It rests on two supporting stones, and has a commanding position on a rocky outcrop. Looking at other propped boulders in the area, I found this one 450 feet to the west (waypoint 42).
It is also on two supporting stones, and overlooks a swamp from a jumble of huge boulders.
If it is true that Natives chose which boulders to prop in order to form a three-sided "corner", there should be another propped boulder site. Figuring that the sides are roughly equal in length, I made waypoints for some possible locations.
Luckily, this afternoon's weather was very pleasant, and I got out and visited these locations.
Possible 5 was in a swamp, and the area for 2 had been bulldozed for development years ago. There was nothing convincing at possibles 1 and 3, but at possible 4...Bingo!
Here is a view from the side.
Also close by is this larger propped boulder. It looks like stone has been chipped away from underneath.
If this looks familiar, it is because it is near this shelter which was shown 6/5/2013. It was probably built into this old quarry by campers or deer hunters.
With the addition of this site, the propped boulder corner is this: