Background

Geomorphological studies of Cordillera Cantábrica and recognition of its glacial and periglacial features date from the beginning of the present century (Reference Hernández PachecoHernández Pacheco, 1914; Reference ObermaierObermaier, 1914). Traditionally, it was recognized that in Picos de Europa there are only perennial snow patches (Reference ClarkClark, 1981; Reference Fernández RodríguezFernández Rod-ríguez, 1992).

Until now, the only glaciers found in the Iberian Peninsula were located in the Pyrenees (Reference SerratSerrat, 1980). This author considered that the snow line in Picos de Europa was 800 m lower than in the Pyrenees although, for Reference ClarkClark (1981), this massif would have developed glaciers with a slight climatic deterioration.

Glacial Ice

In this letter, the presence of glacial ice in the Macizo Central, in the form of glaciers of small dimensions, is reported for the first time. They were formed from the wastage of larger glaciers that were partially covering the uplands of the Macizo Central during the Little Ice Age.

At present, the largest glacier is that in Jou Negro, located at the base of the highest summit of Picos de Europa (Torre de Cerredo, 2651 m). Glacial ice occupies the bottom of a cirque with a northeast aspect, that is well protected from solar radiation by the surrounding crests situated to the east, south and west (Figs 2 and 3). Resting against the cirque walls, at a certain distance from the ice and facing the north-northeast, there is an arcuate push moraine. According to the nomenclature established in the Catalan Pyrenees by Reference Bru, Gómez Ortiz, Serrat, Ventura and VilaplanaBru and others (1985), this moraine could be subactual, corresponding to the historic post-glacial phase. This relation between glacial ice and terminal moraine in Jou Negro is comparable to that described by Reference SerratSerrat (1980) in Madaleta Massif (central Pyrenees), where important glacier retreat took place from the 19th century until 1957. According to Serrat, the best-developed moraines, formed in the 19th century, are separated from the present glacier margins.

Fig. 2. Sketch from Figure 3.

Fig. 3. General view towards the south of the relict glacier of Jou Negro (Macizo Central). The highest peak of the massif (Torre de Cerredo, 2651 m), outside the photograph, lies just to the left of the margin (taken on 20 September 1992).

Besides Glaciar Jou Negro, it is possible that there is glacial ice beneath the northeast snow patch of Torre de la Palanca and the snow patch of Llambrión, both in the Macizo Central. Some snow patches in the Macizo Occidental could also have ice cores, such as Neveron de la Forcadona, on the north face of Peña Santa de Castilla, although the altitudes of the summits here are slightly lower than in the Macizo Central.

It is not surprising that glacial ice has not been seen until now in Picos de Europa as it is usually beneath a layer of snow and firn that acts as an insulator. Due to the low precipitation during the last few years, ablation exceeded precipitation, causing melting of most of the snow and firn. As a result, the ice cores have been exposed in recent summers. In September 1992, Glaciar Jou Negro was discovered by one of the authors (González Suárez).

The preservation of these small glaciers in Picos de Europa can be attributed to heavy precipitation,in the form of snowfall and the permanence of this snow favoured by low solar radiation. As perennial snowcover provides insulation, ablation was considerably reduced, and this allowed the continued existence of the glacial ice. The present state of these glaciers is not known, although future surveys will enable us to establish whether they are stable or whether they are retreating.