Starting at Natural Chimneys, a gentle warm-up leads to a brief steep ascent onto the single-track ridge of Narrow Back Mountain, then the Wolf Ridge climb connecting to Timber Ridge, the Sand Spring Mountain summit and descent, and the Tillman Trail over Narrow Back Mountain again to Lick Run before exiting the forest at Bear Trap for the finish at Natural Chimneys.
A trail ultramarathon run through the George Washington and Jefferson National Forests west of Virginia's Shenandoah Valley, offering 100 Mile, 100K, 50K and 21K distances from a shared start/finish at Natural Chimneys Park. The 100 Mile starts at 6:00 PM Friday and carries a 36-hour cutoff, so every finisher is on the course for two nights. Part of the UTMB World Series since 2023; a dual qualifier for the UTMB World Series Finals in Chamonix and the Western States Endurance Run.
Founded in 2008 by Dr. Clark Zealand as an out-and-back 100-miler starting and finishing at Camp Shenandoah, a Boy Scout of America camp near Swoope, Virginia, climbing Elliott's Knob in both directions. It ran as the fourth race in Virginia's "Beast Series" (Holiday Lake 50k, Terrapin Mountain 50k, Promise Land 50k, Grindstone 100M, Mountain Masochist 50 Mile, Hellgate 100k). The race has started at 6:00 PM Friday since its first year in 2008. In 2023 it joined the UTMB World Series and was rebranded Grindstone Trail Running Festival by UTMB; the start/finish moved from Camp Shenandoah to Natural Chimneys Park & Campground in Mount Solon, Virginia (about 20 miles away, also in Augusta County) to accommodate a larger field, and 100K, 50K and 21K distances were added alongside the original 100 Mile. The night start has continued unchanged through both the rebrand and the venue move. Many third-party listings (Wikipedia, the American Trail Running Association's event database, and other race-aggregator sites) still describe the pre-2023 Camp Shenandoah course and Swoope address as current; they have not been updated for the relocation.
| Mile | Station | Cutoff | Crew | Bag | Pacer | Med | To next |
|---|---|---|---|---|---|---|---|
| 0.00 |
Natural Chimneys - Start
1,342 ft
|
? | ● | ● | ? | ? | 5.70 |
| 5.70 |
Lick Run 1
1,759 ft
|
? | ? | ? | ? | ? | 5.70 |
| 11.40 |
Wolf Ridge
1,814 ft
|
10:00am | ? | ? | ? | ? | 9.60 |
| 21.00 |
Sand Spring
1,936 ft
|
12:45pm | ? | ? | ? | ? | 7.00 |
| 28.00 |
Lick Run 2
1,759 ft
|
? | ? | ? | ? | ? | 4.50 |
| 32.50 |
Natural Chimneys - Finish
1,342 ft
|
4:00pm | ● | ● | ? | ? | ? |
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