Geoscience Reference
In-Depth Information
dating techniques allowed Miocene and Pliocene fossil hominids to be accurately
dated, complementing the use of geomagnetic datingmethods, which provided reliable
but not very precise ages and, in any event, needed independent calibration. Another
revolutionary development was that of luminescence dating, both thermoluminescence
and optically stimulated luminescence dating methods. For the first time, it became
possible to date directly the quartz particles within desert sand dunes and desert loess
deposits to discover when they were last exposed to sunlight. These techniques have
provided reliable ages back to approximately 100 ka, under ideal conditions back to
approximately 500 ka and, with developments underway, may soon yield ages back
to 1 million years ago. Finally, the development of exposure dating methods using
a variety of cosmogenic nuclides has provided reliable ages for glacial moraines,
desert pavements and fluvial sediments, as well as denudation rates in arid and semi-
arid areas. Advances in dating techniques over the past sixty years have thus truly
revolutionised the study of climatic change in deserts.
