The New International Encyclopædia/Zirknitzer See

ZIRKNITZER SEE, tsĭrk'nĭts-ẽr zā, or CZIRKNITZER SEE. A small lake in Carniola, Austria, 28 miles northeast of Triest (Map: Austria, D 4). It lies in a depression of the limestime plateau known as the Karst (q.v.), and exhibits some of the most remarkable features of Karst phenomena. The lake, which under ordinary conditions has an area of about 10 square miles and a mean depth of 20 feet, communicates through a number of openings with a series of subterranean reservoirs or caverns, some of which are above the lake-level in the surrounding hills. In the autumn, when the rainfall is slight, the lake is completely drained into the reservoirs lying below its level, and its bed is speedily covered with rich herbage. With the returning heavy rains the surrounding higher reservoirs are filled and discharge suddenly through the subterranean passages into the lake, so that the latter very rapidly regains its ordinary volume and may even inundate the surrounding country. The changes in level are, however, very irregular. Sometimes the lake does not disappear for several years, and once, in 1834-35, it remained dry for over a year. It is rich in fish, which disappear and return with the water.