Bats use SONAR (Sound Navigation & Ranging).Sonar is a technique that uses sound propagation to navigate, communicate with or detect objects on or under the surface of the water, such as other vessels.
Impact crater is a type of impact landform formed due to collision of astronomical objects. Impact crater is a circular depression formed by the hypervelocity impact of a smaller body. Impact craters should not be confused with landforms like sinkholes, glacial cirques which are different in composition and origin from the impact crater.
Karst landforms are a type of topography formed due to dissolution of soluble rocks like limestone, dolomite and gypsum.Poljes also called as karst fields or karst polje are large flat plains found in karst regions. The word Polje means ‘field’. They are flat floored depression within karst limestone.