Electron paramagnetic resonance studies of unburned archaeological flint artifacts

The dating of unburned flint artifacts is the most significant unsolved problem in archaeological dating, and a method of determining the age of unburned stone tools would be of critical importance for the fields of archaeology and geochronology. This project examines the feasibility of a proposed method of dating unburned flint artifacts ("skinflint" dating) through measurements of beta dose gradients by electron paramagnetic resonance (EPR).; The EPR protocol is carefully optimized for measurements of the E'1 paramagnetic centre. An extensive study of spectrometer stability and normalization procedures is required in order to make quantitative comparisons of the E'1 line intensity between aliquots.; Powder samples of geologic flint are shown to display anisotropy in the EPR spectra, and careful sieving is shown to remove most of the anisotropy. Unheated geologic flint is shown to be sensitive to laboratory irradiations with gamma rays, but strong decreases in E'1 EPR intensity are sometimes observed with additional radiation dose. The effect of crushing is also investigated: light crushing increases the E' 1 line intensity initially while additional crushing ultimately reduces the intensity with additional crushing. Chemical treatment with concentrated hydrochloric add is shown to improve reproducibility between aliquots drawn from the same sample of geologic flint.; Finally, a study of nine unburned archaeological flint artifacts reveals that the gradient in the E'1 intensity cannot be related to an excess smficial beta dose rate. The intensity of the E'1 centre is shown to vary between multiple aliquots of the same sample. Additionally, it is argued that the dependence of the E'1 intensity on internal radioactivity indicates the E'1 centre is not sensitive to natural dose rates of external beta and gamma radiation. Despite attempts to correct for the effects of internal radioactivity, no reliable ages could be determined. Skinflint dating, as proposed, is not feasible.