Raft-Crystal Cone Landscape

A raft-crystal cone is a karst cave depositional crystal cone that grows on a calcite membrane and gets its name from its appearance. It is a composite deposit of water dripping and pool sedimentation. Its formation process is as follows: Upon the impact of dripping water, the cave raft (calcite film or membrane) on the surface of the pool water breaks into fragments and precipitates to the pool bottom to form a fixed-point heap underneath the water. After precipitation, the calcite film in the water attaches to crystals, which further build up the calcite pile, and this heap further facilitates crystallisation in the water. This interactive process forms more symmetrical cone-shaped stalagmites underwater. These cones are found in Chushui (Pouring Water) Cave in Gongcheng and in Bama Crystal Palace and Wanhua Cave in Chenzhou, Hunan Province (Figs. 1 and 2).

Fig. 1

(a) Raft crystal pool (b) I, II & III deposition of raft crystal cone; a. underwater crystal cone; b. raft formation on...