Glossary of Karst and Cave Terms
dating of cave sediments
Determination of the age of development of caves is normally impossible. Only the sediments they contain can be dated, and these must necessarily be younger than the containing passage. Geomorphological correlations may allow more accurate dating of the cave erosion. The most useful dating method in current use is based upon a knowledge of the rates of decay of radioactive isotopes of uranium to thorium in stalagmites. This technique allows measurement of ages in material up to 350,000 years old. Dating of stalagmites has confirmed that many cave ages lie beyond this range. Electron spin resonance (ESR) measures the cumulative effects of radiation that are partly a function of time and can give stalagmite ages back to about 900,000 years. Palaeomagnetism may recognize events up to 2 million years old, but a sequence of palaeomagnetically dated sediments is required to allow identification of the actual ages .