CAUCA, a department of Colombia, South America, lying on the Pacific coast. Pop. (1928) 317,782; area 20,403 sq.m. The Western Cordillera, traversing nearly its whole length from south to north, and the Central Cordillera, forming a part of its eastern frontier, give a very mountainous character to the region. It in cludes, besides, the fertile and healthful valley of the upper Cauca, and a part of the coastal plain. The region is rich in mines and valuable forests, but its inhabitants have made very little progress in agriculture because there are not adequate transportation facili ties. The capital of the department is Popayan, pop. (1928) 31,829.