Jewel Cave National Monument
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40 free Jewel Cave National Monument trivia questions with answers — geography quiz, new questions added Oct 2026.
Jewel Cave is one of the longest caves on Earth, and almost nobody has seen most of it. Beneath a small patch of the Black Hills, passages run for hundreds of miles, and explorers come back from every expedition with more to add to the map. The story of how it was found, named and protected is full of odd turns. This quiz covers the fun facts people most want to know about Jewel Cave National Monument: the brothers who stumbled on it, the couple who turned a small show cave into a giant, the crystals and strange formations on its walls, the bats that winter there, and what the ranger-led tours involve. It is pitched for curious visitors, families planning a Black Hills trip, and anyone who likes a good underground story. Every answer comes with a short explanation, so you will pick up the facts as you play.
30 of 40 questions with answers and explanations. Play the quiz
Q 01What did the Michaud brothers feel coming from a small hole that led them to Jewel Cave in 1900?
Cold air
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.
Q 02What must visitors prove they can do on the patio before joining Jewel Cave's Wild Caving Tour?
Fit through an 8.5-inch gap
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.
Q 03Which food gives its name to the long ribbon drapery that hangs along Jewel Cave's Scenic Tour?
Bacon
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.
Q 04Jewel Cave explorer Herb Conn spent a week each fall filling cracks in which famous rock landmark?
Mount Rushmore
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.
Q 05Which president made Jewel Cave the first cave protected as a US national monument, in 1908?
Theodore Roosevelt
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.
Q 06Which cave system, the longest known on Earth, is the only one in the US longer than Jewel Cave?
Mammoth
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.
Q 07Jewel Cave National Monument lies beneath the Black Hills in the far west of which US state?
South Dakota
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.
Q 08How do visitors on Jewel Cave's popular Scenic Tour get down into the cave from the visitor center?
By elevator
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.
Q 09Explorer Jan Conn was the first woman to climb which Wyoming monolith without its old stake ladder?
Devils Tower
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.
Q 10Jewel Cave is named for the sparkling crystals of which mineral that coat many of its walls?
Calcite
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.
Q 11A national park under 20 miles from Jewel Cave protects a cave named after which kind of weather?
Wind
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.
Q 12Jewel Cave formed in which type of rock, built up from shells on the floor of an ancient shallow sea?
Limestone
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.
Q 13Which fungal disease of hibernating bats was first detected at Jewel Cave in 2018?
White-nose syndrome
Q 21Jewel Cave is a classic example of which kind of cave, named for how it reacts to the weather?
Breathing
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.
Q 22Which New Deal program camped at Jewel Cave from 1935 to 1939, building a cabin and stone stairway?
Civilian Conservation Corps
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.
Q 23Which 1906 law gave presidents the power used two years later to protect Jewel Cave?
Antiquities Act
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.
Q 14Which is the only venomous species among the nine kinds of snake at Jewel Cave National Monument?
Prairie rattlesnake
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.
Q 15What do visitors carry as the only light on Jewel Cave's tour led by a ranger in 1930s uniform?
Lanterns
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.
Q 16Which group has done all of the exploration and mapping of Jewel Cave's 220-plus miles of passages?
Volunteers
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.
Q 17What did the Michaud brothers use alongside hand tools to enlarge Jewel Cave's tiny natural entrance?
Dynamite
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.
Q 18What does Jewel Cave's visitor center lend to winter visitors for use on the surface trails?
Snowshoes
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.
Q 19Which tree dominates the woodland covering the surface of Jewel Cave National Monument?
Ponderosa pine
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.
Q 20Roughly what share of Jewel Cave do scientists believe explorers have discovered so far?
3–5%
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.
Antiquities Act powers cover federal land holding objects of historic or scientific interest. Inspectors judged that the cave qualified, and proposed the monument themselves.
Q 24Which town, the oldest settler town in the Black Hills, lies about 13 miles east of Jewel Cave?
Custer
Custer began in 1875 as a gold-rush camp called Stonewall. Jewel Cave's finders registered their mining claim in the town in 1900.
Q 25Jewel Cave shelters one of the largest known hibernating colonies of which moth-hunting bat species?
Townsend's big-eared bat
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.
Q 26What did Jewel Cave explorers find for the first time in 2015, roughly 600 feet below the surface?
A lake
A lake, named Hourglass Lake, showed where the cave meets the Madison Aquifer. Explorers have since found more than a dozen others.
Q 27Which acid, formed as rain seeps through decaying plants in soil, carved most of Jewel Cave?
Carbonic
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.
Q 28Which mineral grows in dry parts of Jewel Cave in forms called needles, beards, flowers and spiders?
Gypsum
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.
Q 29What kind of club did Jewel Cave's first owners organize in 1902 in a bid to attract tourists?
Dancing
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.
Q 30On which holiday did the Michaud brothers file their Jewel Tunnel mining claim on Jewel Cave?
Halloween
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.