The double river-systems of the Volga and Kama, the Ob and Irtysh, the Angara and Yenisei, the Lena and Vitim on the Arctic slope, and the Amur and Sungari on the Pacific slope, are instances.
Some of the deposits appear to be of Permian age, but others are probably Jurassic; and they are all included under the general name of the Angara series.
Here again there are no marine beds of Mesozoic or Tertiary age, while plant-bearing deposits belonging to the Angara series are known.
The formation of this and of the other great mountain chains of central Asia resulted in the isolation of portions of the former central sea; and the same forces finally led to the elevation of the whole region and the union of the old continents of Angara and Gondwana.
Above the level of the Angara at Irkutsk (Zapiski Russ.
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.
Its only outflow is the lower Angara, which issues through a rocky cleft on the west shore.
After approaching its south-west extremity it abandons the broad valley which leads to the lake, and makes its way northwards through a narrow gap in the mountains and joins the Angara at Irkutsk.
It stretched westwards into the valley of the Irkut, and up the lower valleys of the Upper Angara and the Barguzin.
The principal port on the western shore, Listvinichnoe, near the outflow of the Angara, is an open roadstead at the foot of steep mountains.
Attempts are being made to render the Angara navigable below Irkutsk down to the Yenisei.
4 and 5); Dybowski and Godlewski on "Fauna," in same periodical (1876); Witkowski, on "Seals"; Yakovlev's "Fishes of Angara," in same periodical (1890-1893); "Fishing in Lake Baikal and its Tributaries," in same periodical (1886-1890); and La Geographie (No.
They are named the Usinsk Mountains in West Sayan and the Tunka Alps in East Sayan; the latter, pierced by the Angara at Irkutsk, are in all probability continued north-east in the Baikal Mountains, which stretch from Irkutsk to Olkhon Island and the Svyatoi Nos peninsula of Lake Baikal, thus dividing the lake into two parts.?
Examples are the Ob and the Irtysh, the Yenisei and the Angara (itself a double river formed by the Angara and the Lower Tunguzka), the Lena and the Vitim, the Argun and the Shilka, while the Amur in its turn receives a tributary as large as itself - the Sungari.
The Upper Tunguzka, known also as the Angara, drains Lake Baikal, and is navigable from Irkutsk.
After the confluence of the Angara, the stream continues to widen out to 30 m., its bed being littered with islands until it breaks into its delta (240 m.
As Lake Baikal is approached the stream of Russian immigration becomes narrower, being confined mostly to the valley of the Angara, with a string of villages up the Irkut; but it widens out again in Transbaikalia, and sends branches up the Selenga and its tributaries.
On the Yenisei steamers ply from Minusinsk to Yeniseisk, and to Ghilghila at its mouth; on its tributary, the Angara, of which some rapids have been cleared, though the Padun rapids have still to be rounded by land; and on the Selenga.