Walk down to where the trail curves right, look over to your left, and you will see these mounds and trails.

After school, on weekends, and often over the summers there are pre teen guys with stingray bicycles going around this course, getting airborne as much as they can. I see them do that and it reminds me of the times I did that kind of thing. We never built a course as elaborate as this one though. These kids are lucky.