Interesting facts 

Variety of Rocks in the World Heritage Region

There is a great range of different rocks to be found in the World Heritage Region, which can be quite confusing to the laymen. But basically there are just a few main types, which are easily to keep apart. There are the very old rocks, chiefly gneisses, schists and amphibolite, which are known as old crystalline rocks. Furthermore there are Granites like the Central Aare, the Bietschhorn and the Gastern granites. By far the commonest type of rock here is – Jurassic limestone.

 

Some of the mighty summits in the World Heritage site have their origin in the sea and are made of Jurassic limestone. In the World Heritage Region a number of well-known peaks are composed of it, including the Engelhörner, the Wetterhörner, the Mettenberg, the Eiger, the Gspaltenhorn, the Blüemlisalp group and the Doldenhorn. The limestone was used not so much as a building stone in construction, as the raw material for making mortar. Ruins of small lime kilns for local use can still be found on both the Valais and the Bernese side.

Rather more than half the Aar massif consists of gneisses and schists. For the inhabitants schist and gneiss used to be important for the construction of walls and roofs. In some places there were strict regulations regarding extracting the slabs for people’s own use.

Amphibolite occurs in the World Heritage Region mainly in the area stretching from the Gross Grünhorn via the Finsteraarhorn to the Unteraar glacier. When amphibolite is broken open it is greenish, but over the course of time weathering produces a markedly dark hue. That has left its trace in the names the locals gave the two neighbouring peaks: Grünhorn and Finsteraarhorn, the former referring to its green colour, the second to its darkness.

In the World Heritage Region the boundary between granite and the surrounding rocks is usually very sharp. Granite, which has been turned light grey by weathering, can be clearly distinguished from the brownishred gneisses and schists. This boundary can be clearly seen in the southern face of the Aletschhorn, but also on the northern slopes of the Lötschen valley from the Lötschenlücke to the Bietschhorn. Many of the best climbing routes in the World Heritage Region are in granite areas.