THE BALKAN STATES 1 topographical features of the region which is known as the Balkan Peninsula are very irregular. On the west, the Dinaric Mountains, which are formed by a continuation of the Alpine fold, run from the Austrian lands on the Adriatic, south-east and south through Montenegro and Albania into Greece. These moun tains, which consist of numerous parallel ranges, are formed of limestone, which has in places, and especially in Greece, been affected by metamorphic action. Their average height is over 4,000 feet, and they present considerable barriers to communica tion, as they have been deeply cut into by rivers, which generally follow the direction of the folds. In the north-east of the Peninsula are the Balkan Mountains, which continue the fold lines of the Carpathians. From the Danube, they strike southwards, with an average height of 1,000 feet, and then curve round towards the east, where, for a considerable distance, they run with an average height of 5,000 to 6,000 feet. In the first part of
their course they consist of crystalline rock, but further east they appear to be mainly sedimentary. Between the Dinaric range and the Balkans lies the ancient crystalline mass of the Thraco-Macedonian region, the topography of which is very irregular. It contains high mountain masses like the Shardagh and the Rhodope, open highlands like those of Old Servia and Macedonia, enclosed lake basins like Monastir, river valleys like those of the Vardar and the Struma, and large plains like Thessaly and Thrace. The rivers can best be spoken of in connection with communications in determining the main lines of which they play an important part.