Upper Thracian Lowland

or Maritsa Lowland, low-lying plain in southeastern Bulgaria between the Rhodope Mountains in the south and Sredna Gora in the north. It is about 160 km long and about 40 km wide, with an altitude of 80 to 200 m. It is a downwarp filled with Paleogene (limestone, sandstone) sediments and with a layer of younger fluvial and lacustrine deposits. The sedimentary cover is pierced in places by magmatic rock (for example, the syenitic Plovdiv hills, altitude about 286 m). The climate is transitional between temperate and subtropical. The mean January temperature is 0° C, 0.3° C; the mean July temperature is 23° C, 24° C.

Precipitation is about 500-600 mm a year. The Maritsa River flows across the Upper Thracian Lowland. Chernozem-like soils, smolnitzas, are dominant. Almost all the lowland is plowed. Grapes, tomatoes, pepper, and other vegetables are grown, as are wheat, rice, cotton, and corn. Artificial irrigation is extensively used. There are lignite and gypsum deposits. The large cities of Plovdiv, Pazardzhik, Stara Zagora, and Dimitrovgrad are located on the lowland.