After a quiet day at home which involved unpacking, resting and eating pie at the Purple Pie Place in Custer (not quite Mission Pie but very good nonetheless), the girls and I went out on Tuesday to Wind Cave National Park.
We had lunch in a lovely quiet picnic site in warm sunshine and dappled shade. And then we wandered off to the visitors centre to buy tickets for the tour of the cave.
Wind cave is huge. It is a vast honeycomb network of caves stretching down about 700 feet underground and covering an area of a square mile. I may have all of this wrong. It is unusual - it is very dry as the limestone in which the cave formed is protected from rainfall by a layer of sandstone, which means it isn't an actively changing cave with stalactites and stalagmites. Instead it contains a huge amount of boxwork formations - thin calcite "boxes" standing out from the rock, delicate and beautiful and formed when water which was acidic dissolved the limestone leaving these calcite deposits.
The only known natural entrance is tiny and the cave "breathes" through it. Barometric pressure changes cause wind to flow in or out at speeds of up to 70 miles per hour.
We went in through a revolving door, then descended steps stopping occasionally for things to be pointed out by our ranger or to talk about the geology and history of the cave. At one point, she turned off the lights and showed us what first tours were like lit only by candle. And then she blew the candle out! Two small hands gripped very tightly for the few minutes we experienced true darkness. They weren't so keen on the cave after that.
The girls were taken with the story of Alvin McDonald the boy cave explorer, and first guide. He was passionate about the place and traces of his string (a la Theseus and the Minotaur) are still found in remote parts of the cave. And sadly he died of complications from typhus at only 20 years old.
I tried to take pictures but they were rubbish. So google it. It is gorgeous and surprising and amazing.