This article is a critical review of published data from the earliest evidence of pressure knapped microblade technology from various regions in Northeast Asia (Siberia, Korea, China, Mongolia, Japan, Sakhalin, and Russian Far East), including discussions not only on published dates, but also on published artifacts (drawings and photos) relating to these assemblages. The issue concerning the geographical and chronological origin of microblade technology in Northeast Asia remains a widely debated concern, not only as new data emerge, but also due to researchers having different definitions of the term “microblade” and “microblade core”. In this case, by microblade technology, I refer to the systematic production of microblades using the pressure knapping technique. I therefore review the data in light of this defining feature and conclude that, based on the present state of research, pressure knapping microblade technology probably emerged in the Far East (China, Korea, or Japan) around 30,000–25,000 cal BP, in spite of most authors considering that microblade technology emerged in southern Siberia 40,000–35,000 years ago. In the discussion section, I argue about the potential role of obsidian in the emergence of pressure knapped microblade technology.

Radiocarbon dating of mollusks and barnacles from fossil shoreline deposits in the Persian Gulf and on the coast of Iranian Makran is being used to assess the extent and rate of recent crustal deformation in the area. Samples are selected with the help of x-ray diffraction and of light and scanning electron microscopy; whenever possible, two or more ages are determined for each locality on monospecific samples. Age/height values have been used to compute local uplift rates by allowing for sea-level fluctuations, but eustatic controversy can be avoided by limiting the analysis to fault chronology and to relative vertical movements between dated sections. Short counting times on large, carefully pretreated samples would supply the numerous, cheap, low-resolution ages required to follow up the preliminary results obtained by the survey.

Since the 1950s, observations of radiocarbon (14C) in tropospheric carbon dioxide (CO2) have been conducted in both hemispheres, documenting the so-called nuclear “bomb spike” and its transfer into the oceans and the terrestrial biosphere, the two compartments permanently exchanging carbon with the atmosphere. Results from the Heidelberg global network of Δ14C-CO2 observations are revisited here with respect to the insights and quantitative constraints they provided on these carbon exchange fluxes. The recent development of global and hemispheric trends of Δ14C-CO2 are further discussed in regard to their suitability to continue providing constraints for 14C-free fossil CO2 emission changes on the global and regional scale.

Radiocarbon determinations, employing both decay and direct counting, were obtained on various organic fractions of four human skeletal samples previously assigned ages ranging from 28,000 to 70,000 years on the basis of their D/L aspartic acid racemization values. In all four cases, the 14C values require an order of magnitude reduction in age.

Radiocarbon dating of plant remains is often difficult due to the complete dissolution of the samples in the alkaline step of the ABA pretreatment. At the VERA laboratory, this problem was encountered frequently when numerous Bronze and Early Iron Age samples from the eastern Mediterranean were dated in the course of the special research program SCIEM2000 and in other collaborations with archaeologists focused on that area and time period. For these samples, only a 14C age determination of the humic acid fraction was possible. Humic acids from archaeological samples are always assessed as a second-choice material for 14C dating. It is assumed that the 14C ages may be affected by the presence of humic acids originating from other (younger) organic material, e.g. from soil horizons located above a sample. Therefore, when humic acids are dated a verification of the dates is crucial. To address this basic requirement, we started some time ago to date both fractions of charred seeds, wood, and charcoal samples whenever available, i.e. the residue after the ABA treatment and the humic acids extracted from the samples in the alkaline step. The results of this comparison showed that for the investigated eastern Mediterranean archaeological sites, 50 (out of 52) humic acid dates were in agreement with the 14C dates of the respective ABA-treated samples. Statistical analysis of the age differences leads to the conclusion that the extracted humic acids originated from the samples themselves or from contemporaneous material and were not appreciably contaminated by extraneous material of different age.

The present list comprises only research projects undertaken by the laboratory on the validity of radiocarbon dating of soil, shell, coral and very old samples, all in presence of suspected contamination. All measurements were performed on a Beckman LS-200 liquid scintillation spectrometer (Radiocarbon, 1968, v. 10, p. 179-199). The chemical treatment of samples is given within the text of each section.

This list contains dates for Latin America which have mainly been measured during the past few years. The results are grouped into three categories: geologic, archaeologic, and geophysical, and arranged according to the country of provenance, passing roughly from N to S. Most of the geologic samples are connected with palynologic studies. In cases where the influence of man is apparent in the pollen diagrams, this is explicitly mentioned. Descriptions and comments are based on information provided by the collectors or submitters and on the publications referred to under each sample or series. For the archaeologic section reference has also been made to the general works of Meggers and Evans (1963), Jennings and Norbeck (1964), and Willey (1966).

Two radiocarbon (14C) excursions are caused by an increase of incoming cosmic rays on a short time scale found in the Late Holocene (AD 774–775 and AD 993–994), which are widely explained as due to extreme solar proton events (SPE). In addition, a larger event has also been reported at 5480 BC (Miyake et al. 2017a), which is attributed to a special mode of a grand solar minimum, as well as another at 660 BC (Park et al. 2017). Clearly, other events must exist, but could have different causes. In order to detect more such possible events, we have identified periods when the 14C increase rate is rapid and large in the international radiocarbon calibration (IntCal) data (Reimer et al. 2013). In this paper, we follow on from previous studies and identify a possible excursion starting at 814–813 BC, which may be connected to the beginning of a grand solar minimum associated with the beginning of the Hallstatt period, which is characterized by relatively constant 14C ages in the period from 800–400 BC. We compare results of annual 14C measurements from tree rings of sequoia (California) and cedar (Japan), and compare these results to other identified excursions, as well as geomagnetic data. We note that the structure of the increase from 813 BC is similar to the increase at 5480 BC, suggesting a related origin. We also assess whether there are different kinds of events that may be observed and may be consistent with different types of solar phenomena, or other explanations.

Radiocarbon dating with accelerators requires the manufacture of suitable carbon targets. Carbon yield and 13C fractionation were investigated for the simple and direct pyrolysis of wood and cellulose to charcoal. Under continuous vacuum removal of evolved volatiles, carbon yields of 35 to 40% and δ13C fractionation of −2.5‰ were observed in the pyrolysis of wood to charcoal, whereas yields of 30% and fractionation of −0.8‰ were obtained in the pyrolysis of cellulose to charcoal. Yield and fractionation leveled off at temperatures above 300°C. Yields and fractionations were also measured for pyrolysis of wood and cellulose in a continously-flowing argon atmosphere. Yields were higher and fractionations smaller than for the corresponding vacuum cases. For cellulose sealed in evacuated glass tubes and pyrolized at 550 to 600°C, carbon yields greater than 60% and fractionation of about −0.5‰ were observed. Yields increased and fractionation tended to decrease as the ratio of tube volume/mass of cellulose decreased, ie, as the pressure increased. Reheating of this charcoal under continuous vacuum pumping revealed no loss of mass and no alteration of carbon isotopic composition. Fractionation measurements were additionally performed on wood and the charcoal produced from burning in a fireplace, conditions approximating the “natural“ production of charcoal. Despite the large potential fractionation suggested in the wood pyrolysis experiments, charcoal produced in the fireplace showed very small or no fractionation.

Two radiocarbon counting systems have been established in the Chemistry Department, University of Glasgow, since late 1967.

The counting gas is methane, at pressures up to 10 atm, and 2 alternative procedures are followed for methane production, (a) high pressure synthesis in a stainless steel 4.5 1 reactor and (b) low pressure synthesis in an all glass flow-reactor. Both systems employ 0.5% ruthenium on alumina pellets as catalyst (Engelhard Industries Ltd.). Early samples synthesized with Air Products' hydrogen showed evidence of tritium contamination. This gas supply was later replaced with tritium-free hydrogen supplied by Messrs. Griesheim, Düsseldorf, Germany. Both detectors used for routine measurements are 0.5 1 internal gas counters supplied by Beckman Instruments Inc., California. The detectors are surrounded by a concentric-wall multiple anode anticoincidence counter. The entire counter assembly is encased within a 4-in.-thick lead shield manufactured from aged lead by J. Girdler and Co., London. Counter electronics, anticoincidence system and power supply are of Beckman design (Sharp and Ellis, 1965).

Systematic dating of tufa samples has been undertaken to establish a chronology of tufa deposits in Plitvice National Park, Yugoslavia. We conclude that tufa samples give reproducible data within the time span of ≈ 40,000 years up to recent. The 14C/12C ratio of carbon in the ambient biosphere and hydrosphere gives a detailed picture of the distribution of carbon isotopes in the investigated system. Despite the susceptibility of calcareous material to ambient conditions in the hydrosphere, the original 14C composition of tufa has not been substantially changed. A vertical profile which was cut in tufa during pathway construction showed that the tufa isochrones run vertically in the investigated area. The vertical isochrones and the 14C gradient were horizontal due to tufa build-up in Plitvice National Park which occurs on vertical escarpments that have been flooded. The relatively uniform radiocarbon content of most tufa deposits indicates redistribution of radiocarbon during the formation period. While detailed stratigraphy is often obscured, a general chronology of tufa deposits in the investigated area has been established.

The distribution of 14C concentrations in the dissolved inorganic carbon in the surface waters of the Pacific Ocean is shown to have a primarily latitudinal pattern with Δ14C maxima at mid-latitudes in both hemispheres and a minimum at the equator. Oceanographic causes of this phenomenon are discussed.

Wood from regular timbering of a shallow seated mine in Tuscany gave 14C ages of 5730 ± 100 years BP, much too old to be attributed to one of the known civilizations of Italy. This mine is located in a region of declining volcanic activity, noticeable especially through numerous emanations (natural or incidentally induced by drillings). It was suspected that the analyzed wood had grown in an environment where the normal atmosphere had been diluted by volcanic emanations. To check this hypothesis, living plants (trees, bushes and reeds) and volcanic emanations have been sampled and their 14C content measured. All present day plants are depleted in 14C, giving a fictitious age different from 0 (1805, 1820, 2540, 4350 years BP). Of the gaseous emanations sampled, two have a high pressure and show virtually no 14C (>41,000 years BP). Two others have a pressure close to atmospheric, and small amounts of 14C were introduced by atmospheric contamination (22,570 and 30,580 years BP).

Conclusion: plants grown in the vicinity of volcanic emanations have 14C activities that are too low because of a natural 14C dilution and yield anomalously high ages. The δ13C values obtained for two of these plants (—27.4‰ and —23.7‰) are close to the average for plants in general (—25‰), whereas the CO2 of mofettes is heavier than atmospheric CO2.

COGEMA-La Hague nuclear reprocessing plant in the Cotentin Peninsula (northwest France) releases in the atmosphere about 19 TBq.yr-1 of radiocarbon. Three experiments in a terrestrial environment with sampling of a bio-indicator like furze were performed in 1997, 1998, and 1999, and additional air samples in the chimney plume were measured. Results presented here establish the 14C distribution in the La Hague environment and suggest that a part of the 14C content in the vegetation near the coast results from a 14CO2 degassing of seawater supplied with the liquid waste from the nuclear plant.

Advances in accelerator mass spectrometry have resulted in an unprecedented amount of new high-precision radiocarbon (14C) -dates, some of which will redefine the international 14C calibration curves (IntCal and SHCal). Often these datasets are unaccompanied by detailed quality insurances in place at the laboratory, questioning whether the 14C structure is real, a result of a laboratory variation or measurement-scatter. A handful of intercomparison studies attempt to elucidate laboratory offsets but may fail to identify measurement-scatter and are often financially constrained. Here we introduce a protocol, called Quality Dating, implemented at ETH-Zürich to ensure reproducible and accurate high-precision 14C-dates. The protocol highlights the importance of the continuous measurements and evaluation of blanks, standards, references and replicates. This protocol is tested on an absolutely dated German Late Glacial tree-ring chronology, part of which is intercompared with the Curt Engelhorn-Center for Archaeometry, Mannheim, Germany (CEZA). The combined dataset contains 170 highly resolved, highly precise 14C-dates that supplement three decadal dates spanning 280 cal. years in IntCal, and provides detailed 14C structure for this interval.

The Laboratory for the Analysis of Radiocarbon with AMS (LARA) was established at the University of Bern in 2013. Since then, the quality of sample preparation and radiocarbon measurement procedures have been validated for different materials such as plant remains, macrofossils, bulk sediment, charcoals, and wood. This article presents the optimization of sample pretreatment of bones based on protocols described in the literature. The extraction of collagen was performed with an acid-base-acid treatment, gelatinization, coarse filtration, lyophilization, and graphitization. Dating results were validated as satisfactory for the Holocene by investigation of 36 individual samples previously dated by other 14C laboratories including VIRI/SIRI materials and from well-known archaeological contexts. An additional blank contribution for bone treatment was determined by comparison with the preparation of other sample materials. The cases of two outliers from the Holocene were studied in detail.

Most of the C14 measurements reported here were made between October 1971 and October 1972. Equipment, measurement, and treatment of samples are the same as reported previously (R., 1968, v. 10, p. 36-37; 1970, v. 12, p. 534).

Archaeological surveys conducted in the Negev and Sinai during the 20th century were commonly interpreted as representing short settlement periods interrupted by long gaps. The time factor was usually based on archaeological estimates rather than comprehensive physical dating. For example, the perceived age and time duration of “hole-mouth” pottery sherds and tabular flint scrapers became a source of circular reasoning to “date” sites and their “duration.” Thus, desert sites became to be perceived as temporary, seasonal, short-lived, while the cultures of desert populations were somehow undervalued. However, radiocarbon dating of desert sites from the Late Neolithic to the Early Bronze Age IV presents a very different scenario. The deserts of the Southern Levant exhibit a full sequence of settlement, a longer life span of individual sites, and a higher level of activity and creativity of the desert people. This paper describes the controversy and presents the 14C data that form the basis for the revised view.

A review of recently published temporal data from Shuidonggou Locality 1 indicates that a 40–43 cal ka date for the inception of Initial Upper Paleolithic (IUP) blade-oriented technologies in East Asia is warranted. Comparison of the dates from Shuidonggou to other Asian IUP dates in Korea, Siberia, and Mongolia supports this assertion, indicating that the initial appearance of the IUP in East Asia generally corresponds in time to the fluorescence of the IUP in eastern Europe and western Asia. This conclusion preliminarily suggests that either a version of the IUP originated independently in East Asia just prior to 40 cal ka, or more likely, that an early, initial diffusion of the IUP into East Asia occurred ∼41 cal ka, a hypothesis consistent with current estimates for the evolution or arrival of modern humans in the region.

Most of the determinations reported here were obtained with the 2 L counter described in our first date list (GSC I). All age calculations are based on a C14 half-life of 5568 ± 30 yr and 0.95 of the activity of the NBS oxalic-acid standard, and the ages are quoted in years before 1950. The age errors include: counting errors of sample, background, and standard, the error in the half-life of C14, and an error term to account for the average variation of ±1.5% in the C14 concentration during the past 1100 yr. ‘Greater than’ ages are based on the 4 σ criterion (GSC II).