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Comparative Archaeology Database, University of Pittsburgh
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The Central Alaska Peninsula Radiocarbon Dataset |
The data files MASTER.TXT and MASTER.XLS provide age estimates for specimens collected from cultural and geological contexts in the Chignik-Meshik Rivers Region Cultural Resource Reconnaissance Project. MASTER.TXT is a comma delimited ASCII text file; MASTER.XLS contains the same data in the form of an Excel spreadsheet. Blank cells indicate no data. Each line in the ASCII file corresponds to one radio carbon sample. There are 92 lines, each with 18 variables separated by commas. The variables are listed in the following order:
| 1 | Trinomial. Formal US naming conventions for archaeological sites in the state of Alaska. n/a = sample does not come from a formally designated archaeological site. |
| 2 | Region. Geographic location of the archaeological site or collection area*.
*The use of "Geo" after the region label indicates the sample came from a non-cultural context. |
| 3 | Site name. Names given to known archaeological sites (where applicable). |
| 4 | Description. Brief description of the sample location and context. |
| 5 | Unit. Name of excavation or collection unit. |
| 6 | Depth:
cm = centimeters below datum. cmbs = centimeters below surface. |
| 7 | Feature. When the sample comes from a numbered feature (architectural, cultural, etc.) the feature number is provided. |
| 8 | Brief notes about the provenience of the sample |
| 9 | NPS samp. No.: Name given to the sample by the excavators or field personnel. |
| 10 | Material. Type of organic material measured by accelerator mass spectometry. |
| 11 | Sample taxon. Taxonomic name for the carbonized organic material measured by accelerator mass spectometry. |
| 12 | δ13C. Stable carbon isotope ratio measure and reported by each lab. |
| 13 | Sample pre-treatment ABA = standard acid-base-acid wash HCl = pre-treatment method for peat (see note below) NOTE: the “HCl” pretreatment method indicates that peat samples were treated with 5% HCl at the temperature 80°C for 1 hour, then it were washed and with deionized water on the fiberglass filter and dried at 60°C. For accelerator mass spectrometry analysis the cleaned sample was combusted at 900°C in evacuated / sealed ampoules in the presence of CuO. The resulting carbon dioxide was cryogenically purified from the other reaction products and catalytically converted to graphite using the method of Vogel et al. (1984) Nuclear Instruments and Methods in Physics Research B5, 289-293. Graphite 14C/13C ratios were measured using the CAIS 0.5 MeV accelerator mass spectrometer. The sample ratios were compared to the ratio measured from the Oxalic Acid I (NBS SRM 4990). |
| 14 | Lab no. Name/number given to each radiocarbon measurement by each lab. |
| 15 | Conventional age estimate in radiocarbon years before present (rcybp). |
| 16 | Instrumental measurement error expresed as +/- radiocarbon years. |
| 17 | Subjective evaluation of the reliability of the age estimate. |
| 18 | Project field report that describes the context of the measured sample. |
The first line of the ASCII text file, for example, looks like this:
n/a,Bristol Bay coastal bluff - Geo,12-AN-01-585,coastal bluff exposure,
,585cm,,,,peat,,-27.1,ABA,BETA-330981,9350,50,confident,Jordan etal nd
This means that this sample does not come from a formally designated archaeological site (hence “n/a”; alternatively this cell would have a trinomial designation). The site is found in a geographic area called “Bristol Bay coastal bluff - Geo” (the “Geo” indicates that it is from a non-cultural context). The collection area was named “12-AN-01-585”. The collection area can be described as a “coastal bluff exposure”, there is no unit designation. The sample comes from 585 centimeters below the top of the exposure. There is no feature designation. There are no brief provenience notes. There is no other unique NPS field sample number. The material analyzed was “peat”, and the the plant the charcoal came from was not identified. The stable carbon isotope ratio measured by the AMS lab was -27.1. The sample was treated with the “ABA” (or acid-base-acid) pretreatment method. The name given to the measured sample by the lab is “Beta-330981”. The conventional age estimate is 9350 years before AD 1950. The instrumental error of this measurement is 50 radiocarbon years. The researchers are confident in the age estimate. The context from which the sample came is detailed in a field report entitled “Jordan etal nd”.
The last, or 92nd line of the ASCII text file is:
n/a,Wildman Lake - Geo,12-AN-10-40,beach ridge exposure,,40cm,
,,,charcoal,,-23.2,,BETA-330983,1540,30,confident,Jordan etal nd
This means that this sample does not come from a formally designated archaeological site (hence “n/a”; alternatively this cell would have a trinomial designation). The site is found in a geographic area called “Wildman Lake - Geo” (the “Geo” indicates that it is from a non-cultural context). the collection area was named “12-AN-01-40” and can be described as a “beach ridge exposure”. There is no unit designation. The sample comes from 40 centimeters below the top of the exposure. There is no feature designation. There are no brief provenience notes and there is no other unique NPS field sample number. The material analyzed was “charcoal” and the plant the charcoal came from was not identified. The stable carbon isotope ratio measured by the AMS lab was -23.2. The sample pretreatment method was not reported and the name given to the measured sample by the lab is “Beta-330983”. The conventional age estimate is 1540 years before AD 1950. The instrumental error of this measurement is 30 radiocarbon years and the researchers are confident in the age estimate. The context from which the sample came is detailed in a field report entitled “Jordan etal nd”.
Download the file MASTER.TXT (15 KB) or the file MASTER.XLS (54 KB).