GEOMORPHOLOGICAL ZONATION OF BULGARIA. PRINCIPLES AND STATE OF THE ART

The geomorphological zonation of Bulgaria derived from the morphotectonic zonation was first introduced by Cvijic. Although the morphotectonic zonation remained in the basis of the geomorphological and neotectonic maps, during their evolution they included numerous elements typical of the morphostructures and morphosculptures (for the geomorphological maps) and for the evolution of the relief after the formation of the basic peneplain (orthoplain) in the Middle Miocene time (for the neotectonic maps). Emphasis is laid on different aspects, and consequently, geomorphological zonation and maps may be elaborated on different principles chosen in relation to the aims of the maps and to their scales. A geomorphological map (or atlas) in electronic form will contain broad information situated in different layers, thus enabling its use for various purposes. A new approach for the geomorphological zonation of Bulgaria and the Balkan Peninsula is based on the principal fluvial systems and drainage regions related to the sea basins (Black Sea, Marmara Sea, Aegean Sea, Adriatic/Ionian Sea) and their evolution in the Neogene and Quaternary times.