A polje (or karst polje) is a large flat plain in karst

KARST

Kilometer-square Area Radio Synthesis Telescope is a Chinese telescope project to which FAST is a forerunner. KARST is a set of large spherical reflectors on karst landforms, which are bowlshaped limestone sinkholes named after the Kras region in Slovenia and Northern Italy. It will consist of...

 territory, with areas usually 5 to 400 km². The name derives from the Slavic languages

Slavic languages

The Slavic languages , a group of closely related languages of the Slavic peoples and a subgroup of Indo-European languages, have speakers in most of Eastern Europe, in much of the Balkans, in parts of Central Europe, and in the northern part of Asia.-Branches:Scholars traditionally divide Slavic...

 and is a cognate with the English word field.

In geology

A polje, in geological terminology, is a large, flat-floored depression within karst limestone, whose long axis develops in parallel with major structural trends and can become several miles (tens of kilometers) long. Superficial deposits tend to accumulate along the floor. Drainage may be either by surface watercourses (as an open polje) or by swallow holes (as a closed polje) or ponor

Ponor

A ponor is a natural surface opening that may be found in landscapes where the geology and the geomorphology is characterized by some kind of karst....

s. Usually, the ponors cannot transmit entire flood flows, so many poljes become wet-season lakes. The structure of some poljes is related to the geological structure, but others are purely the result of lateral dissolution and planation

Planation

Planation is a geomorphological process which creates nearly flat surfaces by fluvial , aeolian and marine processes. The process is erosional and takes millions of years, and its legacy from the tertiary period is present in many of today's landscapes. It has been studied since the 1890's but...

. The development of poljes is fostered by any blockage in the karst drainage.

A polje or karst polje covers the flatbottomed lands of closed basins which may extend over large areas, up to 1,000 km². The flat floor of a polje may consist of bare limestone, of a nonsoluble formation (as with rolling topography), or of soil. A polje typically shows complex hydrogeological characteristics such as exsurgences, estavelle

Estavelle

In karst geology, estavelle is a ground orifice which, depending on weather conditions and season, can serve either as a sink or as a source of fresh water....

s, swallow holes, and lost rivers. In colloquial use, the term "polje" designates flat-bottomed lands which are overgrown or are under cultivation. The Dinaric Karst has many poljes.

They are mostly distributed in subtropical and tropical latitudes but some also appear in temperate or, rarely, boreal regions. Usually covered with thick sediment

Sediment

Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....

s, called "terra rossa", they are used extensively for agricultural purposes.

Some poljes of the Dinaric Alps

Dinaric Alps

The Dinaric Alps or Dinarides form a mountain chain in Southern Europe, spanning areas of Slovenia, Croatia, Bosnia and Herzegovina, Serbia, Kosovo, Albania and Montenegro....

 are inundated during the rainy winters and spring seasons as masses of water called izvor or vrelo appears at the margins. The water disappears through shafts called ponor.

Prominent karst poljes are Livanjsko polje (about 60km long and 7km wide) and Glamočko Polje in Bosnia

Bosnia (region)

Bosnia is a eponomous region of Bosnia and Herzegovina. It lies mainly in the Dinaric Alps, ranging to the southern borders of the Pannonian plain, with the rivers Sava and Drina marking its northern and eastern borders. The other eponomous region, the southern, other half of the country is...

, Popovo Polje in Herzegovina

Herzegovina

Herzegovina is the southern region of Bosnia and Herzegovina. While there is no official border distinguishing it from the Bosnian region, it is generally accepted that the borders of the region are Croatia to the west, Montenegro to the south, the canton boundaries of the Herzegovina-Neretva...

, Logaško, Planinsko Polje and Lake Cerknica

Lake Cerknica

Lake Cerknica is an intermittent lake near Cerknica in Inner Carniola, a region of Slovenia. When full, it is the largest lake in the country. It lies in the southern part of the Cerknica Polje...

 in Slovenia

Slovenia

Slovenia , officially the Republic of Slovenia , is a country in Central and Southeastern Europe touching the Alps and bordering the Mediterranean. Slovenia borders Italy to the west, Croatia to the south and east, Hungary to the northeast, and Austria to the north, and also has a small portion of...

, Nikšićko Polje in Montenegro

Montenegro

Montenegro Montenegrin: Crna Gora Црна Гора , meaning "Black Mountain") is a country located in Southeastern Europe. It has a coast on the Adriatic Sea to the south-west and is bordered by Croatia to the west, Bosnia and Herzegovina to the northwest, Serbia to the northeast and Albania to the...

, Ličko Polje in Lika

Lika

Lika is a mountainous region in central Croatia, roughly bound by the Velebit mountain from the southwest and the Plješevica mountain from the northeast. On the north-west end Lika is bounded by Ogulin-Plaški basin, and on the south-east by the Malovan pass...

, Croatia

Croatia

Croatia , officially the Republic of Croatia , is a unitary democratic parliamentary republic in Europe at the crossroads of the Mitteleuropa, the Balkans, and the Mediterranean. Its capital and largest city is Zagreb. The country is divided into 20 counties and the city of Zagreb. Croatia covers ...

.

The term and its origin

The term has is synonymous with interior valley. The word itself can be found in a number of languages including: French

French language

French is a Romance language spoken as a first language in France, the Romandy region in Switzerland, Wallonia and Brussels in Belgium, Monaco, the regions of Quebec and Acadia in Canada, and by various communities elsewhere. Second-language speakers of French are distributed throughout many parts...

, German

German language

German is a West Germanic language, related to and classified alongside English and Dutch. With an estimated 90 – 98 million native speakers, German is one of the world's major languages and is the most widely-spoken first language in the European Union....

, Greek

Greek language

Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

, Italian

Italian language

Italian is a Romance language spoken mainly in Europe: Italy, Switzerland, San Marino, Vatican City, by minorities in Malta, Monaco, Croatia, Slovenia, France, Libya, Eritrea, and Somalia, and by immigrant communities in the Americas and Australia...

, Spanish

Spanish language

Spanish , also known as Castilian , is a Romance language in the Ibero-Romance group that evolved from several languages and dialects in central-northern Iberia around the 9th century and gradually spread with the expansion of the Kingdom of Castile into central and southern Iberia during the...

 and Turkish

Turkish language

Turkish is a language spoken as a native language by over 83 million people worldwide, making it the most commonly spoken of the Turkic languages. Its speakers are located predominantly in Turkey and Northern Cyprus with smaller groups in Iraq, Greece, Bulgaria, the Republic of Macedonia, Kosovo,...

 (which uses polye). The word polje itself is of Slavic origin (best known as the root for the country Poland

Poland

Poland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...

). English borrows polje directly from the former Yugoslav

Yugoslavia

Yugoslavia refers to three political entities that existed successively on the western part of the Balkans during most of the 20th century....

 languages, Croatian

Croatian language

Croatian is the collective name for the standard language and dialects spoken by Croats, principally in Croatia, Bosnia and Herzegovina, the Serbian province of Vojvodina and other neighbouring countries...

, Serbian

Serbian language

Serbian is a form of Serbo-Croatian, a South Slavic language, spoken by Serbs in Serbia, Bosnia and Herzegovina, Montenegro, Croatia and neighbouring countries....

, Bosnian

Bosnian language

Bosnian is a South Slavic language, spoken by Bosniaks. As a standardized form of the Shtokavian dialect, it is one of the three official languages of Bosnia and Herzegovina....

 and Slovene. The equivalent in neighbouring Macedonian

Macedonian language

Macedonian is a South Slavic language spoken as a first language by approximately 2–3 million people principally in the region of Macedonia but also in the Macedonian diaspora...

 and Bulgarian

Bulgarian language

Bulgarian is an Indo-European language, a member of the Slavic linguistic group.Bulgarian, along with the closely related Macedonian language, demonstrates several linguistic characteristics that set it apart from all other Slavic languages such as the elimination of case declension, the...

 is pole, and in Russian

Russian language

Russian is a Slavic language used primarily in Russia, Belarus, Uzbekistan, Kazakhstan, Tajikistan and Kyrgyzstan. It is an unofficial but widely spoken language in Ukraine, Moldova, Latvia, Turkmenistan and Estonia and, to a lesser extent, the other countries that were once constituent republics...

it is polye.