From top down

THE new Top of the Sierra Interpretive Center on Mammoth Mountain has visitors quaking in their ski boots.

No, wait. Make that their hiking boots, as Mammoth begins its transformation to a summer destination this year with the help of the center, which opened June 23.

The shifting screens of the interactive display in the center of the room detail the geologic story of the Sierra and its environment. Nearby pads mark the location of the Mammoth Stomp, a device that digitally displays the seismic impact of any visitor’s boots -- in my case, a size 13.

“Almost everyone who comes here wants to know about the volcanoes and seismic activity,” says Lisa Isaacs, the ski resort’s environmental director. “We wanted to educate people that what we have here is very different from, say, the San Andreas Fault.”

I had taken a gondola ride up near-barren ski slopes. The welcoming sign at the $1.5-million center, which sits just below the summit at 11,053 feet, urges visitor to “experience the magic of the mountains and its influence on our lives.”

The center, which will be open year-round, is designed to be energy efficient.

Project manager Neil Herness said that heating the mostly glass-enclosed center presented a challenge because propane and natural gas don’t work well at higher altitudes. The solution: electric porcelain heaters that conserve energy by radiating heat to objects in the center “rather than just heating the air.”

The center’s green philosophy carries over to the new cafe, which is phasing out disposables in favor of biodegradable cups and plates. The cafe can serve up to 150 guests and offers an opportunity for couples to tie the knot.

Once I had stomped, I peered through mounted scopes that helped viewers identify key landmarks along this section of California’s 300-mile mountainous spine.

In place of winter skiers, the summer ride to the mountaintop was packed with scores of mountain bikers. The riders, in a steady stream of serious wheels and equally serious helmets, rocketed off the landing, pausing only for a few moments to survey the view of the Minarets and Ritter and Banner peaks to the north before hurtling down one of several trails.

Those who preferred the lower reaches of the mountain’s more than 90 miles of trails found themselves wheeling among fragrant pines and over occasional jumps and bumps included in the popular Bike Park.

Mammoth’s Adventure Center is next to the parking lot (and just behind the iconic statue of a large, woolly creature) and is a launching point for more summer activities -- particularly kid-friendly ones.

A few steps away, the line forms for the 32-foot-high climbing rock on which kids can test their climbing skills. Safely snugged into harnesses and supported on belaying ropes, young climbers are encouraged to work their way to the top by using hand and foot holds built into the rock.

But it was in front of the Mammoth Inn where the real shriek-fest unfolded. Kids as young as 4 zoomed down a 100-foot zip line; their expressions ranged from delighted terror to outright exuberance as they slid from a launching platform into the waiting arms of a staffer while their proud (and sometimes nervous) parents waited.

Back down the hill, all 18 holes of the Sierra Star Golf Course are open, and plenty of anglers already are casting their lines into their favorite spots in the Mammoth Lakes Basin. And, Mammoth being Mammoth, an occasional black bear can be seen strolling through town or around campgrounds.

With an early snow melt and clear hiking trails, I decided to hike up to Mammoth Crest, passing some horseback riders on their way down. As I scrambled up the last few yards to the wind-blown ridgeline, I looked off to my right and saw the sun reflected off the windows of the new center.

Maybe there was still time for another stomp.

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TAKE A PEAK

* Mammoth Mountain is about 300 miles north of the Los Angeles area along U.S. 395 and California 203. (Allow extra travel time for construction delays on 395.)

* The Mammoth Adventure Center is the headquarters for tickets and information about all activities on the mountain. Call (800) 626-6684 or visit www.mammothmountain.com.

* Admission to the Top of the Sierra Interpretive Center is free with the purchase of a gondola ride ticket, Bike Park ticket or season pass. The gondola takes you to the top from 9 a.m. to 4:30 p.m. daily. Tickets cost $18 for ages 19 to 64; $14 for ages 13 to 18; 7- to 12-year-olds ride free with an adult.

* An unlimited one-day pass for the Bike Park costs $37 for adults and $19 for children 12 and younger ($10 and $5, respectively, if you skip the gondola or the bike shuttle and pedal in).