Custer (caves)

This morning was completely socked in and wet. I had planned two cave outings (innings?) today, which seemed like a fortuitously good plan. I first drove down to Wind Cave National Park . This cave is so named because of the wind that breathes in and out of both the original small opening and the manmade public entry opening. Whether there is an in draft or an out draft depends on the barometric pressure on the surface. Today there was a distinct low pressure system, so air was being expelled from the cave - breathing out. Actually, the artificial entrance is an airlock, so as to disturb the natural cave system as little as possible.

Dennis was our guide for the hour-long cave tour. The first story he told us was the Lakota Emergence Story - basically how the bison were created and how the Lakota, who were living in the spirit realm in the cave, came to emerge above ground. It is too long to reproduce in the context of this blog post, but I highly recommend reading or listening to the entire legend. It is fascinating.

All caves are comprised of limestone. This is because they are ancient seabeds, and limestone is basically the remains of hard-shelled sea creatures whose shells or exoskeletons contain calcium carbonate. Caves result when various acids - sulphuric in the case of wind cave - either drip down as a liquid or rise up as a gas and erode other substances leaving bizarre and interesting formations. In Wind Cave , bodies of gypsum, made of calcium sulfate, also formed during the time when arid conditions caused seawater to evaporate and the minerals to crystallize. The gypsum formed irregular shaped masses within the limestone. The resulting rock is known as the Madison Limestone formation, or locally as the Paha Sapa (Black Hills) Limestone.

Stalagmites and stalactites are a continuation of that process. These formations grow when dripping water comes into contact with the cave air. The water carries dissolved minerals, picked up on its journey from the surface. As it passes through the cave, it leaves tiny traces of those minerals behind, building each stalactite drip by drip. This cave is also famous for its boxwork formations. Boxwork is made of thin blades of calcite that project from cave walls and ceilings, forming a honeycomb pattern. Slow moving water exposed the boxwork by dissolving limestone at the edges of the former gypsum masses where expansion had formed cracks.

After the cave tour, I took some time to drive one of the gravel roads on the surface of the park. The fog had lifted and the sun had come out. The layers came off. I saw another large prairie dog town, lots of bison and some more pronghorn antelope (as it turns out more closely related to giraffes than antelope).

I then drove back up and over to Jewel Cave National Monument . Brad was our guide for this hour and twenty minute tour. It involved hundreds of steps and took us about 350 ft. down into the bowels of the earth. The erosion of this case was a result of dissolution of soluble substances by carbonic acid. Because of this, the calcium carbonate in this cave formed calcite crystals. Miners originally thought they might be quartz, a harbinger of gold and other precious minerals. As it turned out, the value of the cave, like most others, was in tourism. Brad also told us a lot about the past and current exploration of the cave, and the wonders and risks associated with that activity. It takes a special sort of person to explore further and further into an unknown cave.

The first major winter storm also arrived in the north last night. Its main impact was in North Dakota, Montana and Idaho. Here in South Dakota, the temperatures plummeted below freezing, but we did not get the snow. Another week of sub-freezing temperatures is predicted; the fleece-line pants have now come into the clothing rotation. Hopefully by the time I drive up to North Dakota next week, the roads will have been cleared. The question is always, when is the next storm? The next month will be the most challenging part of the trip in terms of weather. It is all part of the adventure.

Tomorrow I drive a bit east to Wall, to be closer to the badlands.

Additional images are found in the Gallery .