2008 Appleton medal and prize

Professor Ann Wintle

Aberystwyth University

For her outstanding contribution in the development and application of luminescence properties of minerals as a geological dating tool applicable to the past one million years.

The Appleton medal and prize for distinguished research in environment, earth or atmospheric physics has been awarded to Professor Ann Grace Wintle, Professor Emeritus in the Institute of Geography and Earth Sciences, University of Wales Aberystwyth, for her outstanding contribution in the development and application of luminescence properties of minerals as a geological dating tool applicable to the past one million years.

During her first degree, Professor Wintle became interested in applying physics-based techniques to Quaternary geology, which covers the last two million years. Her doctoral research involved testing minerals for thermoluminescence (TL) dating, then in the early stages of being applied to pottery. TL depends on the fact that some minerals such as quartz trap energy from exposure to radiation; when heated, the energy is released as light. The amount of light emitted is proportional to the radiation dose, which depends on the length of time mineral grains are exposed to environmental radioactivity.

In 1979, Wintle showed that the TL signal from mineral grains in deep sea cores could be extracted. This seminal discovery opened up a whole new dating technique for Quaternary sediments which can extend back beyond the range of radio-carbon dating and is applicable to a wider range of sediments.

Since 1991, Wintle became involved in applying the more precise technique of optically stimulated luminescence (OSL), first from feldspars and then quartz. During the past 10 years, she has been at the forefront of developing methods for dating quartz, carrying out basic experiments to characterise the OSL signals.

Her research has also included applications such as dating coastal sediment in Africa, including sands from caves with early human remains from 70,000 years ago, and wind blown silt deposits in China going back to about one million years.