Inner Space Cavern, Georgetown, Texas

The Inner Space Cavern was discovered in 1963 during the construction of Interstate 35. There were several large openings to the caverns during the Ice Age, and several skeletons of prehistoric Ice-Age animals have been found in the caverns; many were trapped in the cave after they fell through the opening, unable to escape, and others drowned in thick, quicksand-like mud at the bottom of watering holes.

The caverns were carved by water passing through Edwards limestone. The caverns are estimated to be 90–100 million years old but were only open to the surface since the late Pleistocene period 20,000–45,000 years ago, evidenced by finds of mammoth and saber-toothed cat bones. All natural entrances closed approximately 14,000 years ago.

Stalagmites rise from the floor and occasionally connect with stalactites hanging from the ceiling to form columns or pillars.

Fossilized sea sponge

Cavern personnel only grant visitors permission to touch one formation - the temptation stone. The formation was sacrificed to demonstrate how physical contact causes discoloration.

Tubular stalactites (soda straws) take the form of hollow mineral cylindrical tubes.

The water is exceptionally clean because the rock acts as a natural filter.

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