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Optical dating is a method of determining how long ago minerals were last exposed to daylight. It is useful to geologists and archaeologists who want to know when such an event occurred.

It refers to techniques including electron spin resonance (ESR), thermoluminescence (TL) and optically stimulated luminescence (OSL).

Conditions and accuracy[edit]

Ages can be determined typically from 100 to 200,000 years BP, and can be reliable when suitable methods are used and proper checks are done. Ages can be obtained outside this range, but they should be regarded with caution.

The optical dating method relies on the assumption that the mineral grains were sufficiently exposed to sunlight ("bleached") before they were buried. This is usually, but not always, the case with aeolian deposits, such as sand dunes and loess, and some water-laid deposits.

All sediments and soils contain trace amounts of radioactive isotopes including uranium, thorium, rubidium and potassium. These slowly decay over time and the ionizing radiation they produce is absorbed by other constituents of the soil sediments such as quartz and feldspar. The resulting trapped charge within these minerals remains as structurally unstable electron traps within the mineral grains. Stimulating samples using either blue, green or infrared light causes a luminescence signal to be emitted as the stored unstable electron energy is released, the intensity of which varies depending on the amount of radiation absorbed during burial and specific properties of the mineral. The trapped charge accumulates at a rate over time determined by the amount of background radiation at the location where the sample was buried. Exposure to sunlight resets the luminescence signal and so the time elapsed since the sample was buried can be calculated.


Optical dating was invented in 1984 in the physics department at Simon Fraser University, British Columbia, Canada, by David Huntley and colleagues.[1] It was quickly used by Martin Aitken's laboratory in Oxford, England, many years before it was adopted elsewhere. Now there are numerous laboratories around the world.

In 1994, the principles behind optical and thermoluminescence dating were extended to include surfaces made of granite, basalt and sandstone, such as carved rock from ancient monuments and artifacts. The initiator of ancient buildings luminescence dating Prof. Ioannis Liritzis has shown this in several cases of various monuments. [2][3][4]


Optical dating is one of several techniques in which an age is calculated as follows: (age) = (total absorbed radiation dose) / (radiation dose rate). The radiation dose rate is calculated from measurements of the radioactive elements (K, U, Th and Rb) within the sample and its surroundings and the radiation dose rate from cosmic rays. The dose rate is usually in the range 0.5 - 5 grays/1000 years. The total absorbed radiation dose is determined by exciting specific minerals (usually quartz or feldspar) extracted from the sample with light and measuring the amount of light emitted as a result. The photons of the emitted light must have higher energies than the excitation photons in order to avoid measurement of ordinary photoluminescence. A sample in which the mineral grains have all been exposed to sufficient daylight (seconds for quartz; hundreds of seconds for feldspar) can be said to be of zero age; when excited it will not emit any such photons. The older the sample is, the more light it emits, up to a saturation limit.


The minerals that are measured are usually either quartz or feldspar sand-sized grains, or unseparated silt-sized grains. There are advantages and disadvantages to using each. For quartz one normally uses blue or green excitation and measures the near ultra-violet emission. For feldspar or silt-sized grains one normally uses near infra-red excitation and measures the violet emission.


  1. ^ Huntley, D. J., Godfrey-Smith, D. I., & Thewalt, M. L. W. Optical dating of sediments" Nature 313, 105 - 107 (10 January 1985); doi:10.1038/313105a0
  2. ^ Liritzis, I. (2011). "Surface Dating by Luminescence: An Overview". Geochronometria (Silesian University of Technology, Poland) 38 (3): 292–302. doi:10.2478/s13386-011-0032-7. 
  3. ^ Liritzis, I., Polymeris, S.G., and Zacharias, N. (2010). "Surface Luminescence Dating of 'Dragon Houses' and Armena Gate at Styra (Euboea, Greece)". Mediterranean Archaeology and Archaeometry 10 (3): 65–81. 
  4. ^ Liritzis, I. (2010). "Strofilas (Andros Island, Greece): new evidence for the cycladic final neolithic period through novel dating methods using luminescence and obsidian hydration". Journal of Archaeological Science (Elsevier) 37: 1367–1377. doi:10.1016/j.jas.2009.12.041. 


  • M.J.Aitken, An Introduction to Optical Dating, Oxford University Press (1998) ISBN 0-19-854092-2
  • A. Wintle and M. Murray. A review of quartz optically stimulated luminescence characteristics and their relevance in single-aliquot regeneration dating protocols. Radiation Measurements v.41. 369-391 (2006).
  • Greilich., S, Glasmacher, U.A, Wagner, G.A (2005) Optical dating of granitic stone surfaces. Archaeometry 47(3), 645-665.
  • Habermann, J, Schilles,T, Kalchgruber,R, Wagner, G.A, 2000. Steps towards surface dating using luminescence, Radiation Measurements 32, 847-851
  • Liritzis,Ι. 1994 A new dating method by thermoluminescence of carved megalithic stone building. Comptes Rendus (Academie des Sciences), Paris, t. 319, serie II, 603-610, ibid. Archaeometry: Dating the past. EKISTICS, t.368/364, 361-366.
  • Liritzis I., Guilbert P., Foti F., Schvoerer M. (1997) The Temple of Apollo (Delphi) strengthens new thermoluminescence dating method. Geoarchaeology International, vol. 12, no. 5, 479-496
  • Liritzis., I (2010) Strofilas (Andros Island, Greece): New evidence of Cycladic Final Neolithic dated by novel luminescence and Obsidian Hydration methods. Journal of Archaeological Science (DOI 10.1016/j.jas.2009.12.041, in press).
  • Liritzis. I, Sideris. C, Vafiadou, A and Mitsis.J (2007) Mineralogical petrological and radioactivity aspects of some building material from Egyptian Old Kingdom monuments. Journal of Cultural Heritage, 9, 1-13
  • Morgenstein, M.E, Luo, S, Ku, T.L, and Feathers J., (2003) Uranium series and luminescence dating of volcanic lithic artefacts. Archaeometry 45, 503-518,
  • Theocaris P.S., Liritzis I. and Galloway R.B. (1994). Dating of two Hellenic pyramids by a novel application of thermoluminescence. J. Archaeological Science, 24, 399-405

External links[edit]

Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/Optical_dating — Please support Wikipedia.
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22 news items

Wed, 22 Apr 2015 10:03:45 -0700

The technique of optical dating was first reported 30 years ago, and has since revolutionized studies of events that occurred during the past 500,000 years. Here, two practitioners of optical dating assess its impact and consider its future.

Vancouver Sun

Vancouver Sun
Tue, 06 Oct 2015 06:07:31 -0700

The researchers applied a technique called optical dating as well as detailed pollen and spore analysis on exposed layers of peat and sediment in a cliffside at Cape Ball in Naikoon Provincial Park on Graham Island to paint a picture of the archipelago ...

The Weather Network

The Weather Network
Wed, 07 Oct 2015 12:30:00 -0700

Mammoth and caribou remains have been found on Vancouver Island and in southwestern B.C. in the past. Researchers used a technique called optical dating combined with pollen and spore analysis to draw their recent conclusions. Source: Vancouver ...

The WSU Sign Post

The WSU Sign Post
Tue, 18 Nov 2014 08:30:00 -0800

“Everyone has heard of radio-carbon dating,” Rich said, “but optical dating is relatively new and is quite a robust dating technique.” Rich explained that you can date things that are relatively recent and also things that are hundreds of thousands of ...

The Hindu

The Hindu
Wed, 05 Nov 2014 21:11:54 -0800

In addition the study will have optical dating of sediments to find out their age upto half a million years, Prof. Sharma explained. This data on dating sediments will be related to global climate change phases and regional ones too since there are ...


Tue, 24 Sep 2013 11:43:12 -0700

Porat used a technique called optical dating to measure the amount of radiation that had been absorbed from the environment in two of the leopard traps. By comparing that with background levels of radiation in the area, which have changed very little ...

UC Davis

UC Davis
Mon, 05 Nov 2012 11:52:30 -0800

Climate change can speed the rate of decomposition, aiding the release of the buried carbon. As a case study, the researchers used radiocarbon and optical dating to calculate the amount of carbon emissions captured in soils and released to the ...

Ars Technica

Ars Technica
Wed, 07 Nov 2012 12:11:25 -0800

However, optical dating techniques suggest the Pinnacle Point tools are 6,000 to 10,000 years older than those found at other sites. So humans may have created and used bows and arrows earlier than previously thought. Not only is this finding ...

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