Obsidian hydration dating obsidian sourcing examplesobsidian obsidian hydration dating examples is a naturally formed volcanic glass that was an important part of the material culture of pre-columbian mesoamericaobsidian was a highly integrated partso much that of one who would love and cherish and defend her under any conditions, changes. Obsidian is a naturally occurring volcanic glass formed as an extrusive igneous rock modern archaeologists have developed a relative dating system, obsidian hydration dating, to calculate the age of obsidian artifacts middle east obsidian tools from tilkitepe, turkey, 5th millennium bc. Hydration on obsidian were temperatures and chemical compositions (friedman and smith 1960) this research has initiated a need to better understand the influence of temperature variances and its effects on obsidian artifacts. Since the seminal work of friedman and smith  obsidian hydration dating (ohd) has undergone several important stages of development and refinement this paper will summarize the history of research and developments as to elucidate some areas for future research. Obsidian hydration dating is a type of dating that uses the weathering rind that develops within artifacts or gravel that are composed of obsidianwhen fresh obsidian is exposed to air it typically contains less than 1% water.
Obsidian hydration dating is a geochemical method which is often used to determine the age - in either absolute or relative terms - of an ancient artifact made of obsidian the technique measures the microscopic amount of water absorbed into freshly broken surfaces. Northwest research hydration analyst jennifer thatcher the xrf laboratory holds an extensive collection of geologic obsidian source reference samples from the far western united states, hawaii, canada, mexico, and. Obsidian surface roughness and rind structure both play a major influence on the obsidian hydration dating (ohd) afm (atomic force microscopy) investigation coupled with quadrupole sims hydrogen data profiles establish a validation criterion of quantitative evaluation of roughness for ohd dating purposes.
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. The hydration rate k, can be calculated by inducing the hydration of a piece of obsidian in a pressure-reaction vessel for a known period of time at a known temperature and then measuring the hydration layer and solving equation (1) for k. Obsidian hydration dating (ohd) is a geochemical method of determining age in either absolute or relative terms of an artifact made of obsidian obsidian is a volcanic glass that was sometimes used as a raw material in the manufacture of stone tools such as projectile points, knives, or other cutting tools through the process of flintknapping.
Recent experimental work has shown that the rate of hydration is significantly influenced by the amount of intrinsic water (0h-) contained within the unweathered obsidian. The hydration rates of 12 obsidian samples of different chemical compositions were measured at temperatures from 95 degrees to 245 degrees c an expression relating hydration rate to temperature was derived for each sample the sio(2) content and refractive index are related to the hydration rate. Obsidian hydration dating ☆video is targeted to blind users attribution: article text available under cc-by-sa image source in video. Fire regimes and fire history: implications for obsidian hydration dating carl n skinner united states department of agriculture, forest service pacific southwest research station redding, california 96001 abstract that fire can alter the hydration bands of obsidian specimens and thus affect the accuracy of dating.
Obsidian hydration: another dating method which has been used to date many american sites is obsidian hydration which can be used for dating sites from 200 to 100,000 years old when a piece of obsidian is chipped to make a tool, the freshly exposed surface begins to absorb water at a rate that depends on the source of the obsidian, the. Obsidian hydration obsidian is a volcanic glass which has seen a multitude of historical applications it can be easily sharpened into a razor-sharp blade, and its uses have included knives, spears, scrapers, saws, drills, and decorative pieces. Obsidian hydration dating is based on the fact that a fresh surface is created on a piece of obsidian in the tool manufacturing, or flintknapping, process obsidian contains about 02 percent water when a piece of obsidian is fractured, atmospheric water is attracted to the surface and begins to diffuse into the glass.
1989 obsidian hydration rates in california in current directions in california obsidian studies, edited by richard e hughes, pp 31-58 contributions of the university of california archaeological research facility no 48, berkeley, california heizer, robert f and adan e treganza. Obsidian hydration category: geology definition: the absorption of water on exposed surfaces of obsidian in each specific environment, the surface of an obsidian artifact absorbs water at a steady rate, forming the hydration layer the thicker the layer, the older the artifact. Friedman i, pierce kl, obradovich jd, long wd three different groups of hydration rinds have been measured on thin sections of obsidian from obsidian cliff, yellowstone national park, wyoming the average thickness of the thickest (oldest) group of hydration rinds is 163 micrometers and can be.
Obsidian butte hydration rate obsidian hydration measurements are widely used for absolute or relative dating, although their validity is still somewhat controversial the method is based on the gradual inward extension of a water-bearing zone, or hydration rim, from a freshly exposed surface of volcanic glass. Obsidian is found in the western united states, alaska, central america, and elsewhere when an archaeologist has identified the source of the obsidian from which an artifact is made, he or she may be able to date the artifact using the obsidian hydration technique. Looking for obsidian hydration services : our former obsidian hydration laboratory is now operating independently as willamette analytics jennifer thatcher, the longtime experienced hydration analyst at northwest research, remains at the helm.