The Stara Planina (Balkan Mountains) cover a total area of 11,600 square kilometres, almost one tenth of Bulgaria’s total land mass, and stretch right across the country from the Serbian border in the west to the Black Sea in the east. As a whole, the range comprises a large number of individual, yet closely associated massifs. However, a distinct main ridge can be delineated, which stretches for 530 kilometres from the Belogradchik Pass to Cape Emine, with an average width of between 15 and 50 kilometres. Although the average altitude of the range is only 722 metres, twenty-nine of its peaks top 2000 metres.The name Stara Planina literally means 'Old Mountains', yet despite this title, they are in geological terms, the youngest mountain range in Bulgaria. The Stara Planina (Balkan Mountains) are on one of the so-called “new fold-mountains” that were uplifted as part of the Alpine-Himalayan system during the Tertiary period. The ancient core of the range mainly consists of Palaeozoic crystalline schists, often interspersed with granites. However, it is only in higher parts of the Western Stara Planina (Western Balkans) and Central Stara Planina (Central Balkans) that these break through to the surface. Elsewhere they have been outflanked by younger Mesozoic rocks, predominantly limestones, sandstones and marls. Due to their comparatively modest altitude, the Stara Planina (Central Balkans) were not subject to the effects of galciation during the Quaternary period, and thus lack many of the most striking features associated with typical alpine terrain. Instead, in many places, the range has been gradually eroded into a broad, rolling ridge of rounded summits and shallow saddles.
