The zonation that extends east and west is very clear; from north to south there extend Sanbagawa Belt, Chichibu Belt and Shimanto Belt, the northernmost belt is the oldest and the southernmost belt is the youngest; and around the belts are Tanabe Group and Kumano Group which were formed in the Cenozoic era.
東西方向の帯状配列が顕著で、北から南に向かって三波川帯、秩父帯、四万十帯と古から新へ配列し、その周辺に新生代の田辺層群および熊野層群が分布する。