手法を比較

	Obsidian Hydration Dating	Archaeomagnetic Dating
分野	考古学	考古学
系統	Process / pipeline	Process / pipeline
提唱年	1960	1968
提唱者	Irving Friedman	Robert Coe
種類	Hydration layer dating technique	Magnetic reference frame dating
原典	Friedman, I., & Smith, R. L. (1960). A new dating method using obsidian: Part 1, the surface rind method. Journal of Geophysical Research, 65(4), 1287-1291.	Coe, R. S. (1968). The determination of paleointensities and neomagnetic effects on pottery. Journal of Geophysical Research, 73(12), 3247-3262.
別名	OHD, obsidian hydration method	paleomagnetic dating, magnetic declination dating
関連	4	3
概要	Obsidian hydration dating (OHD) is a chronometric method that determines the age of obsidian artifacts by measuring the thickness of a hydration layer formed on their exposed surfaces. Developed by Irving Friedman and Robert Smith in 1960, it is based on the principle that fresh obsidian surfaces absorb water from the surrounding environment at a measurable rate. The method is particularly valuable in archaeology for dating volcanic glass tools and other obsidian objects, especially in regions where obsidian was commonly used for cutting and scraping implements.	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.