40 Fun Facts About Jewel Cave National Monument

What did the Michaud brothers feel coming from a small hole that led them to Jewel Cave in 1900?

Cold air blasted out of a hole too small to crawl into, so the brothers widened it. The crystal-lined walls they found inside sparkled like jewels, which gave the cave its name.

What must visitors prove they can do on the patio before joining Jewel Cave's Wild Caving Tour?

Visitors must fit through an 8.5-inch gap, a test block 8.5 inches high and 24 inches wide. The tour itself is three to four hours of scrambling, chimneying and belly-crawling.

Which food gives its name to the long ribbon drapery that hangs along Jewel Cave's Scenic Tour?

Cave bacon is a thin, wavy drapery whose coloured mineral bands look like streaky meat. Jewel Cave's long strip hangs beside the paved half-mile loop of the Scenic Tour.

Jewel Cave explorer Herb Conn spent a week each fall filling cracks in which famous rock landmark?

Mount Rushmore was Herb's autumn job for 13 years, sealing cracks in its four carved faces. He and his wife Jan lived nearby for six decades without electricity or running water.

Which president made Jewel Cave the first cave protected as a US national monument, in 1908?

Theodore Roosevelt signed the proclamation on February 7, 1908. For half a century the cave was thought to be about two miles long; more than 220 miles are now mapped.

Which cave system, the longest known on Earth, is the only one in the US longer than Jewel Cave?

Mammoth Cave in Kentucky has more than 420 miles of surveyed passages. Jewel Cave comes second in the country, with over 220 miles packed beneath about four square miles of land.

Jewel Cave National Monument lies beneath the Black Hills in the far west of which US state?

South Dakota's southwestern Black Hills hold the monument. Its 1,274 surface acres cover less than half of the known cave, which runs on beneath neighbouring public land.

How do visitors on Jewel Cave's popular Scenic Tour get down into the cave from the visitor center?

By elevator: a shaft was sunk to reach rooms found by explorers Herb and Jan Conn. The tour, opened in 1972, still involves 734 stair steps.

Explorer Jan Conn was the first woman to climb which Wyoming monolith without its old stake ladder?

Devils Tower was scaled by Jan Conn and Jane Showacre in 1952, its first all-female ascent. Jan and her husband Herb later mapped more than 60 miles of Jewel Cave.

Jewel Cave is named for the sparkling crystals of which mineral that coat many of its walls?

Calcite crystals called nailhead spar coat most of the walls, laid down while the cave was still flooded. The brothers who found them staked a mining claim on the cave.

A national park under 20 miles from Jewel Cave protects a cave named after which kind of weather?

Wind is the namesake of the park created in 1903, five years before Jewel Cave was protected. No passage linking the two giant caves has ever been found.

Jewel Cave formed in which type of rock, built up from shells on the floor of an ancient shallow sea?

Limestone here dates from about 350 million years ago, when a shallow sea covered the region. The shells came from sea creatures such as brachiopods, and fossils of that age still show in the cave.

Which fungal disease of hibernating bats was first detected at Jewel Cave in 2018?

White-nose syndrome wakes bats from hibernation, burning the fat they need to last the winter. The cave's winter count was over 1,400 bats in 2018 and 602 in the winter of 2023–24.

Which is the only venomous species among the nine kinds of snake at Jewel Cave National Monument?

Prairie rattlesnake sightings are rare at the monument, and its other eight snake species are harmless. Bighorn sheep, mule deer and mountain lions share the rocky ground.

What do visitors carry as the only light on Jewel Cave's tour led by a ranger in 1930s uniform?

Lanterns light a half-mile route with about 500 steep wooden steps, some taken backwards. It starts at the historic entrance, the only one bats use, so visitors may meet them.

Which group has done all of the exploration and mapping of Jewel Cave's 220-plus miles of passages?

Volunteers do it all, on expeditions that can last four days with nights at underground camps. Herb and Jan Conn, who mapped more than 60 miles of the cave, were volunteers too.

What did the Michaud brothers use alongside hand tools to enlarge Jewel Cave's tiny natural entrance?

Dynamite opened the hole enough for the brothers and family friend Charles Bush to crawl inside. They found low rooms and crawlways glittering with crystals.

What does Jewel Cave's visitor center lend to winter visitors for use on the surface trails?

Snowshoes are loaned out for the quarter-mile Roof Trail and the 3.5-mile Canyons Trail. The cave below ignores the seasons, staying at 49°F all year.

Which tree dominates the woodland covering the surface of Jewel Cave National Monument?

Ponderosa pine woods cover most of the monument, mixed with open meadows. Trees matter underground too: wooded ground lets less water seep into the cave than grassland does.

Roughly what share of Jewel Cave do scientists believe explorers have discovered so far?

3–5% is the estimate, worked out from the volume of air moving through the cave. If it is right, thousands of miles of passage are still waiting to be found.

Jewel Cave is a classic example of which kind of cave, named for how it reacts to the weather?

Breathing caves inhale when the outside pressure rises and exhale when it falls. Herb Conn worked out why Jewel Cave does it in a scientific paper published in 1966.

Which New Deal program camped at Jewel Cave from 1935 to 1939, building a cabin and stone stairway?

Civilian Conservation Corps crews of 25 men did the work on a budget of $1,500. Their three-room cabin served as visitor center and ranger home until 1972.

Which 1906 law gave presidents the power used two years later to protect Jewel Cave?

Antiquities Act powers cover federal land holding objects of historic or scientific interest. Inspectors judged that the cave qualified, and proposed the monument themselves.

Which town, the oldest settler town in the Black Hills, lies about 13 miles east of Jewel Cave?

Custer began in 1875 as a gold-rush camp called Stonewall. Jewel Cave's finders registered their mining claim in the town in 1900.

Jewel Cave shelters one of the largest known hibernating colonies of which moth-hunting bat species?

Townsend's big-eared bat made up over half of the 1,400 bats counted in the cave in 2018. It roosts where the airflow is strong and lives about 16 years on average.

What did Jewel Cave explorers find for the first time in 2015, roughly 600 feet below the surface?

A lake, named Hourglass Lake, showed where the cave meets the Madison Aquifer. Explorers have since found more than a dozen others.

Which acid, formed as rain seeps through decaying plants in soil, carved most of Jewel Cave?

Carbonic acid forms when water absorbs carbon dioxide from the soil. Unlike many caves, Jewel Cave was carved by slow, standing groundwater, never by an underground river.

Which mineral grows in dry parts of Jewel Cave in forms called needles, beards, flowers and spiders?

Gypsum is left behind when seeping water evaporates, so it decorates only the dry parts of the cave. The same mineral is the main ingredient of plaster and drywall.

What kind of club did Jewel Cave's first owners organize in 1902 in a bid to attract tourists?

Dancing was the draw at the Jewel Cave Dancing Club, and a lodge went up on the canyon rim. Few people lived nearby and travel was hard, so the venture never paid.

On which holiday did the Michaud brothers file their Jewel Tunnel mining claim on Jewel Cave?

Halloween 1900 is the date on the claim, the earliest written record of the cave. A mining claim gave the finders a fast, easy way to control who went inside.

Which agency ran Jewel Cave National Monument from 1908 until a 1933 executive order moved it?

US Forest Service land still surrounds the monument, and more than half of the known cave lies beneath it. A 1965 land swap let a new tour route be built.

What swept across 90% of Jewel Cave National Monument in August 2000, sparing the visitor center?

A wildfire called the Jasper Fire burned about 83,000 acres in and around the monument. The meadows it opened now bloom with coneflowers, though weeds such as Canada thistle moved in too.

Most crystals mined at Jewel Cave went to a priest building the Grotto of the Redemption in which state?

Iowa's Grotto of the Redemption, in West Bend, is a shrine built from minerals and stones gathered worldwide. Selling crystals also helped prove the cave was a working mine.

What did Jewel Cave's owners petition the government to create in 1906, hoping to draw visitors?

A game reserve was turned down because the area held too little wildlife. The inspectors suggested a national monument instead, for the cave's scientific interest.

Which black mineral permanently stains clothes and boots on Jewel Cave's Wild Caving Tour?

Manganese rubs off on everything, so visitors must bring a clean change of clothes and a bag for the dirty set. Stained gear may not be worn in a neighbouring cave.

Jewel Cave's park geology guide likens chalky white clumps of hydromagnesite to which dairy food?

Cottage cheese is the comparison for the pasty mineral, which settles out where evaporation is very high. It is often a by-product of frostwork or cave popcorn forming.

What are Jewel Cave's rare hollow formations called, made when gas inflates pasty hydromagnesite?

Balloons of hydromagnesite were first discovered in Jewel Cave, and one is nicknamed the earring. Nobody has pinned down where the gas that inflates them comes from.

Jewel Cave's only natural entrance opens into which canyon, also the name of a nearby hiking trail?

Hell Canyon is where the cave meets the surface; its deepest known point lies about 600 feet underground. The 3.5-mile Canyons Trail passes the historic entrance there.

Which squeeze features on Jewel Cave's Wild Caving Tour along with Hurricane Corner and the Roller Coaster?

The Brain Drain is one of the named obstacles on the two-thirds-mile route, which also climbs Martha's Kettle. At most five visitors go on each trip.

What was the profession of Dwight Deal, the friend who first took Herb and Jan Conn into Jewel Cave?

Geologist Dwight Deal told the Conns that when it was too cold to climb, he went underground. They agreed to try caving once, then kept exploring for more than two decades.