Its level is subject to slight oscillations, and after a heavy five weeks' rain in 1869 it rose 7 ft., an immense territory at the mouth of the Selenga being submerged.
The surface-layers of this immense basin are heated in the summer up to temperatures of 55z° to 57° F., both close to the shores and at some distance from the mouth of the Selenga; but these warmer layers are not deep, and a uniform temperature of nearly 39° F.
Lake Baikal receives over 300 streams, mostly short mountain torrents, besides the Upper Angara, which enters its north-east extremity, the Barguzin, on the east, and the Selenga on the south-east.
With the exception of the delta of the Selenga, Lake Baikal is surrounded by lofty mountains.
Steamers ascend this river as far as Bilyutai, near the Mongolian frontier, and bring back tea, imported via Kiakhta, while grain, cedar nuts, salt, soda, wool and timber are shipped on rafts down the Khilok, Chikoi and Uda (tributaries of the Selenga), and manufactured goods are taken up the river for export to China.