The major mountain system is the eastward extension of the Central Asian Altai Range. A volcanic zone exists along Mongolia's northern boundary with Russia. Most of the rivers and streams disappear into salt lakes, marshes, or desert sand, though a few major streams and rivers in the north flow into Siberia and empty eventually into Lake Baikal. A varied and interesting animal and bird life inhabit the many lake areas, especially those in the northwest. Mongolia's climate is continental.
Winters are long, cold, and dry.
Summers are hot, though the heat is tempered by occasional precipitation. There is great fluctuation in temperature on a seasonal as well as daily basis. Plants and animals of the country reflect the extreme climatic conditions. In the northern and western mountains are found forests of such northern deciduous and coniferous trees as birch, aspen, poplar, larch, cedar, spruce, and pine. Grasses are common in the steppe zone and plain, and these give way to desert plants or little vegetation in the Gobi.