of inland drainage or are the result of limestone erosion. Most of the basins take their names from cities or towns located at their rims. Where a lake has formed within the basin, the water body is usually saline as a result of the internal drainage—the water has no outlet to the sea. Eastern Anatolia Region Eastern Anatolia, where the Pontic and Anti-Taurus mountain ranges converge, is rugged country with higher elevations, a more severe climate, and greater precipitation than are found on the Anatolian Plateau. The western part of the Eastern Anatolia Region is known as the Anti-Taurus, where the average elevation of mountain peaks exceed 3,000 meters; while the eastern part of the region was historically known as the Armenian Highland and includes Mount Ararat, the highest point in Turkey at 5,137 meters. Many of the East Anatolian peaks apparently are recently extinct volcanoes, to judge from extensive green lava flows. Turkey's largest lake, Lake Van, is situated in the mountains at an elevation of 1,546 meters. The headwaters of three major rivers arise in the Anti-Taurus: the east-flowing Aras, which pours into the Caspian Sea; the south-flowing Euphrates; and the south-flowing Tigris, which eventually joins the Euphrates in Iraq before emptying into the Persian Gulf. Several small streams that empty into the Black Sea or landlocked Lake Van also originate in these mountains. In addition to its rugged mountains, the area is known for severe winters with heavy snowfalls. The few valleys and plains in these mountains tend to be fertile and to support diverse agriculture. The main basin is the Muş Valley, west of Lake Van. Narrow valleys also lie at the foot of the lofty peaks along river corridors. Southeastern Anatolia Region Southeast Anatolia is south of the Anti-Taurus Mountains. It is a region of rolling hills and a broad plateau surface that extends into Syria. Elevations decrease gradually, from about 800 meters in the north to about 500 meters in the south. Traditionally, wheat and barley were the main crops of the region, but the inauguration of major new irrigation projects in the 1980s has led to greater agricultural diversity and development. Geology Turkey's varied landscapes are the product of a wide variety of tectonic processes that have shaped Anatolia over millions of years and continue today as evidenced by frequent earthquakes and occasional volcanic eruptions. Except for a relatively small portion of its