摘要
NATURAL materials, which possess annual lamination and record annually climatic or environmental changes, can be termed 'natural clocks'. They include tree rings, coral layers, varves, ice layers, and laminated speleothems which were reported only in the last few years. The growth layer rhythm in stalagmites is related to high-frequency and short-term climatic oscillations. The luminescent density of annual layers of stalagmites is the signal of environmental changes. The organic matter contained in drip
