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	テフロクロノロジー	Archaeomagnetic Dating
分野	考古学	考古学
系統	Process / pipeline	Process / pipeline
提唱年	1944	1968
提唱者	Sigurdur Thorarinsson	Robert Coe
種類	Volcanic marker dating technique	Magnetic reference frame dating
原典	Thorarinsson, S. (1944). Tefrokronologiska studier på Island. Geografiska Annaler, 26(1-2), 1-217.	Coe, R. S. (1968). The determination of paleointensities and neomagnetic effects on pottery. Journal of Geophysical Research, 73(12), 3247-3262.
別名	tephra chronology, volcanic ash dating	paleomagnetic dating, magnetic declination dating
関連	4	3
概要	Tephrochronology is a chronometric and stratigraphic technique that uses volcanic ash layers (tephra) as time markers to date and correlate archaeological and geological deposits. Pioneered by Icelandic geologist Sigurdur Thorarinsson in 1944, it exploits the fact that large explosive volcanic eruptions deposit distinctive ash layers across vast geographic regions instantaneously in geological time. Each tephra layer serves as a chronological marker horizon that can be identified, characterized, and dated, enabling archaeologists to synchronize deposits across multiple sites.	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.