Free. You can start with nothing.
One loop out of Marinwood Park and back to it, 31 miles with about 6,700 feet of climbing. The route runs the ridges north of San Rafael: Spring Hill, the 680 Trail up the flank of Loma Alta, over the bald summit of Loma Alta at mile 12.2, down to Big Rock, then the three mile climb up Big Rock Ridge, the second highest point in Marin, and out over Chicken Shack and Ponti before dropping back into Marinwood. Three aid stations, crew at two of them, and nine hours on the clock.
The race calls the course very runnable with some long, stout climbs. Underfoot it is a mix of dirt double track fire road and singletrack, along ridgelines, down ravines and across open grassland and oak woodland, with some gravel fire road and a little pavement at the start and the end. The big one is the three mile, 1,500 foot climb from Big Rock up to the Big Rock Ridge summit.
The Big Alta is a March weekend of trail racing in Marin County, run out of Marinwood Community Center & Park in San Rafael. The 50K goes on the Friday, one loop of 31 miles and 6,700 feet of climbing over Loma Alta and Big Rock Ridge, on fire road and singletrack with the whole Bay Area laid out below. A 28K runs the same ground on the Sunday. Freetrail and Daybreak Racing produce it together, and the name comes off two of the summits the courses cross.
The first Big Alta was run in February 2024 with a 50K and a 28K, and moved to March the following year. In 2026 the event added a point-to-point 100K on the Saturday, which starts at Fort Baker in Sausalito rather than at Marinwood.
| Mile | Station | Cutoff | Crew access | Bag | Pacer | Med | To next |
|---|---|---|---|---|---|---|---|
| 0.00 |
Start - Marinwood Park
NoneSignal wrong?
|
? | ● | ? | ? | ? | 9.40 |
| 9.40 |
Fox Hollow
NoneSignal wrong?
|
9:25am | ● | ○ | ? | ● | 4.90 |
| 14.30 |
Big Rock
NoneSignal wrong?
|
11:00am | ○ | ● | ? | ● | 8.90 |
| 23.20 |
Chicken Shack
NoneSignal wrong?
|
1:30pm | ● | ○ | ? | ● | 7.80 |
| 31.00 |
Finish - Marinwood Park
NoneSignal wrong?
|
4:00pm | ● | ? | ? | ● | ? |
Fox Hollow Aid Station: https://maps.app.goo.gl/KHg2FDGZKLkRbH2j8 . All parking is curbside along Glen Drive. Be respectful of the neighbours when parking and keep speeds respectful.
Parking. All parking is curbside along Glen Drive. It is a residential street.
daybreakracing.comChicken Shack Aid Station: https://maps.app.goo.gl/ragBzPBe3Nk45Vyk6 . All parking is at the Park & Ride off Alameda del Prado, then a quarter mile walk up the paved Chicken Shack Fire Road, behind the gate, to the tennis courts. Do not block the fire gate at any time.
Parking. Crews park at the Park & Ride off Alameda del Prado and walk a quarter mile up Chicken Shack Fire Road to the aid station. The fire gate has to stay clear.
daybreakracing.comParking. All event participant parking is curbside along Miller Creek Road near Marinwood Community Center and Marinwood Park. Do not park on neighbourhood side streets or in the Marinwood Park parking lot, which is kept for the general public, race officials and volunteers.
11 people have been out there with a camera or a microphone.
+ 3 more.
These are other people's work and we link straight to them. Watching costs nothing and needs no account. More of them: every race we hold, on film.
Nobody sees it until we have read it. No account, no sign-in.
This changes nothing on the page on its own. Somebody checks it against the race first.
Somebody watches it before it goes anywhere near this page. What we are after is footage of this course, on the ground. If it would be just as true of any other race, it is not this.
We want the address of the file the race publishes, not the file. We download it from there so the page can say where the line came from.
We read every one of these and we write back. Every fact here carries the source it came from, and the way a wrong one gets fixed is a person checking it against what you tell us.
Cutoffs move, races get postponed, lotteries open and close. We read the race's own sources and record where every fact came from. Put your email in and we will send you what changed, and where we read it.
No account, and nothing to cancel.
What happens to your email. Nothing else. I do not sell it, and I will not send you anything except this race changing. One click gets you out.
I keep this catalog because the information is scattered and hard to trust. Telling you when it moves is the same job.
