Wind Cave National Park

Geology
Gorp.com

To witness the beginning of the formation of Wind Cave, one of the world's oldest caves, you would've had to have been here 320 million years ago. At that time, parts of the limestone that constitute the upper levels of Wind Cave were being dissolved into cave passageways. As ancient ocean levels fluctuated, these passages were filled with sediments. Beneath the ocean, a thick layer of sediments continued to be deposited above that limestone.

About 60 million years ago, the forces that uplifted the Rocky Mountains also uplifted the modern Black Hills producing large fractures and cracks in the overlying limestone. Over millions of years, water moving slowly through those cracks dissolved the limestone to produce the complex maze of the cave's passages.

Later erosion changed surface drainage patterns that caused subsurface water levels to drop, draining the cave passages. As the modern Wind Cave formed, many of these newer passages intersected the original cave, revealing the red clay and sandstone sediments from 320 million years ago.

It was after the cave formed that most of the colorful cave formations began to decorate its walls. One of the most prominent features in Wind Cave is boxwork—thin, honeycomb-shaped structures of calcite that protrude from the walls and ceilings. Nowhere else in the world can such a large display be seen. Some of the better-known cave formations, such as stalactites and stalagmites, are uncommon here.

You might wonder if after more than 100 years of exploration there is anything new to discover in Wind Cave. Barometric wind studies estimate that approximately 5 percent of the total cave has been discovered. In 1891 Alvin McDonald wrote in a diary of his cave trips: "Have given up the idea of finding the end of Wind Cave." The better-equipped cavers of today have not given up. They are continuing to push farther and farther into the cave's cool, black recesses.


Published: 29 Apr 2002 | Last Updated: 15 Sep 2010
Details mentioned in this article were accurate at the time of publication

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