The orography sketched above explains the great development of the river-systems of Siberia and the uniformity of their course.
The first great result of recent geogra phical research has been to modify pre-existing ideas of results vestigate the orography of the vast central region represented by in.
Little is known of the orography of the eastern peninsula.
The orography of the Aldan region is little known; but travellers who journey from the Aldan (tributary of the Lena) to the Amur or to the Sea of Okhotsk have to cross the same plateau and its border-range.
The orography of Portugal cannot be scientifically studied except in relation to that of Spain, for there is no dividing line between the principal Portuguese ranges and the highlands of Galicia, Leon and Spanish Estremadura.
The break in the continuity of the Alpine chain marked by the deep valley, the Vintschgau, of the upper Adige (Etsch) is one of the most remarkable features in the orography of the Alps.
Its orography and geological structure are imperfectly known.
Among his other works may be named Paroles d'un revolte (1884); La Conquete du pain (1888); L' Anarchic: sa philosophie, son ideal (1896); The State, its Part in History (1898); Fields, Factories and Workshops (1899); Memoirs of a Revolutionist (1900); Mutual Aid, a Factor of Evolution (1902); Modern Science and Anarchism (Philadelphia, 1903); The Desiccation of Asia (1904); The Orography of Asia (1904); and Russian Literature (1905).
For orography and geology see an article by P. Verri in Boll.
In order to appreciate the orography of the island the following sections of Sumatra should be discriminated one from another: (1) The valley of the Achin or Atjeh River.