Obsidian hydration dating range

This layer is not visible to the unaided eye and should not be confused with the patina that develops on many materials as a result of chemical weathering.The surface of obsidian has a strong affinity for water, as is shown by the fact that the vapor pressure of the adsorption continues until the surface is saturated with a layer of water molecules.INTRODUCTION | PREPARATION METHODS | REFERENCES The obsidian hydration dating method was introduced to the archaeological community in 1960 by Irving Friedman and Robert Smith of the U. When a new surface of obsidian is exposed to the atmosphere, such as during the manufacture of glass tools, water begins to slowly diffuse from the surface into the interior of the specimen.

Obsidian hydration dating range lloyd dating

In order to use obsidian hydration for absolute dating, the conditions that the sample has been exposed to and its origin must be understood or compared to samples of a known age (e.g.

as a result of radiocarbon dating of associated materials).

A freshly-made surface of obsidian (volcanic glass of rhyolitic composition) will absorb water which slowly penetrates by diffusion into the body of the artifact.

Although the depth of penetration can be measured by various methods, it is generally determined by microscopic examination on thin sections of the artifact cut normal to the surface.

The relationship is disarmingly simple: Age = DX2, where Age is in years, D is a constant and X is the hydration rind thickness in microns.

Obsidian hydration dating (OHD) is a geochemical method of determining age in either absolute or relative terms of an artifact made of obsidian.

Their initial work focused on obsidians from archaeological sites in western North America.

The use of Secondary ion mass spectrometry (SIMS) in the measurement of obsidian hydration dating was introduced by two independent research teams in 2002. It has also been applied in South America, the Middle East, the Pacific Islands, including New Zealand and Mediterranean Basin.

The thickness of the layer can be determined by microscopic examination of a thin section of the sample cut at right angles to the surface.

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