After our short hike on the Zion Canyon Overlook trail, we wanted to hike the nearby Shelf Canyon Trail. The trailhead is just a few hundred yards up the road from the Zion Canyon Overlook trailhead.
According to Alltrails, the trail begins near the rest-stop parking lot. The trailhead isn’t marked and is not a managed trail, but it is rated 4-stars on Alltrails.

We found a path down into the start of the canyon next to the road that appeared to be the start of the trail. Using the Alltrails app on my phone, we followed the footpath along the canyon bed and appeared to be on trail. But after about 1/4mi, we hit a dead end or a recent rockfall that clogged the canyon. We scrambled over the first slab incline but boulders blocked the canyon. Either we were not on the trail, needed to scramble over these boulders to where the trail flattened or there had been a recent collapse into the canyon. I could not see any obvious way around and the height of the scramble was more than we wanted to try. So our Shelf Canyon Trail hike was short. According to Alltrails, the trail leads into a slot canyon but we were unable to make it past the boulders. It’s possible the ‘real’ trail was higher up along the canyon wall but no trail was obvious. We were low on water so headed back. There is no running water at the rest-stop or Zion Canyon Overlook parking lot restroom so bring plenty.