50K

The Big Alta 50K course is an amazing single-loop race route, offering extensive scenic views along some of the highest points in all of Marin County. The course is pretty challenging, with a number of long ascents and steep descents. The route is composed of a rugged mix of dirt double track fire roads and single track trails along extensive ridgelines, down ravines, across hilly open grasslands, wildflower meadows and woodlands. The 50K race offers a stunningly beautiful and tough trail race experience!

Race Day Schedule

Saturday, March 22, 2025

• Bib Pickup: 6:45AM-7:50AM

• Race Start: 8:00AM (single mass start, no waves)

• Awards Ceremony: 2:30PM

• Finish Line Cut-Off: 5:00PM (9 hours)

Course Map

• CLICK on the map image for a high resolution copy to save or print.

• INTERACTIVE MAP: Click HERE for an interactive course map in or click “Open in CalTopo” in the map below for a full window map, where you can change layers, zoom in and out, view elevation profile, etc.

• GPX DATA: Click HERE for a .gpx data file of the course with elevation data included.

Elevation Change

Approximately 6,700' of ascent and 6,700' of descent. 

Aid Stations

There are 3 aid stations on the course, all staffed with experienced, enthusiastic volunteers plus professional medical personnel.

All Daybreak races are CUPLESS. Be sure to bring your own cup for liquids at aid stations (or use your hydration supplies, such as bottles, bladder, etc.). 

Hydration and fuel options included at all aid stations: Gnarly Nutrition Fuel2O energy drink, water, soda, Spring Energy gels, bananas, oranges, chips, PB&J sandwiches, and more. 

Crew & Spectators

Aid or support of any kind to a participant shall only be provided at crew-accessible aid stations and start/finish area.

Crew are allowed at:

• Start/Finish Area

• Fox Hollow Aid Station #1

• Chicken Shack Aid Station #3

There is no crew/spectator access at Big Rock Aid Station #2 due to extremely limited parking.

Driving Directions for Crew:

• Fox Hollow Aid Station: Google Map link

• Fox Hollow Parking: all parking is curbside along Glen Drive. Be respectful of the neighbors when parking and keep speeds respectful.

• Chicken Shack Aid Station: Google Map link

• Chicken Shack PARKING: all parking is at the Park & Ride off the Alameda del Prado roadway, then a .25 mile WALK up the paved Chicken Shack Fire Road 9 (behind the gate) to the tennis courts.

Drop Bags

Drop bags will be delivered from the Start to Big Rock Aid Station #2. Drops bags will not return to the Start/Finish area until the aid station closes, approximately 1:00-1:30PM.

RETURN: Please consider that drop bags will not be returned back to your race staging area until the aid station shuts down after race sweepers arrive.

CONTENTS: Do not store valuables in drop bags! The race is not responsible for missing, damaged, lost or stolen drop bags or contents.

FORGOTTEN BAGS: Please note we do not ship or deliver forgotten drop bags. You can arrange to pick up forgotten drop bags from us if we have them.

Poles

Trekking poles are allowed.

Pacers

No pacers allowed.

Inclement Weather Equipment Policy

If we have wet/inclement weather on race day, we will have a gear requirement for all runners that will help keep them prepared for confronting all types of conditions and in case of a safety incident, allow a runner to wait for rescue and extraction. If implemented, the gear requirement will be in place for the duration of the race from start to finish. Gear checks shall be in place at aid stations. Required gear will include: a running pack, waterproof rain jacket, smartphone with course info and means of contact by race staff, emergency blanket, whistle, 400 calories of nutrition, 1 liter capacity of fluids, hat or bandana, ID.

Course Detail

Overall, the course is very runnable, but there are some long, stout climbs that will ensure much of the fun being had is the Type 2 variety :) Fortunately, this is Marin County, with its globally-renown natural beauty providing ample distraction, as well as opportunity for reflection and gratitude. Course surfaces are predominantly a mix of dirt fire roads and single track trail, with some gravel fire roads and a dash of pavement at the beginning and end of the course.

Start (Marinwood park) to Aid Station 1 (Fox Hollow): 

8.4 miles. Runners depart the Start at Marinwood Community Park, cross Lucas Valley Road, then follow the brief paved Canyon Oak Drive along Miller Creek to enter Marin County Open Space. Runners follow the Old Lucas Valley Road, now a bike/pedestrian path, for 1/4 mile, then veer LEFT onto Water Tank Fire Rd for the first climb of the day. Gaining the Spring Hill ridge, runners get their first big views of the day as they veer RIGHT onto Spring Hill Fire Rd then veer LEFT onto the 680 Trail, a super fun rolling trail with several quaint footbridges over babbling creeks, early season wildflower patches and oak groves. The 680 Trail makes a series of switchbacks as it climbs the eastern flank of Loma Alta, then ends onto Smith Ridge Fire Rd for a ripping descent past two big water towers, then continue descending on Glen Fire Rd to Fox Hollow Aid Station 1, near the Glen Fire Rd Trailhead at mile 8.4 on the course.

Aid Station 1 (Fox Hollow) to Aid Station 2 (Big Rock): 

5.9 miles. Runners depart Fox Hollow Aid Station on the Fox Hollow Trail, then veer LEFT onto the Old Railroad Grade Trail, which eventually transitions to Old Railroad Grade Fire Rd after passing above White Hill School. Old Railroad Grade offers a mix of open views and shaded oak forest as well as the lovely Fairfax Falls waterfall at approx mile 10.1 on the course! Shortly after passing the waterfall, the course veers RIGHT onto Sunrise Fire Rd at mile 10.5 and thus begins the second significant signficant climb of the day. Ascending Sunrise Fire Rd, the course makes it way back up to a junction and veers LEFT onto a brief 1/4 mile segment of Smith Ridge Fire Rd, for the only segment of the course used more than once. Runners then veer LEFT onto Loma Alta Fired Rd as the course continues to climb, reaching the bald summit of Loma Alta at mile 12.2. Savor the epic 360° views as the course traverses over the top of Loma Alta, followed by a steady 2.1 mile descent down to Big Rock Aid Station at mile 14.2.

Aid Station 2 (Big Rock) to Aid Station 3 (Chicken Shack): 

8.9 miles. Leaving Big Rock Aid Station, the course uses a pedestrian tunnel under Lucas Valley Road to connect onto the Big Rock Trail for a tremendous 3 mile, 1500’ ascent to gain the sublime ridgeline of Big Rock Ridge, the second highest point in all of Marin County, offering 360° views of the entire San Francisco Bay Area and beyond. From the Big Rock Ridge summit at the radio towers, the course follows Big Rock Ridge Fire Rd on a gradual, rolling descent for 2 miles to the junction with Queenstone Fire Rd at mile 20.0 on the course. Runners will veer LEFT at this junction onto Chicken Shack Fire Rd for a steady 3 mile descent into the Chicken Shack Aid Station at mile 23.1.

Aid Station 3 (Chicken Shack) to Finish (Marinwood Park):

7.8 miles. Departing Chicken Shack Aid Station, runners descend a brief paved service road, cross Alameda del Prado street at the crosswalk to get on the paved Pacheco bike path for 1/4 mile, then veer RIGHT to reach the bottom of Ponti Trail. Runners begin a steady climb up the Ponti Trail for a big climb through oak forest. At the top of the Ponti Trail climb, runners veer LEFT onto Chicken Shack Fire Road and begin a rolling climb to the junction with Queenstone Fire Rd, where the course veers LEFT for a big 2 mile descent, with sweeping views of Marinwood and the Lucas Valley below. At the bottom of Queenstone Fire Rd, runners pass the fire gate into the Marinwood neighborhood on Queenstone Drive, cross Mill Creek Road at the cross walk, then veer RIGHT along the sidewalk of Mill Creek Road for the final gradual half mile descent back to Marinwood Community Park for the finish!

Cancellations

See the Daybreak Racing Cancellation Policy.