Sea Region The physical geography of the Black Sea Region landscapes is characterized by the mountain range forming a barrier parallel with the Black Sea Coast and high humidity and precipitation. The Eastern Black Sea Region presents alpine landscapes with steep and densely forested slopes. Steep slopes, as a morphological feature, occur both under the sea, and in the mountain ranges, with the sea floor at below 2000 m along a line from Trabzon to the Turkish–Georgian border, and the mountains quickly reaching over 3000 m, with a maximum of 3971 m in Kaçkar Peak. The parallel valleys running north to the Black Sea used to be isolated from one another until a few decades ago because the densely forested ridges made transportation and exchange very difficult. This allowed for the development of a strong cultural identity— the Laz language, music and dance—linked to this specific geographic context. From west to east, the main rivers of the region are the Sakarya (824 km), the Kızılırmak River (1355 km, the longest river of Turkey), the Yeşilırmak (418 km) and the Çoruh (376 km). Year-round high precipitations—varying from 580 mm/year in the west to more than 2200 generate dense forests, with oak, beech family trees, hazel (Corylus avellana), hornbeam (Carpinus betulus) and sweet chesnut (Castanea sativa) prevailing. Isolated from one another because of steep valleys, the Black Sea Region includes 850 plant taxa of which 116 is endemic to the area, and of which 12 are endangered and 19 vulnerable. Hazelnut is a native species for this region, which covers 70 and 82% of the world's production and exports respectively. The Kaçkar Range at altitudes of 3000 m and above is heavily glaciated (see map on the right) owing to the suitable geomorphological- climatological conditions during the Pleistocene. Marmara Region The European portion of Turkey consists mainly of rolling plateau country well suited to agriculture. It receives about 520 millimeters of rainfall annually. Densely populated, this area includes the cities of Istanbul and Edirne. The Bosphorus, which links the Sea of Marmara and the Black Sea, is about twenty-five kilometers long and averages 1.5 kilometers in width but narrows in places to less than 1,000 meters. There are two suspension bridges over the Bosphorus, both its Asian and European banks rise steeply from the water and form a succession of cliffs, coves, and nearly landlocked bays. Most of the shores are densely