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.
The orography sketched above explains the great development of the river-systems of Siberia and the uniformity of their course.
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 this alpine region is very imperfectly known; but the chains have a predominant direction from south-west to north-east.
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.