structural:expansion, linguistic:voice_change
Geography

The Balkan Mountains are, technically, a chain of fold mountains —mountains formed by the compression and breaking of layers of rock. On a geological time scale, they are a rather young and recently formed part of the Alp-Himalayan chain which stretches across most of Eurasia. The Balkan Mountains can be divided into two parts—the main Balkan Chain and the Pre-Balkans (Fore-Balkan) to the north, which extend slightly onto the Danubian Plain. To the south, the mountains border the Sub-Balkan valleys, a row of 11 valleys running from the Bulgarian-Serbian border east to the Black Sea, separating the Balkan Mountains from a chain of other ranges known as Srednogorie (which includes Vitosha and Sredna Gora).

The Balkan Mountains consist of around 30 distinct peaks; within Bulgaria, the range can be divided into three sections: