Here are two pictures of a split boulder near Oley Hills. The Oley Hills site is just a central concentration of stonework. The woods near it are full of minor separate sites of various kinds. This split boulder is part of a rock outcropping that showed signs of use. Unfortunately, when I took these pictures I didn't know to look for a wedged rock between the boulder pieces. However, in the picture above you can see a stick laid on the boulder so that it extended into the split.
One person who saw it thought the split boulder represented a deer hoof. It does bear a resemblance. However, another person said it might be a 'yoni' stone, representing female fertility. I guess it's in the eye of the beholder.
It would be worthwhile to get formal permission from as many property owners as possible along the hills near Oley Hills and make a survey of what's out there while it's still there. That's the sort of thing that might be easier to do with academic backing and student researchers, another reason to keep pushing for scientific recognition of the phenomenon of eastern indigenous stonework.