Cave deposits (speleothems) as archives of past environments and climates (lecture)

Professor Ian Fairchild, Professor of Geosystems, University of Birmingham

A clear understanding of long-term climatic change over the Quaternary has come primarily through studies of sediments in the deep ocean and cores through the major ice sheets, forming a framework to which the myriad more fragmentary and less definitive records can be related. Caves used to be thought of as complex environments unlikely to yield records of widespread significance. The search for better climate proxies on land, as well as a series of advances in technology has transformed this situation so that well-dated speleothem records now provide definitive records of regional to global environmental change.

In this talk, an introduction to Quaternary palaeoclimates is followed by a discussion of how caves function (they have a “physiology”!) and the manner of formation of speleothems. Next we consider the many properties that speleothems display that may be modified depending on an interaction of climate with the cave and karst system. The crucial role of good dating of the archives is illustrated with a discussion of uranium-thorium radiometric dating combined with counting of annual layers. Finally, some case examples are used as illustrations of the varied ways in which past climates and environments have been brought to life by studying the underworld.