These openings are usually the sandy beds of dried-up or intermittent affluents, such as the Bak, Ham, Houm, Aub (or Great Fish) rivers of Great Namaqualand.
The best known in this section are the three Baksan passes of Chiper (io,800 and 10,720 ft.), Bassa (9950 ft.) and Donguz-orun (10,490 ft.), south of Elbruz; those of Becho (11,070 ft.), Akh-su (12,465 ft.), Bak (10,220 ft.), Adyr-su (12,305 ft.) and Bezingi (10,090 ft.), between Elbruz and Dykh-tau; and those of Shari-vizk (11,560 ft.), Edena, Pasis-mta or Godivizk (11,270 ft.), Shtulu-vizk (10,860 ft.), Fytnargyn (11,130 ft.), between Dykh-tau and Adai-khokh; the Bakh-fandak (9570 ft.), between Adai-khohk and Kasbek; and the two Karaul passes (11,680 and 11,270 ft.) and Gurdzi-vizk (10,970 ft.), connecting the valley of the Urukh with that of the Rion.
This model is particularly illustrative of Bak's ideas and the theory of SOC.