Archaeomagnetic Dating
Also known as: paleomagnetic dating, magnetic declination dating
Archaeomagnetic dating uses changes in Earth's magnetic field intensity and direction recorded in fired clay artifacts to determine age. Pioneered by Robert Coe in the 1960s, the method measures the magnetization of pottery and baked clay features, comparing measurements to a master curve of geomagnetic variation through time. Archaeomagnetic dating is most effective for materials dated to the last 10,000 years and is particularly powerful in arid regions where clay artifacts are well-preserved.
Key highlights
- Can date materials not suitable for radiocarbon or other methods
- Potentially provides high chronological resolution if reference curves are detailed
- Non-destructive to archaeological context
- Applicable to diverse fired clay materials
Intuition
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How it works
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When to use it
Apply archaeomagnetic dating to fired clay artifacts and features when absolute dating is needed and artifacts are less than ~10,000 years old. Particularly effective for kiln structures, hearths, and burnt clay features. Works well in arid regions where preservation is excellent. Less effective in wet contexts where diagenetic alteration affects magnetization.
Strengths & limitations
- Can date materials not suitable for radiocarbon or other methods
- Potentially provides high chronological resolution if reference curves are detailed
- Non-destructive to archaeological context
- Applicable to diverse fired clay materials
- Requires well-established regional reference curves, which are limited for many areas
- Paleointensity determination requires careful laboratory procedures and skilled personnel
- Older materials (> ~10 kyr) beyond the established reference curves cannot be dated
- Diagenetic alteration in wet contexts can alter original magnetization
- Regional variation in the geomagnetic field introduces uncertainty
Common pitfalls
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Applications
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Frequently asked
What is the Curie temperature and why is it important?
The Curie temperature is the temperature above which magnetic minerals lose their permanent magnetization. For most iron oxides, this is ~580 degrees Celsius. When clay is heated above the Curie temperature during firing, it acquires a new magnetization. The strength and direction of this magnetization record Earth's magnetic field at the time of heating.
How are paleointensity curves constructed?
Reference curves are built by analyzing paleointensity from artifacts of known age from radiocarbon dating, dendrochronology, or historical records. By plotting paleointensity against age, a curve emerges showing how Earth's magnetic field intensity has changed through time. New measurements are then matched to this curve to estimate age.
Can archaeomagnetic dating distinguish between two events separated by a few centuries?
Only if the paleointensity variation is steep during that time interval. If paleointensity changes gradually (flat curve), distinguishing between events is difficult. Resolution depends on the rate of paleointensity change and measurement precision.
Sources
- 1.Coe, R. S. (1968). The determination of paleointensities and neomagnetic effects on pottery. Journal of Geophysical Research, 73(12), 3247-3262.
- 2.Kissel, C., & Laj, C. (1999). Paleomagnetic secular variation at the Brunhes/Matuyama boundary. Physics of the Earth and Planetary Interiors, 116(3-4), 175-196.
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Cite this page
ScholarGate. (2026, June 3). Archaeomagnetic Dating. ScholarGate. https://scholargate.app/archaeology/archaeomagnetic-dating