The explorers made their way carefully climbing and crawling through two miles of vast cavern passage. After making this amazing discovery, they returned to the surface to tell the landowners. The discoverers knew immediately what an astonishing find they had made and the land owners decided to develop the first 1/2 mile, the most spectacular part of the caverns, for the enjoyment of guests from around the world. That first 1/2 mile is now the Discovery Tour. Natural Bridge Caverns Discovery Tour was developed with two main goals in mind: preservation of the cavern environment and comfort of its guests. The result is one of the world premier show caverns, and one of the most popular attractions in Texas.
The cavern formed by an underground “river” moving slowly through cracks and pores within the limestone. Rainwater seeping through cracks started dissolving the limestone. In time, the original narrow cracks or joints enlarged to form huge underground conduits or passages.
Perhaps around 20 million years ago, a number of faults formed in Texas due to settling of the costal regions. These movements created an extensive series of faults known as the Balcones Fault Zone. The eroded face of the Balcones Escarpment marks both the fault zone and the beginning of the Texas Hill Country. In addition to creating the faults, the tectonic stresses also created joints, or cracks in the rock. Underground water moving along the joints eventually carved the passages at Natural Bridge Caverns, one of the main sources of San Antonio fun.