Dating Methods

Isotope Techniques

• Uranium to Lead
  • Principle: radioactive decay
  • Materials: minerals
  • Range: 1 mya to 4.5 bya
• Rubidium to strontium
  • Principle: radioactive decay
  • Materials: minerals
  • Range: 60 mya to 4.5 bya
• Potassium to argon
  • Principle: radioactive decay
  • Materials: minerals
  • Range: 10 kya to 3 bya
• Uranium series disequilibrium
  • Principle:
  • Materials: minerals, shell, bone, teeth, coral
  • Range: 0 to 400 kya
• Carbon 14
  • Principle: radioactive decay, selective uptake of cosmic-ray generated ¹⁴C by living organisms.
  • Materials: minerals shell, wood, bone, teeth, coral
  • Range: 0 to 40 kya

Radiation Exposure Techniques

• Fission tracks
  • Principle:
  • Materials: minerals, natural glass
  • Range: 500 kya to 1 bya
• Thermoluminescence
  • Principle:
  • Materials: minerals and natural glass
  • Range: 0 to 500 kya
• Electron spin resonance
  • Principle:
  • Materials: minerals, teeth enamel, shell, coral
  • Range: 1 kya to 1 mya

Others

• Geomagnetic polarity reversals
  • Principle:
  • Materials: minerals
  • Range: 780 kya to 200 mya
• Amino acid racemization
  • Principle:
  • Materials: shells and other bicarbonates
  • Range: 500 to 300 kya
• Obsidian hydration
  • Principle:
  • Materials: natural glass
  • Range: 500 to 200 kya
• Dendrochronology
  • Principle:
  • Materials: trees rings
  • Range: 0 to 12 kya
• Lichenometry
  • Principle:
  • Materials: lichens
  • Range: 100 to 9 kya

Reference:"How old is it?". Carl Zimmer. National Geographic. Sept 2001. Vol 200. No. 3 pp78-101.