This story is one of those stories that, had someone told it to me, I'd probably figure they were having me on. If you decide that, I can't stop you. However, this story, as with all my other stories, is true.
It was the summer of '82, and some of my friends and I were camping in the same general area as always. But back then, we camped downstream from the park, rather than upstream, as we did later. Our campsite was right on the riverbank, with the shale cliffs behind us a-ways. The spine of one of the cliffs was about 50 yards behind us. It had a path winding up to the top, with projecting ledges. Some almost as large as a small room, coming off on both sides.
At the top of the cliff was a natural spring, our source of water while out there. We'd take gallon milk jugs, slung on leather straps, three apiece, hike to the top, then bring them down to camp.
This particular trip, it was Dave and my turn to fetch and carry, so we grabbed up a half-dozen empties, and trucked over to the base, then up the path.
When we were about halfway up, we came upon one of these ledges, and found we had company. Two young guys, about in their 20s, were relaxing in chaise lounges on the shelf. They were decked out in t-shirts, cutoffs, sneakers, shades, and ball-caps, and they each were holding a can of Bud. Although it was about one in the afternoon, and quite warm, they had a fire going in the pit, although nothing was cooking. An ice chest full of cubes and cans of beer sat between them, along with a "ghetto-blaster" type cassette player, which was pumping out the Stones.
As we reached the shelf, they greeted us warmly, and invited us for a beer. We demurred, citing the need to fetch the water, but offering to stop back by later. Dave and I continued up the spine.
We reached the spring, and set about filling our jugs. This took us perhaps 10 minutes, as the spring was slow, and we stopped periodically to scoop up drinks of the cold, pure water. We finished, and started back down. And received a shock.
The two young men were gone, as was all their stuff; not a sign or trace of them left, even though it was perhaps 15 minutes since we'd last seen them.
The only remnant of the experience was the firepit, and it was cold, and bone-dry, as if it hadn't been used in ages.