If you trudged up the mountain and walked through the caves at Timpanogos Cave National Monument any time in the last 60 years, you probably met Arlo Shelley.

The man who fell in love with the caves of American Fork Canyon during a fourth-grade field trip class in 1938 and worked as a ranger guide there for 57 years passed away last month.

Arlo, 80, was as much as a treasure at the caves as the Great Heart formation and the numerous helictites that decorate the Timpanogos Cave labyrinth. He was a personnel fixture in a National Park System that rarely sees employees stick around for more than a decade.

The people of Utah and the citizens of the world who visited the monument enjoyed his vast knowledge of the cave and the canyon and appreciated his wit and humor.

Return visitors to Timpanogos would often inquire when Arlo would be leading tours and plan their trip around his schedule.

Arlo retired at the end of the 2006 summer season, due largely to pain in his knees, but made a couple of trips up the 1.5-mile trail --which has a 1,065 vertical-foot gain -- in 2007. Timpanogos Cave National Monument superintendent Denis Davis was with Arlo on one of those trips.

"We slowly walked to the top. It was a great opportunity for us to talk about the issues related to the cave," Davis said. "When we got to the top he sauntered in like he owned the place. He took a flashlight from the ranger and guided the next tour. It was my only time to hear his version of the tour and it was a delight."

I met Arlo during a family trip in 1999 and returned to spend some time with the ranger. He told me how he had worked as a chemistry, biology and physical-science teacher at American Fork High School for more than 30 years and that the six years he took off from being a guide at Timpanogos was so he could focus his attention during his stint as a principal at the school.

He got a big kick out of telling me the mascot for American Fork High School is the cavemen.

Arlo said he enjoyed the physical nature of the work, but he also enjoyed the loneliness of the cave.

"Being inside the mountain gives you a chance to examine your own thoughts," he told me. "In the cave, you can hear your heartbeat in your eardrum."

But the real draw for Arlo was the chance to meet people and share his love for the cave system.

"Every time I lead a tour it is the first time for somebody and it really gives me a charge," he said. "For the people, the cave is the point of interest. For me, it is how the caves affects the people. I love that I get to participate in so many people's vacations."

Royce Shelley, one of Arlo's six children, was so enamored of his father that he followed precisely in his footsteps. Royce has been working as a seasonal ranger guide at Timpanogos for 18 years and is also a teacher in American Fork.

"He loved interacting with people from all over the world and the people from next door," Royce said.

And Royce wasn't the only family member to follow in Arlo's footsteps. Three of Royce's four children -- Rosalind, MaryAnn and Stewart -- have worked at the national monument.

Arlo was fond of saying he had hiked more than 180,000 miles in American Fork Canyon, most of it on the national monument trail, but he also made it to the top of Mount Timpanogos (11,750-feet) 55 times.

There are no definitive plans to do anything to memorialize Arlo at Timpanogos Cave National Monument, but Davis says there has been some talk about including his name in some form involving a possible new visitors center.

Arlo dedicated himself to sharing his love for Timpanagos Cave for six decades. It seems only fitting that the National Park Service should honor that dedication.

Brett Prettyman is an outdoors columnist. Reach him at brettp@sltrib.com