Described here, near the bottom: http://thetrailprovides.com/2014/06/24/i-havent-blogged-in-550-miles-time-to -catch-up-now-with-a-beer-in-hand/ Looks like it was small and low-intensity at the time, but apparently originated at the camping spot at Soldier Creek (mile 1331). If I had to guess, I'd say someone didn't police their campfire very well. L Eric