It was a rock like many other rocks.

Actually, it was like every other rock, indistinguishable from the thousands of identical rocks surrounding it along the trail.

But we stopped to look at it anyway.

"Is it an arrowhead?" asked Isabel, her hands on her knees.

"I think it's an arrowhead," said Dillon, bending over.

It wasn't an arrowhead. It was a rock (see above) that happened to taper to a vague point at one end. But still, we looked.

Twenty paces later, we stopped again.

"Look at this one," said Dillon, squatting.

"Mmmmmm," said Isabel, peering.

And thus we hiked -- if that's the right word -- for six miles into the backcountry of Montana's Glacier National Park. We were two dads -- Jim Sebastian of Takoma Park and myself -- and two daughters -- both just shy of 7 -- on a one-night backpacking trip through Glacier's peak-to-pebble marvels. Having watched them master soccer, outgrow all the boys in first grade and show at least as much interest in spiders and snakes as in Barbies and Bratz, we decided Dillon and Isabel would nicely round out a backcountry foursome.

We were right. Packs filled with clothes, water and trail mix were nothing for little backs already toughened by school bags that groan with math books and Harry Potter hardcovers. Hours of single-filing it between art and recess and gym made keeping to the trail a snap. What could be better training for a one-pot mystery stew than two years in a school cafeteria?

Forget reading and writing; what public schools do well these days is turn out a first-rate wild girl (the nature kind, not the Daytona Beach kind -- although I'm sure that's coming). I remember whining and crying for every step of my own first six-mile hike up a mountain. And I was in college.

Still, there's no question that the venerable guy sacraments of roughing it in the woods get reworked when you add daughters to a dads' backpacking trip. (Don't worry, the most fundamental birthrights of a male in the wilderness remain intact -- long live the pleasures of peeing anywhere, never shaving and wanton belches.) But when Generation Powerpuff hits the trail, the mood shifts a bit from Hemingway to Hello Kitty. Tying flies becomes less important than braiding hair. Swigging bourbon from the bottle gives way to picking out every single raisin from a bowl of oatmeal. The greatest test of your woodcraft is trimming the crust off a peanut butter sandwich. And you hike. Very. Slowly.

"Is this one bigger than this one?" Dillon paused to ask, pondering two identical blades of grass.

As Isabel gave this question all the slow, measured consideration it deserved, I tugged on my shoulder-crushing backpack straps and did a little mental math -- Let's see, six miles to go at one-tenth-of-a-mile per hour . . . If there were still a glacier in Glacier park, it would have blown past us like a Maserati.

"Dunno," was Isabel's conclusion.

Bless the boundless curiosity of children! It's just that for someone like me, for whom a certain rhythmic stride is central to the joy of hiking, stopping every five feet or so is actually a form of torture. It's like being woken up every 10 minutes, just before you begin to dream. After an hour at a pace more appropriate to an art gallery than a mountain range, you start going a little bit insane. It gets harder to muster the requisite awe for the pine needle that is shaped like the numeral four. At its worst, some depraved part of you wants to take that exquisite dragonfly wing and grind it into dust before those four wondering eyes.

It would be a teachable moment, The Madness whispers, to just stretch out and walk around the bend, not caring about the moment when those big little eyes finally lift from the bug-that-looks-like-a-bug and grow wide with the realization that they should have listened when Daddy was saying, "Let's go girls. Let's go. Okay? Let's go. Girls?"

That would show 'em, says The Madness, wringing its withered hands.

But of course you don't do that. You never get more than three feet from your ward because the Northern Rockies are grizzly country and you know from legend, rumor and the chilling safety video in the ranger station that if you so much as blink, a bear will eat your daughter and your wife will never let you hear the end of it. So per instruction, we clapped and whooped and sang and generally shattered the wilderness peace as we made our halting way along the trail, Jim and I trying not to envision an encounter between a 12-foot rearing grizzly and a 50-pound rising second-grader. Anything to avoid startling -- and thus provoking -- Mother Bear is fine with us. But after 43 rounds of "Found a Peanut," Mother Bear should worry about avoiding me.

We mapped out a relatively softball route, just enough to give the girls a taste of backcountry camping and break up an otherwise comfy week of Glacier park lodges. Of course, if it had been just us men, we would have pounded out 20 miles a day, bagging summits along the way and taking a few minutes each evening to kill something for dinner (an elk for me, some feral tofu for Jim the vegetarian). But six miles seemed enough of a challenge for the bicycle-spoke legs of our trail mates -- four miles along the southern edge of Two Medicine Lake, then a gentle two-mile climb to a campsite on the shore of Upper Two Medicine Lake. It's a spectacular setting, where the turquoise water of the mountain lakes are rimmed with tall evergreens and watched over by the high molars of the surrounding peaks.

It was cap-snatching windy at the trail head -- a parking lot at the lower end of the lake -- but as soon as we got in the woods the air settled and the temperature climbed a degree. That was the first of 136 subtle temperature changes we would experience. They were nothing a normal human would even notice, but to little girls, each one was akin to the difference between cremation and cryogenics.

"I'm hot," said Dillon after a minute. Less than a minute, actually. More like seconds.

Fair enough. We stopped and Dillon unshouldered her small red backpack, took off her fleece, folded it and stuffed it carefully into her pack. Isabel watched with interest. We all watched. We watched and watched. And then off we went.

"Found a peanut! Found a pea . . . "

"I'm hot too," said Isabel, 40 seconds later. We stopped again. Her backpack was green. Watch, watch, watch.

A few minutes down the trail, a sparse clearing opened onto the wind-whipped lake. I felt a soft warning breeze and tried to speed past the narrow opening ("foundapeanutfoundapeanut"). But not fast enough.

"I'm cold," they beseeched in unison, planting their little feet.

I tried to suggest that with the sun climbing and some harder hiking ahead that they just push through this cool patch and see whether . . .

They both looked remarkably like their mothers at that moment. Someday, the Human Genome Project is going to trace the gene for the "would-you-finish-yammering-so-we-can-get-on-with-doing-what-we-need-to-do?" facial expression right to the X chromosome.

"You're using logic," Jim said, as the girls began methodically to unpack. "Why are you using logic?"

The day did bloom into a mountain beauty. We climbed, sometimes under high white clouds in a wide blue sky, sometimes in the speckled shade of the deep forest. Eventually the girls stabilized at T-shirts and ball caps, and we cheerfully reeled off the miles until we came to a waterfall, cleaved in two, plunging into a frothy black pool.

Could a biologist please explain to me how two tiny beings, both of whom had been wracked all day by the tiniest waft of cool air, could look at a body of clearly freezing glacial runoff and declare, with one voice, "Let's go swimming!"?

In the time it took Jim to say "Don't look at me," the girls had dropped their packs, kicked off their shoes and charged into the freezing current. They never even flinched. Whereas I, once I'd stripped down to shorts, crept forward with a bad case of rigor mortis and a hideous deathhead grin. When Isabel -- that playful sprite! -- splashed me, it was like being splattered with acid, and my banshee shriek echoed off the cliff walls for a good five seconds. That's another way to keep the bears away.

Soon after -- a mere seven hours after we began our three-hour hike -- we topped a final ridge and looked down at a smaller, narrower lake within the bathtub walls of Lone Walker Mountain and other peaks. Upper Two Medicine, our campsite.

It was a lovely spot, deserted except for a chummy volunteer ranger taking measurements of the trail. Since the feds were around -- and because we didn't want the kids to turn up the next day as grizzly poop somewhere on the mountainside -- Jim and I followed all the rules. We immediately hung our food in a designated spot 50 yards from the campsite. (The theory being that if our Swiss Miss cocoa was going to attract bears, better to attract them far enough away from the tent to give us time to call Hollywood and sell the movie rights before they traced all the screaming to the evening's main course.) We set up the tents in a feng-shui-perfect spot near the lakeshore. And then we went exploring.

Forty yards away was the latrine, the standard wooden one-seater filled with the usual spider webs and the customary fruity ambiance. While nothing compared to the girls' room at school, it still required some deliberation. But nature, the interior kind, took its course and they both agreed to go in; Isabel insisted I go with her.

Outside, Jim had the kitchen set up -- also well away from the tent zone -- and with the lowering sun casting glittering red shadows on the lake, we rustled up freeze-dried bean burritos. I worked on my specialty camp dessert, an invention of my own called Cheesecake a la Zip-loc. All day long -- through the sweaty climbs up the mountain and the glacial dips in the waterfall pool -- we'd been talking about this fancy treat, which I've been perfecting for years. "Is there any more trail mix?" Dillon asked after one bite.

"Do much camping?" the volunteer ranger wondered politely, having accepted a proffered bowl.

Jim said it tasted like formaldehyde, which was patently untrue. Like he knows how formaldehyde tastes.

Who needs dessert anyway, when the evening is this sweet? (Grade-schoolers do, of course, but bear with me.) The mountain shadows slid across the water, over our tents, up the opposite cliffs. We did our chores in deepening shade, brushing pine needles out of hair, wheedling the girls toward a final potty break.

I made a great show of policing our tent for every last ant and moth and beetle, and we zipped up. Isabel drifted off after a few pages of "The Borrowers," her hand on my shoulder.

I turned off the flashlight and the stars winked on through the screen ceiling. I could hear Jim murmuring a chapter of "Lemony Snicket" to Dillon a few yards away, their weird Siamese puppet shadows dancing on the side of their glowing tent. I settled back and savored one of those precious moments that are the payoff for backpacking's inherent hassles. It only takes a few minutes on a bed of silky down under a glittering heaven to soothe the blisters and uncoil the tendons. Fatigue gives way to serenity, and in the moments before you let yourself be engulfed, your eye drifts across the sky and the whole great vastness of creation is suddenly as snug as a boudoir.

Looking dreamily down, I realized that the question of why a father-daughter wilderness trip is at once harder and better than any other kind could be answered by the touch of those little fingers on my skin. What load could be too heavy, what pace too slow, when the day ends with the caress of an angel?

With the last of my will, I surfed that exquisite curling edge between wakefulness and sleep, at one with the stars, drifting on a moment of gossamer perfection . . .

Ouch! Suddenly the caress of an angel was more like the clutch of a vulture.

"Daddy," came an urgent whisper. "I really, really, really have to go the bathroom.

"Will you come with me?"

Steve Hendrix will be online to discuss this story Monday at 2 p.m. during the Travel section's regular weekly chat on www.washingtonpost.com.

On a father-daughter backpacking trip in Montana's Glacier National Park, the author communed with nature, his child (left) and her friend. A Glacier National Park hike is fun for kids (the rocks!) and dads (the kids!).