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  2. K–Ar dating - Wikipedia

    en.wikipedia.org/wiki/K–Ar_dating

    Potassiumargon dating, abbreviated K–Ar dating, is a radiometric dating method used in geochronology and archaeology. It is based on measurement of the product of the radioactive decay of an isotope of potassium (K) into argon (Ar). Potassium is a common element found in many materials, such as feldspars, micas, clay minerals, tephra, and ...

  3. Chronological dating - Wikipedia

    en.wikipedia.org/wiki/Chronological_dating

    Chronological dating, or simply dating, is the process of attributing to an object or event a date in the past, allowing such object or event to be located in a previously established chronology. This usually requires what is commonly known as a "dating method".

  4. Radiometric dating - Wikipedia

    en.wikipedia.org/wiki/Radiometric_dating

    Radiometric dating has been carried out since 1905 when it was invented by Ernest Rutherford as a method by which one might determine the age of the Earth. In the century since then the techniques have been greatly improved and expanded. [17] Dating can now be performed on samples as small as a nanogram using a mass spectrometer. The mass ...

  5. Argon–argon dating - Wikipedia

    en.wikipedia.org/wiki/Argonargon_dating

    Argonargon (or 40 Ar/ 39 Ar) dating is a radiometric dating method invented to supersede potassiumargon (K/Ar) dating in accuracy. The older method required splitting samples into two for separate potassium and argon measurements, while the newer method requires only one rock fragment or mineral grain and uses a single measurement of argon isotopes.

  6. Absolute dating - Wikipedia

    en.wikipedia.org/wiki/Absolute_dating

    Other radiometric dating techniques are available for earlier periods. One of the most widely used is potassiumargon dating (K–Ar dating). Potassium-40 is a radioactive isotope of potassium that decays into argon-40. The half-life of potassium-40 is 1.3 billion years, far longer than that of carbon-14, allowing much older samples to be dated.

  7. Geochronology - Wikipedia

    en.wikipedia.org/wiki/Geochronology

    Potassiumargon dating and argonargon dating. These techniques date metamorphic, igneous and volcanic rocks. They are also used to date volcanic ash layers within or overlying paleoanthropologic sites. The younger limit of the argonargon method is a few thousand years. Electron spin resonance (ESR) dating

  8. Thermochronology - Wikipedia

    en.wikipedia.org/wiki/Thermochronology

    The age can be found by knowing the half-life of potassium. [9] Argon-argon dating uses the ratio of 40 Ar to 39 Ar as a proxy for 40 K to find the date of a sample. This method has been adopted because it only requires one measurement of an isotope.

  9. Laetoli - Wikipedia

    en.wikipedia.org/wiki/Laetoli

    Two dating techniques were used to arrive at the approximate age of the beds that make up the ground layers at Laetoli: potassium-argon dating and analysis of stratigraphy. Based on these methods, the layers have been named as follows, starting with the deepest: Lower Laetolil Beds, Upper Laetolil Beds, Lower Ndolanya Beds, Upper Ndolanya Beds ...