Besides the Bokovoi Khrebet several other short subsidiary ranges branch off from the main range at acute angles, lifting up high montane glens between them; for instance, the two ranges in Svanetia, which divide, the one the river (glen) Ingur from the river (glen) Tskhenis-Tskhali, and the other the river (glen) TskhenisTskhali from the rivers (glens) Lechkhum and Racha.Down all these glens glacier streams descend, until they find an opportunity to pierce through the flanking ranges, which they do in deep and picturesque gorges, and then race down the northern slopes of the mountains to enter the Terek or the Kuban, or down the southern versant to join the Rion or the Kura.
The Rion is the Phasis of the ancients and flows through the classic land of Colchis, associated with the legends of Medea and the Argonauts.
Arid upland plains and parched hillsides take the place of the rich verdure and luxuriant arborescent growth of Imeretia, Svanetia and Mingrelia, the districts which occupy the valleys of the Ingur and Rion and the tributaries of the latter.
M.), may be divided into four natural zones or sections: - (i.) the plains north of the Caucasus mountains, comprising the administrative division of Northern Caucasia; (ii.) the Caucasus range and the highlands of Daghestan; (iii.) the valleys of the Rion and the Kura, between the Caucasus range and the highlands of Armenia; and (iv.) the highlands of Armenia.
This line of heights separates the basins of the Chorokh and the Rion (Black Sea) from those of the Aras and the Kura (Caspian Sea).
In both orographical systems the principal rivers start nearly all together from a central nucleus, and in both cases they radiate to opposite quarters of the compass; but whereas in the Alps the Rhone and the Rhine, flowing south-west and north-east respectively, follow longitudinal valleys, and the Aar and the Ticino, flowing north-west and south-east respectively, follow transverse valleys, in the Caucasus the streams which flow south-west and north-east, namely, the headwaters of the Rion and the Terek, travel along transverse valleys, and those of the Kura and the Kuban, flowing south-east and north-west respectively, traverse longitudinal valleys.
This was notably the case with the claim of Russia to Poti and the valley of the Rion (Phasis), which was still outstanding at the time of the congress of Vienna (1814-1815) and prevented the question of a European guarantee of the integrity of Turkey from being considered.