Obsidian—hydration—rind datingmethod of age determination of obsidian black volcanic glass that makes use of the fact that obsidian freshly exposed to the atmosphere will take up water to form a hydrated surface layer with a density and refractive index different from that Obsidian hydration dating the remainder of the obsidian. 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. The hydration—rind dating technique also has been used to date glassy rhyolitic flows that have erupted more than years ago but less thanyears ago. We welcome suggested improvements to any of our articles. You can make it easier for us to review and, hopefully, publish your contribution by keeping a few points in mind. Your contribution may be further edited by our staff, and its publication is subject to our final approval. Unfortunately, our editorial approach may not be able to accommodate all contributions. Our editors will review what you've submitted, and if it meets our criteria, we'll add it to the article. Please note that our editors may make some formatting changes or correct spelling or grammatical errors, and may also contact you if any clarifications are needed. The Editors of Encyclopaedia Britannica. Learn More in these related Britannica articles: This relationship is confirmed both…. More About Obsidian—hydration—rind dating 1 reference found in Britannica articles Assorted References nonradiometric dating In geochronology: Help us improve this article! Contact our editors with your feedback. You have successfully emailed this. You may find it helpful to Obsidian hydration dating within the site to see how similar or related subjects are covered. Any text you add should be original, not copied from other sources. At the bottom of the article, feel free to list any sources that support your changes, so that we can fully understand their context. Internet URLs are the best. Thank You for Your Contribution! There was a problem with your submission. Please try again later. Keep Exploring Britannica Education. Education, discipline that is concerned with methods of teaching and learning in schools or school-like…. Fascism, political Aishwarya abhishek sex and mass movement that dominated many parts of central, southern, and eastern…. Global warming, the Obsidian hydration dating of Obsidian hydration dating average air temperatures near the surface of Earth over…. If Skin hurting on belly during pregnancy prefer to suggest your own revision of the article, you can go to edit mode requires login. Thank you for your Twin rivers food. Facts matter and Britannica Insights makes it easier to find them.
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 used by prehistoric people as a raw material in the manufacture of stone tools such as projectile points, knives, or other cutting tools through knapping, or breaking off pieces in a controlled manner, such as pressure flaking. Obsidian obeys the property of mineral hydration , and absorbs water , when exposed to air, at well defined rate. Over time, water slowly diffuses into the artifact forming a narrow "band," "rim," or "rind" that can be seen and measured with many different techniques such as a high-power microscope with power magnification , depth profiling with SIMS secondary ion mass spectrometry , and IR-PAS infra red photoacoustic spectroscopy. The use of Secondary ion mass spectrometry SIMS in the measurement of obsidian hydration dating was introduced by two independent research teams in Today the technique is applied extensively by archaeologists to date prehistoric sites and sites from prehistory in California  and the Great Basin of North America. To measure the hydration band, a small slice of material is typically cut from an artifact. This sample is ground down to about 30 micrometers thick and mounted on a petrographic slide. The hydration rind is then measured under a high-power microscope outfitted with some method for measuring distance, typically in tenths of micrometers. The technician measures the microscopic amount of water absorbed on freshly broken surfaces. The principle behind obsidian hydration dating is simple—the longer the artifact surface has been exposed, the thicker the hydration band will be. In case of measuring the hydration rim using the depth profiling ability of the secondary ion mass spectrometry technique, the sample is mounted on a holder without any preparation or cutting. This method of measurement is non-destructive. There are two general SIMS modes: Any mass-spectrometer can work in static mode very low ion current, a top mono-atomic layer analysis , and dynamic mode a high ion current density, in-depth analysis. SIMS in general refers to...
Obsidian, or volcanic glass, is formed by the rapid cooling of silica-rich lava. Humans often used obsidian as a raw material when making chipped stone tools. In , two geologists, Irving Friedman and Robert Smith, began looking into obsidian's potential as a time marker. They introduced the obsidian hydration dating method to the archaeological community in It may be used in two ways: The decision to use it as a relative or absolute dating method depends upon whether the environmental conditions eg. 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 0. When a piece of obsidian is fractured, atmospheric water is attracted to the surface and begins to diffuse into the glass. This results in the formation of a water rich hydration rind that increases in depth with time. The hydration process continues until the fresh obsidian surface contains about 3. This is the saturation point. The thickness of the hydration rind can be identified in petrographic thin sections cut normal to the surface and observed under a microscope. A distinct diffusion front can be recognized by an abrupt change in refractive index at the inner edge of the hydration rind. These fronts or rinds of hydration are more dense than the unhydrated inside, and the unhydrated zone has different optical properties. Friedman and Smith reasoned that the degree of hydration observed on an obsidian artifact could tell archaeologists how long it had been since that surface was created by a flintknapper. Hydration begins after any event which exposes a fresh surface e. Providing one can identify which process created the exposed surface or crack in the rock, it is possible to date when that process took place....
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. Obsidian hydration dating (OHD) originally promised to be a rapid, inexpensive, simple and reliable method for dating obsidian artefacts. The perceived. Chronometric Dating in Archaeology pp | Cite as Comparisons are made between the results of obsidian hydration and other dating methods. Full-Text Paper (PDF): Obsidian Hydration Dating -SPRINGER ENCYCLOPEDIA OF SCIENTIFIC DATING METHODS, Obsidian hydration dating (or OHD) is a scientific dating technique, which uses the understanding of the geochemical nature of the volcanic.
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