On the summer solstice the shadow cast by the higher stone moves across the lower stone, which stands 4.3m away.
The animation shows the shadow’s passage both 4 and 8 days prior to, as well as on the day of the summer solstice:
The gradient of the lower stone is in good alignment with the sun’s path. The passage of the shadow is exactly correct the day of the summer solstice.
A tree obscures the sun which makes the shadow unvisible.