Wind Cave National Park: below and above

Saturday June 18
Another great day today, heading southwest to Wind Cave National Park, on the edge of the Black Hills. The temperatures are heating up - a little over 90F for the high today in Rapid City where we are staying. Fortunately Wind Cave is a couple of thousand feet higher, so it was a little cooler. However we had booked a cave tour for 2pm, to avoid some of the hottest time of the day. In the morning we walked a couple of trails, enjoying some beautiful views of the Black Hills, and seeing a family of wild turkeys (see extra collage). After our walks, we were glad to seek out the air conditioning in the Visitor Centre before going on the tour.
The first documented discovery of the cave by white Americans was in 1881, when the brothers Tom and Jesse Bingham heard wind rushing out from a 10-inch by 14-inch hole in the ground. The park was established on January 3, 1903 by President Theodore Roosevelt, it was the seventh national park and the first cave to be designated a national park. Wind Cave is the seventh longest cave in the world, and the third longest cave in the U.S. with 154.2 miles of explored cave passageways (as of 2021). Above ground, the park includes the largest remaining natural mixed-grass prairie in the United States. The cave is especially notable for its calcite formations known as boxwork (lower left of collage). Approximately 95 percent of the world's discovered boxwork formations are found in Wind Cave. in geology, In geology, Boxwork is defined as a honeycomb-like structure that can form in some fractured or jointed sedimentary rocks. If the fractures in the host rock are mineralized, they can become more resistant to weathering than the surrounding rock, and subsequent erosion can produce boxwork structures. Another formation we saw was popcorn formations, lower centre. We had a good informative guide, but unfortunately since we were such a large group, I couldn’t always hear what he was saying.
As we left the park, we saw more great wildlife sightings - lots of American bison, including some young, and a number of pronghorns. See second collage.