This research aims at radiocarbon dating 2 structures of archaeological interest from Petra, south Jordan, using lime plaster and mortar. Initially, the samples' content of calcareous contamination was examined by petrography and cathodoluminescence. In order to date clean lime binders, the samples were gently crushed and 63–45 μm powders were collected by dry sieving, then the CO2 gases, collected by a hydrochloric acid hydrolysis of the powders, were dated. The interpreted 14C dates clarify the chronology of the studied structures, show an agreement with the archaeological and historical data, and may indicate the efficiency of the cleaning and hydrolysis procedures.

This study focuses on radiocarbon dating of mortars that have withstood city fires and display visible fire damage effects. Some fire-damaged and undamaged original Medieval mortars from the same site have also been tested. The mortars were heated at different temperatures and then analyzed using the same preparation procedures as in 14C dating of mortars to see what kind of changes the heating would introduce to the mineralogy, chemistry, and the carbon and oxygen isotope ratios. We found that decarbonation during heating starts at ∼600 ° and recarbonation starts as soon as the temperature drops. Already after a few days, most of the lost CO2 has been replaced with atmospheric CO2. The renewed carbonates are readily soluble in the acid hydrolysis process and their carbon and oxygen isotopes have a light signature. Fire-damaged historical mortars display the same features. If a long time has elapsed between hardening of the original mortar and the fire, the new carbonates have 14C concentrations that point to the fire event rather than to the building event. In several cases, the fire-damaged mortars have an easily soluble carbonate fraction with a 14C age that could be related to a major fire event, but still most of the soluble carbonate yields a 14C age that seems like a reasonable age for the original construction.

Radiocarbon dating was first applied to historic lime mortars during the 1960s. However, despite the relative simplicity of the technique in principle, a number of subsequent studies have highlighted important aspects that should be considered. One of the most significant of these challenges arises from sample contamination by carbonaceous substances such as incompletely burnt limestone and aggregates of fossil origin containing “dead” 14C. More recent studies have shown that in the majority of old lime-based mixtures the contamination problem can be avoided through selection of pure lime lumps. These particular types of lumps are believed to originate from areas where the lime is incompletely mixed with the aggregate. It has been demonstrated that even a single lime lump can provide sufficient material for a 14C date of the mortar from which the lump was taken (Pesce et al. 2009). This paper describes the practical challenges associated with location, extraction, and preparation of 4 lime lumps extracted from 2 new sites for 14C dating. These include distinguishing the lime lumps from other lumps present in the matrix and the removal of material surrounding the lime lump. The coherence of 14C dating with other archaeological information on the chronology of historic sites is highlighted through case studies.

Radiocarbon dating of closely associated marine mollusk shells and terrestrial material (charred wood or bone) collected from archaeological contexts on Tenerife and Fuerteventura islands allowed us to quantify the marine 14C reservoir effect (ΔR) around the Canary Archipelago. Coastal Fuerteventura has a positive weighted mean ΔR value of +185 ± 30 14C yr, while for Tenerife a range of negative and positive values was obtained, resulting in a ΔR weighted mean value of 0 ± 35 14C yr. These values are in accordance with the hydrodynamic system present off the Canary Islands characterized by a coastal upwelling regime that affects the eastern islands (Fuerteventura and Lanzarote) but not the other islands of the archipelago, namely Tenerife. Because of this oceanographic pattern, we recommend the extrapolation of these results to the remaining islands of the archipelago, i.e. the first value must be used for the eastern islands, while for the central and western islands the acceptable ΔR value is 0 ± 35 14C yr.

Local reservoir ages are often estimated from the difference between the radiocarbon ages of aquatic material and associated terrestrial samples for which no reservoir effect is expected. Frequently, the selected aquatic material consists of bivalve shells that are typically well preserved in the archaeological record. For instance, large shell middens attest to the importance of mussel consumption at both coastal and inland sites. However, different physiological mechanisms associated with tissue and shell growth may result in differences in reservoir effects between the surviving component (shell) and the component relevant to dietary reservoir effects in consumers (tissue). The current study examines bivalve tissue-shell age differences both from freshwater and marine contexts close to archaeological sites where human consumption of mollusks has been attested. Results exhibited significant 14C age differences between bivalve tissue and shell in a freshwater context. In a marine context, no significant bivalve tissue-shell age differences were observed. The results also showed that riverine and lacustrine shells show large and variable freshwater reservoir effects. The results have important implications for establishing local reservoir effects especially in a freshwater environment. For good a priori knowledge of expected 14C differences in organic and inorganic water, carbon is thus necessary. Furthermore, the high variability in freshwater shell 14C ages implies the need for representative sampling from the archaeological record.

Herbivorous and deposit-feeding gastropods are a major component of archaeological shell middens worldwide. They provide a wealth of information about subsistence, economy, environment, and climate, but are generally considered to be less than ideal for radiocarbon dating because they can ingest sediment while they graze, inadvertently consuming terrestrial carbon in the process. However, few studies of 14C activity in herbivores or deposit-feeding gastropods have been conducted into this diverse range of animals that inhabit many environmental niches. Here, we present results investigating 14C variability in shells belonging to the families Strombidae and Potamididae from the Bogi 1 archaeological site, Caution Bay, southern coastal Papua New Guinea (PNG). These shells make up 39.3% of the shell MNI in the excavation units studied and some of these species are the most common taxa of neighboring sites. It would therefore be advantageous to establish if there are any 14C offsets associated with such animals, and identify those that can give reliable calendar ages. Our methodology combines a high-resolution excavation protocol, selection of short-lived samples identified to species level, and a triisotope approach using 14C, δ13C, and δ18O to evaluate the source of variability in shells. Our results indicate that considerable variation exists between different species of Strombidae with some inhabiting muddier environments that act as sinks for limestone-derived sediments with depleted 14C content. The magnitude of variation is, however, overshadowed by that measured in the mudwhelk, Cerithidea largillierti, which has the largest spread in 14C of any shellfish studied so far at Caution Bay. This animal ingests sediment within the estuary that contains 14C derived from both enriched and depleted sources.

We submit that anomalies in radiocarbon data in archaeological studies should be viewed positively as a stimulus to undertake further targeted research. Additional analyses to resolve anomalies have the potential to provide important insights into heretofore unstudied or incompletely understood depositional or geochemical processes affecting 14C values, particularly in certain types of samples and samples from certain types of environments. We consider 2 major categories or sources of 14C dating anomalies that we posit are mostly responsible for the vast majority of problematic 14C results: anomalous sample contexts and anomalous sample composition. Two additional sources of 14C anomalies are much more rarely encountered. Six case studies taken from New World archaeological studies are briefly presented to provide examples of where questions concerning the validity of 14C measurements generated additional and ultimately more accurate understandings of temporal relationships. AMS-based 14C measurement technology has rendered detailed investigations of 14C anomalies routinely feasible.

In 2008–2009, during construction of the ring road around the town of Sztabin in NE Poland, archaeological rescue excavations were carried out at site no. 12 in Horodnianka. The excavations revealed the remains of a defensive settlement from the Bronze Age, with a total surface of 3 ha. Concentric wooden palisades reinforcing the settlement were situated on sandy, elevated embankments of the Biebrza River. Altogether, 189 samples of archaeological wood, mainly oak (Quercus sp.), were collected. Dendrochronological analysis demonstrated that the trees were cut down within a relatively short period of only 22 yr. On the basis of 22 contemporaneous dendrochronological sequences, the average curve HOR_AA1 (89 yr long) was constructed. However, attempts at dating the average curve against the chronologies from adjacent areas were unsuccessful. Therefore, determination of the time interval represented by the palisade oaks was attempted with the wiggle-matching method. Radiocarbon dating using liquid scintillation counting (LSC) was conducted for 6 suitable samples selected from the average curve. The 14C results, after calibration, suggest the dates of cutting the oaks outlining the Horodnianka chronology most probably fall in the time interval 870–795 cal BC. This means that Horodnianka could be the furthest northeastern defensive fortification of the Lusatian culture.

Progressive stages in the development of the Old Town region of the city of Klaipėda (in German, Memel) were ascertained by analyzing archaeological and historical data combined with an analysis of pollen, diatom, plant macrofossil, and osteological findings as cross-referenced with radiocarbon measurements. The port city of Klaipėda, located on the eastern part of the Baltic Sea, was an important political, economic, and religious center during the last millennium. In addition to its environmental history, the character of human activity and urbanization of the area during the 16th–17th centuries AD were examined. The chronology of these records is based on archaeological, historical, and 14C data. The results obtained indicate the predominance of a wet boggy environment and the presence of a pond in the investigated territory of Klaipėda during the late 15th and early 16th centuries AD. The formation of a new Danė River channel created an island town, resulting in a defensible residual area for the town inhabitants. An ongoing deposition of a cultural layer began in the mid-16th century AD. Rich zooarchaeological data found in this layer provided new details on human diet and exposed a predominance of domestic animals, especially cattle. Due to intensive amelioration of this area, layers of sandy and clayey deposits were formed during the second half of the 16th century AD. A significant presence of cultivars, ruderals, and weeds were recorded, indicating substantial human activity and increasing urbanization of the landscape. According to the paleobotanical, archaeological, and historical data, the culmination of this process took place at the end of the 16th and beginning of the 17th centuries AD, when residential areas were established.

Archaeological, geological, and paleoecological investigations supported by radiocarbon dating enabled us to present a reconstruction of chronologically based paleoenvironmental and human activity changes in the Šventoji region, NW Lithuania, during the period 4000–800 cal BC. In addition, we describe the main stages of the Late Glacial and Holocene periods in the area. The Baltic Ice Lake regression was succeeded by a terrestrial period until the Littorina Sea maximal transgression at 5700–5400 cal BC. A marine bay with brackish water was transformed into a freshwater lagoon before the oldest archaeological evidence of human presence, i.e. 4000/3700 cal BC. However, the presence of Cerealia type and Plantago lanceolata pollen dating back to about 4400–4300 cal BC suggests earlier farming activities in the area. Pollen analyses show the minor but continuous role of cereal cultivation after 3250 cal BC. Due to the predominance of the boggy landscape in the immediate vicinity of the Šventoji sites, agricultural fields were situated further away from the sites themselves. Exploitation of remote areas of the freshwater basin by diverse fishing gear was proven by the discovery of a new fishing site, Šventoji 41 (2900–2600 cal BC). This finding together with data of previous research suggest a complex and elaborate coastal economy involving seal hunting and year-round freshwater fishing during the 3rd millennium cal BC. A decline in human activity is seen in the pollen diagram after 1800 cal BC, which could be due to significant environmental changes, including overgrowth of the freshwater lagoon basin with vegetation.

This article discusses 18 accelerator mass spectrometry (AMS) radiocarbon dates from the peat bog sites Sakhtysh 2a, Ozerki 5, and Ozerki 17 in the Upper Volga region. The aim is to contribute to a better understanding of the emergence and dispersal of early ceramic traditions in northern Eurasia and their connection to the Baltic. With 1 exception, all dates were obtained from charred residue adhering to the sherd. A possible reservoir effect was tested on 1 piece of pottery from Sakhtysh 2a by taking 1 sample from charred residue, and another sample from plant fiber remains. Although a reservoir effect was able to be ruled out in this particular case, 4 other dates from Sakhtysh 2a and Ozerki 5 seem too old on typological grounds and might have been affected by freshwater reservoir effects. Considering all other reliable dates, the Early Neolithic Upper Volga culture, and with it the adoption of ceramics, in the forest zone of European Russia started around 6000 cal BC.

The unique archaeological monument of Okhta 1 (Neolithic-Early Metal Age) was excavated in 2008 in central Saint Petersburg (Russia). Radiocarbon and wiggle-match dating of organic materials and artifacts (charcoal wood samples and ceramic food crusts) from lithological and cultural layers helped to determine the main stages of cultural-historical processes and paleogeographical events in the coastal zone of the Baltic Sea bay during the Holocene. Humans occupied the Okhta Cape from 4200–3600 cal BC, after the Littorina Sea regression. Prehistoric people of the Middle-Late Neolithic, identified by their characteristic Pit Combed Ware ceramics, used this territory for fishing and hunting. The wood pile constructions used for fishing in 3500 cal BC were built on the coast and in river channels. From 3200–3000 cal BC, settlements and burials appeared of the Late Neolithic-Early Metal Age. The strategic geographical position of this territory was favorable for trade activity, fishing, and hunting, and shaped important interactions for different cultural groups.