Down Inside Mammoth Cave, Kentucky

We are at Mammoth Cave in Kentucky and have gone down through the deep entrance in the ground. The cold air coming out was very refreshing in the mid summer heat and lulls you deeper and deeper into the cave. After walking down several hundred steps put in by the National Park system, you come to a huge cavern with a stone ceiling. This appears to be one stone that spans the 300 foot ceiling. There are many tunnels and caves going off in every direction from this large cavern. The walls of the caves have been extensively scratched and harvested by native Americans hundreds of years ago, but what they were taking is unknown. There was so little light down there that I shot this at ISO 16,000.