He keeps the sewers of Mercer Island working by day. But once the weekend arrives, Tom Babcock is off into the wild, walking stick in hand, backpack stocked, ready to search for his personal treasure — agate rocks.

Rock hunting has been a lifetime passion for the city maintenance worker. Whether it’s rare blue agates — sometimes worth hundreds of dollars a piece — petrified wood or ancient Native American arrowheads, each discovery catches Babcock’s breath and compels him to search for more.

“There’s no better rush for me, other than bending over and finding an arrowhead that somebody’s dropped,” said Babcock. “I found an indigo blue agate — just a beautiful one — last summer, and I was offered $400 cash for it, but I said, ‘No way. This one I’m going to keep.”’

It’s not just about finding rocks and historical artifacts, Babcock explained — it’s about the adventure that comes with the search. And this, he said, is why he chose rock hunting as the subject of his Island Books “Answer the Call” writing contest.

The competition is part of this summer’s “Big Read on Mercer Island.” The book chosen for the 2009 Big Read, a communitywide initiative to encourage leisurely reading, was Jack London’s “The Call of the Wild,” going along with this summer’s Alaska-Yukon-Pacific Centennial celebration. Hundreds of copies of “The Call of the Wild” were distributed for free to Island students, businesses, city employees and residents. Island Books helped sponsor the event by organizing an “Answer the Call” writing contest for those who finished the book. Readers were invited to submit a one-page personal reflection answering the question, “What’s calling you?” Two contests were held; one for adults and one for children. Babcock, with his personal essay on agate hunting, won the adult contest — a $75 gift certificate to Island Books.

The city employee said he was thrilled to win the award, especially because it was his first attempt at creative writing.

“That is the first story I ever wrote. I wanted to thank Island Books for donating the novel, so when owner [Roger Page] asked me to write a one-page response, I thought, ‘I’ll give it a whirl.’ And it was fun,” Babcock said.

Page said that Babcock’s “personal voice” helped his writing submission stand out above the others. This quality was the same for the winner of the children’s contest, a piece written by 9-year-old Malcolm Davis.

“Both responses were written with a great deal of care,” Page said, adding that he and his fellow Island Books employees judged the writing. “Both were very personal stories about heading off on an adventure and life’s surprises along the way.”

Babcock focused on one of his most memorable rock-collecting moments when, after hours of arduous searching in 90-degree weather, he came across the rare and bedazzling Plume Agate.

“Walking back with my head down, looking at every rock, I suddenly spot what I’ve been looking for. I yell, ‘Eureka!’ at the top of my lungs. There it is, a Plume Agate the size of a golf ball and it’s worth hundreds of dollars; a real treasure!” Babcock wrote. “Walking the last few yards, I realize that to me it’s priceless and I will never sell it. Forever, I will look at the prize in my case and think of that day, frozen in time in my head as if it were yesterday.”

Davis, like Babcock, wrote a personal story about navigating a small tin boat from Lopez Island to Seattle with his father when he was 7 years old. The trip was one of Davis’ most memorable experiences, not to mention greatest adventures.

“Imagine zigzagging through a bunch of whirlpools in cold, dark water with only a small tin boat for protection,” Davis wrote in the opening of his response, titled “The Big Adventure.”

The fourth-grader’s descriptive writing and enthusiasm about his nautical experience earned him first place among more than two dozen student submissions. As a reward, visiting author Gary Paulsen recognized Davis during his Big Read appearance at Mercer Island High School last Wednesday. Davis said he was thrilled to meet the author, who gave him autographed copies of his books “The Hatchet” and “Mudshark.”

“It was really exciting to meet him. I’ve already read of a couple of his books. Adventure books are my favorite type of books,” Davis said.

Copies of “The Call of the Wild” can be checked out at the Mercer Island Library, Island Books and several other Island locations.