Ruby Falls Rocks! 6th & Up

Geology Rocks! Get it?

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 fascinating story of the formation of Lookout Mountain and Ruby Falls is told by the rocks themselves.

Cave structures slowly formed over millions of years...

About 200 million years ago, on an ancient sea bed, 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:

	Stalactites: These formations hang from the ceiling in the cave.
	Stalagmites: Formations that develop upward from the floor of the cave.
	Columns: Formations that develop when stalactites and stalagmites grow together..
	Flowstone: Thin bands of calcite on the walls or roof of the cave.
	Drape Formations: Formed by water emerging through a small crack in the ceiling.

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.

Ruby Falls - The US' largest viewable underground waterfall!

The truly amazing feature of the Lookout Mountain caves is not the many and varied formations which you see, 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.

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