On the day of the new quarter the shadow cast by the higher stone moves across the lower stone, which stands 7m away. The higher stone is leaning 8° and its straightened up position is calculated. The positions of the stones after this adjustment were used to calculate the sun line.
The animation shows the new quarter based on the Autumnal Equinox defined as 1) “Heigth model equinox”, and 2) “Refraction equinox”. see definitions in Days-of-the-calendar.
The gradient of the top of the stone is in good alignment with the sun’s path. Note that the shadow has a step corresponding to the difference in height of the sun from from one day to the next. One may wonder whether there is any intention with this?
Both the shape of the lower stone and the shadow is such that the outcome for us is difficult or impossible to interpret. It may be that what we see is quite accurate for the new quarter on both October 18 and 19, ie 28 days after the autumnal equinox according to the “Refraction equinox” and to the “Heigth model equinox”.
Since one stone is leaning the shadow will not be in the correct position to show the day of the new quarter.