Wind Cave National Park Caverns

On Friday we headed over to Hill city, SD to the Wind Cave NP.  It includes the third largest underground Caverns in the world, and is noted for its boxwork.  Jewel NM is not too far away and is the 2nd largest.
This Cavern has very little moisture, and a lot of calcite which forms this boxwork on its walls and ceilings.   One can also see popcorn, and frostwork This outside opening is the original that was found in 1890 by Alvin McDonald, when he was not quite 18 years old as he followed the wind into these caverns with only a candle and a role of string.  The cave is named because of the wind that blows from this hole to the point it will blow your hat off, and at other times it will suck it in due to the changes in barometric pressure.  There are many tunnels yet to be explored.  It is like a piece of swiss cheese if you can imagine!
On the surface, the park includes over 28,000 acres of prairie land, where the buffalo have been preserved, and roam free, as well as other kind of animals.
On the way home, there was a thunderstorm with hail.  The temperature dropped 30 degrees in a matter of minutes. But a beautiful rainbow appeared, and it was double.  Might be hard to see on the picture, but I had never seen this….a nice ending to an interesting day.