Updating evidence from Archaeology and Geology, and comparing to a number and type of proxies that together throw more light on the history of the megalithic calendars, and simultaneously on ‘Earth’ events.
In the historical chronology of the calendars there were two abrupt events, where the axial orientation of the calendar changed substantially (from an East/sunrise or West/sunset direction); between 42-45 degrees CW. From the calendar design evolution the last orientation change occurred around 3200bce. Evidence indicates the occurrence of ‘micro-plate’ tectonic rotation. Various proxies point, ambiguously, to such event; also to an earlier such event at 5200bce (ice rafting).
The design evolution indicated in the structural changes clearly shows the evolution of the technique adopted, and thus the chronological sequence of the various buildings. A critical part of the design is the ‘oculus’ or pinhole in the main portal, the latter designed similarly to the lens barrel of the photographic camera. The field of view (VA) is always limited to horizon sunrise point, solstice to solstice. At latitude 35.8 deg, this raises important questions on Earth obliquity. Variations in Earth ‘Temperature Anomaly’ appear to support such interpretation, in that polar versus equatorial variations agree in abruptness, direction and time of occurrence. Other proxies indicate such changes also, but give no hint as to what took place.
Recent finding that the archaic calendar design was used in Lampedusa provides corroboration of both tectonic rotations in the Med, and since VA is same at near same latitude, add support to hypothesis.
Additional data is superimposed on chart, showing good correlation at ~5200bce and ~3200bce, both major tectonic events. (Source: https://tallbloke.wordpress.com/2019/06/25/zharkova-uses-solar-planetary-theory-in-new-paper-predicting-earth-temperature-rise-to-2600-following-imminent-grand-solar-minimum/ )
Pics updated ( May 2021) to show civilisations wax/wane dates relative to other info. Collated since from various sources.