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It has led to the first discovery of the Vedde ash on the mainland of Britain, in Sweden, in the Netherlands, in the Swiss Lake Soppensee and in two sites on the Karelian Isthmus of Baltic Russia.
Thermoluminescence and optically stimulated luminescence are used in archaeology to date 'fired' objects such as pottery or cooking stones and can be used to observe sand migration.
A sequence of paleomagnetic poles (usually called virtual geomagnetic poles), which are already well defined in age, constitutes an apparent polar wander path (APWP).
Thus, once the volcanic event has been independently dated, the tephra horizon will act as time marker.
The main advantages of the technique are that the volcanic ash layers can be relatively easily identified in many sediments and that the tephra layers are deposited relatively instantaneously over a wide spatial area.
It has also revealed previously undetected ash layers, such as the Borrobol Tephra first discovered in northern Scotland, dated to c.