I recently visited the site and found a stone with a raised line on it. The compass proved that the line is on the NE-SW axis (I photographed this stone). I also noticed some offerings had been placed at the base of long meg.
I do think that the slight dip in the top on the main stone is meant to cast a shadow to some significant point but this would mean visiting on one of the solstices/ equinoxes.
Something is not right. This message is just to keep things from messing up down the road