The largest central European raised bog areas are the southern North Sea coastal area and the Alpine Foreland. As in North America there is a succession of raised bog types along the line of descent towards the ocean, from northwest to southeast. As a result of peat use, raised bogs have been harvested for peat and cultivated, apart from a few remnants (less than 10% of the original area). The largest contiguous raised bog in central Europe was the Bourtange Moor, which originally covered an area of about 2,300 km² including the Dutch portion, but only small sections remain. The largest remaining raised bog in northern Europe is the 76 km² Lille Vildmose. Other large raised bogs are the Teufelsmoor northeast of Bremen, the Vehnemoor (exhausted) and the Esterweger Dose (formerly about 80 km², exhausted) between Oldenburg and Papenburg. The raised bogs of the Central Uplands of the Harz, Solling, Thuringian Forest (Großer Beerberg, Schneekopf - Teufelsbad, Fichtenkopf, Saukopf), Giant Mountains, Ore Mountains, Fichtel and Rhön (Black Moor, Red Moor) are, by contrast, comparatively small. In the Black Forest the Wildseemoor has been protected and, in the Vosges on le Tanet, north of the Col de la Schlucht a large area has been protected. The Alpine Foreland, which was formed by ice-age glaciation, is also rich in peatland. The Wurzacher Ried (Haidgauer Regenmoorschild) is considered the largest and best preserved raised bog in central Europe. Other raised bogs and peatland areas include the Federsee, the High Fens on the Germano-Belgian border, the Ewiges Meer near Aurich and the Lengener Meer near Wiesmoor. In 2003, Estonia exported 3.6 million m³ of peat for west European garden use, more than 60% of the state production. In Lithuania 60% of the usable peat area has been prepared for extraction or is already exhausted.