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Outdoorsy 4: Exploring The Underground World Of Caves

Ezra David Romero
Paul Martzen is about to crawl into the Millerton Cave system.

In this episode, we’re venturing to a different kind of destination.

Credit Ezra David Romero / KVPR
Millerton Caves were created by an underground stream carving through granite.

It’s not exactly outdoors…but there’s no heating or air conditioning. 

It’s musty, damp and that’s what some people love about it. Often the only light source is the light you bring.

We’re going underground. In this episode we’re exploring the world of spelunking. But people who do this don’t actually call it that. They refer to the activity as caving.

We’ll meander through a threatened cave system in the region, find out all about the gear you need for underfoot activities and learn about subterranean spots in Sequoia National Park.

Did you know there are more than 300 caves there?

Millerton Caves

In December we went underground to a place called Millerton Caves along the San Joaquin River Gorge with a local caver.

Credit Ezra David Romero / Valley Public Radio
Valley Public Radio
The cave system is over a mile long and has three main sections.

The caves are about a 20-minute drive from Fresno, plus a 30-minute hike once you arrive. They’re in an area where the river cuts through a steep canyon. A 13-mile one-way trail runs along the river. We took a shortcut off Auberry Road to get there.

About halfway up the trail you’ll find the caves and you’ll know you’re there when you see huge piles of boulders on either side of the trail. Caver Paul Martzen showed me around the mile-and-a-half-long system split up into three main sections. We were about 30 feet into the cave when he began singing.

“It is cathedral like,” Martzen says. “The echo, the sounds, the acoustics are pretty amazing.”

Credit https://rayholt.wordpress.com/2009/10/04/millerton-lake-caves/

The cave system was formed by an underground stream flowing through granite, but it isn’t accessible year round because when there’s a lot of rain, the cave is roaring with water.

“During the flooding, that’s when it carves and it's powerful enough to keep swishing the gravel around and keep digging down and down,” says Martzen. “It’s like sandpaper and it carves these amazing shapes, grooves, sharp edges. And if you hadn’t seen it you would have no idea that water is capable of doing something like that.”

Credit Ezra David Romero / Valley Public Radio
Valley Public Radio
Some rooms in the granite caving system are over 20 feet high.

But the thing is, plans for a new reservoir above Millerton Lake are threatening the cave system’s existence. If plans for Temperance Flat go through and the dam is built then Millerton Caves would sit several hundred feet under water. That water would be used for farms and cities across California.

“We have something that’s so unique to this area and really even to the world and we’re going to destroy in favor of crops that we already have surplus of and that just seems like a tremendous shame because we’ve got gazillions of oranges and we only have one cave like this, says Martzen.

Even if the project is approved it’s years away from being built. To listen to the story about Temperance Flat click here.

Caving In Sequoia

Credit qJake / Creative Commons/Flickr https://creativecommons.org/licenses/by-sa/2.0/
Creative Commons/Flickr https://creativecommons.org/licenses/by-sa/2.0/
The entrance to Crystal Cave in Sequoia National Park is marked by a metal spider web gate.

Millerton Caves may not be around forever, but there are others in this area. There are lots of caves in the region, but most are unmarked and many aren’t open to the public. Some of those are in Sequoia National Park.

For the last six years Katie Wightman managed Crystal Cave in Sequoia National Park. It’s one of the most popular caves in California. She says there are more than 300 caves in that park alone.

“They’re not huge,” Wightman says. “We don’t have caves that go for 400 plus miles like Mammoth Cave National Park. The beauty of these caves isn’t necessarily in the stalactites and the stalagmites, but it’s in the walls. That really beautiful marbled rock that you kind of wind your way through.”

Credit S. Rae/Creative Commons/Flickr / https://creativecommons.org/licenses/by/2.0/legalcode
Crystal Cave is known for its large rooms carved from limestone.

Wightman loves to explore Crystal Cave. More than 65,000 people visited there last year and it opens in May. The marble cave has three miles of passage but only about a half mile is open to the public. Other parts of the complex maze of a cave can be explored in special programs. Wightman says her favorite section is usually off limits. It’s called the Phosphorescent Room.

“You turn off your light and you’re kind of thrown into just this mysterious darkness. I remember sitting there thinking how lucky I was to be sitting in a place that I couldn’t actually see because it was totally dark, but I was part of this journey that was protecting this darkness,” says Wightman. “And then it was really fun to get out because we had to squeeze out through this other passageway that you had to be completely on your stomach and it was so tight that you actually had to remove your helmet in order to be able to fit through.”

"The big thing is no touching. It's kind of a weird message just because you need to touch the cave in order to move around it." - Katie Wightman

As one of California’s most visited subterranean places Crystal cave often needs cleaning. But we’re not talking about just candy wrappers and debris.

“It’s estimated that every visitor leaves about a belly button size full of lint when they travel through a cave,” Wightman says. “Kind of a disgusting picture and that can affect not only the aesthetics of the cave where you can get this kind of like grey film along sides of the trails and these kind of lint balls everywhere, but it also affects the ecosystem. The invertebrates will actually feed on that cave lint.”

That lint is made up of dead skin cells, hair and fiber left behind from our clothes. To stop millipedes and other bugs from gorging on that fuzz, crews periodically clean the cave. Last year volunteers removed 1,300 pounds of lint from Crystal Cave. 

Credit https://www.geocaching.com/geocache/GC2VWPY_crystal-cave?guid=2b774fa0-5457-4d14-90a5-15af90aa41e5
Here's a map of water flow through Crystal Cave.

To prevent harm to caves, Wightman says there’s certain etiquette that visitors should follow.

“The big thing is no touching,” says Wightman. “It’s kind of a weird message just because you need to touch the cave in order to move around it. As cavers we always wear gloves so that way the harmful oils on our skin don’t come in contact with the cave surface and we’re not disrupting any of those natural processes that’d helped to form the cave.”

Wightman says the only thing you want to leave behind in caves are footprints. And for the safety of the caves it’s actually illegal to go into most of the other 300 plus underground parts of the park. You have to become a cave trustee to enter them. But that process is on hold as the program is being developed.

Here's How to Get Started

Just because Sequoia's cave trustee program is on hold, there's no need to be disappointed: There are plenty of other caves to explore in the Sierra. Check out our list at the bottom of the page. The trick is that they’re not always marked, so you have to do some sleuthing—or, find someone who knows the area.

And if that’s what you’re looking for, we’ve found the guide for you: Meet Mark Balcom, a hiker, backpacker and caver living conveniently near Millerton Cave outside Fresno.

Credit Kerry Klein / KVPR
Mark Balcom explores in a caving suit to protect his clothes and keep his elbows and knees padded.

He’s been caving seriously for about 10 years—which means he got started in his 50s. He actually went caving once as a kid in Montana. He says he always remembered how fun it was, but decades passed and he never got back out there. Until he attended a Sierra Club dinner a few years ago and learned about a local caving club called the San Joaquin Valley Grotto. “I went to a meeting there and the rest is history,” says Balcom. He says the group is made up of around 30 cavers from around the Valley.

Joining a local “grotto” is a great way for anyone to get started, Balcom says. Just call them up and ask for a beginner trip.

“People in the caving community are remarkably willing to work with you if you show interest and show up, but it takes some effort on your part,” he says.

Caving’s not a solo sport, so getting involved really means finding your people.

“A cave is a really bad place to get panicky, because there's no quick, easy way out,” he says. “So having people that you trust, you can use that as a tool to calm yourself.”

You always want at least one person with experience, and knowledge about the cave you’re exploring is essential.

Mark says the ideal group size is about 3-6 people. That way, if someone gets injured, at least one person can stay behind while another gets help. But if your group gets too big, it can just take forever to get through tight spaces. Balcom learned that lesson a few years ago.

Credit Kerry Klein / KVPR
Balcom says helmets and multiple light sources are essential for safety and navigation.

“There was one fairly big cave that we went to with about 10 people, and it was anticipated to be about a 5-hour trip. But some of the people had problems and we needed to take more safety precautions to get them through, and we ended up being there 18 hours. We started at 11:00 one day, and when we came out it was about 6:00 the next morning.”

Think you’d panic in that situation? Balcom says it wasn’t actually a big deal. They had actually planned to camp that night anyway, so they had pretty much all their supplies on hand.

So, then, what gear is necessary? For most trips, the most important supply is light. It can get dark in there. Balcom recommends every caver have 3 light sources, including a powerful headlamp and batteries. That way, if you lend a light to a fellow caver and you need to change the batteries on your backup, you still have one more to light the way.

And then there’s protective gear: Helmet, gloves, and a cave suit to protect your clothes and give you padding where you need it most. There’s a lot of specialized gear, too, if you’ll be climbing up or down or if you expect a lot of water.

But no matter how prepared or experienced you are, Balcom says caving can still be scary. What’s important is knowing how to stay calm and work your way out of tough situations.

Credit Kerry Klein / KVPR
Balcom’s gear closet is full of ropes, webbing, carabiners and other gear for overnighting and climbing up and down through caves.

"There are times that you're trying to go through a narrow space,” Balcom begins. “And what I call tight, which is way beyond what other people call tight, is when I have to exhale in order to make forward progress. That's getting tight. There are times when something gets stuck, like a foot or an arm, and I really can't figure out what I need to do, and it's like, panic is really not going to help you here. Usually somebody nearby and gee, can you take a look at my foot and move it and see if you can get it free?”

So why would Balcom put himself through this? He loves the challenge of having to literally get out of tight spots. And he enjoys being in contact with the Earth through caves.

“They're unique places with unique life forms,” he says. “The activity itself requires doing it with a small group of people that you really need to trust, and that special bond that forms. It’s really a fun mind game. It's kind of like a form of meditation.”

Caves and Other Info

Ezra David Romero is an award-winning radio reporter and producer. His stories have run on Morning Edition, Morning Edition Saturday, Morning Edition Sunday, All Things Considered, Here & Now, The Salt, Latino USA, KQED, KALW, Harvest Public Radio, etc.
Kerry Klein is an award-winning reporter whose coverage of public health, air pollution, drinking water access and wildfires in the San Joaquin Valley has been featured on NPR, KQED, Science Friday and Kaiser Health News. Her work has earned numerous regional Edward R. Murrow and Golden Mike Awards and has been recognized by the Association of Health Care Journalists and Society of Environmental Journalists. Her podcast Escape From Mammoth Pool was named a podcast “listeners couldn’t get enough of in 2021” by the radio aggregator NPR One.
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