polje

Polje is a term used in karst geology to describe a large, flat-floored depression within karst terrain. The word comes from South Slavic languages where polje means field. In the Dinaric Karst of the Balkans, poljes are among the region’s most distinctive landforms, often tens of kilometers long and several kilometers wide, bounded by steep hills or limestone ridges and surrounded by uplands.

Poljes form through a combination of tectonic subsidence and extensive dissolution of soluble rocks, followed by sediment infill that creates a broad, flat floor. They typically exhibit internal drainage, with most streams disappearing into ponors or subterranean channels and surface water often seasonal. The floor is commonly covered by alluvial, lacustrine, or loess-like sediments and may host marshy areas, temporary lakes, or wetlands.

Hydrology in poljes is complex: groundwater flows are connected to large karst springs at the margins, and surface streams may be ephemeral. The high permeability of the floored area, together with periodic water input from springs, supports varied land use. Human settlements and agriculture are typically concentrated along the polje margins rather than on the wide, flat interior.

Notable examples include Livanjsko polje in western Bosnia and Herzegovina and Croatia, and Imotsko polje near the Dalmatian coast. Beyond geology, the term polje is also used in Slavic languages to merely denote a field or plain, and appears in numerous geographic place names within karst regions.