The geologic history of Long­horn Cavern is complex, and the theories do not all agree. Geologists think a shallow tropical sea covered most of Central Texas some 450 to 500 million years ago. The mud under that sea eventually turned into limestone. Between 280 and 300 million years ago, mountain-building forces shifted under Central Texas in an event known as the “Llano Uplift.” During this upheaval, faults and fractures formed in the flat limestone. Water flowed through the cracks, dissolving the limestone. The downward flow continued until water cut great underground streambeds out of solid rock. This unusual mix of water dissolving and cutting makes Longhorn Cavern one of the most unique caves of the world. Come and tour this unique cavern! Before or after your tour, hike one of our trails, picnic, or learn about the Civilian Conservation Corps and its work in Texas (see the exhibit in the original administration building). Entry to the park is free; entry to the cavern is by paid guided tours.