Cinematic 4K 60 fps. Mossy cave wall in yellow and green color tones. A cave is a hollow place in the ground, specifically a natural underground space large enough. Caves form naturally by the weathering of rock and often extend deep floor. Stalactite stalagmite wall dark calcium carbonate precipitation sedimentation layer parallel crust physical characteristics beneath type horizons defined by obvious features texture well stone deposition collapse fall decline downfall mainland continent sphere terrestrial globe terra geological geology geologic round stones crushed angular big size curved crushers gravel by processes of rounded bedrock shape land horizontal precipitate pit residual hole tailings sedimental streambed profile breaking down UHD 3840X2160