Abstract
For the extraction of environmental information, absolute dating of sample must be done. As a result of measurements of samples using fluorescence microscopy, it has been clarified that the stalagmite samples obtained from Akiyoshi-dai and Hirao-dai Plateau have fluorescent microbanding with respective average thickness of 26.4 µm and 23.8 µm. The thickness of the layers of a tufa sample from Akiyoshi-dai was 0.5 mm, and that of a tufa sample from Hirao-dai was ranged from 0.1 to 2 mm. The main fluorofore was found to be fulvic acid both for the stalagmite and tufa samples. In case of the Hirao-dai tufa sample, the measurements of the 137Cs g-ray activity were also carried out, and the 137Cs peaks due to the 1945 and the early 60s were detected.
