a river in the Yakut ASSR, a right tributary of the Indigirka River. Length, 406 km; basin area, 30,200 sq km. The Moma rises from two sources, the Ilin-Iuriakh and Kieng rivers in the Ulakhan-Chistai Range (system of the Cherskii Range), and flows through a broad intermontane valley. The middle and lower courses have rocky rapids. The river is fed primarily by rain. During the winter giant ice sheets form in the Moma valley (for example, Ulakhan-Taryn, 160–180 sq km). There are coal deposits in the basin.

a mountain range in the Yakut ASSR, extending southeast from the middle course of the Indigirka River. It has elevations of 1,600–2,300 m (maximum elevation, 2,533 m, at the arctic circle). The mountain range is composed primarily of sandstones and siltstones. Alpine forms of relief predominate in the axial section; the slopes are strongly dissected by river valleys. Sparse hardwood forests grow to an elevation of 900 m on the northern slopes and to 1,100 m on the southern slopes; at higher elevations there are thickets of dwarf stone pine, alder, willow, and dwarf birches. Above 1,500 m there is mountain tundra. There are numerous ice masses in the valleys.