Fifty years of obsidian hydration dating in archaeology christian dating friendship personals
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 rate of penetration of water is dependent upon several factors, primarily the chemical composition of the glass and the temperature at which the hydration occurred.Discussions are given of techniques for measuring the hydration thickness, measurement (or estimates) of ambient hydration temperature, chemical composition of the obsidian, and the conversion of hydration thickness to dating the time of manufacture of the artifact.Comparisons are made between the results of obsidian hydration and other dating methods.But OHD is troublesome in regions like the Andes mountains of South America, where people brought their obsidian artifacts across enormous ranges in altitudes, from the sea level coastal regions to the 4,000 meters (12,000 foot) high mountains and higher.Even more difficult to account for is differential glass chemistry in obsidians.Eerkens JW, Vaughn KJ, Carpenter TR, Conlee CA, Linares Grados M, and Schreiber K. Obsidian hydration dating on the South Coast of Peru. 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.
Obsidian's measurable rate of rind growth has been recognized since the 1960s. Since that time, significant advancement in the recognized impacts of water vapor, temperature and glass chemistry has been undertaken, identifying and accounting for much of the variation, creating higher resolution techniques to measure the rind and define the diffusion profile, and invent and improved new models for EFH and studies on the mechanism of diffusion. "Obsidian Hydration - An Inexpensive, but Problematic Dating Technique." Thought Co.
Obsidian hydration dating (or OHD) is a scientific dating technique, which uses the understanding of the geochemical nature of the volcanic glass (a silicate) called obsidian to provide both relative and absolute dates on artifacts.
Obsidian outcrops all over the world, and was preferentially used by stone tool makers because it is very easy to work with, it is very sharp when broken, and it comes in a variety of vivid colors, black, orange, red, green and clear.
When a fresh surface of obsidian is exposed to the atmosphere, as when it is broken to make a stone tool, more water is released and the rind begins to grow again.
That new rind is visible and can be measured under high-power magnification (40-80x).
The measurement of rind growth since the break can be done with a piece of equipment that probably already exists in most laboratories. The problem is, the constant (that sneaky D up there) has to combine at least three other factors that are known to affect the rate of rind growth: temperature, water vapor pressure and glass chemistry.