Much of Pennsylvania 's bedrock is limestone,and where there's limestone, there are caves. You might not realize it, but caves need special protection--for their striking rock formations, for the wildlife that relies on caves, and because protecting caves protects the water you drink. On this week's Pennsylvania Radio Expedition, WPSU's Cynthia Berger goes underground in one of the most beautiful caves in PA, to learn how local groups are protecting cave habitat.