Radiocarbon Samples and Archaeological Excavation: a Commentary Based on the "Valdivia Absolute Chronology"

Summary

The cultural chronology of Ecuador is based on several hundreds radiocarbon determinations. Most of the dated samples, which come from coastal sites, are charcoal, however a good number were shell and few were the collagen of human bone. Some dates were obtained by other methods. Early in the fifties, obsidian hydration dates served to complete the 14C sequence, and more recent Thermoluminescence assays have not only completed some missing dates for a more refined sequence, but have served to validate some 14C calibrations and to explain some aberrant determinations. In the following commentary, we will refer mostly to Valdivia dates, since they were obtained by the most varied field methods, during the forty years Valdivia sites have been under excavation.

This paper has two parts: firstly, an archaeological discussion of the Valdivia absolute chronology by Jorge Marcos; and secondly, the presentation of the calibration of the Valdivia dates in the Gliwice Radiocarbon Laboratory, by Adam Michczynski. Marcos, discusses the importance of selecting a 14C sample in order to obtain a secure date, and the most common errors that have affected the Valdivia absolute chronology. The necessity to calibrate dates, and the importance of publishing them properly. (1)

The results of calibration of individual 14C dates by Adam Michczynski are presented in Table 1 and Figure 1. Finally, as a corollary, a commentary on the problems presented in the combined presentations is provided by the senior author.

Summary

This paper is intended to consider a problem of possibility of applying the C-14 method application to establish the Inca state chronology. We attempted to find out the time intervals of Inca Imperial Phase and Inca Preimperial Phase and to make rough estimation of time intervals corresponding to periods, when succeeding rulers of The Inca Empire reigned. To this end we applied the composite probability distribution of calibrated radiocarbon dates. Obtained results seems to confirm time intervals established basing on the chronicles.

Mariusz S. Ziółkowski

It is obvious that the basis of all archaeological research is to establish the chronology (relative and absolute) of the analyzed phenomena. In Andean archaeology, absolute dating is mainly accomplished by the C-14 dating method, and the dates from the Andean sites appeared in the very first radiocarbon laboratory lists, in the early fifties, i.e. more than 40 years ago. The thermoluminescent, paleomagnetic and obsydian methods are considerably less frequently used. Unfortunately, in spite of very prominent advancement of the exploration of Prehispanic cultures, and the above mentioned fact of the very early application of the C-14 method in the Andean archaeology, the absolute chronology for this region is still the object of many controversies.