Part I, The Development of the Method
Abstract A freshly exposed surface of obsidian will take up water from the atmosphere to form a hydrated surface layer. This layer has a different density and refractive index than does the remainder of the obsidian. Using special techniques, a thin section of the obsidian cut at right angles to the...
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Language: | English |
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Cambridge University Press (CUP)
1960
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Online Access: | http://dx.doi.org/10.2307/276634 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0002731600037987 |
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crcambridgeupr:10.2307/276634 2024-05-19T07:35:46+00:00 Part I, The Development of the Method Friedman, Irving Smith, Robert L. 1960 http://dx.doi.org/10.2307/276634 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0002731600037987 en eng Cambridge University Press (CUP) https://www.cambridge.org/core/terms American Antiquity volume 25, issue 4, page 476-493 ISSN 0002-7316 2325-5064 journal-article 1960 crcambridgeupr https://doi.org/10.2307/276634 2024-04-25T06:51:48Z Abstract A freshly exposed surface of obsidian will take up water from the atmosphere to form a hydrated surface layer. This layer has a different density and refractive index than does the remainder of the obsidian. Using special techniques, a thin section of the obsidian cut at right angles to the surface can be prepared. When examined under the microscope the hydrated layer is visible and its thickness can be measured. Photomicrographs of such thin sections are shown. Factors that determine the rate of hydration were considered. Using artifacts from archaeological sites of known age, the influence of temperature, relative humidity, chemical composition of the obsidian, burning and erosion of the obsidian on the rates of hydration was determined. Temperature and chemical composition are the main factors controlling the rate of hydration. Obsidian hydrates more rapidly at a higher temperature, and thus progresses at a faster rate in tropical than in arctic climates. Rhyolitic obsidian hydrates more slowly than does trachytic obsidian. Using archaeological data from various parts of the world, several tentative hydration rates were determined for tropical, temperate, and arctic climates. The method in its present state of development is especially suited to determine relative chronologies in layered sequences of artifacts from a single site, or region. It is also useful for detecting fake artifacts. Future work to refine the method is suggested. Article in Journal/Newspaper Arctic Cambridge University Press American Antiquity 25 4 476 493 |
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Open Polar |
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Cambridge University Press |
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crcambridgeupr |
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English |
description |
Abstract A freshly exposed surface of obsidian will take up water from the atmosphere to form a hydrated surface layer. This layer has a different density and refractive index than does the remainder of the obsidian. Using special techniques, a thin section of the obsidian cut at right angles to the surface can be prepared. When examined under the microscope the hydrated layer is visible and its thickness can be measured. Photomicrographs of such thin sections are shown. Factors that determine the rate of hydration were considered. Using artifacts from archaeological sites of known age, the influence of temperature, relative humidity, chemical composition of the obsidian, burning and erosion of the obsidian on the rates of hydration was determined. Temperature and chemical composition are the main factors controlling the rate of hydration. Obsidian hydrates more rapidly at a higher temperature, and thus progresses at a faster rate in tropical than in arctic climates. Rhyolitic obsidian hydrates more slowly than does trachytic obsidian. Using archaeological data from various parts of the world, several tentative hydration rates were determined for tropical, temperate, and arctic climates. The method in its present state of development is especially suited to determine relative chronologies in layered sequences of artifacts from a single site, or region. It is also useful for detecting fake artifacts. Future work to refine the method is suggested. |
format |
Article in Journal/Newspaper |
author |
Friedman, Irving Smith, Robert L. |
spellingShingle |
Friedman, Irving Smith, Robert L. Part I, The Development of the Method |
author_facet |
Friedman, Irving Smith, Robert L. |
author_sort |
Friedman, Irving |
title |
Part I, The Development of the Method |
title_short |
Part I, The Development of the Method |
title_full |
Part I, The Development of the Method |
title_fullStr |
Part I, The Development of the Method |
title_full_unstemmed |
Part I, The Development of the Method |
title_sort |
part i, the development of the method |
publisher |
Cambridge University Press (CUP) |
publishDate |
1960 |
url |
http://dx.doi.org/10.2307/276634 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0002731600037987 |
genre |
Arctic |
genre_facet |
Arctic |
op_source |
American Antiquity volume 25, issue 4, page 476-493 ISSN 0002-7316 2325-5064 |
op_rights |
https://www.cambridge.org/core/terms |
op_doi |
https://doi.org/10.2307/276634 |
container_title |
American Antiquity |
container_volume |
25 |
container_issue |
4 |
container_start_page |
476 |
op_container_end_page |
493 |
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1799474788195893248 |