Causse is an Occitan word which means limestone plateau, the geology formed by erosion via the chemical dissolution of layers of soluble limestone. Surface water is very limited because the rain that falls drains away quickly, finding its way into fissues thereby creating subterranean passages. In this limestone country the rivers run deep underground.
Criss-crossed by dry stone walls, covered in small oaks, maples of Montpelier and juniper, the land is rugged, often with the limestone exposed on the surface.
Distinctive surface features include rocky uplands suitable only for sheep farming and hunting, dry valleys known as combes with relatively fertile soil suitable for growing cereals or vegetables, potholes, and deep circular or elliptical depressions known as dolines. Dolines can vary in depth from several metres to hundreds of meters, with fertile soil in the bottom.
The sheep are a special, hardy breed, called Caussenardes. They appear to wear 'lunettes' or dark glasses. Goats also abound in the area, and a special small, round, white cheese called a 'cabecou' is the local speciality. Goats also abound in the area and a special small, round, white cheese called a 'cabecou' is the local speciality.
The causse is typical of the landscape of Quercy, covering approximately two-thirds of the department. The Parc naturel régional des Causses du Quercy has been created to safeguard and promote this natural resource.
The causse of Gramat stretches from the river Dordogne southwards towards Cahors. On the north side of the river, the limestone area around Martel is known as the causse of Martel and extends northwards beyond Cressensac and almost to Brive. A sign on the Autoroute A20 "Le causse Corrèzien" marks the edge of the causse just south of Brive.
A swallow hole or aven, a typical feauture, is often very deep and in the shape of an upturned funnel with steep sides, opened on the surface of the limestone by erosion and leading to underground caves and streams. The gouffre de Padirac is formed from a swallow hole where the ground underneath has collapsed to reveal a deep cylindrical hole in the ground, connected to passages leading to an underground stream. The water from the gouffre of Padirac emerges from the ground at the foot of the cliffs in Montvalent.
Lacs de Saint-Namphaise are watering holes or ponds carved in big solid slabs of limestone on the surface of the plateau. There are hundreds of such watering holes on the causses of Quercy, named after an officer of Charlemagne who abandoned the war to live the life of a hermit on the causses where, according to legend, he dug these watering holes. Generally rectangular in form they are fed by rainwater and rarely by a spring. In a region where water is rare they are indispensable for the life of humans and their livestock.
These days the lacs de Saint-Namphaise are used less by herds of sheep. But they are still essential for wildlife, such as small mammals and birds who come to drink, bathe and feed. Many species of reptiles, amphibians and insects reproduce and frequent these valuable sources of water.