Absolute dating

Absolute dating in archaeology

HideShow resource information
  • Created by: Emma
  • Created on: 26-05-10 21:17


  • Most acurate form of chronometric dating
  • early cells- early in annual growth
  • late wood- late in annual growth
  • produces visible rings until the bark
  • the rings are wider in good conditions e.g heavy rainfall
  • rings a narrower where there are bad conditions e.g. little rainfall.


  • Sapwood discarded by carpenters can hold up to 16 rings, making the date an estimate.

site example

  • central slump in sea henge (april/june 2050 BC)
1 of 11

Radio Carbon Dating ( C-14)

  • All living things absorb several types of carbon from the atmosphere
  • 1% of this is unstable and decays at a known rate.
  • by comparing the amount of carbon remaining with the the carbon isotopes(don't decay) when in organic sample we can work out how much C14 has decayed.
  • this indicates how long it has been since decaying began.


  • amount of carbon in the atmosphere has varied over time,leading to many dates being underestimated by up to 1000 years
  • due to this results have to also be calibrated
  • carbon in sea is 400 years older than that on land.


  • bone, shell, plant remains, charred bone, wood samples, twigs, nuts from trees

200-10000 years most reliable

40,000 less reliable.

80,000 pushing it

2 of 11

thermoluminescence (TL)

  • radiocarbon decay in quartz crystals found in clay builds up an electric charge at a known rate which is then released as light when crystals are heated .
  • when crystals are heated the 'clock' is re-set.


  • flash of light energy released by a given weight of a ceramic sample can be measured in a lab to calculate the number of years since pottery was fired.


  • less acurate than C14 and can give faluse readings die to radiation from soil or if firing was at a low temperature


  • glass and burn flint or stone

400,000 years to present day

3 of 11

Optically Stimulated Luminescence (OSL)

  • electrons from decaying radio active elemnts are trapped in crystals/ quartz.
  • when stimulated with light the electrons free themselves giving off luminescence(light energy) in the process.
  • amount released is used to date the last 'clock setting event'
  • measures the time since sediment was last exposed to sunlight/ heated.
  • calculated with more accuracy than TL

50- 1 million years

4 of 11

Potassium Argon dating

  • as potasium in rock crystals decay it produces argon gas at a known rate
  • measuring amount in a lab provides the date that crystals are formed
  • used in volcanic regions to date layers of rock which sandwich human remains.
5 of 11

Amino acid racemization

  • chemical structures of amino acids found in all living things change slowly over time at a known rate


  • can vary with climate


  • bones
  • teeth
  • shells


  • ostrich eggs on Paleolithic sites in Africa

1000-1 million years

6 of 11

Fluorine dating

  • buried bones take up fluorine from surrounding soils.
  • the amount of fluorine that it absorbs is proportional to ammount in the sorrounding deposit and the length of time that the bone has been burried


  • pitdown man
7 of 11


  • earths magnetic field changes over time. when iron oxide is heated to 600c and then cools it record the magnetic field at that time.
  • variations in earth field have been calculated which enables the data to be established.


site mustn't be disturbed.


  • ceramics
  • lava
  • hearth
  • kiln- containing iron oxide

up to 50,000 years

8 of 11

Electron Spin resonance (ESR)

  • electric charge build up at a known rate in some crystal structures. time since process begin can be calculated by measuring the charge.


  • works best in dry environments


  • teeth enamel
  • shells
  • calcite depostis in caves

50,000- 1 million years

9 of 11

Fission track dating

  • uranium decays regularly though fission (SPLITTING) which releases energy and damages crystalline structures leaving a TRACK.
  • tracks and holes then counted to estimate the time the process of decay has taken


  • 10% error margin


  • glass
  • obsidian (burnt)
  • heated stones(containing uranium)
  • sites sandwiched between volcanic layers

10,000 - several million years

10 of 11

Varve Analysis

  • stems flowing into still bodies commonly deposit layers (varves) or summer silt and winter clay through the year.
  • autumn/winter- dark colour due to dead vegetation
  • reast of year- light colour
  • this creates annual layers -like tree rings
  • changing climate will lead to changing deposits, which can be cross referenced over large areas

up to 12,000 years

11 of 11


No comments have yet been made

Similar Archaeology resources:

See all Archaeology resources »