Lande de Saint-Laurent
The Lande de Saint-Laurent is a heathland in the south of the French department of Haute-Vienne . It is under nature protection , especially because of its geological features .
geography
The Lande de Saint-Laurent, German heathland region of Saint-Laurent , surrounds the hamlet of the same name, Lande de Saint-Laurent . The area is located one kilometer north of the center of La Roche-l'Abeille . It is separated from the village by the valley of the Ruisseau de la Ganne - a small stream - flowing west . The surface of the reserve is 69.58 hectares. Located at the foot of the Monts de Fayat in the middle of the Plateau du Limousin , it is between 360 and 400 meters above sea level. It is clearly distinguished from the surrounding landscape, consisting of pastures and small forests, by its very barren vegetation - caused by the rocky subsoil and its overgrazing by sheep.
geology
The heathland is underlain by a very rare serpentinite , which belongs to the Limousin ophiolite - remnants of the meanwhile almost disappeared ocean of the Massif Central . The formerly ultramafic series of rocks is inserted below the base of the upper gneiss cover in plagioclase-leading paragneiss of the Briance unit , which dip here at 25 ° to the north. The oval-shaped serpentinite lens extends 1,400 meters in an east-northeast and 800 meters in a north-northwest direction. It is cut off on its western edge by a north-east trending lateral shift and therefore comes to rest against a leptynite . A fault also crosses the eastern edge, but it strikes north-northeast.
The serpentinite outcrops of the Limousin run in a discontinuous band from La Porcherie to near Ladignac-le-Long . The deposits near Vayres further to the west - treated under Merlis serpentinites - occupy a different tectonic position, as they occur at the base of the lower gneiss cover .
The reconstructed stratigraphic sequence of the ophiolite from the lying to the hanging wall is as follows:
- layered and isotropic gabbros plus amphibolites
- Wehrlite and a few troctolites
- Dunite with pockets of chromite
- Harzburgite
- Diopside- bearing Harzburgite with rare Lherzolites
It is therefore mainly about peridotites , which only change into gabbros and amphibolites in the hanging wall.
The predominant minerals are antigorite , chrysotile and remains of olivine .
The serpentinite weathers to soils that are very poor in calcium and aluminum , but have very high concentrations of heavy trace elements such as chromium , cobalt and nickel .
The serpentinite used to be mined to extract asbestos .
flora
Numerous plant species that have been adapted to xerophilic locations and are quite rare in the area thrive in the heather . One example is the taxon Notholaena marantae , which belongs to the potted fern family and only thrives on serpentinite. In the heather, however, there are also more classic plant species such as numerous heather and fescue . The lung gentian ( Gentiana pneumonanthe ), the blue star Scilla verna and the black-stemmed striped fern ( Asplenium adiantum nigrum ) are also currently under protection in the Limousin .
fauna
Several species of birds can be found among the notable animal inhabitants of the heather, all of which are protected in France . These include, for example, the nesting taxa Hen Harrier ( Circus cyaneus ), Provence warbler ( Sylvia undata ) and stonechat ( Saxicola rubicola ). The common snipe ( Gallinago gallinago ) is a puller . Also Bunting and Rock Bunting are represented. Notable among the amphibians are the yellow-bellied toad ( Bombina variegata ), which is under national protection and can be found in damp places and in smaller pools, and the natterjack toad ( Epidalea calamita ). Among the grasshoppers, it is worth mentioning Calliptamus barbarus and the Italian beautiful shrimp ( Calliptamus italicus ), which are strictly bound to dry and open locations.
Protective measures
The Lande de Saint-Laurent is under nature protection and forms a continental ZNIEFF of type 1 (the abbreviation stands in French for Zone Naturelle d'Intérêt Écologique, Faunistique et Floristique - nature zone of ecological, faunistic and floristic interest). Also Natura 2000 concerns the heath.
Others
The heather forms part of the French natural heritage. An educational trail with signs in French and Occitan now leads through it , which was set up jointly by the Institut d'études occitanes ( Institute for Occitan Studies ) and the Communauté de communes du Pays de Saint-Yrieix . Reference is made, among other things, to the battle of Bataille de La Roche-l'Abeille , which was fought during the Huguenot Wars in 1569 and which took place in the immediate vicinity, to the Occitan tradition and local customs.
See also
literature
- M. Chenevoy et al .: Notice explicative de la feuille Nexon à 1/50 000 . In: Éditions du BRGM . Orléans 1990.
Individual evidence
- ↑ J. Berger, O. Femenias, JCC Mercier and D. Demaiffe: Ocean-floor hydrothermal metamorphism in the Limousin ophiolites (western French Massif Central): evidence of a rare preserved Variscan oceanic marker . In: Journal of Metamorphic Geology . tape 23 , 2005, pp. 795-812 , doi : 10.1111 / j.1525-1314.2005.00610.x .
- ^ G. Dubuisson, JCC Mercier, J. Girardeau and JY Frison: Evidence for a lost ocean in Variscan terranes of the western Massif Central, France . In: Nature . tape 337 , 1989, pp. 729-732 .
Coordinates: 45 ° 36 ′ 42 ″ N , 1 ° 13 ′ 58 ″ E