Research directed toward high precision obsidian hydration dating
Obsidian hydration dating has served as one of the chronological indicators for the Hopewell Culture earthworks ca. This work presents new obsidian hydration dates developed from high precision hydration layer depth profiling using secondary ion mass spectrometry SIMS. These data suggest that long-distance exchange in obsidian occurred throughout the Hopewell period.
La datacion por hidratacion de obsidiana ha servido como uno de los indicadores cronologicos para los monticulos de la cultura Hopewell c. Este trabajo presenta nuevas dataciones por hidratacion de obsidiana, conseguidas a partir de una medicion de la profundidad del estrato de hidratacion de alta precision , usando espectrometria de masa ion secundaria SIMS.
Absolute dating techniques attempt to pinpoint a discrete, known interval in time such as a including radiocarbon dating, obsidian hydration, thermoluminescence, Archeologists use a statistical standard deviation to increase the range of.
Kudriavtsev a. Asomoza-Palacio a. This led us to the conclusion that water molecules split into hydrogen and oxygen at the obsidian surface and then the atomic hydrogen and 18 O isotope diffused into the obsidian via two different mechanisms. The hydrogenated obsidians were heated in vacuum without hydrogen emission. A hypothesis is put forward that the obsidian hydrogenation results from a chemical reaction between atomic hydrogen and a glass network.
A new linear-parabolic equation is suggested for obsidian hydrogenation dating. Aluminosilicate glass is considered as a promising material for hydrogen fusion cells. In Friedman and Smith 1 suggested a new method for dating of obsidian artifacts. The original obsidian hydration dating method relies upon measuring the water diffusion depth in a freshly created obsidian surface and converting thickness measurements to an age. Obsidian artifacts are widely distributed in Mesoamerica, USA, Japan, Oceania, and for this reason the obsidian hydration dating method OHD was met with great enthusiasm.
However, it was difficult or even impossible to explain serious discrepancies between experimental facts accumulated during the last 55 years by the original OHD model. Serious discrepancies between the OHD results and the chronological data obtained by other methods were reported 4 , 5 , 6. The diffusion coefficients obtained in laboratories by the intrinsic rate method 7 , 8 were found to differ from the coefficients calculated for archaeological artifacts by the radiocarbon calibration 9.
Obsidian hydration dating
This article discusses the current status of archaeological obsidian studies, including techniques used in characterization and sourcing studies, obsidian hydration, and regional syntheses. It begins with an overview of obsidian and the unique formation processes that create it before turning to a discussion of the significance of characterization and sourcing techniques for understanding prehistoric obsidian trade and exchange. It also explores obsidian hydration dating methods and equations, factors that can affect the date assignments for hydration specimens, and the various uses of obsidian in prehistoric times.
Finally, it addresses some important questions relating to obsidian research and suggests new directions in the field. Keywords: obsidian studies , sourcing , obsidian hydration , archaeology , archaeometry , X-ray fluorescence , chemical characterization , obsidian , obsidian hydration dating. Approximately fifty years ago, a great leap forward occurred in obsidian studies, marking the beginning of obsidian research as it is conducted today.
lo c a litie s in the w estern U.S. using obsidian hydration dating tech niques. The ages for these events range from 12 ka to over I Ma and the hydration dates.
View exact match. Display More Results. 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. If the local hydration rate is known and constant, this phenomenon can be used as an absolute age determination technique through measurement of the thickness of the hydration layer.
The hydration layer is caused by absorption of water on exposed surfaces of the rock. The surface of obsidian starts to absorb water as soon as it is exposed by flaking during manufacture of an artifact. The layer of hydrated obsidian is visible when a slice of the artifact is examined under an optical microscope at a magnification of x
Obsidian Hydration – An Inexpensive, but Problematic Dating Technique
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 The decision to use it as a relative or absolute dating method depends upon whether the environmental conditions eg.
Obsidian–hydration–rind dating, method of age determination of obsidian (black volcanic glass) that makes use of the fact that obsidian freshly exposed to the.
Grant-in-Aid for Scientific Research C. Geological and archaeological obsidians from Easter Island Chile , Takayama obsidian-mining source Nagano , Nojiriko group Nagano and Nakamoto Hokkaido archaeological sites were analysed for their main and trace element content using the instrumental activation analysis expanded from 7 to 23 elements and the element X-ray fluorescence analysis.
The accelerated obsidian hydration experiments were standardized initially at the elevated temperatures of , , and degree Celsius for the durations of 4, 8, 16, 32, and 64 weeks, and then subsequently applied to obtain the hydration rates of geological and archaeological obsidians at the respective soil temperatures and soil relative humidities that were directly measured by cell-pairs buried at the sites for 1 year before the measurements.
Nearly fifty burnt obsidians from archaeological sites are collected and dated using the fission track dating method, thus allowing the possibility to calibrate the carbon dates older than 10 thousands B. The obsidian hydration dating method is temperature dependent, giving the ages younger or older according to the thermal history of obsidian specimens.
Therefore, extrapolation into the past is possible if we combine FT dates or well-calibrated C dates with corresponding obsidian hydration dates, and a reconstruction of the palaeoclimate surroundings of the archaeological sites becomes plausible. All Other.
Redefining the Working Assumptions of Obsidian Hydration Dating
Daniel Burris. The thicker the hydration layer, the longer since the tool was made. OHA can be used to test hypotheses about changes through time in past trade and exchange systems at the Grissom site 45KT in Kittitas County. The results show that the range of hydration rim thickness are consistent with human occupation over the last 3, years. There was no visible correlation between the artifact type and the hydration rim thickness. Of the seven sources of obsidian artifacts that were analyzed, two sources have hydration rim thicknesses only greater than two microns.
It also explores obsidian hydration dating methods and equations, factors that a radar gun and a price tag that ranges from approximately $20, to $50,
Skip to search form Skip to main content You are currently offline. Some features of the site may not work correctly. Stevenson and M. Stevenson , M. Gottesman , Michael Macko Published History. 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.
Current Questions and New Directions in Archaeological Obsidian Studies
Select the first letter of the word you are seeking from the list above to jump to the appropriate section of the glossary or scroll down to it. Old World artifact types used as time markers. All rights reserved. This technique is now also used to count carbon isotope atoms for radiocarbon dating. The advantage of this technique over the conventional radiocarbon method is that it requires a far smaller sample size and can potentially provide dates going back to around , B.
At present, however, AMS dates generally are for events less than 6 0, years old.
Obsidian hydration data on Coso obsian arttifacts from upland Pinyon Zone and lowland Volcanic Field localities in Inyo County pinyon zone of the Coso Range, at elevations between Hydration Dating of Coso Obsidian: Problems.
Obsidian : Obsidian is an aluminosilicate, or rhyolitic, glass, formed by rapid cooling of volcanic magma under the proper geologic conditions. As any other glass, it is not a crystal, and thus it lacks the lattice structure typical of crystals at the atomic level. However, glasses do possess some degree of spatial order. The surface is weathered in the atmosphere and the environmental context. Obsidian rocks were used by early peoples for the making of their tools and implements.
Environmental water molecules adsorb on the surface which exhibits roughness at the nanoscale creating a large surface concentration. Absorption into the glass and diffusion into the interstices in the glass matrix occurs. The diffusion process seems to be driven by two properties of the water molecules: a concentration gradient and osmotic pressure or chemical potential. Although it has been suggested that chemical reactions play a role Doremus , ff. A water saturation layer is then formed within a short period of time after the start of the diffusion process.
Following this period, the saturated layer increases with depth as time progresses. The saturation conditions on the surface represent the average conditions of the physical surroundings for the diffusion system during the elapsed time in a particular archaeological context.