The story of Ruby Falls begins with the original Lookout Mountain Cave that had a natural entrance on the banks of the Tennessee River at the foot of Lookout Mountain. It has been known to visitors for centuries. The cave was used as a campsite by American Indians, as a hideout for outlaws, and as a Civil War Hospital.

The most significant artifact of the Lookout Mountain Cave is Andrew Jackson's signature. In 1905, the Southern Railway built a railroad tunnel through the edge of Lookout Mountain, which permanently sealed off the natural entrance to the cave.

In 1923, Leo Lambert, a local cave enthusiast, formed a corporation for the purpose of opening the historic Lookout Mountain Cave to the public. Leo Lambert's corporation purchased land on the side of Lookout Mountain above the cave. Then, in 1928, a site for an elevator shaft into the original cave was selected and drilling began. While drilling straight down through solid limestone rock, a small opening was found at the 260-foot level that measured two feet high and four feet wide. Mr. Lambert decided to explore this opening.

Seventeen hours later, he emerged and described many beautiful rock formations and a spectacular waterfall. During his next trip, Mr. Lambert brought along his wife, Ruby, and named the magnificent waterfall in her honor - "Ruby Falls". Mr. Lambert decided to develop both caves so people would have two caves to visit. The entrance building was modeled after a fifteenth century Irish castle and was constructed from limestone excavated from the elevator shaft.

From 1930 to 1935, tours were offered to both caves, but Ruby Falls proved to be the most popular. In 1935 the original cave was closed to the public. Since 1929, millions of visitors have enjoyed the natural beauty and wonder of Ruby Falls!

Lookout Mountain is noted for its unusual geological phenomena. One of its unique features is Ruby Falls, an underground waterfall located deep inside the mountain. The rocks themselves tell the fascinating story of the formation of Lookout Mountain and Ruby Falls.

About 200 million years ago, on an ancient seabed, skeletons of small creatures accumulated forming layers of limestone. Successive layers of shale, sand, and pebbly sand were deposited on top of a limestone-type material and gradually these thick layers hardened. A powerful earthquake, or more likely a series of them, caused the layers of rock to bend or fold upwards. As the brittle layers of limestone and sandstone rose from the ocean floor, cracks or crevices occurred. It was along these cracks, which scientists call joints, that Ruby Falls was formed. Many of these joints can be seen along the roof and walls of the Lookout Mountain Caverns.

Ruby Falls is located in the limestone layer of the mountain. As the subterranean streams found their way through the crevices, the water dissolved the limestone and released an acid which aided in the formation of the cave. Lookout Mountain Caverns actually consists of two caves. The lower cave is about 50 feet above the level of the Tennessee River. The upper cave, containing Ruby Falls, lies directly above the original cave. Both were formed along the same fault line.

The formation of cave deposits (called speleothems) on the walls, floor and ceiling of the cave is a very slow process. The rate of growth varies from cave to cave; the average being one cubic inch every one hundred to one hundred fifty years. Some of the factors that can affect the growth of formations include:

• The amount of ground water flowing through the cracks in the area.
• The types of rock found in the cave.
• The chemistry of the ground water and the rocks themselves.
• The relative humidity of the cave, its temperature, its surface evaporation and the amount of air circulation.

There are many different types of formations found in the Ruby Falls cave. The most common are (click the links for an example) stalactites, stalagmites, columns, drapes, and flowstones. These formations are caused by water containing minerals, such as calcium carbonate, dripping down from the ceiling. They range in size from the tiny helicitites found in the Hall of Dreams to the large column found in the Onyx Jungle. Rows of stalactites found on the ceiling are normally found along some joint or crevice in the limestone.

The truly amazing feature of the Lookout Mountain caves is not the many and varied formations present there, but rather in the large vertical shaft at the end of the main passage. A flowing underground stream falls from the very top of this shaft 145 feet into a pool on the floor of the cave. The size of the waterfall depends on the amount of rainfall. Water from Ruby Falls flows back through the cave and then down another waterfall (which is inaccessible) and into the Tennessee River.