From here their course led up through an enormous gorge, or cleft, that grew narrower as they ascended, until it terminated in a long, steep slope of boulders and loose rocks. Here they encountered the first real danger of the ascent. Every now and then a boulder, that appeared firmly seated until burdened with the weight of one of them, would give way and go crashing and thundering down with great leaps behind them until lost in the forest below.