CLARIFYING THE AGE OF INITIAL SETTLEMENT HORIZON IN THE MARIANA ISLANDS AND THE IMPACT OF HARD WATER: A RESPONSE TO CARSON (2020)

ABSTRACT This paper is a response to criticism by Carson (2020) concerning the age of the Unai Bapot archaeological site in the Mariana Islands. Of specific contention are supposed errors in the marine radiocarbon (14C) research reported by Petchey et al. (2017). According to Carson, this work produced marine reservoir offsets (ΔR) of “suspiciously wide variance from each other … and those results were incompatible with the site’s reported stratigraphy and dating (Carson 2008) as well as with other previously calculated marine reservoir corrections in the Mariana Islands (Carson 2010: 3).” This statement is misleading on all three points. Our reply discusses the problems encountered when dating shells from near-shore “marine” environments where terrestrial input, in particular hard water, may complicate date interpretation. We outline a cautionary tale relevant to any researcher using “marine” shell dates to develop regional archaeological chronologies in regions dominated by limestone.

Discovery of annual growth in a modern olive branch based on carbon isotopes and implications for the Bronze Age volcanic eruption of Santorini

The volcanic eruption of Santorini in the Bronze Age left detectable debris across the Mediterranean, serving as an anchor in time for the region, synchronizing chronologies of different sites. However, dating the eruption has been elusive for decades, as radiocarbon indicates a date about a century earlier than archaeological chronologies. The identification of annual rings by CT in a charred olive branch, buried alive beneath the tephra on Santorini, was key in radiocarbon dating the eruption. Here, we detect a verified annual growth in a modern olive branch for the first time, using stable isotope analysis and high-resolution radiocarbon dating, identifying down to the growing season in some years. The verified growth is largely visible by CT, both in the branch’s fresh and charred forms. Although these results support the validity of the Santorini branch date, we observed some chronological anomalies in modern olive and simulated possible date range scenarios of the volcanic eruption of Santorini, given these observed phenomena. The results offer a way to reconcile this long-standing debate towards a mid-sixteenth century BCE date.

Revision of the human’s occupations chronologies at the Senegalese and Mauritania sites by using marine reservoir ages corrections

The prehistoric settlement of the west coast of the Senegalese-Mauritanian basin is established from archaeological remains and coal samples collected, sometimes in a stratigraphic context. However, the chronology issued, in the Before Present (BP) age, does not take into account the taphonomic context of the sites and the local reservoir age. Therefore, this article revisits the chronologies obtained based on the 14C literature and dating(s) acquired. Changes in time and duration of human occupancy of the area are shorter or longer depending on adequate yields of local reservoir age (Ndeye, 2008), which is a relevant element for marine samples. Thus, the archaeological implications observed with the reservoir effect are the rejuvenation or ageing of the dates, the age of the sites, the duration of occupation prehistoric or historical sites studied. Using the calibration programmes, it is noted that for the site of Senegal (Khant), without taking into account the reservoir effect, the human occupation is a priori, from the fifth millennium (Ancient Neolithic) to the third millennium BC (Middle Neolithic). However, if this marine reservoir effect is applied, the chronological periodisation goes from the fourth millennium to the first millennium. For the Mauritanian sites, the reservoir age correction is necessary for the Chami site while for the Tintan site is not required. Therefore, the calibrated archaeological chronologies obtained after the application of the marine reservoir effect are more relevant.

RE-EVALUATING THE BRONZE AND EARLIEST IRON AGE IN LATVIA: CHANGES IN BURIAL TRADITIONS IN THE LIGHT OF 14C DATES

ABSTRACTUntil recently, there was a lack of radiocarbon (14C) dates from the Bronze and Earliest Iron Age (1800–500–1 BC) burial sites in Latvia. The chronology of the sites was assessed on the basis of archaeological analogies with neighboring regions and typological studies of the rather meagre grave inventory. In order to establish a firm foundation for an absolute chronology of burial sites and to better understand changes in mortuary practices during the period, sequences of samples from various burial sites have been dated. In this paper we report 48 14C dates from 12 different sites and discuss them in the context of previously established archaeological chronologies. 14C reservoir effects are addressed: regarding FRE, stable isotope analysis is helpful; however, more data should be gathered in future research. In some cases, the new dates are in accord with previous chronologies, while in other cases some widely accepted assumptions may need to be revised. The new dates have proved false several previous assumptions about both the dates of individual graves and whole sites. Based on the 14C dates, we model the chronological spread of burial barrows in Latvia along waterways, the earliest examples appearing in coastal western Latvia.

ESTIMATING MARINE RESERVOIR EFFECTS IN ARCHAEOLOGICAL CHRONOLOGIES: COMPARING ΔR CALCULATIONS IN PRINCE RUPERT HARBOUR, BRITISH COLUMBIA, CANADA

The best method for quantifying the marine reservoir effect (MRE) using the global IntCal Marine13 calibration curve remains unresolved. Archaeologists frequently quantify uncertainty on MRE values as errors computed from single pairs of marine-terrestrial radiocarbon ages, which we argue significantly overstates their accuracy and precision. Here, we review the assumptions, methods, and applications of estimating MRE via an estimate of the additional regional offset between the marine and terrestrial calibration curves (ΔR) for the Prince Rupert Harbour (PRH) region of British Columbia, Canada. We acknowledge the influence on ΔR of MRE variation as (1) a dynamic oceanographic process, (2) its variable expression in biochemical and geochemical pathways, and (3) compounding errors in sample selection, measurement, and calculation. We examine a large set of marine-terrestrial pairs (n= 63) from PRH to compare a common archaeological practice of estimating uncertainty from means that generate an uncertainty value of ±49 years with a revised, more appropriate estimate of error of ± 230 years. However, we argue that the use of multiple-pair samples estimates the PRH ΔR as 273 ± 38 years for the last 5,000 years. Calculations of error that do not consider these issues may generate inaccurate age estimates with unjustifiable precision.

Dating Archaeological Cultures by Their Moats? A Case Study from the Early Bronze Age Settlement Fidvár near Vráble, SW Slovakia

This article uses age-depth models based on 29 accelerator mass spectrometry (AMS) dates from charred plant macroremains (seeds, chaff), wood charcoal, and snail shells found in two moats from the settlement Fidvár near Vráble (SW Slovakia) to improve the absolute chronology of the Early Bronze Age in central Europe. The charred macroremains were taxonomically identified to species or genus level and the lifespan of the objects and the archaeological context were considered carefully. The selected snail shells were identified to provide reliable age information. This study demonstrates that under certain conditions, ditch archives can be well suited to contribute to archaeological chronologies. For the first time, the transition from the Hatvan to the Únětice period is dated absolutely.

Assemblages, relationality and recursivity. Comments on ‘Archaeology and contemporaneity’ by Gavin Lucas

I warmly welcome Gavin Lucas's discussion of time and contemporaneity. I view this as another component of a sustained (and much-needed) investigation of the ontological character of archaeology. Gavin Lucas is presently at the forefront of this line of enquiry. His analysis is much more than an exploration of the ontology of archaeology. It is also a radical rethinking of the basis of the discipline. His analysis takes us back to ‘first principles’ and reveals unexpected and thought-provoking conclusions. Excitingly, his discussion touches upon the very basis of archaeological chronologies and archaeological stratigraphies, and forces us to think about them afresh. Worsaae, Montelius, Childe: these figures stalk the pages of elementary textbooks on archaeology, yet Lucas's analysis allows us not only to appreciate their analytical skills, but also to rethink and question them.