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Radiocarbon Dating in Environmental Archaeology
   overview | collecting samples | calibrating practice | 14C data tables


14C Data Tables

The tables below present information on dated samples from New Zealand (South Pacific) and Trinidad (Southern Caribbean). The radiocarbon ages indicated here are not directly equivalent to calender years.

Transform the radiocarbon ages into calendar dates using the calibration program CALIB (you can see this and other programs at: http://www.radiocarbon.org/Info/index.html#programs).

New Zealand

Lab No. Wk-2501 Wk-2502 Wk-2924 Wk-2100 Wk-2191 Beta-13555 Beta-13556 Beta-13557
Lab Site Material Context Conv. Date Cal. BP Cal. BC/AD Probability
N5/302 Shell (Strombus sp.) food refuse 630 ± 60 1530 - 1830 (1, 2) 1.000
N5/302 Shell (Tridacna sp.) food refuse 1200 ± 60
N5/302 Shell (Cockle) midden 926± 50
N5/302 Wood charcoal in cultural layer 400 ± 50 1452 - 1633 (1)
N5/301 Wood charcoal at base of cultural layer 510 ± 50
N5/301 Wood charcoal at base of cultural layer 550 ± 30
Shady Grove Human bone surface> 854 ± 42
Shady Grove Human bone Burial 2 feature 657± 48

Trinidad

Lab No. GrN OS-49084 OS-49085 AA-999 AA-1000 AA-1001 AA-1002 GX-56769 GX-56770
Lab Site Material Context Conv. Date Cal. BP Cal. BC/AD Probability
Tanki Flip Charcoal (indet. species) Layer 3 1708 ± 35
Tanki Flip Cocos nucifera Charcoal Layer 5 1865 ± 45
Tanki Flip Arcidae Shell Layer 5 2020 ± 50
Tanki Flip Human Bone primary burial 1700 ± 40
Tanki Flip Human Bone secondary burial 1650 ± 100
Smugglers's Cove Strombus gigas Shell Layer 3 2100 ± 40
Smugglers's Cove Citarrium pica Shell Layer 3 2040 ± 50
Beggar's Lane Charcoal (indet. species) hearth feature (110 cmbs) 1660 ± 45
Beggar's Lane Charcoal hearth feature (100 cmbs) 2000 ± 60

Notes:

1Calibrations made using CALIB 4.4 software. A delta R factor (Delta R) of 12±15 was used.

2Look at the graphic below for this sample to see probability distributions.

Lab No.
The laboratory number is a unique identifier given to each radiocarbon sample. The prefix identifies the laboratory that processed the sample. The 'Wk' prefix shown here indicates that these samples were processed at the University of Waikato Radiocarbon Dating Laboratory.

Site
The site number identifies the specific archaeological site the sample came from. The New Zealand numbers are part of the New Zealand Archaeological Association Site Recording Scheme.

Site numbers in the United States are based on the "Smithsonian Trinomial System" where each State has its own number (e.g., WA=45), the County within the state has a two letter abbreviation (e.g., Crook County = CR), and sites within the county are given numbers consecutively as they are found and recorded (i.e., 45xxnnn). So, a site labelled as "45CR121" would be the 121st site recorded in Crook County, Washington. However, not all countries have their own specific numbering system.

Material
It is important to know what kind of material was dated, as materials are processed and calibrated differently. To learn more, follow the links at the bottom of the page.

Context
It is also useful to know which part of a site that samples came from (e.g., stratigraphic layer, relationship to other cultural remains, excavated versus surface, etc.).

Conventional Age
Most laboratories report radiocarbon determinations as "Conventional Ages." The Conventional Age for the sample Wk-2191 (below) is 510 ± 50 BP. Conventional ages cannot be directly translated into calendar years; this requires a further step.

Calibrated Age Ranges
When radiocarbon dating was developed, it was assumed that the concentration of 14C in the atmosphere was constant over time. However, we now know that it has varied over time, mostly because of changes in the earth's magnetic field. In order to compensate for these fluctuations, conventional radiocarbon ages need to be adjusted using a calibration curve. Fortunately, there are a number of computer programs that can perform this task.

In addition, we also know that marine samples are susceptible to fluctuations in carbon 14 because of ocean upwelling and other factors. Therefore, archaeologists have tested charcoal/shell pairs and dated historically recovered shell samples to determine what the local reservoir effects may be.

To adjust our conventional age 14C dates, we can use special software programs such as CALIB to calibrate our dates.

 

 

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