The Balkan Mountains, the extension of the Carpathians, divide Bulgaria into two sections differing in relief, soil, climate, products, and type of population. North of the mountains an uplifted plateau slopes gradually toward the Danube and breaks off abruptly in a wall of loess and limestone about 500 feet high facing the river. This wall or cliff presents a remarkably sharp contrast to the very flat plains and broad swamps along the Rumanian side of the river. At the top of the cliff the plateau is quite flat, and is covered with fertile loess, but it is broken into many small sections by deep, steepsided valleys where the streams have entrenched themselves.
There is a strong contrast between the valley bottoms with their narrow but level, well-watered, and fertile plains, and the uplands with their far broader stretches of soil which is also fertile but which is dry and poorly watered. The valleys are full of villages, and in them lie the small cities; the surrounding valley floors are devoted to corn and to crops like lucerne, sugar beets, vines in some sheltered spots, and vegetables like tomatoes and peppers which are very important among people whose main food is so tasteless a product as corn. From the villages in the valley the peasants climb long distances to their wheatfieds on the plateau above. Although the individual fields up there are small, the general effect is of one vast field of wheat and corn, or perhaps barley, unbroken by trees or houses, except at long intervals. The wheat is sold as a money crop and is consumed in the towns or exported; the cheaper and less easily transported maize is eaten in the villages. A similar situation prevails very widely in most of the countries of Europe, although the product eaten at home may be rye, potatoes, or even oats, rather than corn.
The contrast between the valleys and the plateau is the joint result of relief and climate. The general climate is like that of the Wallachian Plain of Rumania north of the Danube. The winters are cold; and strong, disagreeable, dusty winds are common. The summers are warm, averaging above 70° F. in July, and most of the rain falls in early summer. The eastern section is too dry for crops and is therefore largely devoted to sheep, but in the western section and along the mountains the rainfall is heavier. The porous character of the loess and limestone combine with the pronounced drop in the rainfall in August and September to make it hard to get water at all seasons on the plateau. The valleys, however, have plenty of springs, and they are also protected from the bitter, dusty winds of winter. So it is not strange that the people prefer to live there in spite of the long walk to the fields. Cattle are kept mainly for draft purposes, dairying is little developed, and dung is so often used for fuel that the value of the animals as a help in agriculture is much reduced.
The population of the plateau, including of course its valleys, is relatively dense. It produces a surplus of grain that is exported from the Danube harbors, of which Ruschuk is the most important, or from Varna, the northern Bulgarian harbor on the Black Sea. The plateau is the old center of the Bulgarian race, where they settled on their first arrival during the time of the Hungarian invasion, and whence they advanced toward the south. Here again was the cradle of their movement for independence in the nineteenth century.