Using Raman Spectroscopy to Analyze Fire-Cracked Rock from Earth Ovens in South-Central North America
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Earth ovens are complex cooking features that have been important worldwide, throughout human history. Knowledge of what was cooked in an individual earth oven is only available if food was charred, so other lines of evidence are being sought by archaeologists. The purpose of this dissertation is develop a method using Raman spectral analysis of biochemical residue found on fire cracked rock (FCR), to assess what was being cooked in archaeological earth ovens. Specifically, the carbohydrate inulin is being pursued, because it is important in earth oven cooking but is not associated with any diagnostic microfossils. A reference collection was created, including modern and archaeological macrobotanicals, and raw and cooked samples. FCR from Fort Hood and Lower Pecos, both in Texas, were analyzed and compared to control samples. This study demonstrated that is possible that food residues identifiable by Raman spectroscopy are persevered on archaeological FCR from earth ovens – while cooking and diagenetic processes do affect the spectra of food samples, they do not render them unidentifiable. While it is not possible to identify precisely what plants were cooked in an earth oven, there was a tentative identification of carbohydrates on 3 FCR samples from a total of 16 samples. These finds are in line with other research on residue from archaeological FCR. The archaeological samples were different from the non-diagnostic control samples, indicating that it is unlikely that the residue is from the environment. There is potential for the use of Raman spectroscopy to study earth oven residue; however, it requires substantial continued study before conclusive analysis is consistently achieved. Of primary concern is separating the signal from the target carbohydrate spectra from background and environmental spectra, as well as identification of residue-rich FCR for sampling.
Short, Laura Marie (2018). Using Raman Spectroscopy to Analyze Fire-Cracked Rock from Earth Ovens in South-Central North America. Doctoral dissertation, Texas A & M University. Available electronically from