Geochemical Characterization of Brown Chalcedony During the Besant/Sonota Period

Abstract

Suitable lithic material for toolmaking is fairly common across the Northern Plains and often can be found within the glacial till that still blankets the area. However, high quality toolstone tends to be limited to specific and well-known quarry locations such as the Knife River flint quarries of North Dakota. Archaeologists have long identified high-quality brown chalcedony found in archaeological sites as Knife River flint (KRF) based on a visual inspection. This material has been found throughout the Northern Plains region and is believed to have been a highly desired trade item. However, the discovery of local sources of high-quality brown chalcedony that is macroscopically identical to KRF has called into question whether this material was traded as widely as previously assumed. Samples of visually identical brown chalcedony from source locations across the Northern Plains, specifically Alberta, Saskatchewan, Manitoba, Montana, North Dakota, and South Dakota, along with KRF from the Primary Source Area in North Dakota, were collected in order to undergo geochemical characterization. This analysis was designed to determine if these source areas could be distinguished from one another and what elements aid in this differentiation. It was found that while similarities between a number of source locations exist, certain source areas such as the KRF Primary Source Area and source areas in Alberta, North Dakota and South Dakota can be distinguished from one another. For this reason further analysis into the archaeological implications of local varieties of high-quality brown chalcedony material were undertaken. The use of high-quality brown chalcedony seemed to have peaked during the Besant/Sonota time period (c. 2100 – 1100 BP) on the Northern Plains. Artifacts from well-known Besant/Sonota archaeological sites across Alberta, Saskatchewan, and Manitoba were selected to undergo geochemical characterization using laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS). This analysis has resulted in the discovery that local source areas of brown chalcedony were being exploited by Precontact groups rather than the KRF quarries in North Dakota. The implications of this are discussed in terms of trade and exchange relationships, ethnic/cultural landscapes, and economic efficiency.