Age of mankind, dating, and the flood

Varves are no longer being produced in Suigetsu. In 1664 they built a canal connecting the freshwater (on top) lake Suigetsu to the brackish lake Hiruga (see Mikata-goko lakes) and that was the end of the show. IIRC there was also an earthquake which may have affected the varve formation.So until recently the Suigetsu varve chronology was "floating"; it didn't contain within itself any known direct link to an independently dateable event. The chronology was anchored by connecting it to dendrochronology by way of 14C dating of both, and solidly anchored tree ring counts.There's been some good progress in another independent anchor, Ar-Ar dating of tephras (from volcanic eruptions) found in the varves. It's a little tricky because they can't collect enough material from the varves to do the dating. But they can do geochemical analysis of the tephras in the varves and correlate that to tephra deposits found nearby which are extensive enough to do the Ar-Ar dating. There's only one result so far but it fits. See Tephra.

Hum, I missed that. But I see it now.