- OBSIDIAN HYDRATION LAB -

::: The ARC Obsidian Hydration Laboratory is an in-house resource available for student, staff and faculty research interests. Obsidian hydration is a relative dating technique which uses the natural occurrence of a moisture band that forms within the broken surface of any natural or man-made glass as a means of discerning time depth. When a natural volcanic glass like obsidian is broken, the new surface is exposed to the elements. This surface will begin to take on moisture at a constant rate. As this occurs, over time a thin band, or rim, will develop that is visible under microscopic magnification. In cross section, this visible rim can be measured in micron increments. Using a specific hydration rate established for a particular glass source, the micron reading can be converted into a specific calendrical date estimate. Often these ages are paired with C-14 dates to establish dating consistency in archaeological contexts. The ARC Obsidian Hydration Lab is comprised of a lapidary saw for making small cuts into obsidian artifacts as well as a  computer-assisted  microscope for reading hydration rim thicknesses. Small thin-sections of the tools edge are fixed and mounted on to glass slides to be placed under the microscope. A series of readings are taken from along the rim and a mean reading is given along with the standard deviation. This process ensures the most accurate reading is being applied when establishing a date for the artifact. This type of analysis has become an invaluable tool in California and parts of the Great Basin when dealing with lithic assemblages and allows the researcher the opportunity to make a statement about time depth when radiocarbon dates are not available :::     

::: KEY PERSONNEL :::
William Norton

Department of Anthropology California State University, Sacramento 6000 J Street, Sacramento, CA 95819-6106
Phone: (916) 278-5330Fax: 278-4854 e-mail: arc@csus.edu

WEB SITE DESIGNED AND COMPILED //  BRIAN JAMES AND WILLIAM LARSON // 2010