Natural Bridge Caverns. Discovered March 27, 1960, by four students of St. Mary's University, San Antonio. Named for the rock bridge that marks entrance. Dedicated on August 5, 1964 by Governor John Connally. Of early cretaceous age; still forming. Site of artifacts from 5000 B.C., and human remains at least 8,000 years old; also Indian campsites. 1967 #3552