestae) , cytisus (Senecioni carpetani-Cytisetum oromediterranei) , chionophilous cervunales (Campanula herminii-Festucetum ibericae) , hygrophilous oromediterranean cervunales (Luzulo carpetanae-Pedicularietum sylvaticae, Campanulo herminii-Festucetum rivularis) , rupicolous communities (Saxifragetum willkommianae) and oromediterranean glericolous (Digitali carpetanae-Senecionetum carpetani, Rumicetum suffruticosi, Criptogrammo crispae-Dryopteridetum oreadis). The northern slopes, enjoying more rainfall, show
7458-445: The area. The humid forests of the mountain chain also provide habitat for nemoral species such as the woodcock ( Scolopax rusticola ) , a scarce nester, wintering and regular migrant, the barbastelle bat ( Barbastella barbastellus ) , the also nesting tree pipit ( Anthus trivialis ) , the song thrush ( Turdus philomelos ) and the red-backed shrike ( Lanius collurio ), with breeding areas further north. The hydrographic system in
7571-450: The beech forests de Tejera Negra and Montejo are the perfect refuge for the wild fauna of the area. Depending on the location in the massif, different animal species can be found: Among the insects it is worth mentioning the great diversity that exists in the Macizo de Ayllón. Numerous species of lepidoptera , coleoptera , hymenoptera and diptera can be observed throughout the mountain chain, some of them autochthonous and exclusive to
7684-537: The beginning of the 20th century, advancement in geological science was facilitated by the ability to obtain accurate absolute dates to geological events using radioactive isotopes and other methods. This changed the understanding of geological time. Previously, geologists could only use fossils and stratigraphic correlation to date sections of rock relative to one another. With isotopic dates, it became possible to assign absolute ages to rock units, and these absolute dates could be applied to fossil sequences in which there
7797-459: The birches (Melico-Betuletum celtibericae), also relict, which occupy the bottoms of the ravines and watercourses with high edaphic humidity. These forests, together with the humid Pyrenean oak groves (Festuco heterophyllae-Quercetum pyrenaicae) , constitute important refuges of Eurosiberian plant species absent in other areas of the Meseta. Although the beech is not the most widespread tree in
7910-465: The conditions are more humid, humid Pyrenean oak groves or beech forests appear, of relict presence in Ayllón (Tejera Negra), with interesting enclaves of yews , holly , rowan or climatic birch trees. Under oromediterranean or more continental conditions, climax pine forests of Scotchs pine (Coeno-Pinetum sylvestris) appear, as occurs on the northern slopes of the Sierra de Alto Rey and Condemios. The most widespread vegetation in this mountain chain
8023-515: The creation of topographic gradients, causing material on the rock unit that is increasing in elevation to be eroded by hillslopes and channels. These sediments are deposited on the rock unit that is going down. Continual motion along the fault maintains the topographic gradient in spite of the movement of sediment and continues to create accommodation space for the material to deposit. Deformational events are often also associated with volcanism and igneous activity. Volcanic ashes and lavas accumulate on
8136-437: The crust, the uplift of mountain ranges, and paleo-topography. Fractionation of the lanthanide series elements is used to compute ages since rocks were removed from the mantle. Other methods are used for more recent events. Optically stimulated luminescence and cosmogenic radionuclide dating are used to date surfaces and/or erosion rates. Dendrochronology can also be used for the dating of landscapes. Radiocarbon dating
8249-470: The current hydrographic system was established, forming the valleys and the silhouettes of the mountains. The last glaciation partly affected the Macizo de Ayllón forming some glacial cirques such as those found at the source of the Berbellido river, next to the Pico del Lobo, and at the Peña Cebollera Vieja . The Sierra de Ayllón is divided into three main lithological zones depending on
8362-564: The dolomites of Tamajón there is a very well developed limestone pavement , with forms reminiscent of the Ciudad Encantada and accompanied by calcareous rupicolous communities (Chaenorhino-Sarcocapnetum) and terophytic communities (Saxifrago tridactylitae-Hornungietum petrae). The juniper , despite being a Mediterranean tree, adapts to continental climatic conditions. In the surroundings of Tamajón and Galve de Sorbe there are also good examples of juniper groves. The degradation of
8475-460: The extreme end of their distribution area. In spite of the great exploitation that the oak forests have suffered in the Sierra de Ayllón for their timber value, the extension of pastures and charcoal production, the oak is still the most widespread tree in the massif. Two types of oaks are found in the area: The Pyrenean oak groves of the Sierra de Ayllón, (Festuco heterophyllae-Quercetum pyrenaicae and Luzulo forsteri-Quercetum pyrenaicae) , are
8588-570: The fault is a normal fault or a thrust fault . The principle of inclusions and components states that, with sedimentary rocks, if inclusions (or clasts ) are found in a formation, then the inclusions must be older than the formation that contains them. For example, in sedimentary rocks, it is common for gravel from an older formation to be ripped up and included in a newer layer. A similar situation with igneous rocks occurs when xenoliths are found. These foreign bodies are picked up as magma or lava flows, and are incorporated, later to cool in
8701-403: The faults are not planar or because rock layers are dragged along, forming drag folds as slip occurs along the fault. Deeper in the Earth, rocks behave plastically and fold instead of faulting. These folds can either be those where the material in the center of the fold buckles upwards, creating " antiforms ", or where it buckles downwards, creating " synforms ". If the tops of the rock units within
8814-483: The folds remain pointing upwards, they are called anticlines and synclines , respectively. If some of the units in the fold are facing downward, the structure is called an overturned anticline or syncline, and if all of the rock units are overturned or the correct up-direction is unknown, they are simply called by the most general terms, antiforms, and synforms. Even higher pressures and temperatures during horizontal shortening can cause both folding and metamorphism of
8927-2879: The forests, the abandoned crops and the forest fires that occurred over time favored the extension of scrubes and pastures , good for livestock feeding. Depending on the altitude and exposure of the slope can be found cytisus , juniper , Cornish heath , codesos, hiniestas or rockroses . It reaches a total extension of 94.686,40 ha distributed in 819,14 ha in Albendiego , 447,76 ha in Arbancón , 1.316,06 ha in Bustares , 9.063,91 ha in Campillo de Ranas , 11.707,33 ha in Cantalojas , 18.468,44 ha in El Cardoso de la Sierra , 1.060,58 ha in Cogolludo , 467,59 ha in Condemios de Abajo , 3.516,27 ha in Galve de Sorbe , 1.899,43 ha in Gascueña de Bornova , 453,93 ha in Hiendelaencina , 3.046,31 ha in La Huerce , 5.505,19 ha in Majaelrayo , 154,82 ha in Miedes de Atienza , 88,10 ha in La Miñosa , 374,68 ha in Las Navas de Jadraque , 1.865,70 ha in El Ordial , 2.709,10 ha in Prádena de Atienza , 44,28 ha in Puebla de Valles , 736,89 ha in Retiendas , 8.763,26 ha in Tamajón , 38,41 ha in La Toba , 3.198,04 ha in Tortuero , 206,02 ha in Ujados , 2.060,02 ai n Valdepeñas de la Sierra , 1.916,45 ha in Valdesotos , 4.531,46 ha in Valverde de los Arroyos , 870,99 ha in Villares de Jadraque , 510,29 ha in Zarzuela de Jadraque and 1.516,87 ha in Semillas . As indicated above,
9040-426: The form of snow, coinciding with the summer, a long dry season. The average annual rainfall is between 800 and 1000 mm. The coldest months correspond to the central months of winter, December and January, and when periods in which cold waves of Central Europe that cause heavy snowfall to relatively low altitudes are approaching. The average minimum temperature reached in winter is around 2 °C or 3 °C in
9153-404: The formation of faults and the age of the sequences through which they cut. Faults are younger than the rocks they cut; accordingly, if a fault is found that penetrates some formations but not those on top of it, then the formations that were cut are older than the fault, and the ones that are not cut must be younger than the fault. Finding the key bed in these situations may help determine whether
9266-423: The internal composition and structure of the Earth. Seismologists can use the arrival times of seismic waves to image the interior of the Earth. Early advances in this field showed the existence of a liquid outer core (where shear waves were not able to propagate) and a dense solid inner core . These advances led to the development of a layered model of the Earth, with a lithosphere (including crust) on top,
9379-464: The later end of the scale, it is marked by the present day (in the Holocene epoch ). The following five timelines show the geologic time scale to scale. The first shows the entire time from the formation of the Earth to the present, but this gives little space for the most recent eon. The second timeline shows an expanded view of the most recent eon. In a similar way, the most recent era is expanded in
9492-454: The lowest layer to deposition of the highest bed. The principle of faunal succession is based on the appearance of fossils in sedimentary rocks. As organisms exist during the same period throughout the world, their presence or (sometimes) absence provides a relative age of the formations where they appear. Based on principles that William Smith laid out almost a hundred years before the publication of Charles Darwin 's theory of evolution ,
9605-474: The main one from north to south. In the heart of the Sierra de Ayllón rise the last peaks of more than 2000 meters of the Sistema Central . The mountain climate of the Sierra de Ayllón is marked by two fundamental factors: on the one hand, the latitude , marking the Mediterranean character with hot summers and low rainfall; on the other hand, the orientation of the massif causes the interception of
9718-460: The main rivers ( Lozoya , Jarama , Sorbe , Bornova, Cristóbal), in whose canyons habitats and communities of great ecological value are located. There are also periglacial reliefs (quartzite cliffs) and remains of glacial activity in the vicinity of Pico del Lobo. The geological evolution of the mountain chain is marked by two major foldings : on the one hand, the Hercynian orogeny , towards
9831-497: The mantle and show the crystallographic structures expected in the inner core of the Earth. The geological time scale encompasses the history of the Earth. It is bracketed at the earliest by the dates of the first Solar System material at 4.567 Ga (or 4.567 billion years ago) and the formation of the Earth at 4.54 Ga (4.54 billion years), which is the beginning of the Hadean eon – a division of geological time. At
9944-405: The matrix. As a result, xenoliths are older than the rock that contains them. The principle of original horizontality states that the deposition of sediments occurs as essentially horizontal beds. Observation of modern marine and non-marine sediments in a wide variety of environments supports this generalization (although cross-bedding is inclined, the overall orientation of cross-bedded units
10057-510: The most extensive and representative of Castilla-La Mancha , presenting as characteristic cortege Arenaria montana , Luzula forsteri , Viola riviniana , Poa nemoralia, Primula veris , Viola sylvatica, Holcus molli, Conopodium bourgaei, etc. . The abandonment of charcoal production and the great reduction in the use of firewood outlines an optimistic future for the natural recovery of the Pyrenean oak grove in this mountain chain. The rest of
10170-501: The most mature arboreal vegetation corresponds in most of the supramediterranean territory to Pyrenean oak groves, reserving the holm oak groves to the basal areas, sloping sills and the steep slopes of the fluvial gorges. The Pyrenean oak grove has been intensively exploited as a source of firewood by man until a few decades ago, so many of its masses have the appearance of small or medium-sized groves in recovery, although extensive mature Pyrenean oak groves are preserved (El Cardoso). If
10283-436: The mountain chain has a high degree of conservation until the arrival of the rivers to the line of regulating reservoirs located south of the natural area, (Pontón de la Oliva, Vado reservoir, Beleña reservoir, Alcorlo reservoir) . The absence of polluting industries and the reduced human population (<2 people per /km²) guarantee the absence of water pollution. Thus, the rivers of this area represent an unbeatable habitat for
10396-465: The mountains of Ayllón. With the conquest in 1085 by Alfonso VI of what from then on would be called Extremadura Castellana and the consequent transfer of the fighting frontier to the banks of the Tagus river , the valleys of the Macizo de Ayllón would be repopulated from then until the end of the 13th century with Castilians, Leonese and Galicians, with people who were once again cattle breeders. Many of
10509-416: The mountains of the Sierra de Ayllón have been populated since ancient times. Arevaci to the east, Vaccaei to the north and Carpetani to the south, followed by Celts and Celtiberians populated the valleys of the mountain chain attracted by the hunting and livestock possibilities as well as by the isolation provided by its mountains allowing them a better survival before the neighboring peoples. From
10622-640: The northern slope of the Cebollera Vieja , it receives water from two streams that usually dry up in summer in most of its sections, the Cerezuelo river and the Serrano river, both of which rise on the slopes of the Pico del Lobo. The Riaza river rises near Puerto de la Quesera and receives water from the Sierra de Ayllón, mainly on its right bank. Its tributaries are longer, although equally of little flow. The Aguisejo river, which rises near Villacadima and in turn receives water from other smaller streams including
10735-580: The old tainas were reconverted into small villages with a permanent population that maintained the ways of life of before the depopulation. Monastic repopulation was granted by Alfonso VIII in 1164 and was carried out by the Knights Templar of the houses of Albendiego and Bonaval , who founded small monasteries such as Royal Site of Santuy. The creation in 1214 of a convent and a factory in Ayllón by Francis of Assisi would give jurisdiction to
10848-569: The principles of succession developed independently of evolutionary thought. The principle becomes quite complex, however, given the uncertainties of fossilization, localization of fossil types due to lateral changes in habitat ( facies change in sedimentary strata), and that not all fossils formed globally at the same time. Geologists also use methods to determine the absolute age of rock samples and geological events. These dates are useful on their own and may also be used in conjunction with relative dating methods or to calibrate relative methods. At
10961-425: The red-billed chough ( Pyrrhocorax pyrrhocorax ) . Other species of great interest such as Bonelli's eagle ( Hieraaetus fasciatus ) , Egyptian vulture ( Neophron percnopterus ) the common rock trush and the blue rock thrush ( Monticola saxatilis and Monticola solitarius ) use the Sierra de Ayllón as a breeding area. The importance of the natural area of Ayllón for some rare or endemic invertebrate species, such
11074-428: The rocks. This metamorphism causes changes in the mineral composition of the rocks; creates a foliation , or planar surface, that is related to mineral growth under stress. This can remove signs of the original textures of the rocks, such as bedding in sedimentary rocks, flow features of lavas , and crystal patterns in crystalline rocks . Extension causes the rock units as a whole to become longer and thinner. This
11187-433: The simplified layered model with a much more dynamic model. Mineralogists have been able to use the pressure and temperature data from the seismic and modeling studies alongside knowledge of the elemental composition of the Earth to reproduce these conditions in experimental settings and measure changes within the crystal structure. These studies explain the chemical changes associated with the major seismic discontinuities in
11300-532: The southwestern United States, sedimentary, volcanic, and intrusive rocks have been metamorphosed, faulted, foliated, and folded. Even older rocks, such as the Acasta gneiss of the Slave craton in northwestern Canada , the oldest known rock in the world have been metamorphosed to the point where their origin is indiscernible without laboratory analysis. In addition, these processes can occur in stages. In many places,
11413-714: The species in the Sistema Central, very vulnerable to external disturbances and probably threatened by the proliferation of the American mink . The frequent cliffs and crags form a habitat of exceptional importance for a wide range of rupicolous birds. The natural area of Ayllón exceeds the numerical criteria established in the EU Birds Directive for the golden eagle, ( Aquila chrysaetos ) , griffon vulture ( Gyps fulvus ) , peregrine falcon ( Falco peregrinus ) and eagle-owl ( Bubo bubo ) , being also abundant
11526-550: The subsurface. Sub-specialities of geology may distinguish endogenous and exogenous geology. Geological field work varies depending on the task at hand. Typical fieldwork could consist of: In addition to identifying rocks in the field ( lithology ), petrologists identify rock samples in the laboratory. Two of the primary methods for identifying rocks in the laboratory are through optical microscopy and by using an electron microprobe . In an optical mineralogy analysis, petrologists analyze thin sections of rock samples using
11639-407: The surface of the Earth and the convecting mantle is called plate tectonics . The development of plate tectonics has provided a physical basis for many observations of the solid Earth . Long linear regions of geological features are explained as plate boundaries: Plate tectonics has provided a mechanism for Alfred Wegener 's theory of continental drift , in which the continents move across
11752-488: The surface of the Earth over geological time. They also provided a driving force for crustal deformation, and a new setting for the observations of structural geology. The power of the theory of plate tectonics lies in its ability to combine all of these observations into a single theory of how the lithosphere moves over the convecting mantle. Advances in seismology , computer modeling , and mineralogy and crystallography at high temperatures and pressures give insights into
11865-479: The surface, and igneous intrusions enter from below. Dikes , long, planar igneous intrusions, enter along cracks, and therefore often form in large numbers in areas that are being actively deformed. This can result in the emplacement of dike swarms , such as those that are observable across the Canadian shield, or rings of dikes around the lava tube of a volcano. All of these processes do not necessarily occur in
11978-742: The surface. Igneous intrusions such as batholiths , laccoliths , dikes , and sills , push upwards into the overlying rock, and crystallize as they intrude. After the initial sequence of rocks has been deposited, the rock units can be deformed and/or metamorphosed . Deformation typically occurs as a result of horizontal shortening, horizontal extension , or side-to-side ( strike-slip ) motion. These structural regimes broadly relate to convergent boundaries , divergent boundaries , and transform boundaries, respectively, between tectonic plates. When rock units are placed under horizontal compression , they shorten and become thicker. Because rock units, other than muds, do not significantly change in volume , this
12091-407: The third timeline, the most recent period is expanded in the fourth timeline, and the most recent epoch is expanded in the fifth timeline. Horizontal scale is Millions of years (above timelines) / Thousands of years (below timeline) Epochs: Methods for relative dating were developed when geology first emerged as a natural science . Geologists still use the following principles today as
12204-519: The town and grant it as Común de Tierra what today is known as Tierras de Ayllón , hence the name given to the entire mountain chain that concerns us because a large part of it belongs to the Comunidad de Villa y Tierra de Ayllón . Thus, with the creation of the Comunidades de Villa y Tierra the different towns that flourished again in the Sierra de Ayllón were divided into several of these: El Cardoso de la Sierra , Colmenar de la Sierra, El Vado,
12317-439: The type of rock that predominates in each one: From west to east, from Puerto de Somosierra to El Cervunal, and from north to south, from Riaza to Puerto del Cardoso, following the right bank of the Ermito river, granite abounds among the rocks that form the mountains of this area of the Sierra de Ayllón. The gneiss is, however, the least widespread of the three predominant rocks in the Sierra de Ayllón. It forms mainly in
12430-451: The valleys; the average maximum temperature is reached in the months of July and August around 15 °C. The thermal amplitude in autumn and spring periods can be very wide, with pleasant days and extremely cold nights in some cases, becoming more severe in the valley bottoms. The number of days with frost varies between 50 and 150 depending on the southern or northern slope. From the Sierra of Ayllón waters flow into two large basins :
12543-417: The wetter area transforms into avellanae (Geo urbani-Coryletum avellanae) . The fluvial gallery vegetation is well represented in its supramediterranean siliceous variants. Of special interest are the alder groves (Galio broteriani-Alnetum glutinoseae) , of great extension and an excellent degree of conservation in the rivers Jarama , Sorbe and Bornoba, this type of habitat is in increasing expansion, due to
12656-615: Was datable material, converting the old relative ages into new absolute ages. For many geological applications, isotope ratios of radioactive elements are measured in minerals that give the amount of time that has passed since a rock passed through its particular closure temperature , the point at which different radiometric isotopes stop diffusing into and out of the crystal lattice . These are used in geochronologic and thermochronologic studies. Common methods include uranium–lead dating , potassium–argon dating , argon–argon dating and uranium–thorium dating . These methods are used for
12769-540: Was only punctuated by the war against the French Napoleonic Empire between 1808 and 1810, when the Macizo de Ayllón was the scene of battles for the control of the mountain passes. Geology Geology describes the structure of the Earth on and beneath its surface and the processes that have shaped that structure. Geologists study the mineralogical composition of rocks in order to get insight into their history of formation. Geology determines
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