Arid land at ââ¬ÂPaclele Miciââ¬Â natural reservation in Romania. The Berca Mud Volcanoes from ââ¬ÂPaclele Miciââ¬Â are a geological and botanical reservation located in the Berca, in Romania. Its most spectacular feature is the mud volcanoes, small volcano-shaped structures typically a few meters high caused by the eruption of mud and natural gases.