Thermoluminescence dating
![Figure 1: The three stages of thermoluminescence as outlined by Aitken (1985, 1998) and applied to a quartz grain (Keizars, 2008b)](/Images/godic/202502/16/Keizars_TLexplained22456.jpg")
![Figure 2: The process of recharging and discharging thermoluminescent signal, as applied to beach sands. (modified from Aitken, 1998; Keizars, 2008a)](/Images/godic/202502/16/Keizars_TLexplained2456.jpg")
![Figure 3: Thermoluminescence signature lost during migration of two sand grain sizes (Keizars, 2008).](/Images/godic/202502/16/Keizars_lossduringmigration2457.jpg")
![Figure 4: Illustrated method of passively monitoring sand input (Keizars, 2003).](/Images/godic/202502/16/Keizars_passivemonitoring2457.jpg")
Thermoluminescence (TL) dating is the determination, by means of measuring the accumulated radiation dose, of the time elapsed since material containing crystalline minerals was either heated (lava, ceramics) or exposed to sunlight (sediments). As a crystalline material is heated during measurements the process of thermoluminescence starts. Thermoluminescence emits a weak light signal that is proportional to the radiation dose absorbed by the material. It is a type of luminescence dating.