Solving the Mystery of the Wooden Construction

On last week's loop hike, I stumbled across some mysterious wooden construction, in the middle of nowhere, just before I reconnected with my earlier GPS track. I wanted to get back up to that ridge and see if I could figure out what this was.

I also wanted to try and put my recently acquired knowledge of route finding to use, and try to find an easier way up to that ridge. All my earlier routes had been along the signs of the old trails on the hill shade map. But the old trails are very hard to use as they're lower in the canyon, covered in brush and downed trees. Higher up the ridge, the soil is more rocky and it's much clearer. I navigated up to a track closer to the ridge and tried to meet that at a point before I ran into heavy brush and downed trees. Also made use of the aerial imagery map to find small clearings to link together and ended up with a relatively brush-free track up to the ridge top.

So the mystery wooden construction turned out to me an abandoned, secret, user-built mountain bike terrain park. This was built in the late 1990's or early 2000's by about 3 riders. They had an unmarked trail down from Charcoal Road, likely close to where I hiked down. Apparently, the maintenance of these obstacles got to be too much for the group, with fallen branches and trees requiring removal and repair after every big storm.

The area was then somewhat abandoned, but later revived briefly by a new group. At some point, the county park rangers found this area and chased off the new group. That was sometime before 2008 and the area has been essentially abandoned since then.

I did communicate with one or two of the original builders to put this story together, so it should be fairly accurate without revealing too many details. I also think I may have found signs of the 2 other riding areas they constructed in my other hikes, so those discoveries now make more sense.

Some photos of the area:
https://photos.app.goo.gl/1LRX3NGdpfVqGYgFA

USGS Na..