Djibouti lies in a hot, arid area of the Horn of Africa. Its area is 8,960 square miles. The soil is rocky and sandy and lies on volcanic layers. In the hot and humid climate, rainfall is very low. Most of the soil is not suitable for agriculture, and only about 10 percent is used as pasture. The vegetation consists mainly of desert shrubs and acacia trees. There are only a few patches of perennial forest. The traditional mode of life was nomadic pastoralism, in which state borders were not recognized. Fishing in the Red Sea provides a limited source of income; horticulture is possible only on a small scale.The Bay of Tadjoura cuts into the country from the Gulf of Aden. The terrain is mainly a desert like plain with some intermediate mountain ranges near Arta and the eastern border. There is one active volcano. There are seasonal streams that flow toward the sea or into the two salt lakes. Apart from Djibouti City, the capital and large urban center, there are a few small towns: Tadjoura, Obock, Dikhil, Ali Sabieh, and Yoboki.