Background chart courtesy Andy May (from WUWT). Additional material from paper “Glacier response to North Atlantic climate variability during the Holocene” by N. L. Balascio1, W. J. D’Andrea, and R. S. Bradley.
Chart has been updated to include events corresponding to dates, from various papers.
Dates and events in chart and in paper correlate, also with megalithic astronomical calendar changes, in both orientation changes and in design changes. The calendars retain evidence of repeated cataclysmic events during the Holocene maximum.