tributary of the Orange River in southeastern Africa. It rises in the Drakensberg, on the Lesotho–South Africa border, and flows generally southwest, forming most of the boundary between Lesotho and Free State province, South Africa. Maseru, capital of Lesotho, lies on the river. The Caledon leaves Lesotho near Wepener, Free State, and flows through southeastern Free State to join the Orange River near Bethulie after a course of 300 miles (480 km). Its valley has one of the greatest temperature ranges in South Africa and is a prolific corn- (maize-) producing area.