The hypothesis is presented that an abrupt rise in atmospheric radiocarbon concentration evident in the Cariaco Basin varve record at 12,837 ± 10 cal yr BP, contemporaneous with the Rancholabrean termination, may have been produced by a super-sized solar proton event (SPE) having a fluence of ~1.3 × 1011 protons/cm2. A SPE of this magnitude would have been large enough to deliver a lethal radiation dose of at least 3–6 Sv to the Earth's surface, and hence could have been a principal cause of the final termination of the Pleistocene megafauna and several genera of smaller mammals and birds. The event time-correlates with a large-magnitude acidity spike found at 1708.65 m in the GISP2 Greenland ice record, which is associated with high NO-3 ion concentrations and a rapid rise in 10Be deposition rate, all of which are indicators of a sudden cosmicray influx. The depletion of nitrate ions within this acidic ice layer suggests that the snowpack surface at that time was exposed to intense UV for a prolonged period, which is consistent with a temporary destruction of the polar ozone layer by solar cosmic rays. The acidity event also coincides with a large-magnitude, abrupt climatic excursion and is associated with elevated ammonium ion concentrations, an indicator of global fires.

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.

The C14 dating laboratories of Saclay (Saclay I, 1964 and Saclay II, 1965) and Gif (Gif-sur-Yvette, 1966) have joined together under the name of Gif C14 Dating Laboratory. The first series of dating results appears here with code designation Gif, Sa now being obsolete.

The remains of Vindonissa, the Roman legionary camp in Switzerland, have been the subject of extensive archaeological studies. Knowledge of the building time plays a role in reconstructions of the history of this site. We radiocarbon dated mortar samples selected from one of the Roman monuments (Westtor) as well as a nearby Medieval monastery. 14C ages obtained on the first fraction and second fraction of very short dissolution appear close to the expected Roman age of ∼2000 BP, while the monastery is dated to historic times, after AD 1308.

Cartridges containing a zeolite molecular sieve are used for the field collection of CO2 from a variety of environments (e.g. atmosphere, soil respiration, evasion from surface waters) for accelerator mass spectrometry (AMS) radiocarbon analysis by the NERC Radiocarbon Facility. Previously, sample CO2 was recovered from the sieves by heating under vacuum prior to cryogenic purification and graphitization. An additional heating and evacuation stage was used to prepare the cartridge for the next sample. We have recently developed an alternative method using heating and purging with nitrogen gas to remove sample CO2 from the molecular sieve. An infrared gas analyzer (IRGA) is used to continuously monitor CO2 content in the purge gas. The preparation of the molecular sieve cartridge for the next use is performed simultaneously and the IRGA reading is used to verify that all sample CO2 has been removed from the sieve, ensuring insignificant carryover of CO2 into the next sample. We present the results of a suite of standards of distinctly different 14C and stable-carbon isotope composition, which we used to confirm the reliability of the new procedure. The new method has considerably reduced the time required to process a single sample from at least 2 hr to less than 40 min, and reduced the minimum sample size by 50%.

Anthropogenic activities that introduce an excess of nutrients and other pollutants into rivers and lakes are causing significant changes in their aquatic environment. Excessive nutrients greatly accelerate eutrophication, and lake marl formed during eutrophication differs from that formed in oligotrophic water.

We analyzed recent sediment cores from Prošće and Kozjak lakes located in Plitvice National Park, central Croatia. Analyses consisted of 14C activity of calcareous lake marl, the ratio of stable isotopes (δ13C, δ18O), organic compounds in the sediment and the distribution of diatoms. Previous 14C activity measurements helped to determine the sedimentation rate and thus the time period of increased input of nutrients into lakes. We determined the increased 14C activity in lake sediments caused by nuclear bomb effect in recent depth profiles. We attributed the sudden increase in diatom species, Cyclotella operculata unipuctata and Achnanthes clevei rostrata, in the uppermost 5-cm layer, to eutrophication of the lake water.

We performed a molecular characterization of hydrocarbons isolated from the sediments, and applied computer-assisted high-resolution gas chromatography/mass spectrometry to estimate contributions of biogenic, fossil and pyrolytic hydrocarbons.

The 14C content in 1961–1967 rings of each of three spruce pines grown at (68° N, 130° W), (47° 30' N, 129° 16' E) and (27° 13' N, 100° 20' E) were measured. Δ14C values of the three specimens rise dramatically from a common level (∼250‰) in 1961 to their respective maxima, 964‰, 909‰, and 743‰ in 1964 and then fall to a common level ∼680‰ in 1967. The observed Δ14C increase comes most likely from the nuclear bomb test of the USSR at 75° N in 1961, although there were many other tests since the 1950s. The different effects at different latitudes reflect the atmospheric circulation patterns in the stratosphere and the transport of 14C nuclei from the stratosphere to the troposphere.

During the last decade, several radiocarbon-dated varve chronologies have been produced. The main goal at first was the extension of the 14C calibration curve beyond 10,000 BP. This paper aims to discuss varve chronologies of Soppensee and Holzmaar Lakes. Although both chronologies encountered problems, high-resolution 14C dating and relative varve time have been obtained for events during the Late Glacial.

The Radiocarbon Dating Laboratory is installed in theDepartment of Geophysics and Geochemistry, Instituteof Advanced Studies of the Australian NationalUniversity. The Australian Institute of AboriginalStudies has materially aided the establishment ofthe laboratory and is allocated a major proportionof the dating time over the next three years forsamples in Australian Aboriginal archaeology. Beyondthis the laboratory is to serve research needswithin the University. To facilitate communicationbetween collectors and laboratory a handbook oncollection of specimens and interpretation ofresults has been prepared (Polach and Golson, 1966)and a radiocarbon sample record and an agedetermination sheet are in use.

Bomb 14C has been used as a tracer for CO2 in ocean surface water to study CO2 exchange between atmosphere and ocean. Using ordinary cargo ships for sampling, we have been able to cover some parts of the Atlantic, Pacific, and Indian Oceans for certain periods. A total number of 520 samples from 89 locations were measured during the last 15 years. The data are presented both in tables and graphs. A maximum 14C concentration (Δ14C) of ca 20% was observed in temperate northern latitudes, and a few per cent lower at southern latitudes. A seasonal trend in the 14C variation, with summer maximum and winter minimum, was observed both in downwelling and upwelling areas.

The chronological problems of the Steppe zone have been under intensive investigation during the last years but no generally accepted chronological system existed up to now. We present new radiocarbon dates of samples from several excavation sites. The dates allow a comparison of the Bronze Age development in the Siberian Steppe Zone with other neighboring regions.

In all measurements reported in La Jolla I through IVand for the first of those herein reported (LJ-994to LJ-1025 and LJ-GAP-1 to LJGAP-15), we followedthe procedure designed by Suess (1954) in producingacetylene (C2H2) forradiocarbon counting. For the subsequent samples,however, the following reaction forC2H2 synthesis was used:

Archaeologists have traditionally relied upon relative ceramic chronologies to understand the occupational histories of large and socially complex polities in the Maya lowlands. High-resolution accelerator mass spectrometry (AMS) radiocarbon dating can provide independent chronological control for more discrete events that reflect cultural change through time. This article reports results of AMS 14C dating of stratified sequences at the residential group Tzutziiy K’in, associated with the major Maya polity of Cahal Pech in the Belize Valley. Cahal Pech is one of the earliest permanently settled sites in the Maya lowlands (1200 cal BC), and was continuously occupied until the Terminal Classic Maya “collapse” (~cal AD 800). We use Bayesian modeling to build a chronology for the settlement, growth, and terminal occupation of Tzutziiy K’in, and compare our results to chronological data from the monumental site core at Cahal Pech. The analyses indicate that Tzutziiy K’in was first settled by the Late Preclassic period (350–100 cal BC), concurrent with the establishment of several other large house groups and the growth of the Cahal Pech site core. Terminal occupation by high-status residents at this house group occurred between cal AD 850 and 900. This study provides a framework for interpreting patterns of spatial, demographic, and sociopolitical change between households and the Cahal Pech site core.

I discuss here a series of radiocarbon dates from sites of the earliest phase of the Linearbandkeramik (LBK) culture. The samples were collected during excavations directed by Prof. Jens Lüning (Frankfurt am Main) between 1979 and 1987. The samples were mainly charcoal, including cereals and food remains, but bones and potsherds containing organic temper were also included in the study. Although the results on cereal, bone and food remains were consistent, almost all differed from those measured on charred wood. From a series of dates measured by accelerator mass spectrometry (AMS) on organic temper in potsherds, variable amounts of sample contamination were observed, probably deriving from the natural organic components of the clay used in the ceramic production. By critically evaluating 14C dates, individual activities on the sites were dated as accurately as possible. A chronological framework could then be established for the earliest phase of the LBK culture. The dating results provided information on taphonomic processes.

Annual tree rings from Thailand were analyzed by radiocarbon AMS for AD 1938–1954. The results showed no significant depletion in atmospheric 14C over Thailand during the pre-bomb period, even though the air mass to Thailand during the growing season of tree rings is transported over a potentially significant source of oceanic 14C-depleted CO2, out-gassing in the northern Indian Ocean. When compared with Washington and Chile for different periods from the 17th century to AD 1954, Thailand appears to have the characteristics of Southern Hemisphere 14C. This supports our previous finding that Thailand was strongly influenced by the entrainment of Southern Hemisphere air parcels in the southwest Asian monsoon (Hua et al. 2004). For Thailand, this effect is much stronger than the reduction of atmospheric 14C in association with CO2 out-gassing in the northern Indian Ocean.

14C dates of relict tufa deposits at Gordale indicated a Subboreal age when the carbonate age was corrected with empirical bedrock dilution factors ‘q’ of 0.79 or 0.85. Estimates of ‘apparent age,’ based on extrapolated δ 13C values were about twice those obtained with q, and the 1σ error was large. The δ 13C values of tufa samples were not correlated with carbonate age and were close to −10. Application of q values in this district requires caution as they appear to be site-specific. We recommend that wherever possible, levels of 13C and 14C are measured in the associated tufa-depositing water, and an empirical dilution factor employed.

In this work, archaeological radiocarbon data gathered from eastern Fennoscandia have been scrutinized to discuss their suitability for studies of population history. The temporal distribution of the archaeological 14C dates has been analyzed against possible research priorities and sample material deterioration. An outstanding “Stone Age” maximum has been observed in practically all the displayed temporal date distributions. The pattern remains the same throughout the history of 14C dating in Finland. Due to sample material differences, equal taphonomic corrections based on 14C-dated volcanic deposits cannot account for all the sample degradation effects; therefore, material-dependent correction procedures are suggested.

The Royal Institute for Cultural Heritage (RICH) radiocarbon (14C) laboratory in Brussels, Belgium, has acquired experience for pretreating samples with 60 years of involvement in 14C dating, and the implementation of routine protocols. These procedures as applied to wood, seeds, charred materials, bones, ivory, textiles (silk, wool, cotton, linen), paper, shells, cremated bones, mortars, lead carbonates, sediments, etc. are described in detail in this paper. They are evaluated against reference materials.

In Siberia, the accumulation of radiocarbon dates from archaeological sites since the 1960s makes it possible to compile a general Paleolithic 14C database, which contains about 440 entries as of late 2005. With these data, we can reveal the main chronological patterns of Paleolithic complexes, with a focus on the late Middle Paleolithic (Mousterian) and Upper Paleolithic. The 14C dates for late Middle Paleolithic industries in Siberia are quite “young,” up to about 30,000–28,500 BP and perhaps ∼27,000 BP. The emergence of the Upper Paleolithic in Siberia took place relatively early compared with Eastern Europe. At about 43,000–35,000 BP, blade-dominated industries existed in the Altai Mountains and Lake Baikal region, and numerous adornments are known from several sites of that age. The late Upper Paleolithic complexes with microblade technology from the Altai Mountains are 14C dated to about 35,000–28,000 BP, and represent the earliest unequivocal evidence of microblade manufacture in northern Eurasia. The end of the Paleolithic in Siberia is related to the appearance of pottery, which indicates the beginning of the Neolithic period. In northern Transbaikal, the earliest pottery complexes are dated to about 12,000–11,000 BP and in the Russian Far East even to ∼13,000 BP, while in most of Siberia they date to approximately 8000–6000 BP. The most important features of the Siberian Paleolithic chronology are: a) the long persistence of Middle Paleolithic complexes, until about 30,000–27,000 BP; b) very early Middle to Upper Paleolithic transition, ∼43,000 BP, closely connected with the emergence of art and symbolic behavior in the earliest Upper Paleolithic at this time; c) the very early origin of microblade complexes, at least at about 35,000 BP; and d) a gradual Paleolithic–Neolithic transition, beginning in the Russian Far East at ∼13,000 BP and in Transbaikal about 12,000–11,000 BP, in most of Siberia at about 8000–6000 BP, and even later in some northern regions.

In this paper, we report 11 AMS radiocarbon dates from 8 Prehispanic fortifications located in the Huaura Valley, central coast of Perú. Small fragments of organic material embedded in preserved mud mortar in architecture, and samples from construction layers exposed by looter's holes were used to date architectural features without undertaking extensive excavations. These dates contribute toward refining the chronology of fort building in the valley, and provide a test for assumptions about temporal change and architectural style. The results indicate that fortifications date to at least 3 periods. These data provide a starting point for exploring the occurrence of warfare through time on a regional scale.