Vrtača is a geological feature characterized by a deep, cylindrical hole or pit formed by the erosion of rock, often found in karst landscapes. These formations are typically created by the dissolution of soluble rocks like limestone, leading to the collapse of the surface layer. Vrtača can vary in size and depth, and they often serve as important ecological habitats. They may collect rainwater, creating unique microenvironments that support diverse plant and animal species. These features are significant for studying geological processes and biodiversity in karst regions.