The trip down Upper Gaseline Trail is a short but thrilling ride along a steep and rocky pathway between the Prospect Heights trailhead and the Hilltop Ski area. The ride can also be done as an out-and-back by starting from the Hilltop access and making the very strenuous ride up a loose rocky trail. There are some large rocks on the trail and it can be very slippery if wet so be very cautious and pay attention to current trail conditions.