High-precision dating of significant geologic phenomena in Post-Glacial age

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In order to develop and popularize high-precision dating of significant geologic phenomena of the Post-Glacial age, we introduced a composite techniques of high-precision radiocarbon dating and relative dendrochronology. The first successful dating by wiggle matching, which gives better constraints on probabilty distribution of dendrocorrected radiocarbon age, was carried out for samples related with large mass-movment events and volcanic eruptions. For example, the age of the Kawago-daira tephra formarly dated as 2800 to 3300 yearsBP was precisely determined as 3120 Cal. years BP with a huge trunk sample of over 400 rings, 5 high-precision conventional dating with definite intervals of 75 to 100 years, and wiggle matching. For the relative dendrochronological analyses, we introduced very high resolution imaging of polished tree rings with 10000 dpi flatbed scanner. Scanned tree ring images are retouched and enlarged to make recognition and counting of the rings. This method of electronic tree ring analysis will improve the representability of tree-ring studies. On the other hand, recognition and dating techniques for paleo-earthquakes are refined through detailed analyses of lake deposits for chemical and physical signatures of faulting events that affected the lake environment. Once the horizon of disturbance is recognized, usual procedures for high-precision dating were., successfully applied. The investigators are propagating to the Japanese geologist the idea of high-precision dating and refinment of the dates for the advancement of precise chronology for all related sciences.