Archaeologists believe they have identified a new way of putting accurate dates to great events of prehistory. Rare and spectacular storms on the sun appear to have left their mark in forests and fields around the planet over the past 5,000 years. They think evidence of such solar storms could help put precise years to some of the great uncertainties of history: the construction of Egypt’s Great Pyramid of Giza, the collapse of the ancient Mayan civilisation in Central America, and perhaps even the arrival of the Vikings in the Americas. Every tree maintains its own almanac in the form of annual growth rings. For decades dendrochronologists have been using tree-ring evidence and radiocarbon dating to build a timetable of events that confirm historical accounts, even those predating the first written chronicles. Carbon dating works by comparing the ratio between two isotopes of the element carbon, C-14 and C-12, present in old samples of organic material. Because of constant bombardment by cosmic rays, ratios of C-14 in the upper atmosphere are more or less constant, and since radioisotopes decay with time, at a predictable rate, the ratio of C-14 to the stable form C-12 is a guide to the age of any timber in a cathedral roof or a stone age burial site, for example. The technique is imprecise, with an error range of 50-100 years, and also expensive. However, the discovery of unusually high levels of C-14 – up to 20 times the normal level – laid down in during especially violent solar storms may enable scientists to date material much more accurately. Every tree growing at the time of such a sun storm, anywhere in the world, would have preserved a record of it. A new science, proposed to harness this solar storm evidence is named astrochronology. https://www.theguardian.com/science...firm-ancient-historical-dates-astrochronology
I believe that examination of Bristle Cone Pine tree stumps has been used to correct various other methods of dating weather events of the past 8000 years.
