PREFACE

4. Size and Number of Samplesa. A sample weight of 30 grams (Beta Analytic, Inc. 1997 guidelines) of charcoal or othercharred vegetal material is recommended. If the sample is charcoal fragments and flecksmixed in sediment, a larger sample (about 60 grams for Beta Analytic) is needed. Foruncharred material, a 100-gram sample is recommended. If only a small volume of materialis available, such as a few corn kernels, extended counting or Accelerator Mass Spectrometry(AMS) dating can be obtained. Samples of bulk soil have proven useful for extraction ofsamples suitable for AMS dating if no macroscopically visible charcoal is available.b. The number of samples is dependent upon the amount of material available, and on theresearch questions. Commonly, one sample per feature or use episode is taken. Largercontexts may warrant collection of more samples. If the feature is stratified, take a samplefrom each cultural stratum. Check with crew chief before collection.5. Field Sample PreparationCollect the sample with a clean trowel or hands (if necessary) and place it into a double-thicknessaluminum foil envelope. Include sediment if necessary or if most expedient. Handling of thematerial should be kept to a minimum. Label sealed foil envelope and put into a bag with fullprovenience labeling.6. Laboratory Methodsa. Give samples to archeobotanist for species identification.b. Once identified, give priority to samples of annual plants.c. Submit multiple samples from same provenience to allow for more accurate dating.d. Wrap samples in aluminum foil and place in zip-lock bag to send.e. Send samples as early as possible.f. Give highest priority to samples from proveniences with other datable materials, e.g.,archeomagnetic, obsidian hydration, thermoluminescence, tree-ring.g. If possible, submit at least 3–5 grams of good charcoal per sample. Larger samples arepreferred.MaterialClean charcoalDirty charcoalWoodShellsLimestoneBonePeatHumus soilTypicalCarbonContent Optimum Weight Minimum Weight25–75%10–25%20–30%8–12%5–10%0.5–4%5–20%0.2–4%10–20 grams10–50 grams30–100 grams50–100 grams100–200 grams200–500 grams100–200 grams200–800 grams3 grams5 grams5 grams5 grams25 grams150 grams70 grams150 grams7. Interpretation and Reporting GuidelinesRadiocarbon determinations are probability statements that in many ways are raw data. Almostwithout exception, a C-14 determination will be older than the target event. Interpretations ofradiometric data, or at least providing a context of such data, is the responsibility of theinvestigator. Presentation of these data requires an interpretative framework. A protocol must befollowed to report radiocarbon determinations. It is especially critical to present such datacorrectly when performing C-14 data manipulations. In particular, the following precautionsmust be addressed when reporting and interpreting C-14 dates.6-23