The cross country skiing marathon is back.

The fourth annual Tour de Ski Nordic Skate Ski Race is back for the 2011 edition in the backcountry of the San Juan Mountains on Jan. 22.

The popular cross country event, with distances up to 42 kilometers on groomed tracks, is a benefit for Trails 2000 and the Durango Nordic Ski Club.

The Tour de Ski again will utilize the Hermosa Valley for a big part of the course.

The start and finish will be at the top of Purgatory at Durango Mountain Resort.

The race features one of the highest starts and finishes in Colorado.

Skiers can opt for the half-marathon 20K distance or the full 42K marathon.

Those skiers will face an elevation gain of 3,000 feet.

Skiers also will have the option to ski a 6K or 12K loop course in the Hermosa Creek Valley.

The event, on the groomed surfaces, is one of the longest races groomed for skate-skiing in the state.

The course will feture views of Grizzly Peak, climbs up the Cascade Divide Road and rest stations with hot chocolate and cookies from local bakery Bread.

There is a tour division for the more casual skier.

The Tour de Ski was developed by Durango residents Travis Brown and his wife Mary Monroe, the executive director of Trails 200. Brown is a former U.S. Olympic mountain biker.

The tour grew markedly after the first year with a large field anticipated for the fourth running.

The event organizing committee is led by Chief of Race and Nordic coach Jeanne Pastore.

The team includes three-time Nordic Olympian Mike Elliott, Bob Rule of San Juan Ski Co., Chief of Course Helen Low of the Nordic Center and veteran race official Sarah Tescher.

Registration is advance registration only. There will be no race-day registration. Advance registration is available at www.tourdeski.org.

Registation also is available at Pine Needle Mountaineering and Backcountry Experience in Durango.

The field is limited to 250 skiers; early registation is encouraged.

Entry fee is $40 for the 42K and $30 for the 20K. Entry also is $30 for the 20K tour event.

For the 12K, fee is $12. And for the 6K, the fee is also $12.

Proceeds go to the Durango Nordic skiers and Trails 2000.

Bib pickup is scheduled for 5-9 p.m. Jan. 21 at Pine Needle Mountaineering.

Race-day bib pickup will be at Hoody’s at DMR from 7-8 a.m.

Participants will ride Chair 4 at Purgatory, starting at 8 a.m.

The lift will take the skiers to the start. The 42K will take off at 9 a.m.

The 20K will follow at 9:10 a.m. with the shorter races following in order.

The start and finish are at the intersection of Pinkerton Roll Road and Hermosa Park Road, near the top of Chair 4.

Course details are available online at www.tourdeski.org.

heraldsports@durangoherald.com