Caves in the United States

Caves are found in every state in the United States, with over 44,000 recorded caves in the 48 contiguous states (Culver et al. 1999). Where are these caves?

The map above shows the karst areas of the U.S. in green. Karst is a type of terrain that includes limestones, dolomites, and gypsum. These rocks are soluble, and caves, sinkholes, and underground drainages are common features. Nearly one-quarter of the U.S. is comprised of karst. Looking at the map above, you might guess that Florida has the most caves because it has the most karst. But just because karst is present does not mean that a cave is present. In many cases, the rock is soluble, but the water table is so high that the caves are flooded and can only be entered by highly trained cave divers, or the caves are still forming and are not large enough for humans to enter. 

This second map, made by Culver et al., shows a dot for every cave by county. So if a county has ten caves, there will be ten dots randomly placed in that county. These caves may be found in karst, but also could be lava tube caves, talus caves, or other types of caves. What is obvious in this map is that there are some sections of the country that are just filled with caves, like the middle part of Texas, Missouri, Kentucky, Tennessee, and others. The desert southwest doesn't have as many caves, but it still has quite a few black dots.

When I headed to Kentucky last week, it was with the knowledge I was heading towards cave central. Kentucky is home to the longest cave in the world, Mammoth Cave, which stretches over 360 miles with more passageways still being found. My brother offered to take us to one of the smaller caves in the state, and I couldn't resist.

The trip to a cave almost always includes a hike to the entrance. Sometimes this hike can be grueling, involving many miles, rough terrain, poisonous plants, unpleasant weather, and obnoxious mosquitoes. Fortunately, on this fine fall day, the weather was great and we followed a trail most of the way.

The entrance was huge, with large boulders providing good perches as we looked off into the Kentucky woods. We put on our helmets and headlamps and got ready to enter the large, dark void.

This cave, called Wind Cave, is about 1.3 miles in length. It was formed by water dissolving the limestone rock. Water still flows through parts of the cave, but because Kentucky has had a drought this last year, my brother didn't think we would get too wet. I was skeptical. In my experience, I nearly always get wet and muddy in Midwest caves.

One of the first passages we went into was a canyon-like passage. The walls were fairly smooth and dry. I enjoyed the walking passage, because many of the caves in the area where I live are small and require lots of crawling.

Eventually the canyon passage got smaller and it was time to squeeze through a little hole. You can see some graffiti to the right of the hole. Unfortunately some people don't respect caves and leave trash or paint stupid things on the cave walls. They don't think about the cave being a home.

Caves are home to a variety of cave biota. Squeezing provides the opportunity to be very close to the cave surfaces, and then it's easier to see some of the creatures that make the cave their home, like this cave cricket. Notice the extremely long back legs and antennae, which help the cricket find its way around the totally dark cave. We saw lots of crickets--some cracks had about 15 together. 

In addition to crickets, we also saw this neat looking spider, along  with flies, moths, and millipedes. Water flowing into the cave provides nutrients for these cave creatures.

Back in the main passageway, we can see that the water has been flowing through the cave for a long time to dissolve away this much rock. 

Eventually the ceiling got lower and we had to stoop walk. We also came to mounds of sand, places where the water has slowed and deposited the finer sediments.

And then we got into another crawling passage. We found many side passages going off from the main trunk passage. Basically smaller drainages are emptying into a larger drainage, but instead of happening in rivulets and gullies up on the surface, it's occurring underground.

Some passages got even tighter, requiring some nearly contortionist moves to get past the ninety-degree turns. (Can you see the foot and leg in the photo?) To make things more complicated, water was flowing and bubbling up on the bottom of the passage. I was right about getting wet!

It was a fun trip, and it felt great to be underground again. I always enjoy the silence and mysterious nature of caves. Are there still more passageways to be found? How much bigger will the cave get over time as the water keeps dissolving away more rock? How is it connected to the surface, and will it be impacted by surface activities? What else lives in the cave? I always leave a cave with more questions than I went in with!

If you'd like to learn more about caves, a good place to start is the National Speleological Society website.

Exploring a Lava Tube

I've had the opportunity to explore some lava tubes in different areas of the deserts, like El Malpais National Monument in New Mexico, Wupatki National Monument in Arizona, and Snow Canyon State Park in Utah, to name a few. The lava tubes fascinate me, as I think about the time when hot lava was flowing right where I am standing now. The lava was just the right consistency and temperature and moving at just the right speed to leave behind a tube. 

Many times the entrance to a lava tube is where part of the lava tube collapsed. It's common to enter a lava tube, go for a short while, and pop out another entrance at another collapse point. 

Here's my brother Andrew coming out of a secondary entrance, which has a gate across it to protect bats part of the year. Yep, you've guessed it, we're going to start on another Andrew adventure. That means it's got to be good! Andrew took his friends Bobby and Shae caving. I went along with Desert Boy to take photos and provide commentary.

As you might imagine, lava tubes are usually just a tube, but once in awhile the lava did some crazy things, and here Andrew is checking out a side passage. He is doing his best to lose Shae and Bobby, but it is hard to get lost in a lava tube.

Please note he is not wearing Desert Survivor-approved caving gear. That lava is really sharp, and the floor is littered with loose boulders that make footing treacherous.

As we continued further into the cave, I spotted this little cave cricket on the ceiling. He can hold on to the lave just fine, and likes to spend part of his life cycle in this lava tube. The extra long antennae help him find his way around in the dark. When I saw him, the ecologist part of me got all excited and I couldn't resist taking a photo. Okay, now back to the caving adventure. 

And then we come upon a sight even more amazing than a cave cricket--it's Bobby! (Or is it the ghost of Bobby?) If you missed Bobby's earlier adventure, click here to read all about it.

Bobby is trying to light up this huge passageway with his lights. Bobby and Shae followed Andrew, and as the passage kept getting smaller, Andrew kept going, and they kept following. Eventually it became a crawl, and still they followed him. Then it became a squeeze on the belly. And still they followed. And for what?

To see cool formations like this ice stalagmite. Okay, it's not that cool of a formation, but lava tubes rarely have formations, so you've got to take what you get. The floor of the cave was also covered with a thin layer of ice. Sometimes when they took a step, the ice broke, and they plummeted through to cold water below. Sounds like fun, doesn't it?

Or maybe they were following because they trusted Andrew with their lives. (Okay, I expect to see a few comments about that!) Perhaps they couldn't resist the adventure of seeing what else was in the lava tube. I understand the feeling.

Nevertheless, Shae, Andrew, and Bobby survived their trip through a lava tube with only a minor amount of dirt and no obvious blood. And look at the smiles on their faces--I think they enjoyed it!

Desert Destination: A Marshmallow Cave

Over the weekend I went on a fun adventure to a cave. Full disclaimer: I love caves. I go in a cave whenever I can. Usually the caves involve lots of mud and/or lots of crawling. To my great surprise, this cave didn't involve either.

That little hole way up on the mountainside is Goshute Cave, but it's more fun to call it Marshmallow Cave because much of the interior is filled with giant white mammilaries that look like marshmallows! You'll see in a minute.

The trip was sponsored by the Northern Nevada Grotto. Grottoes are caving clubs, and they're located all over the country. They are part of the National Speleological Society, which has lots of great information about caves. One of the best parts about the Northern Nevada Grotto is that it has no dues. And it meets online. So all in all, it's a rather convenient organization to be a part of. The downside is that to actually see other members, you have to turn off the TV, get off the couch, and go somewhere. It worked out that I could go on this trip at the last minute because my wonderful hubby agreed to come along and watch Desert Boy. Desert Boy doesn't love caves, at least not yet, and my hubby can't get very excited about crawling so he didn't mind skipping the cave. 

Here's a view from the trail up to the cave. (It was a steep trail, so I had to do something while I was gasping for air.) You can see the Great Basin desert stretching out into the smoke-filled hazy horizon. The California wildfires are definitely having an impact on much more than California.
Here's the rock scramble below the entrance. Actually the entrance is a smaller hole to the left of the big, gaping one, but you can't see it until you're up there.
In case I didn't know where I was. Rooms throughout the cave had been named, apparently by a group back in 1912.
Here are those marshmallows I was talking about! These are mammillaries, which formed under water. Although they look sort of soft, they are hard calcite.
In some places the mammilaries have been eroded away, showing rings. These indicate that the mammilaries formed one layer of calcite at a time.
Another white, intriguing formation was the folia, layer upon layer of honeycomb looking calcite.
This is a closeup of the folia, where you can see that the layers aren't quite parallel. One suggestion as to their formation is that bubbles created the slightly sloping edges.
The main cave passage descended steeply, and we had to slide down some sections.
The proper caving gear of helmet, headlamps, sturdy clothing and boots, and kneepads, made the caving trip much more enjoyable and safe.
These aragonite crystals were tucked away in a little alcove. It is amazing to see such a delicate-looking formation and marvel how it has survived for thousands of years.
Here is a cave shield, a fairly rare speleothem. Its color contrasted with the wall behind it, suggesting that the water percolating into the cave to form the shield is picking up minerals along the way.
We climbed into an upper passage to go down a tight little hole called The Toilet Bowl. It is so small that your whole body completely fills the hole, and you can't see where you're going.
Eventually even your head disappears, and you are flushed into another part of the cave. (Sorry, I couldn't resist.)
These colorful draperies were part of the attraction of the cave. I was impressed with the diversity of formations and the large walking passages. The entire group seemed to enjoy the cave trip.
After reading this post, you're either ready to head down into the nearest hole or you're saying that cavers are a weird group of people, for who in their right mind would want to descend into the bowels of the earth? If you're in that second group, this photo helps explain why it's great to go into a cave. When you see a weird formation like this helictite, which grew upward and curving in spite of gravity, you realize that caves are one of the last frontiers, where we don't understand exactly how they formed and don't know what their bounds are. It might just be possible that you're sitting on top of a cave right now! 

The Allure of Going Underground

It's starting to warm up, and during the hot summer afternoons I think about what the animals are doing to stay cool. I especially admire the animals that go underground--the burrowing owls, snakes, marmots, badgers, kit foxes, and many insects. If you just go a couple feet underground it's amazing how much cooler the temperature is. I spent many afternoons as a kid in the basement to take advantage of the natural coolness the ground provided (and Mom wouldn't let us go to the swimming pool until late afternoon when the sun rays weren't as strong). Perhaps those many afternoons in the basement helped develop a love of caves in me.When I see a dark hole beckoning, I can't help but wonder what is in there. The desert is full of caves; perhaps the most famous one is Carlsbad Caverns in the Chihuahuan desert of New Mexico. Gigantic rooms are followed by even larger ones. Towering formations that reach to the ceiling are overwhelming. I can't really fathom the time it took for these formations to grow, one drop of water at a time, the calcite slowly accumulating over years, decades, centuries, millenia. Seeing so many formations in desert caves makes it obvious that the desert above the cave has not always been around, at one point the climate was much wetter. A trip through a cave like Carlsbad Caverns is breathtaking and awe inspiring.
But what really gets my blood pumping is when I'm in a cave off the beaten path and see a hole that perhaps no one has been down. I'll wiggle through to see what's on the other side. I even know how small a hole I can fit through and not get stuck. That's important when your hobby is wiggling through little holes in the ground.
There are always holes too small for me, but I know that other creatures might be there. I'm just a visitor to the cave. There are creatures who make their homes underground. This cave cricket spends part of its life cycle in a cave and has extra long antennae to be able to feel around in the entirely dark environment. I always make sure to take three sources of light and a helmet because I don't want to be left in the dark and bump my head. But sometimes I turn off my light in the cave, and the rest of the group I'm with does the same, and we stay as quiet as we can. The dark becomes so intense that I start imagining that I'm seeing cave walls or creatures. The quiet becomes a dull roar in my ears, sometimes punctuated by a drop of water hitting the cave floor. Drip, drip, drip. The monotony becomes torture, and before long someone makes a noise so that we can reassure ourselves that we aren't alone. We'll continue on the trip, enjoying the journey of being in a place that few people experience.
No matter how beautiful and exciting the cave, I always feel a little surge of adrenalin when I see daylight peeking through the entrance. I emerge from the cave and take a deep breath of the vegetation-tinged air and feel the heat of the sun on my cheeks. I've made it out; the cave has not claimed me. It doesn't take long, though, to start thinking about that next trip into the unknown.