At the neotectonic stage the Western Caucasus developed as an accreting mega-arch complicated with a system of superimposed horsts and grabens, different in age and in order and oriented both along and across the arch's axis. The block structure was alternately activated at different stages. The river network readjusted itself to the changing differentiation. Transversal valleys more likely use tranversal grabens than develop as watergaps resulting from general migration of the main water divide.