Vietnam: Phong Nha NP – Tower Cones Formations in Hang Va Cave
At the far end of the Hang Va cave is a massive halls with stunning tower cone formations, the only such place in the world, as tower cones like this haven’t been seen in any other cave. The entire large hall on the upper level on the cave consisted of a series of gours or travertine pools, each with a 2m/6ft high walls. Inside each pool are equally tall tower cones. Sureeal! The cone height is the same as the height of the pool walls, which suggests that their formation is related to the water filling the pools to the rim when the cave floods annually for months during the wet season. These are not stalactites and they are not formed by dripping water. Rather, and this is not clear to scientists yet, the standing water generates small floats of calcite rafts (like a film on the water surface), that then sink and form layers of the tower cones (still it’s not clear why these rafts would sink in certain spots and why the cones are so high). It is totally an otherworldly site – over 100 of these tower cones standing like natural terra-cotta army in a dark and wet cave, reachable after hours of technical spelunking. They are covered by a thin layer of mud, but underneath is a hard calcite core with elaborate spiky and bumpy surfaces. Special ladders and metal steps are installed to view the formation as to not damage them and the environment.
