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Kiawah Canoe Re-Dating Project - The Charleston Museum

8 Jul 2021 2:40 PM | Dina Rivera (Administrator)

120 Riverbend Road 

Athens, Georgia 30602 

TEL 706-542-9816 | FAX 706-542-6106 

hadden@uga.edu 

cais.uga.edu 

July 8, 2021 

Martha Zierden 

The Charleston Museum 

360 Meeting Street 

Charleston, SC 29403 


The results for the Kiawah canoe re-dating project are attached. The project was funded by the Register of  Professional Archaeologists Dating Grant.  

Sampling 

The canoe fragment was examined and sampled by dendrochronologist Dr. Katharine Napora. Dr. Napora  confirmed the canoe was made from hard pine (Pinus sp.), and counted 18 annual growth rings in the  canoe fragment. Wood samples were collected from the “innermost” and “outermost” individual tree  rings using clean scalpel and forceps. 

Pretreatment 

Cellulose (α-cellulose) was extracted from the tree-ring samples following Hoper et al. (1998), with the  following modifications. Subsamples were first treated with an organic solvent (acetone) to remove  resins/waxes and other relatively mobile fractions. The subsamples were then treated with excess 1N HCl  at 80°C, followed by treatment with excess 0.1 M NaOH at room temperature, followed by a second HCl treatment at 80°C; samples were rinsed to neutral with ultrapure (Milli-Q) water between each step. A  final bleaching step of NaClO2 mixed with dilute HCl heated to 80°C yielded α-cellulose. Cellulose  samples were dried at 105°C and combusted in evacuated and sealed quartz tubes at 900°C in the  presence of CuO, yielding CO2. The CO2 samples were cryogenically purified from the other reaction  products for stable isotope and radiocarbon analyses. The “outermost” ring failed to yield a sufficient  quantity of CO2 for further analysis.  

δ13C by IRMS 

The stable isotope ratio (δ13C) was measured on the purified sample CO2 gas on a dual-inlet isotope ratio  mass spectrometer (IRMS) housed at the University of Georgia Center for Applied Isotope Studies.  Values are expressed as δ13C with respect to VPDB with an error of less than 0.1‰. 

14C by AMS 

The CO2 sample was catalytically converted to graphite using the method of Vogel et al. (1984). The  graphite 14C/13C ratio was measured using the CAIS 0.5 MeV accelerator mass spectrometer. The sample  ratio was compared to the ratio measured from the Oxalic Acid I standard (NBS SRM 4990). The quoted  uncalibrated date is given in radiocarbon years before 1950 (years BP) and percent Modern Carbon  (pMC) using the 14C half-life of 5568 years. The error is quoted as one standard deviation and reflects  both statistical and experimental errors. The date has been corrected for isotope fractionation using the  IRMS-measured δ13C value. 

Table 1. Results for Sales Order #RCS194.

UGAMS 

Sample ID 

Material 

δ13C, 

14C age years,  BP 

± 

pMC 

±

53245 

Kiawah Canoe 

α-cellulose 

-25.0 

970 

40 

88.59 

0.47



Calibration 

The radiocarbon date was calibrated in OxCal version 4.4 (Bronk Ramsey 2020) using IntCal20 for the  Northern Hemisphere (Reimer et al. 2020). 

OxCal v4.4.4 Bronk Ramsey (2021); r:5; Atmospheric data from Reimer et al (2020) 

UGAMS-53245 R_Date(970,40) 

 

References 

Bronk Ramsey, C. 2020. OxCal Program, Version 4.4. Bronk Ramsey, C. 2020. OxCal Program, Version  4.4.  

Hoper ST, McCormac FG, Hogg AG, Higham TF, Head M. 1998. Evaluation of wood pretreatments on  oak and cedar. Radiocarbon 40(1):45-50. 

Reimer, P.J., Austin, W.E., Bard, E., Bayliss, A., Blackwell, P.G., Ramsey, C.B., Butzin, M., Cheng, H.,  Edwards, R.L., Friedrich, M. and Grootes, P.M., 2020. The IntCal20 Northern Hemisphere  radiocarbon age calibration curve (0–55 cal kBP). Radiocarbon 62(4): 725-757. 

Vogel, JS, Southon, JR,Nelson, DE, and Brown, TA. 1984. Performance of catalytically condensed  carbon for use in accelerator mass spectrometry. Nuclear Instruments & Methods 223(B5):289-293. 

Report prepared by 

Carla S. Hadden, Ph.D. 

Assistant Research Scientist



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