Ordesa Valley

The Ordesa Valley is a glacial valley in Aragon, in the Spanish Pyrenees, forming part of the Ordesa y Monte Perdido National Park. The valley is approximately 11 kilometres (7 mi) long.^[1]

Ordesa Valley
The Ordesa Valley
Length	11 kilometres (7 mi)
Geology
Type	Glacial valley
Geography
Location	Aragon, Spain
Rivers	Arazas River

In autumn, Bosque de La Pardina del Señor, between Fanlo and Sarvisé.

River in Cotatuero

History

The Ordesa Valley was first documented in 1820 and was later mapped in detail during the 1920s.^[1] It became part of the Ordesa y Monte Perdido National Park in 1918, making it one of Spain's earliest protected natural areas.^[2]

Geography

The valley's east–west orientation, which is unusual in the Pyrenees, allows Atlantic Ocean influences, contributing to its moderate climate.^[3]

The Arazas River flows through the valley, creating multiple waterfalls, such as the Cola de Caballo (Horsetail Waterfall).^[4]

Ecology and conservation

The valley hosts diverse ecosystems, ranging from subalpine forests to high-mountain meadows. Notable tree species include Scots pine (Pinus sylvestris), Silver fir (Abies alba), and European beech (Fagus sylvatica).^[5]

It also has one of Europe’s largest populations of the Pyrenean Chamois (Rupicapra pyrenaica).^[6] Other wildlife includes griffon vultures (Gyps fulvus), golden eagles (Aquila chrysaetos),^[7] and brown bears (Ursus arctos),^[8] though the latter are extremely rare.

Designated a UNESCO Biosphere Reserve in 1997, the park implements measures to balance tourism with habitat protection, including restricted access zones.^[9][10]

Geology

The valley's formation stems from the collision of the Iberian and Eurasian tectonic plates during the Alpine orogeny, creating folds and faults in its limestone and dolomite bedrock.^[11] Erosional processes further shaped the terrain:  

• Glacial activity carved the U-shaped Ordesa and Pineta valleys, while river erosion formed the Añisclo and Escuaín canyons.^[9]
• Karstification produced features like underground drainage systems and sinkholes, contributing to the valley’s aridity at higher elevations.^[11]

At the north-east end of the valley, several prominent peaks can be seen, including:

• Monte Perdido – 3,355 metres (11,007 ft) (third-highest peak in the Pyrenees)^[9]
• Cilindro de Marboré – 3,328 metres (10,919 ft)
• Soum de Ramond – 3,263 metres (10,705 ft)

These three peaks form part of the Monte Perdido Massif, dominating the northeastern end of the valley.^[12]

Tourism

The valley’s trails attract over 600,000 annual visitors:  

• Cola de Caballo Route: A 17.5 km round-trip trail leads to the iconic "Horsetail" waterfall, passing landmarks like the Gradas de Soaso cascades and Circo de Soaso glacial cirque.^[13]
• Faja de Pelay: A challenging 22 km loop offering cliffside views from the Senda de los Cazadores path.^[9][13]
• Góriz Refuge: A key basecamp for ascents of Monte Perdido and adjacent peaks.^[9]

Visitor management includes shuttle buses from Torla to reduce traffic and trail erosion.^[10][13]