Wind Cave and Custer State Park

Saturday.                                                                                                                   You can listen to this while you read  

Hurray! The sun is out, it is a beautiful day! We pack up a picnic and head south to Wind Cave NP. We had sort of made arrangement with the Park Ranger to visit today, as they need to make special arrangements for wheelchair users.
Wind Cave is a very large cave system, some 440 miles of it! We only expected to do a part of that. We were met by a very pleasant ranger, who loaded us into an elevator and took us a hundred feet below ground to a part of the cave system. Wind cave is special in several ways, first of all though it is large it only has very small access to the outside world, so it breathes! As the air pressure outside changes so air must move in or out to equalise that, sometimes the wind can get up to 50 m.p.h, so they say, however there was a gentle breeze as we left the elevator to enter the Garden of Eden cavern.
Here it was explianed that the caverns are limestone, though it seems that the water erosion simply exaggerated the cracks that were already in the rock. It seems that the limestone was formed 350 million yeasrs ago, but around 65 million years ago a batholith (basaltic domelike intrusion) lifted the limestone over a large area. In being lifted the limestone cracked causing many fissures which the ground water exploited to make a large network of caverns. This made for a very interesting map of the caverns. These caverns are characterised by showing very few of the traditional forms of stalagmites and stalactites.
We were then taken further down to The Assembly Rooms, which were much larger and contained the unique BoxWork phenomena. The box work lattice are made from calcite. It seems that water percolated through a layer of gypsum above the limestone, dissolving the gypsum, which was then deposited in cracks in the lower limestone. The Gypsum then hardened to Calcite. Over time the limestone was removed by chemical erosion, leaving a strange latticework of calcite, very pretty.
Well as usual we really enjoyed our tour of the cave, and as usual it took much longer than anticipated. We emerged again into the sunlight and moved on. It was now the turn of Custer State Park to entertain us.

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The first piece of good news was that this weekend was their 'Open Weekend'. Entry was free!! So we set out on to the Wildlife Loop. The scenery was very pretty, rolling hills and prairie. We stopped at 'Prairie Dog Town' and watched their antics for a while as we ate our picnic lunch. They are very funny.

We rode on and saw lots of other wildlife, we saw many more bison, lots of them had a calf in tow, often they were very close, they seemed more tame than those in Yellowstone.
Then we ran into the 'Begging Burros'. A herd of burros who, as soon as you stopped the car, put their heads through any open window, begging for food.  There were several very cute foals of various sizes and colour. This was a very popular stopping place for visitors, many of whom had brought apples and carrots to feed the burros.
On our trip round the Wildlife Loop we saw quite a few pronghorn, some deer and some very pretty bluebirds as well as a song thrush.
Finally we stopped at place called Legion Lake Lodge, where, as part of the open weekend we could attend an 'Ice Cream Social', complete with a free scoop of Blue Bunny ice cream. So we had a coff/T as well and watched the geese with their goslings on the lake.
All in all a very pleasant day in the Black Hills.

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