SAYAN MOUNTAINS  , a range of

Asia, forming the eastern continuation of the Sailughem or Altai range, stretching from 89° E. to ro6° E . Orographically they are the N. border-ridge of the plateau of N.W . Mongolia, and separate that region from Siberia . The geology is imperfectly known . While the general elevation is 7000 to 9000 ft., the individual peaks, consisting largely of granites and metamorphic slates, reach altitudes of Io,000 ft. and 11,450 ft., e.g. in Munko Sardyk; while the principal passes lie 6000 to 7500 ft. above the sea, e.g . Murtagh 7480 ft., Mongol 6500 ft., Tenghyz 7480 ft. and Obo-sarym 61oo ft . In 92° E. the system is pierced by the Bel-kem or upper Yenisei, and in Io6°, at its eastern extremity, it terminates above the depression of the Selenga-Orkhon valley . From the Mongolian plateau the ascent is on the whole gentle, but from the plains of Siberia it is much steeper, despite the fact that the. rave is masked by a broad belt of subsidiary ranges of an Alpine character, e.g. the Usinsk, Oya, Tunka, Kitoi and Byelaya ranges . Between the breach of the Yenisei and the Kosso-gol (lake) in Too° 30' E. the system bears also the name of Yerghik-taiga . The flora is on the whole poor, although the higher regions carry good forests of larch, pitch pine, cedar, birch and alder, with rhododendrons and species of Berberis and Ribes . Lichens and mosses clothe many of the boulders that are scattered over the upper slopes .