Pyrenees

(Spanish, Pirineos; French, Pyrénées), a mountain system in southwestern Europe, in Spain, France, and Andorra; an important natural frontier separating the Mediterranean from Central Europe. The Pyrenees stretch for some 450 km from the Bay of Biscay to the Mediterranean Sea, reaching a maximum width of 110 km in the central and eastern sections and rising to 3,404 m at Aneto Peak in the Maladetta Range.

As a result of mountain-building movements, primarily alpine, the ancient Hercynian core of the Pyrenees was uplifted to a considerable height, and the sedimentary strata overlying it were sharply folded, in some places forming overthrusts. The topography combines medium-elevation flat-topped massifs and folded linear ranges. The relief is alpine in the highest parts of the mountains, which underwent Pleistocene glaciation. Contemporary glaciers, covering about 40 sq km, are concentrated in the Central Pyrenees, composed chiefly of crystalline rocks (granites and gneisses), as well as slates and sandstones. The Western Pyrenees are medium-elevation mountains composed primarily of Mesozoic limestones with massifs of crystalline rock. The Eastern Pyrenees consist of ranges and massifs of crystalline rock, sandstone, and limestone dissected by inter-montane depressions with flat bottoms. Natural resources include deposits of iron ore in the west near Rentería and in the northeast at Vernet, brown coal at Figols on the south slope, bauxite near Tarascon on the north slope, manganese ores in the Neste Valley, and marble and granite. There are many hot springs.

The climate is moderate and humid, except in the southeast, which has a subtropical Mediterranean climate. The mean January temperature, 4°-8°C at elevations of up to 500–600 m, falls to between — 8°C and — 10°C in the highest ranges. In July temperatures average about 18°C in the western foothills and reach a maximum of 24°C in the eastern foothills. Near the snow line, lying at 2,400–2,800 m on the northern slopes and at about 3,000 m on the southern slopes, the temperature is about 5°C. The northern slopes receive 1,500–2,400 mm of precipitation annually and the southern slopes, up to 500–750 mm. Over most of the Pyrenees the precipitation falls throughout the year; the east has dry summers. The rivers are full and flow in deep narrow valleys, sometimes forming waterfalls, such as the famous Gavarnie Falls. Their hydroelectric potential is considerable. The rivers that empty into the Mediterranean have a low flow in summer and dry up in places during years of drought. There are numerous shallow lakes of glacial, avalanche, or tectonic origin. Lakes and rivers that flow underground for part of their stretches are found in limestone areas and regions with a karst topography.

Forest landscapes predominate over much of the Pyrenees to elevations of 1,800–2,100 m. Deciduous and coniferous forests are found primarily on the northern and western slopes. In the lower part of the forest zone are broad-leaved forests of oak, chestnut, maple, and beech; in the middle part pine forests alternate with oak and beech forests; and the upper part is covered chiefly by beech, spruce, and fir forests with an admixture of birch. On the southern and eastern slopes, forests alternate with shrub thickets and heathland, with shrubs predominating near the Mediterranean Sea. Here, up to 500–700 m are found evergreen formations of the maquis, garigue, and tomillares type, as well as open woodlands of holm and cork oak and subtropical species of pine. Above the forest zone, high-mountain shrub thickets of mountain pine, juniper, rhododendron, and azalea give way to alpine meadows. Much of the natural vegetation of the Pyrenees has survived.

Wildlife includes such mammals as the chamois, wild boar, badger, Spanish ibex, and genet. Among birds are capercaillies, partridges, eagles, vultures, and hawks. The mountain fauna and landscapes are protected in the Aigues Tortes and Ordesa national parks in Spain and in the Néouvielle Preserve in France. In the foothills and intermontane basins are fields of wheat, corn, barley, and oats, as well as vineyards and orchards; groves of cork oak and olives are also found in the east. Cattle, sheep, and goats are raised in pastures in the forest zone and in the high-mountain meadows. Tourism is an important source of revenue.

Based on natural conditions, the Pyrenees are divided into the Western Pyrenees, extending from the Atlantic Ocean to Somport Pass, the Central Pyrenees, encompassing the area from Somport Pass to Carlitte Peak, and the Eastern Pyrenees, stretching from Carlitte Peak to the Mediterranean Sea.