Solid like a Roc de Chère

Lapiaz are limestone rocks characterized by many cracks. Created by the erosion caused by surface water runoff, they point out the presence of an underground karstic network.

Several other lapiaz formations are present in this region: the plateau of Parmelan, the desert of Platé in Passy and Margeriaz in the massif of les Bauges.

Limestone is a sedimentary rock formed by the accumulation of shells and skeletons of marine animals. Temperature and pressure turned the accumulated material into rock.

About -130 to -120 million years ago, Roc de Chère was covered by sea. Fossils of the limestone shells of many organisms were formed at this time on the seabed. The soil of the Roc de Chère at this location is composed by limestone from the Urgonian geological period, rich in fossils.

Further on, as shown in the picture, you can notice limestone with small nummulites, an indication of a different formation period.

Nowadays limestone is present in different forms: chalk on the blackboard, snail shells...

Roc de Chère, a karstic massif, is full of holes in the undergound due to the dissolution of the soluble rocks by running water. Because of this dissolution, it has lots of underground caves, most of which are connected to the lake.
The largest one is Grand Pertuis (see photo), which means crack, narrow passage between rocks. This cave is only accessible by the lake.

Respect the biodiversity of this fragile environment by staying on the tracks.

Facing the Château de Duingt, you can observe the remains of a civilization dating back more than 3000 years before our era. Indeed, the lake of Annecy hides ancient pile-dwelling sites under its water. Wooden piles prove the existence of old dwellings on stilts, built on the current location of the lake of Annecy / built on the shores of the lake of Annecy which water level was then lower than it is today.

Three areas of this type have been identified on the lake of Annecy (two at Sévrier and one at St Jorioz). They are part of the 111 pile-dwelling sites found throughout the Alpine arc and listed as UNESCO World Heritage Sites.

Beyond this beautiful view, you have certainly noticed the circular traces of old millstone extractions in the sandstone slabs. An engraved cross represents the former limit between the territory of the County of Menthon and that of the monks of the abbey of Talloires. During the 17th century, some stones were removed, probably to be used as millstones for grapes, wheat or nuts, to produce wine, flour or oil.

Roc de Chère is composed by two main types of rock : limestone and sandstone.

Sandstone is a sedimentary rock mainly composed of sand-sized silicate grains. It erodes easily, producing a very acidic grey sand that you can observe at the last belvedere.

Vegetation that grows on the sandstone has therefore a high tolerance for acidity. It is strangely similar to the vegetation of the forest of Fontainebleau, which also grows on sandstone.

Sandstone being an impermeable rock, you can observe more than 30 temporary ponds from autumn to spring on Roc de Chère.