The Lookout Mountain Caverns, which includes Ruby Falls Cave, is a limestone cave. These caves occur when slightly acidic groundwater enters subterranean streams and eats away at the relatively soft limestone, causing narrow cracks to widen into passages and caves in a process called chemical weathering. The stream which makes up the Falls entered the cave sometime after its formation.
The Falls are located at the end of the main passage of Ruby Falls Cave, in a large vertical shaft. The stream, 1120 feet underground, is fed both by rainwater and natural springs. It collects in a pool in the cave floor and then continues through the mountain until finally joining the Tennessee River at the base of Lookout Mountain.While Ruby Falls Cave combines with Lookout Mountain Cave to form the Lookout Mountain Caverns, the two caves were not actually connected by any passage. Ruby Falls Cave is the upper of the two and contains a variety of geological formations and curiosities which Lookout Mountain Cave does not have.
Electric lights were installed in the cave, making it one of the first commercial caves to be so outfitted. Motorists travelling on I-75 in the 70’s were subjected to dozens – maybe hundreds – of billboards along their route with the words “VISIT RUBY FALLS” beginning hundreds of miles north and south of the falls itself. Ruby Falls remains a staple of Chattanooga tourism, operating daily. Ruby Falls is owned by the Steiner family of Chattanooga, Tennessee.