"...Understanding changes in flora, fauna, physical landscape, and climate not only expands our understanding of the environment in which people lived but is related to the environment in which artifacts formed by those people were deposited. Depositional, erosional, and pedogenic conditions are linked with the physical landscape as well as the climatic and vegetative patterns interacting with that landscape. Natural formation processes, as defined by Schiffer (1987), include all environmental processes that affect the archaeological record.
A geoarchaeological analysis was conducted on sediments from Area 15 at the Gault site to reconstruct the natural formation processes that affected the excavation block. Particle-size analysis, calcium carbonate percentage, organic matter content, and magnetic susceptibility were utilized to explore sedimentary, pedogenic, and post-depositional processes that have affected the sediment and cultural materials. The ultimate goal of this study was to determine the depositional and post-depositional integrity of the sediment and cultural material.The conclusions which can be made from this study are as follows:
1. Results suggest Buttermilk Creek, or one of its tributaries, deposited stream cobbles (Unit 1), abandoned its channel, and migrated across the valley floor. Once it abandoned, a thin layer of coarse channel abandonment sediments was deposited (Unit 2). The abandoned channel was then overlain by fine grained, vertically accreted floodplain deposits (Unit 3-10).
2. Units 1 and 2 contain cultural material that has been OSL dated to pre-Clovis times. At the base of Unit 3, between 92.50-92.70 m, there is a decrease in the number of artifacts, suggesting a break in occupation. Unit 3 (above 92.60) and Unit 4 contain Clovis artifacts. Therefore, the pre-Clovis and Clovis artifacts are contained in geologically distinct and thick strata that are separated by a cultural break in occupation.
3. Magnetic susceptibility indicates the base of the plow zone may be at 94.65 m in Column A. Additionally, magnetic susceptibility suggests there may be an erosional surface in the Archaic midden (94.00 m), a possible erosional surface in the Clovis deposits (92.80-92.90 m), and another in the pedestaled cobbles in Column D (92.14 m).
4. As the floodplain deposits accreted, they underwent diagenesis and in-soil formation. Paleosols are buried soils and represent periods of stability. The association of a paleosol and Clovis material suggests there was a period of landscape stability at this time. Another paleosol or anthrosol, which dates to the Archaic period, is present toward the top of the profile. The Archaic-aged sedimentary deposits were heavily affected by the intensity of human occupation.
5. A modern A-horizon and plowzone are present at the top of the profile.
6. Units 1 and 2 have been introduced to a reduced environment by fluctuations in the water table. Additionally, a decrease of calcium carbonate at the base of the profile may be indicative of water movement through the profile.
7. The dates for the erosional surfaces and periods of stability as well as for textural changes through the profile indicate that the sediments at Gault reflect aspects of the history of environmental change in Central Texas as identified in various regional paleoclimatic studies.
8. Ultimately, the results of this study support the preserved context of the Paleoindian strata. The pre-Clovis archaeological material is contained in a different and clearly distinguishable stratigraphic context than the Clovis material. These results, when paired with archaeological materials from Area 15, not only increase the understanding of the Paleoindian record at the Gault site but provide further evidence supporting pre-Clovis occupation of North America..."
Geoarchaeological Investigations of Site Formation Processes in Area 15 at the Gault Site, Bell County, Texas. Gilmer (2013)
https://digital.library.txstate.edu/bitstream/handle/10877/4617/GILMER-THESIS-2013.pdf?sequence=1
Charlie Hatchett
PreClovis Artifacts from Central Texas
http://www.pre-clovis.com
http://www.forum.pre-clovis.com
http://www.blog.pre-clovis.com
A geoarchaeological analysis was conducted on sediments from Area 15 at the Gault site to reconstruct the natural formation processes that affected the excavation block. Particle-size analysis, calcium carbonate percentage, organic matter content, and magnetic susceptibility were utilized to explore sedimentary, pedogenic, and post-depositional processes that have affected the sediment and cultural materials. The ultimate goal of this study was to determine the depositional and post-depositional integrity of the sediment and cultural material.The conclusions which can be made from this study are as follows:
1. Results suggest Buttermilk Creek, or one of its tributaries, deposited stream cobbles (Unit 1), abandoned its channel, and migrated across the valley floor. Once it abandoned, a thin layer of coarse channel abandonment sediments was deposited (Unit 2). The abandoned channel was then overlain by fine grained, vertically accreted floodplain deposits (Unit 3-10).
2. Units 1 and 2 contain cultural material that has been OSL dated to pre-Clovis times. At the base of Unit 3, between 92.50-92.70 m, there is a decrease in the number of artifacts, suggesting a break in occupation. Unit 3 (above 92.60) and Unit 4 contain Clovis artifacts. Therefore, the pre-Clovis and Clovis artifacts are contained in geologically distinct and thick strata that are separated by a cultural break in occupation.
3. Magnetic susceptibility indicates the base of the plow zone may be at 94.65 m in Column A. Additionally, magnetic susceptibility suggests there may be an erosional surface in the Archaic midden (94.00 m), a possible erosional surface in the Clovis deposits (92.80-92.90 m), and another in the pedestaled cobbles in Column D (92.14 m).
4. As the floodplain deposits accreted, they underwent diagenesis and in-soil formation. Paleosols are buried soils and represent periods of stability. The association of a paleosol and Clovis material suggests there was a period of landscape stability at this time. Another paleosol or anthrosol, which dates to the Archaic period, is present toward the top of the profile. The Archaic-aged sedimentary deposits were heavily affected by the intensity of human occupation.
5. A modern A-horizon and plowzone are present at the top of the profile.
6. Units 1 and 2 have been introduced to a reduced environment by fluctuations in the water table. Additionally, a decrease of calcium carbonate at the base of the profile may be indicative of water movement through the profile.
7. The dates for the erosional surfaces and periods of stability as well as for textural changes through the profile indicate that the sediments at Gault reflect aspects of the history of environmental change in Central Texas as identified in various regional paleoclimatic studies.
8. Ultimately, the results of this study support the preserved context of the Paleoindian strata. The pre-Clovis archaeological material is contained in a different and clearly distinguishable stratigraphic context than the Clovis material. These results, when paired with archaeological materials from Area 15, not only increase the understanding of the Paleoindian record at the Gault site but provide further evidence supporting pre-Clovis occupation of North America..."
Geoarchaeological Investigations of Site Formation Processes in Area 15 at the Gault Site, Bell County, Texas. Gilmer (2013)
https://digital.library.txstate.edu/bitstream/handle/10877/4617/GILMER-THESIS-2013.pdf?sequence=1
Charlie Hatchett
PreClovis Artifacts from Central Texas
http://www.pre-clovis.com
http://www.forum.pre-clovis.com
http://www.blog.pre-clovis.com
