Cave Raft Landscape
A travertine film or membrane on the water surface inside a karst cave is called a cave raft or a calcium film, and the scenery composed of these films is called a cave raft landscape. These calcium films are composed of micro-calcite grains released from the over-saturated cave bottom solution. They look like a thin membrane, are less than 1 mm thick and float on the pool water like thin floating ice. When their thickness increases to the point exceeding the buoyancy, they sink to the bottom in flakes.