The walk down was a steep switchback asphalt walkway with guard rails. Every so often placards described our surroundings. As we passed the dark passage which led to the Bat Cave, we were joined by Ranger Chuch Oliver who explained that this is the summer home of thousands of Mexican freetail bats. The bats roost here from March to October During the day bats hang by their feet from the ceiling in great clusters. At sunset they stream out past this point to hunt flying insects. The actual roosting area is closed to the public. Guano (bat manure) has accumulated on the floor of Bat Cave to depths of more then 40 feet. Large quantities of guano create a toxin requiring those near it to wear breathing apparatus. Near the bottom we began to see formations along the way. Stalactites, stalagmites and other cave deposits made chiefly of calcite are called "decorations" or "Speleothems". Speleothems are formed when groundwater containing calcium bicarbonate solutions seeps into the cave. When the solution becomes exposed to cave air, carbon dioxide gas is released, leaving calcite as a deposit. The beginning of these deposits are called "Soda Straws" which are thin hollow stalactites formed by the dripping water. In time they may become stalactites or stalagmites. On the limestone walls, we could see a series of vertical cracks called "joins". The unusual size of the cavern was explained on a placard which described how a weak carbonic acid, permeated the joints and dissolved portions of the limestone into small cavities along the joints. This chemical process is called "solutioning". Hydrogen sulfide gas bubbled up from deep oil and gas deposits. Combining with water it formed corrosive sulfuric acid which further dissolves the limestone cavities to form large passages. At the bottom, the main attraction is a walk around in the "Big Room", a distance of about a mile and a half. It is here that we found the giant structures in the section called the "Hall of Giants" which bore such names as "Rock of Ages", "Giant Dome", "Temple of the Sun" and "Top of the Cross". The lighting is not brilliant, being somewhat subdued to accent the delicate colors caused by iron and other mineral deposits present in the water. Even so it takes thousands of lights, strung along hidden wires to create the effect desired. There is an emergency generator as a power backup and the cave is generously covered with emergency battery operated lights should all else fail, still, taking a flashlight with you is recommended. All in all this was a once in a lifetime adventure which was worth all the time and effort, and what a time it was. 

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