Speleothems - Cave Popcorn
NPS Photo by Paul Horsted
Small, knobby growths of calcite on the cave walls are called cave popcorn. Popcorn commonly forms in one of two ways in the cave: where water seeps uniformly out of the limestone wall and precipitates calcite; or, when water drips from the walls or ceilings of the cave and the water splashes on the floor or on ledges along the walls. This splashing action causes loss of carbon dioxide and the subsequent precipitation of calcite.