From almost anywhere in the central valleys you'll be able to see the High Caucasus as a long white wall to the north; in many places you'll also be able to see the Lesser Caucasus, to the southwest along the Turkish border. This is a gentler, more rounded range, rising to 3,300m; the Trialeti Ridge, covered in rich pastures and forests, stretches to the outskirts of the capital, Tbilisi. The two ranges of the Caucasus are linked by the very young Suran range, which forms the watershed between the Black and Caspian Seas and separates eastern and western Georgia, Kartli and Kolkhida.    The country is dominated by one main river, the Mtkvari (Kura in Russian; 1,364km in total), which rises in Turkey, enters Georgia near Vardzia, then flows east through Kartli and Tbilisi and then through Azerbaijan to the Caspian. The main river of western Georgia is the Rioni (327km) which flows from the foothills of Racha through Kutaisi to the Black Sea; others are the Inguri (213km) which flows from Svaneti to the Black Sea, the Iori (320km) and Alazani (351km, the longest within Georgia), which flow through Kakheti and into the Mtkvari, and the head waters of the Terek (623km in all) which flows north into Russia and eventually into the Caspian.    The main centres of industry and population lie along an east-west axis, from Rustavi through Tbilisi, Gori, Zestaponi, Kutaisi, Samtredia and Senaki to Poti; the only other major cities are two Black Sea ports, Batumi, near the Turkish border, and Sukhumi, in the secessionist republic of Abkhazia.  .