PALMDALE - Palmdale resident Nancy Rosas and Jay Lariviere of Long Beach spent 13 days trekking through the Andes on a quest to conquer 22,880-foot Mount Aconcagua in Argentina.

Rosas, 38, experienced early symptoms of altitude sickness at 14,000 feet, but there was a doctor present and she managed to continue the climb after three days of rest and medication.

"You have to go slow to get acclimated to the altitude. When we got up there and were dealing with the elements ... we covered too much altitude in too short of a time. So I got altitude sickness, " Rosas said.

Two days later at 18,000 feet she again experienced early symptoms of pulmonary edema and had to quit the climb.

While Lariviere continued on to the summit, Rosas established a base camp at the 14,000-foot level, where she maintained a communications link with Lariviere.

"You're not supposed to cover more than 2,000 feet per-day, and we actually covered 6,000 in 24 hours" Rosas said.

Altitude sickness consists of pulmonary and coronary edema, a buildup of fluid in the lungs or brain.

The second time Rosas experienced altitude sickness she said it totally drained her of energy and she had no choice but to quit the climb.

Altitude sickness can affect anyone, regardless of physical condition, climbers say.

"Altitude is tough," concluded Lariviere. -It helps when you know what you're doing in the way of food, water and shelter."

Lariviere shows promise and the ability of becoming a world-class, freestyle climber, said Lee Bergthold, director of the Center for Wilderness Studies.

"He's always been a top contender," Bergthold said. "He has the physical strength and agility to move well in tough places like severe ridgelines, walls and cliffs."

"We do a lot of stuff with Lee locally," Rosas said. "He takes you to places that, once he's gone, it's gonna be lost."

Rosas had done occasional hikes but became hooked on climbing in the summer of 1999 when she took her first 10-day trip with Bergthold. "I found something that I really loved, and that was it for me," Rosas said. "The allure is that you're focused on living and surviving on your own."

During the past year, Lariviere successfully completed the summits of four of Mexico's highest peaks ranging from 15,000- to 18,000-foot elevations.

Rosas said she does one mountain climb a year. Last year it was Machu Pichu and come February it will be Aconcagua, once again. Lariviere is aiming for Kilimanjaro in Africa with a peak of 19,241 feet.

Rosas came to Bergthold through a program sponsored by the Los Angeles County Probation Department, dubbed Reach for a Mountain.

The program caters to youths in danger of failing into crime and drugs. They make short-term backcountry treks guided by Bergthold and accompanied by probation officers.

Bergthold trains and leads hand-picked trekkers into the more remote areas of the Southwest: Death Valley to the sea; northern Nevada to the Mexican border-, the Superstition Mountains and Grand Canyon to the east; the Great Basin to the Mojave Desert, and all points between.

Participants in the Center for Wilderness Studies program work through a series of required physical levels in order to finally become involved in long haul, seven- to I O-day treks.

"I just guide and direct," Bergthold said. "The rest is up to those who can focus; to those of a mind-set geared toward basic survival."

When Bergthold does solo work, often for periods of up to 10 days, then resupply becomes necessary.

"Finding water, staying warm or cool, and finding your way without a compass is expected," Bergthold said. "A lot of the times you make your own rules."