The Barkley consists of 5 20-mile loops with no aid except for water at two points. The cutoffs for the 100 mile race are 12 hours per loop. The 60 mile "fun run" has a cutoff of 40 hours, or 13:20 per loop. To prove you completed each loop, you must find 9 to 11 books (varies) at various points along the course and return a page from each book.
Local time: 1:26 PM