Most of the upper passages are catacombs, carved by the force of flowing water. Streaks show where water levels rose and fell. The cavern walls shine, alive with developing formations in a variety of colors. White indicates pure calcite. Red and brown streaks come from iron ore, and the light gray walls contain zinc oxide.
Smoke stains the drier walls of the cave.
Since the lighting system is left on during the duration of day tours, mosses grow in niches and crevices in the cavern walls. One type of dark lichen thrives on the cool damp walls, making squiggly patterns that look like ancient writing. In the Giant Salad Bowl, mosses flourish in a wet, well-lit limestone hollow. After the cavern s discovery, turn of the century partygoers built a bandstand and held dances in a tall grotto now called the Crystal Chapel. In the upper level of the chamber, delicate rimstone formations hold back dozens of tiny pools of water.