With Boone on the Frontier by Edward Stratemeyer

It must be acknowledged that the pace was now beginning to tell upon all in the race. On even ground it would not have been so trying, but it took wind, and plenty of it, to clear some of the rocks, gullies, and fallen logs that marked the novel racecourse.

One racer was out of it entirely, having sprained his foot by an unlucky slip on a rock, and another dropped so far behind that he soon after gave up entirely.