This tiny opening is the natural entrance to Wind Cave, where explorers originally entered...I must admit, even with previous knowledge, it was strange feeling a 23 mph whooshing out of the ground...

Arriving at Custer State Park well ahead of schedule allowed our group to fit in a visit to one of our more unique National Parks, Wind Cave. Wind Cave National Park was established in 1903 as our 7th National Park, and the first that protected a cave. It is so named due to the strong winds that constantly blow into and out of the small natural entrance due to pressure differences above and below ground. Above ground the park covers over 28,000 acres and includes everything from prairie to mountain pine forest. Beneath ground, over 130 miles of caverns have been explored! Being early in the season the only tour available was the Natural Entrance Tour. This tour covered about a half-mile and was a bit over an hour long. It introduced us to the most common formations in Wind Cave, the colorfully named boxwork, frostwork, and popcorn...

5-5-2011

Wind Cave National Park

Some 350 bison roam the prairie's above Wind Cave, and this small herd greeted us as we drove in...
We didn't get to explore the above ground portion of the park (over 28,000 acres) but through the windows of our bus...here, the high plains meet the forested Black Hills providing for a wide variety of flora and fauna...
The beautiful arch bridge over Beaver Creek Canyon...
A moving shot of the park entrance sign...
From 1934-39 the CCC built many of the structures you see in the National Park, including the visitor center...
Heading in...
A pre-National Park Visitor Log Book from July 5th, 1893...Wind Cave was run as a private attraction until becoming the country's 7th National Park in 1903...
Differences in pressure in and outside the cave create the namesake 'wind' at the cave entrance...today air was rushing out of the cave at 23 mph but I read that on rare days it can blow at over 60!!
There are over 130 miles of cave passages that have been explored to date...all under only 1 square mile of ground!!
This tiny opening is the natural entrance to Wind Cave, where explorers originally entered...I must admit, even with previous knowledge, it was strange feeling a 23 mph whooshing out of the ground...
After passing through pressure-equalizing doors, we started the descent...
Watch your head!
Looking up...
The coloration on places was very cool...
Cool formations...
Our first example of 'boxwork', Wind Caves' most famous formation...
Frostwork, created when seeping water is exposed to high rates of air flow creating a fine, fan-like pattern...
Lots of 'frostwork'...
Another of Wind Cave's most common formations, 'popcorn'...formed when water seeps through limestone at uniform rates...
More boxwork...boxwork forms when hard 'veins' of calcite are exposed as the softer surrounding rock erodes...
An interesting stone shelf we had to make our way around...
Cool rocks...
Boxwork formations...boxwork forms when hard 'veins' of calcite are exposed as the softer surround rock erodes...
Layers of stone...