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University of Pennsylvania Radiocarbon Dates XVI
Abstract
On two previous occasions we have published lists of 14 C results of precisely dated wood samples in Radiocarbon as per mil deviations (R, 1965, v 7, p 179–186; R, 1969, v 11, no. 2, p 469–481). We have also published a list of 14 C dates, consolidating all dated wood samples processed in our lab to July 1969 (Ralph and Michael, 1970).
... Two further samples were dated by the University of Pennsylvania laboratory in the mid-1970s (Fishman et al. 1977). These sediment samples were pre-treated in 3M HCl before conversion to carbon dioxide and measurement by gas proportional counting (Fergusson 1955;Ralph 1959;Michael and Ralph 1974). It is recorded that the humic fraction of P-2411 was dated (Johnston and Wailes 2007, 29). ...
It would not be exaggerated to claim that the "Gray Ware Culture" of the second millennium B.C. was one the most important phenomenon in history of archaeology of Iran. Apart from all its intricacies and complexity, its exact dating and chronology has also been a major challenge for archaeologists. Most of the literature is still based on very old dating and chronology, and even recent publication do not have any coherent idea about the dates of its begging and expansion. This paper first tries to show that the early dating of this culture was not as precise as it should be, due to different causes, and then proposes a more precise date for the begging and the expansion of the "Gray Ware Culture" and cemeteries of the second millennium B.C. in central Iran. Contrary to early dating, our revision of old literature and new chronological evidences, show the beginning of this famous archaeological culture and appearance of first detached (independent or dependent form a known settlement) cemeteries does not go back to 13-14 century B.C., but they originated in 18-17 century B.C. Hence, if our evidences and analysis would be compelling to other scholars, it would be the time, after more than 8 decades, to claim that the famous "Iron Age Gray Ware Culture", actually is a Middle to Late Bronze Age phenomenon that continue to develop through the Early Iron Age. Finally, if the claim of this paper will come to be true, based on more absolute dating of the begging of this archaeological culture in the recent future, then a new model for socio-cultural dynamics of central Iran in the first half of the second millennium B.C. would be necessary.
This date list includes most of the archaeologic and geologic samples dated in this laboratory since publication of our last date list (R, 1975, v 17, p 196-215) as well as many samples dated previously which lacked adequate sample information.
This date list includes most of the archaeologic samples dated in this laboratory since publication of our last date list (R, 1974, v 16, p 219–237), as well as some samples dated previously, which lacked adequate sample information. The BP ages are based on AD 1950, and have been calculated with the half-life value of 5568 yr. All samples were counted at least twice for periods of not less than 1000 min each. Errors quoted for each sample are derived from the measurement of the sample, the background, and several counts of our mid-19th century Oak sample, but do not include the half-life error. All samples were pretreated with 3N HCl and some, where noted, were given additional pretreatment with 2% NaOH for the removal of possible humic acid contaminants.
This date list includes most of the archaeologic and geologic samples dated in this laboratory since publication of our last date list (R, 1978, v 20, p 210–233), as well as some samples dated previously which lacked adequate sample information.
Ages reported in this date list are calculated using the Libby half life of 5568 ± 30 years with 1950 as the standard year of reference; results are quoted in years b.p. and on the a.d./b.c. time scale.
In this date list we have included most of the archaeologic samples dated in this laboratory since publication of our last date list (R, 1977, v 19, p 188-228).
The following list comprises a selected number of measurements made up to November, 1965. Age calculations are based on a contemporary value equal to 95% of the activity of the NBS oxalic-acid standard, and on a half life for C 14 of 5570 yr. Results are reported in years before 1950, and in the A.D./B.C. scale. Errors quoted include the standard deviations of the count rates for the unknown sample, the contemporary value, and the background. Because possible errors arising from isotopic fractionation in the plants, or from the de Vries effect, have not been included, calculated errors smaller than 100 yr have been increased by rounding to that figure as a minimum.
The following list of dates was compiled since 1967 (R., 1967, v. 9, p. 382-386). Procedures of measurements are essentially unchanged from those reported previously (R., 1964, v. 6, p. 31-36; 1966, v. 8, p. 423-429). The only major change in procedure is that the practice adopted in previous date lists of widening the errors due to fluctuations in C 14 content of the exchange reservoir has been discontinued. This leaves the users free to apply the necessary corrections as they become available, e.g., Stuiver and Suess (1966) and Ralph and Michael (1969). The two gas proportional counters were rebuilt in 1968. It was found that outgassing the polytetrafluoroethylene insulators at 100°C under vacuum for 48 hours prior to reassembling the counters considerably hastened attainment of stable operating conditions.
The Radiocarbon Dating Laboratory of Tehran University Nuclear Centre began operation in autumn 1970. Benzene synthesis and liquid scintillation counting was chosen as the best method for processing a large number of archaeologic specimens most of whose ages are less than twice the half-life of C 14 . Advantage of benzene synthesis; ease of chemical processing light transfer properties, lack of isotopie fractionation and radioactive contamination, removal of radon, and improbability of cross-contamination, have been discussed (Noakes et al. , 1964; Noakes, Stipp, and Hood, 1964; Kowalski, 1965).
Recent experimental work has suggested that the relative fractionation of 14C to 13C may differ from the accepted value of b = 2. In order to explore the implications of this possibility, the standard formulae for correcting radiocarbon dates for fractionation effects are rederived, but without making any of the usual assumptions or approximations. A generalized dating equation
is derived (where ASN and AON are normalized sample and standard activities, β is a factor which reflects changes in atmospheric 13C and 14C content, {RST(o)/RST}b accounts for post-depositional changes in sample 13C ratio, and tcal is calendar age in years before ad 1950. The errors in calculated ages which might arise from different b values are estimated and shown to be small relative to other dating uncertainties. The effect of b ≠ 2 may be important in the calibration of radiocarbon dates using tree-ring samples of known age. A theoretical analysis suggests that b ≠ 2 effects may result in a correlation between age anomaly (ie, the difference between radiocarbon age and calendar age) and sample 13C data. However, an analysis of published data reveals no meaningful correlation. This result, while not eliminating the possibility that b ≠ 2, highlights its unimportance even in this high-precision application of radiocarbon dating.
While investigating the archaeological background of early maize on the coast of Peru, I realized that several factors affect interpretation. The estimated date for the start of common use of maize there is close to the apparent dates of a large tsunami, the abandonment of many coastal sites, and the start of occupation at Chavin de Huantar in the highlands. While investigating the possible relations between the principal pre-tsunami coastal culture and Chavin, I discovered that depictions of a monstrous head link the two cultures. Dating of first millennium B.C. materials is complicated by changes in the atmospheric 14C level, so iconographic, stylistic, and material linkages are even more important in thinking about cultural development in this period. Inconsistencies between older inferences and newer observations can be resolved by a new model.
INTRODUCTION In this date list we have included most of the archaeologic samples dated in this laboratory since publication of our last date list (R, 1977, v 19, p 188-228). The BP ages are based on AD 1950, and have been calculated with the half-life value of 5568 yr. An asterisk (*) before an AD/BC date indicates a date that has been calculated with the half-life value of 5730 yr and then corrected by means of MASCA correction factors. For further ex-planation see Univ of Pennsylvania Dates XVI (R, 1974, v 16, p 198-218) and Ralph et al,197 3, p 1-20. All samples were counted at least twice for periods of not less than 1000 min each. Errors quoted for each sample include the statistical counting uncertainties in the measurement of the sample, the back-ground, and the running mean of several counts of our mid-19th century oak sample, but do not include any additional errors associated with the correction factors. In addition to our 2 8L counters, a small 1L counter is employed for counting undersized samples. Larger errors associated with these dates are a direct result of small sample size and the consequently re-duced number of counts. Samples counted in the small counter have been so noted. We continue to use pure CO2 in the proportional counters. All samples were pretreated with 3N HCL, and some, where noted, were given additional pretreatment with 2% NaOH for the removal of possible humic acid contaminants.
This radiocarbon laboratory was established by a grant from Brooklyn College to support the work of its archaeologists and geologists. The method of dating is that of benzene synthesis and liquid-scintillation counting developed by a number of investigators (Noakes et al , 1965; Polach and Stipp, 1967; Tamers, 1975). This list includes nearly all samples processed so far, most of which were done since September 1975.
In the Central Sahara lying approximately between 27° N and 18°
N, rains were primarily due to tropical depressions in the early
Holocene up to about 6500 BP. Then the monsoon rains of Sahelian type
dominated up to about 4400 BP.
The Taupo eruption was a complex volcanic event that represents the most recent activity at the Taupo Volcanic Centre1 in the North Island of New Zealand. The average2 of many radiocarbon ages dates the eruption at ~AD 130. The records of ancient China and Rome refer to events in ~AD 186 of the type which follow a major volcanic eruption, and we present here reasons for considering that these events were due to the Taupo eruption, and that the true date of the eruption is ~AD 186.
Gliding spectral windows illustrate the changes as a function of time in the relative prominence of signals in a given frequency range, viewed in 3D or as surface charts. As an example, the method is applied to a 2,189-year series of averages of ring measurements on 11 sequoia trees published by Douglass. Analyses of the original data and after filtering reveal, among others, components with periods of about 10.5 and 21 years similar to the Schwabe and Hale solar activity cycles. An alignment of gliding spectra with a global spectrum serves to define, by minima, the ranges of variability around the anticipated Schwabe and Hale cycles. This procedure may have more general applicability when dealing with ranges of only transiently synchronized, wobbly, and perhaps sometimes free-running periodicities. Solar activity is known to affect climate and changes in climate are reflected to some extent in tree growth. The spectral structure in tree rings could serve not only to check any relations of climate with sunspots, auroras and more modern measures of solar activity, but also to check any purely mathematical extrapolations from the much shorter available actual data on solar activity. With such extrapolated series and the data analyzed herein, the task remains to align physical and physiological variables to further study the influence of natural environmental factors near and far on biota, including international battles, which cover an even longer span of 2,556 years.
This list is a continuation of Univ. of Pennsylvania Dates VII (Radiocarbon, 1965, v. 7, p. 179-186). It includes results for samples of Sequoia gigantea and for Pinus aristata , most of which were tree-ring dated at the Lab. of Tree-Ring Research, Univ. of Arizona.
All sequoia and bristlecone pine samples have been corrected for deviations in C ¹³ /C ¹² ratios. The δC ¹³ values listed represent the deviations (multiplied by 2) of the samples measured from the δC ¹³ value of our 100-yr old standard oak sample which is also the reference value (adjusted for zero age) for the calculation of δC ¹⁴ . In our previous publication (Radiocarbon, 1965, v. 7, p. 179-186), δC ¹³ values were erroneously reported as negative deviations from our oak standard. For the calculation of the Δ's, however, they were used in the correct sense. This mistake has been corrected in this list and one notes that the sequoias and bristlecone pines tend to be enriched slightly in C ¹³ as compared with the oak standard.
Measurements of samples of known age have been undertaken in this laboratory since its beginning in 1951 when it was found that modern wood samples taken from the outer rings of young trees did not afford a basis of counter calibration consistent with archaeologically dated samples (Ralph, 1955). This depletion was explained by Suess (1955). Subsequent measurements of samples representative of the early Egyptian dynasties, however, revealed that even with the counter calibration corrected for the modern depletion, there was a discrepancy between C 14 dates and the early Egyptian chronology (Arnold and Libby, 1951; deVries, Barendsen, and Waterbolk, 1958; deVries and Waterbolk, 1958; Barker and Mackay, 1959, 1961; Ralph, 1959; Damon and Long, 1962). Obviously, there was, and still is, a need to find samples of known age for this time range. Dendrochronology may ultimately provide the answer, and in the meantime tree-ring dated samples have afforded a means of assessing the atmospheric C 14 inventory during the last 3000 yr.
Climatic versus magnetic perturbation of the atmospheric C14 reservoir Radiocarbon variations and absolute chronology
- Pe Damon
Damon, PE, 1970, Climatic versus magnetic perturbation of the atmospheric C14
reservoir, in: Olsson, I U, (ed), Radiocarbon variations and absolute chronology,
12th Nobel symposium Proc, Uppsala, Sweden, Aug 11-15, 1969: Stockholm,
Almqvist and Wiksell; New York, John Wiley and Sons, p 571-593.
Ob odnoy vozmozhnosti izucheniya variatsiy kosmicheskikh luchey v proshlom (A possible cause of cosmic ray variations in the past)
- V A Dergachev
- G E Kocharov
Dergachev, V A, and Kocharov, G E, 1972, Oh odnoy vozmozhnosti izucheniya
variatsiy kosmicheskikh luchey v proshlom (A possible cause of cosmic ray variations in the past). Izv Akad nauk SSSR, XXXVI, no. 11, ser fiz, p 2312-2318.
Geophysical implications of radiocarbon measurements: PhD dissect
- E K Ralph
Ralph, E K, 1973, Geophysical implications of radiocarbon measurements: PhD
dissect, Univ Pennsylvania, Philadelphia, Pennsylvania.