Science Fair Project Encyclopedia
- For other meanings see: Pyrenees, Victoria and Montes Pyrenaeus.
The Pyrenees (French: Pyrénées; Spanish: Pirineos; Occitan: Pirenèus or Pirenèas; Catalan Pirineus; Aragonese: Perinés; Basque: Pirinioak) are a range of mountains in southwest Europe that form a natural border between France and Spain. They separate the Iberian Peninsula from France, and extend for about 430km from the Bay of Biscay on the Atlantic Ocean to Cap de Creus on the Mediterranean Sea.
For the most part the main crest forms the Franco-Spanish frontier, with the principality of Andorra sandwiched between them. The principal exception to this rule is formed by the Val d'Aran, which belongs to Spain but lies on the north face of the range. Other minor orographical anomalies include the Cerdagne fall and the Spanish exclave of the town Llívia.
Finally, the Pyrenees are also part of the independent principality of Andorra.
The Pyrenees are typically divided into three sections: the Central, the Atlantic or Western, and the Eastern.
The Central Pyrenees extend eastward from the Port de Canfranc to the Val d'Aran, and include the highest summits of the range:
- Aneto or Pic de Néthou (3,404 m) in the Maladetta ridge,
- Mont Posets (3,375 m),
- Mont Perdu or Monte Perdido or Mont Perdut (3,355 m).
In the Atlantic Pyrenees the average elevation gradually decreases from east to west. In the Eastern Pyrenees, with the exception of one break at the eastern extremity of the Pyrénées Ariégeoises, the mean elevation is maintained with remarkable uniformity until a sudden decline occurs in the portion of the chain known as the Albères.
The Pyrenees are older than the Alps: their sediments were first deposited in coastal basins during the Paleozoic and Mesozoic eras. In the Lower Cretaceous period, the Gulf of Gascony (Bay of Biscay ) fanned out, pushing Spain against France and putting large layers of sediment in a vice grip. The intense pressure and uplifting of the Earth's crust first affected the eastern part and stretched progressively to the entire chain, culminating in the Eocene epoch.
The eastern part of the Pyrenees consists largely of granite and gneissose rocks, while in the western part the granite peaks are flanked by layers of limestone. The massive and unworn character of the chain comes from its abundance of granite, which is particularly resistant to erosion, as well as weak glacial development.
Four conspicuous features of Pyrenean scenery are:
- the absence of great lakes, such as fill the lateral valleys of the Alps
- the rarity and great elevation of passes
- the large number of the mountain torrents locally called gaves, which often form lofty waterfalls, surpassed in Europe only by those of Scandinavia
- the frequency with which the upper end of a valley assumes the form of a semicircle of precipitous cliffs, locally called a cirque.
The highest waterfall is that of Gavarnie (462 m), at the head of the Gave de Pau ; the Cirque de Gavarnie , in the same valley, is perhaps the most famous example of the cirque formation. Not only is there a total lack of those passes, so common in the Alps, which lead across the great mountain chains at a far lower level than that of the neighbouring peaks, but between the two extremities of the range, where the principal highroads and the only railways run between France and Spain, there are only two passes practicable for carriages: the Col de la Perche , between the valley of the Têt and the valley of the Segre, and the Col de Somport or Port de Canfranc, on the old Roman road from Saragossa to Oloron .
The metallic ores of the Pyrenees are not in general of much importance, though there are considerable iron mines at Vie de Sos in Ariège and at the foot of Canigou in Pyrénées-Orientales. Coal deposits capable of being profitably worked are situated chiefly on the Spanish slopes but the French side has numerous beds of lignite.
Mineral springs are abundant and very remarkable, and specially noteworthy are the hot springs, in which the Alps, on the contrary, are very deficient. The hot springs, among which those of Bagnères de Luchon and Eaux-Chaudes may be mentioned, are sulphurous and mostly situated high, near the contact of the granite with the stratified rocks. The lower springs, such as those of Bagnères de Bigorre (Hautes-Pyrénées), Rennes les Bains (Aude) and Campagne (Aude), are mostly selenitic and not very warm.
The amount of the precipitation, including rain and snow, is much greater in the western than in the eastern Pyrenees, which leads to a marked contrast between these sections of the chain in more than one respect. In the first place, the eastern Pyrenees are without glaciers, the quantity of snow falling there being insufficient to lead to their development. The glaciers are confined to the northern slopes of the central Pyrenees, and do not descend, like those of the Alps, far down in the valleys, but have their greatest length in the direction of the mountain chain. They form, in fact, a narrow zone near the crest of the highest mountains. Here, as in the other great mountain ranges of central Europe, there are evidences of a much wider extension of the glaciers during the Ice age. The case of the glacier in the valley of Argelbs in the département of Hautes-Pyrénées is the best-known instance. The snow-line varies in different parts of the Pyrenees from 2700-2800 m. above sea-level.
Flora and fauna
A still more marked effect of the preponderance of rainfall in the western half of the chain is seen in the aspect of the vegetation. The lower mountains in the extreme west are very well wooded, but the extent of forest declines eastwards, and the eastern Pyrenees are peculiarly wild and barren, all the more since it is in this part of the chain that granitic masses prevail. There is a change, moreover, in the composition of the flora in passing from west to east. In the west the flora, at least in the north, resembles that of central Europe, while in the east it is distinctly Mediterranean in character, though the difference of latitude is only about 1°, on both sides of the chain from the centre whence the Corbières stretch north-eastwards towards the central plateau of France. The Pyrenees are relatively as rich in endemic species as the Alps, and among the most remarkable instances of that endemism is the occurrence of the sole European species of Dioscorea (yam), Dioscorea pyrenaica, at a single high site in the central Pyrenees, and that of the monotypic genus Xatardia , only on a high alpine pass between the Val d'Eynes and Catalonia. The genus most abundantly represented in the range is that of the saxifrages, several species of which are endemic here.
In their fauna also the Pyrenees present some striking instances of endemism. There is a distinct species of ibex (Capra pyrenaica) confined to the range, while the Pyrenean desman or water-mole (Galemys pyrenaicus ) is found only in some of the streams of the northern slopes of these mountains, the only other member of this genus being confined to the rivers of the Caucasus in southern Russia. Among the other peculiarities of the Pyrenean fauna are blind insects in the caverns of Ariège, the principal genera of which are Anophthalmus and Adelops . The last female Pyrenaic bear was shot dead on November 2004.
Both sides of the Pyrenees are popular spots for winters sports, like alpine ski and mountaineering. Some resorts are Formigal , Panticosa , Baqueira-Beret . Pyrena is a mushing competition held in the Pyrenees.
External link and references
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