Susan Purvis, formerly of Marquette, has written a memoir, “Go Find,” which tells the story of her searching for life in the high country of Colorado with her “avalanche dog,” a black Labrador retriever named Tasha.

Sebastian Junger, author of “The Perfect Storm: A True Story of Men Against the Sea,” called it “a brave and profound book.”

Purvis spoke about her adventures on Monday at the Peter White Public Library in Marquette.

However, those adventures weren’t limited to the wilderness. Tasha’s last mission was rescuing Purvis from her own personal “avalanche,” which she describes in her book.

This is Susan Purvis and her “avalanche dog,” Tasha, waiting for the return of a helicopter after their mission on the flanks of Whitehouse Mountain in Ouray, Colorado, in 2005. The area was the site of a fatal plane crash. (Photo courtesy of Susan Purvis)

“‘Lost’ has been not a location,” Purvis said in a video shown at the presentation. “It’s a transformation. It’s a failure of the mind. It can happen in the woods or it can happen in life.

“It took me years to learn that ‘lost’ doesn’t only apply to losing the trail and going off the map in the wilderness. I didn’t know then that people can get lost in an ocean, in a relationship, in a marriage, in a business or in a life.”

Since 1998, Purvis has owned and operated Crested Butte Outdoors International, based in Whitefish, Montana, whose mission is to teach students how to think critically in unconventional settings.

Purvis spent a decade working at an urgent care ski clinic in Crested Butte where she also worked as a professional ski patroller, guide, K-9 avalanche expert and search-and-rescue member.

All these accomplishments came after first learning to use a compass at age 10 when her dad took her fishing for lake trout on Lake Superior.

She left Marquette at age 17, and studied at the University of Montana.

“Part of my job, then, was to always know where I was,” said Purvis, who became a working geologist following college.

That meant looking at maps for a living, a skill that came in handy during her search-and-rescue efforts.

“Half the battle is trying to figure out where you are and where you’re going,” Purvis said.

Eventually — vowing never to leave anyone behind in an avalanche situation — Purvis acquired 5-week-old Tasha.

She trained and deployed Tasha from 1995 to 2007, having been trained in avalanche dog tactics, alerts, problem solving, dog psychology, case studies, automobile burials on highways and helicopter deployment.

Scent plays an important part in the avalanche dog world.

“They can smell like we see,” Purvis said.

That’s understandable, considering receptors in a dog’s nose number about 220 million compared with a human’s mere 5 million.

Search-and-rescue teams, Purvis stressed, are constantly paying attention to the wind to determine where human scent goes. In fact, she recommends searches using avalanche dogs take place at night because the colder air pushes scent down.

Day or night, finding bodies following an avalanche can be difficult.

The harrowing experience of finding four passengers killed in a single-engine plane crash on Colorado’s Whitehouse Mountain in the summer of 2005 was detailed throughout “Go Find.”

Ouray Mountain Rescue had located three of the victims, but one man still was missing, and it was up to Purvis and Tasha to find him after the local sheriff suspended the recovery mission after deeming it too dangerous.

After finding the remains of that last victim, Purvis kissed Tasha’s forehead, telling her: “My good girl, you found him. You sat next to him like a good little soldier. You did what I asked of you.”

This came after Tasha went to a particular spot twice, with Purvis initially failing to see a rounded sock that sprouted “bulbous from the snow, different from the surrounding, undulating, pebble-covered bumps.”

Unfortunately, typically by the time people are called, teams are involved in a body recovery instead of a live save, she said.

However, Purvis was involved in one “live find” during her career: a 12-year-old boy lost in a blizzard. It took three hours of tracking to locate him.

Purvis still focuses on outdoor pursuits, combining wilderness medicine, desert survival, exploration geology, and K-9 search and rescue to land jobs on all seven continents. Purvis teaches high altitude medicine for the local Mount Kilimanjaro and Mount Everest guides and has served as a medic at a remote field camp and ice breaker in Antarctica. She also has explored for gold in the Dominican Republic and produced a documentary in the Amazon jungle.

Her pursuits, though, now don’t include Tasha, who eventually was put to sleep after suffering seizures.

It’s a difficult scenario — having to put down a cherished pet — but in the case of Purvis and Tasha, it was particularly poignant.

In the book, Purvis wrote:

“My beautiful Tasha is purring. My nose nestles deep into her ear. ‘You saved many lives…and mine too. You never left anyone behind.’ I give her one last command.

“‘Go find!'”

So in the end, why was she involved in search and rescue?

“It’s a way to give back,” Purvis said. “It gave me purpose and passion.”

For more information about Crested Butte Outdoors and links to purchase “Go Find” on Amazon and at Barnes & Noble, visit cboutdoors.com. The book also is available at Snowbound Books, 118 N. Third St., Marquette.