In the north is the municipality of Wildflecken. From there the natural region's boundary with the Kreuzberg Group runs east-southeast along the valley between the Feuerberg and Kreuzberg in order finally to follow the Kellersbach after the Guckas Pass. North of Langenleiten the boundary runs southwards in order to leave the valleys of the tributaries of the Kleiner Steinach. Continuing westwards, the boundary of the natural region runs through the villages of Platz and Geroda. Between the Kellersbach and Geroda the Black Mountains border on the Adelsberg Forest, part of the Schondra-Thulba-South Rhön, which in turn is part of the Hammelburg South Rhön. The latter is part of the South Rhön which in turn belongs to the major natural region unit of Odenwald, Spessart and South Rhön, which is part of the South German Scarplands and not the Central Uplands. The natural regional boundary with the Brückenau Kuppenrhön, which is part of the Kuppenrhön, follow the Milzbach as it flows north past Schildeck. After its confluence with the Sinn the boundary follows the river downstream heading northwards. North of Oberbach the region is bounded by the Dammersfeld Ridge to the west as far as Wildflecken.
Geology
As well as the Black Mountains, the Southern High Rhön also includes the Kreuzberg Group and the Dammersfeld Ridge. All three mountain ridges consist of a basalt shield, which is occasionally intruded, and thus are different from Long Rhön and, to a lesser extent, the Wasserkuppenrhön, even if they clearly differ from the individual summits of the Kuppenrhön. In terms of its rock composition, the region compares to the Kreuzberg Group. The Black Mountains consist of two mountain ridges, which are formed of individual domed summits or kuppen. The basement is formed of red clays and marls overlaid by rocks of the Lower Muschelkalk. The summits are mostly composed of basalt. In most places the rock s covered by a layer of loam soil.
The natural region is drained to the east by the Thulba and Aschach into the Franconian Saale. No noteworthy streams flow into the Sinn. In 1968, at the time of the publication of Sheet 140 "Schweinfurt", the annual precipitation was 1000–1100 mm, on 90–110 days of the year there was a continuous layer of snow. In addition, extensive pastures characterised the area and there were deciduous woods on the mountainsides. Since then, over half the area has become colonised by coniferous forest.
