The tour leads visitors along the subterranean course of the Orbe (an outflow from the Vallée de Joux), passing by stalactites, stalagmites, drip-stone formations, columns and galleries. Once upon a ...

If such a highly porous rock have a space underneath, a fresh deposit of liquid lava will trickle through the porous cooled lava, forming as it solidifies the pendant stalactites shown in the ...

Over millennia, this builds up within weird cave structures known as speleothems, which protrude from every surface where water flows, including stalagmites on the cave floor and stalactites on ...