Martin Hansen was exhausted. A logger by trade, he had spent all day felling trees for lumber and firewood on the south wall of American Fork Canyon, near the foothills of Mount Timpanogos. As he prepared to return to his Lehi home that day in October 1887, he leaned his ax against a tree so he could use it the next day.

A light dusting of snow fell that night. When Hansen returned to resume his work, he noticed something unusual: mountain lion tracks. Grabbing the ax, he followed the tracks even higher up the canyon wall until they ended in an opening in the cliff face – it was a cave filled with wonderous mineral formations.

Today, we know this as Hansen Cave, one of the three caves that comprise Timpanogos Cave National Monument. The caves are a testament to the awesome forces of nature working over millions of years – and to the group of Utahns who worked quickly to preserve the caves as a national monument.

News of Hansen’s discovery spread quickly, and soon he was leading cave tours. It was no casual trip for the first cave tourists; they had to climb up on trees Hansen had cut down and lashed to the cliff, then crawl through the cave with only candlelight to see the wonders within.

No one is sure exactly what those early visitors saw. Within a few years of Hansen Cave becoming known, a Chicago-based company filed a mining claim to the land and removed most of the cave’s mineral deposits.

Though stripped of much of its grandeur, the cave remained a popular daytrip destination for locals around American Fork. In 1913, a pair of 14-year-old boys were with a group visiting Hansen Cave when they got bored and decided to explore the rock ledges beyond. When they realized the cliff was too steep for them to get down the way they got up, they searched for an alternate route back.

One of the boys noticed a rock with mineralization on it. Thinking it might lead to precious metals, they began to dig – until the rock fell into a deep, dark hole. They had discovered what is now known as Timpanogos Cave. The boys retrieved the rest of their group to investigate the cave. Though they did not publicly announce their find, talk of the new cave circulated.

Intrigued by the rumors, Vearl Manwill of Salt Lake City decided to look for the cave while with a group of mountain climbers on Aug. 14, 1921. They first went to Hansen Cave, which left them very disappointed. Then Manwill started poking around at the same elevation, eventually disturbing some rocks that had been piled around Timpanogos Cave’s entrance. He called for the rest of his party and went inside.

“It was a thrilling experience, as there were no trails or tracks to follow,” Manwill later wrote. “In places we had to lay on our stomachs and squeeze through. Other places we had to make ourselves into human bridges or ladders to help the ladies along.”

As they reconvened in camp that evening, they marveled at what they had seen.

“By the light of campfire, (we) discussed our find and talked about ways and means to preserve its beauty for posterity instead of allowing it to be vandalized as Hansen’s Cave had been,” Manwill wrote.

Two months later, on Oct. 15, 1921, Heber and Wayne Hansen – son and grandson of the discoverer of Hansen Cave – were hunting deer in American Fork Canyon on the opposite side from the caves. When 18-year-old Wayne used his binoculars to look across the canyon, he noticed what looked like a third cave opening between Hansen Cave and Timpanogos Cave.

The Hansens abandoned their hunt and set off to find this new entrance. They reached it and, using matches to light their way, entered as far as they could before stopping at a very deep pit. As this third cave was located between the two previously discovered caves, it became known as Middle Cave.

As news of the discoveries spread, people clamored to see the caves for themselves. But the caves were on U.S. Forest Service land. Forest Service rangers put doors on the caves, but they didn’t have the staff or funding to offer tours.

Local civic groups stepped in to form the Timpanogos Cave Committee to do that work. Volunteers built a steep path up the canyon wall and installed lighting in the caves to facilitate tours. The group began the first official cave tours exactly 100 years ago in the spring of 1922.

Despite the rough hike to get to the caves, thousands of people made the trek to see them. But the publicity also drew the attention of people who said they had mining claims to the site.

To prevent a repeat of what happened to Hansen Cave, in September 1922, the local U.S. Forest Service requested the caves be protected as a national monument. In what might be record time, President Warren G. Harding issued a proclamation just one month later declaring the creation of Timpanogos Cave National Monument.

Since 1939, Hansen Cave, Middle Cave and Timpanogos Cave have been connected to each other by manmade tunnels. National Park Service rangers guide groups on tours that traverse 1,800 feet through all three caves in just under an hour; the total combined length of cave passages, including areas off-limits to visitors, is 5,600 feet.

The floor of American Fork Canyon at Timpanogos Cave National Monument is more than a mile above sea level. By the end of the strenuous hike to the entrance at Hansen Cave, visitors are at a lofty 6,735 feet above sea level.

So it comes as some surprise when one of the first things people see when they enter the cave is … coral.

The fossilized coral is embedded in the cave’s Deseret limestone, which, despite its name, didn’t form in Utah – at least not in the location where Utah is now. The limestone formed at the bottom of a warm, shallow sea near the equator. Over the course of 340 million years, the slow but steady drift of the Earth’s tectonic plates moved it thousands of miles to its present location near American Fork.

To enter the caves is to be confronted with such stories, illustrating the credulity-straining wonder of geologic time. But even if one were completely oblivious to how the cave formed, the weird beauty of the stalactites, helictites and other remarkable mineral formations that lie hundreds of feet underground is astounding.

Though the caves’ limestone formed 340 million years ago, the actual cave passages are relatively young, geologically speaking, forming somewhere around 750,000 years ago. Before the mountains uplifted to their present height, the limestone was beneath the water table. Geothermal waters percolated up through faults in the limestone, gradually dissolving the rock to hollow out the caves.

Once the caves lifted above the water table, they didn’t completely dry out. Water seeped in from above through cracks in the rock. This water carried with it the dissolved mineral calcium carbonate. When the water eventually evaporated, the mineral was left behind as a speleothem, or cave deposit.

The most famous speleothem at the national monument is the Great Heart of Timpanogos, a massive stalactite that is actually several large stalactites that fused together. The formation is 5 ½ feet long and weighs 4,000 pounds.

The speleothems at Timpanogos Cave take many forms beyond the familiar stalactites, which droop down from the cave ceiling, and stalagmites, which are built up from the floor. There is cave popcorn, which looks exactly like it sounds; this forms either from drops of water that splatter against the cave wall or from condensation. Similarly appetizing is cave bacon, which forms when water repeatedly runs in the same path down a sloped ceiling.

However, the feature that sets Timpanogos Cave apart from nearly all other caves are its helictites, which occur here in greater abundance than nearly anywhere in the world. Some say they look like spaghetti, while others have said they look like calamari or curly French fries – thin spirals that seldom surpass 6 inches long.

Helictites are extremely delicate and extremely mysterious – no one know exactly how they form. The most generally accepted theory is that they form as hollow tubes, and water is drawn out by capillary action.

Whether it’s blisteringly hot or freezing cold outside, the inside of the cave system at Timpanogos Cave National Monument remains within 43 and 49 degrees. The cool cave temperatures can come as a relief to those who have huffed and puffed their way up the steep, 1 ½-mile trail to get there.

“The cave feels so different from the world you’re accustomed to,” the monument’s Acting Superintendent Cami McKinney said. “You can feel it in your skin.”

And though the passages are fairly well lit, there is one part of the tour where the ranger turns out all the lights, producing a blackness so profound that visitors truly cannot see their own hands in front of their faces. It is an eerie experience.

“There’s something about the darkness that challenges human nature a little bit,” McKinney said.

For the past 31 years, National Park Service Ranger Royce Shelley has guided cave visitors through the darkness at the monument. Shelley is a living repository of Timpanogos Cave lore, thanks both to his own experience and that of his father, Arlo, who himself worked as a guide at the cave for 57 years, starting in 1944.

For decades, Shelley said, the National Park Service used a series of small diesel dump trucks – originally used in uranium mines near Moab – to haul supplies up and down the narrow trail to the caves. A man named Don Robinson of American Fork was the “one guy with the nerves of steel to get it up there,” he said.

It certainly wasn’t a job for the faint of heart. Robinson would drive it up like normal until he got to the first switchback, at which point he would drive the next leg in reverse, as there wasn’t enough room to make a proper turn. He would continue up, alternating driving forward and backward, until he reached the top. When Robinson died, the National Park Service stopped using the truck, as no one else dared to attempt the dangerous ascent.

The most memorable of the thousands of tours Shelley has given came late one Sunday afternoon. About 45 minutes after the cut-off time for ticket sales, he got a call on the radio from the ranger below, saying he had just sold three more tickets. “I couldn’t tell them no,” the ranger told him.

Shelley and his tour guests waited for the latecomers, finally seeing three orange-robed Buddhist monks come walking up the trail. Also on the tour were families from South America, Central America, California and Ogden.

“It was the most delightful exchange between different people and cultures I have ever witnessed in my life,” he said.

Experiences like that are what keep Shelley hooked on Timpanogos Cave National Monument. As beautiful as the cave formations are, it is just as beautiful to see the power the caves have to bring people together.