Endodynamic determination and rearrangement of valley systems in Bulgaria at the Pliocene-Quaternary boundary

Abstract

Valleys are an important relief element. Valley systems include genetically and dynamically connected valleys of different taxonomic rank and order. The regional and local endodynamic features are reflected in their plan outlines and configuration. Centers of valley divergence and convergence are formed morphologically. The present work considers these phenomena in Bulgaria at the Pliocene-Quaternary boundary. The Fore-Carpathian basin was entirely annihilated at that time, the Black Sea basin was extensionally opened and the Mediterranean basin was also subjected to changes. Regional erosion bases were changed. The formation and orientation of almost all the big rivers was influenced by the linear tectonic structures. The main watershed at the Balkans (in the Bulgarian territory) was stable with small exceptions, its line being broken by tectonic deformations. The space between the valley systems was more dynamic. As a result, the position of the secondary and tertiary watersheds was changed. New centers of valley divergence and convergence were created. Many new data about the geodynamics of the Bulgarian territory are presented.