Radiocarbon Age Determinations Research Articles

Paleoenvironmental and paleoclimatic records from permafrost deposits in the Arctic region of Northern Siberia

Ice Complexes, extremely ice-rich permafrost deposits with large ice wedges, are widely distributed in the Arctic region of northeast Siberia. They present excellent archives for the reconstruction of Late Quaternary paleoenvironmental conditions in non-glaciated areas. In 1998, 1999, and 2000 Russian and German scientists worked together on the Bykovsky Peninsula southeast of the Lena Delta in order to investigate the Ice Complex and its associated sediments. Intensive cryolithological and sedimentological studies, Radiocarbon age determinations, paleobotanical studies, micropaleontological investigations, studies of mammal and insect fossils, and stable isotope analyses of ground ice were performed. Radiocarbon data have been obtained from the entire exposed sequence covering approximately the last 60,000 years. The results indicate that compared with modern time the investigated Ice Complex sequence was formed during two cooler and more arid stages of the Late Pleistocene with relatively uniform environmental conditions, separated by a stage with environmental variations and more intensive soil formation caused by climate amelioration. The Late Pleistocene environmental changes were not as strong as those occurring during the Pleistocene/Holocene transition where a sharp break is evident.

Life on the edge: prehistoric settlement and economy on Utrōk Atoll, northern Marshall Islands

AbstractThe prehistoric settlement pattern and economy of Utrōk Atoll, situated near the northern limit of permanently‐inhabited atolls in the Marshall Islands, is described and interpreted from a complete intensive survey and excavations totalling 64 m2 (70.45 m3). Sites range from the most expansive, 25 hectare habitation and horticultural system on the largest islet, to smaller, temporarily‐occupied habitations situated on diminutive islets. A suite of 16 radiocarbon age determinations suggests human occupation of the atoll by the first few centuries AD (Beta‐103903). Four additional dating samples, collected from emerged beachrock, determined when the islets adjusted shape in response to changing sea levels and coastal processes.Some 173 prehistoric tools and ornaments included 39 shell adzes, pumice abraders, pearl shell scrapers, pounders and hammerstones, a trolling lure point, a single piece fishhook point and ornaments such as Conus shell rings, Spondylus beads and disks, pendants and a small drilled whale tooth.Of the 13,545 bones, 88.6% were of fish, mostly inshore taxa, with dog (Canis familiaris), Pacific rat (Rattus exulans), sea turtle (cf. Chelonia mydas), lizard and bird (Puffinus, Phaethon, Sula, Fregata, Egretta and Heteroscelus), as well as three human burials. Some 45.7 kg of shellfish representing 34 families was dominated by bivalves (67%) of mostly Tridacnidae. The Bullmouth helmet, Cypraecassis rufa, was extirpated as a result of human predation, although the archaeological evidence suggests that low human populations on this relatively dry atoll had little noticeable impact on the marine ecosystem, while the terrestrial landscape was markedly altered.

Mass Spectrometric Radiocarbon Dates from Three Rock Paintings of Known Age

Radiocarbon age determinations are presented on three hieroglyphic texts from Naj Tunich cave in Guatemala containing Maya calendar dates. The ages obtained are on average 110–140 years older than the calendar dates. Several possible reasons are discussed for this discrepancy: one that is applicable to all radiocarbon dates on charcoal, one that applies to rock paintings, and one that is specific for the tropics. Possible problems with the ages ascribed to the Maya calendar dates are also discussed. Even with the potential problems that may exist, these dates still fall within 110–140 years of the ascribed calendar dates. Caution is urged in the interpretation of dates on charcoal pigments from rock paintings; consideration of the “old wood” and “old charcoal” factors is important.

The Macy Site (14RY38): A Multi-Component Early Ceramic Occupation in Northeastern Kansas

Salvage excavations were conducted at the Macy site (14RY38), a multi-component campsite on a terrace remnant of an unnamed second-order stream that drains into the Kansas River near Manhattan, Kansas. Five Early Ceramic (Plains Woodland) cultural components were defined using a variety of data sets. The lower four components date to A.D. 2-654, based on calibrated radiocarbon age determinations, while the upper component is a mix of Early and Middle Ceramic and Euroamerican age materials. The earliest two components represent short-term occupations focused on lithic tool production and maintenance. The later components represent more complex site activities and longer-term occupation. The extensive record of Early Ceramic occupation from this part of northeastern Kansas was largely undated prior to investigations at the Macy site. The age estimates from the site are a first step toward anchoring that occupation in calendar time and providing data needed for studying cultural dynamics and other problems in regional prehistory.

Further Attempts at Dating the Palynological Sequence of the Hula L07 Core, Upper Jordan Valley, Israel

The palynological sequence of the Hula L07 core was previously correlated with the global oxygen isotope stages 3–5, based on a radiocarbon age determination and comparison with other Levantine paleoclimatological curves. An attempt was made to validate this correlation with Th/U dating. Unlike typical European peat, which is acidic, the soil pH of the Hula peat is mildly basic. Not only does this contribute to the oxidation of palynomorphs, but it also helps to preserve the carbonate material that can be a variable mixture of allogenic, endogenic, and authigenic components. Each component may represent a different degree of uranium series disequilibrium. The thorium (232Th) concentrations of the carbonate are low. Total digestion or acid leach of the sample may not always enable the proper correction for initial thorium. The dating derived from a NaOH-extraction of the organic material, while giving apparently better ages, also suffers from the presence of the carbonate admixture. It appears that, while 14C dating can be considered suitable for the younger portions of the core, techniques based upon the U-series may not be as efficacious in dating this important record of climatic change.

Preliminary Estimate of the Reservoir Age in the Lagoon of Venice

The Lagoon of Venice was formed about 6000 years ago due to the marine transgression associated with the late Pleistocene sea level rise. Already by the time of the Republic of Venice (727–1797 AD) it was recognized that the future of the city and its many historical buildings was strongly correlated with the future of the lagoon itself. During the centuries many engineering projects such as modification of the fluvial systems, construction of coastal barriers, and dredging of navigation channels were carried out to preserve the lagoonal environment. The present-day lagoon is the result of all these processes and covers an area of 540 km2 with an average depth of 0.6 m. A series of radiocarbon age determinations carried out on material obtained from cores collected in the Lagoon of Venice indicate within the sedimentary units the existence of a number of discontinuities and slumping events due to the highly active lagoonal environment. The evaluation of data obtained from a variety of different materials—both terrestrial and marine—allowed us to determine for the first time the marine reservoir effect in the lagoon of Venice. The discussion includes a comparison with other relevant measurements and a possible explanation to the relatively high reservoir age (1200–1300 yr).

Estimation of Inbuilt Age in Radiocarbon Ages of Soil Charcoal for Fire History Studies

Radiocarbon age determinations of wood charcoal are commonly used to date past forest fire events, even though such ages should be greater than the fire event due to the age of the wood at the time of burning. The difference in the14C-derived age of charcoal and the time-since-fire (the “inbuilt age”) may be considerable in some vegetation types and thus must be estimated before interpreting fire dates. Two methods were used to estimate the potential range of inbuilt age of soil charcoal dated to determine ages of forest fires on the west coast of Vancouver Island (Canada). First, 2614C ages on charcoal in surficial soil were compared directly with ages of forest fire determined by tree-ring counts, suggesting inbuilt ages of 0–670 years. Second, a simulation model that uses estimated fuel loads, fuel consumption, charcoal production, and the ages of charred wood (time since wood formation), suggests that the combination of slow growth rates and slow decay rates of certain species can account for inbuilt ages of more than 400 years in this forest type. This level of inbuilt age is large enough such that the actual age of a fire may not occur within the 2σ confidence interval of a calibrated charcoal14C age determination, and thus significantly affect the interpretation of fire dates. A method is presented to combine the error of a calibrated14C age determination with the error due to inbuilt age such that the larger adjusted error encompasses the actual age of the fire.

Radiocarbon Dating of Porewater – Correction for Diffusion and Diagenetic Processes

Two simple algorithms are suggested here to correct for the effect of diffusion and diagenetic sulfate reduction on radiocarbon age determination of marine porewater. The correction algorithms were developed from mass balances of sulfate, dissolved inorganic carbon (DIC), and 14C of the DIC (14CDIC) in vertical concentrations profiles in porewater starting from the sediment water interface. The algorithms were tested on data collected during our recent study of sediment porewaters extracted from the deep Eastern Mediterranean. The real ages of these porewaters varied from present (top of the core) to approximately 30 ka BP (bottom of the core) covering most of the dynamic range of the 14C method (approximately 5 half lives). These ages were markedly older than the ages calculated from 14CDIC analyses by the regular age equation.It is clearly demonstrated that in this case the correction of the apparent age for diffusion across the sediment/water interface is overwhelmingly larger than the correction for the effect of sulfate reduction. The correction for the effect of 14C diffusion alone results in a perfect match between the calculated apparent 14C ages and the real ages of porewater and therefore is the preferred algorithm for correcting apparent ages of porewater.

Radiocarbon Dating of the Iron Age Sequence in the Limpopo Valley

Some of the points that need to be considered with respect to radiocarbon age determinations and their calibration to produce historical dates are reviewed. Based on these considerations, a procedure is proposed that allows sets of radiocarbon dates for four key sites in the Limpopo Valley to be interpreted in order to understand the historical dating and duration of occupation at these sites. They cover a period between the 10th and 13th centuries and then again a period during the 15th and 16th centuries.

Geomagnetic secular variations over the last 6500 years as recorded by sediments from the lakes of south Argentina

Summary Regional type curves depicting secular variations in declination and inclination through the last 6700 calendar years constructed for southwestern Argentina (about 41°S, 71°30′W) by stacking palaeomagnetic data derived from lake sediment cores are described and analysed. The data consist of records from four lakes which have been previously studied (El Trebol, Brazo Campanario, Moreno and Escondido), and are here integrated. Within-lake correlation was based on magnetic susceptibility (χ) and intensity of the natural remanent magnetization (NRM). Interlake correlation was derived from declination and inclination patterns and a set of radiocarbon age determinations. The secular variation (SV) of the geomagnetic field was studied using spectral analysis and precession analysis of the magnetic vector. The spectrum obtained from spectral analysis of declination (D) and inclination (I) at the same time shows major peaks at periodicities of about 3400, 1600 and 1200 yr for both parameters. In order to test the stability of the periodicities obtained, spectral analysis has been applied to every 3500-yr time span at intervals of 500 yr for both records. Patterns of circularity during the last 6700 yr appear to recur with a near constant interval of about 2000 yr. Both open and closed loops are associated with clockwise and counter-clockwise circularity.

Boulders transport by catastrophic waves along the Ionian coast of Apulia (southern Italy)

Several tracts of the Ionian coast of Apulia (southern Italy) are characterized by large boulders, up to 80 t in weight, scattered some meters above present sea level. The largest boulder is about 80 t in weight and slid for about 40 m from the mean sea level up to about 1.8 m of altitude. Elongated boulders show a remarkably narrow range of orientation of the long axis as well as of the imbrication axis, suggesting that they had been transported by a single catastrophic event, most likely a tsunami, connected to a wave train approaching the coast from the South. Stratigraphic, morphological and historical data suggest that this event occurred during the late Holocene. Conventional radiocarbon age determination performed on Lithophag shells collected from a large boulder yielded a calibrated age between 1421 and 1568 A.D. Then, the catastrophic wave train, probably a tsunami, could be a local effect of the strong earthquake which hit southern Italy on December 5th, 1456.

Chronology and geochemistry of late Holocene eolian deposits in the Brandon Sand Hills, Manitoba, Canada

Abstract Accelerator mass spectrometry and conventional radiocarbon age determinations of organic matter from paleosols indicate that the Brandon Sand Hills area of southern Manitoba has been subjected to recurrent intervals of eolian activity in the past 5000 years. Although precise regional correlations are precluded by dating uncertainties, periods of most notable paleosol development occurred around 2300 to 2000, 1400 to 1000, and 600 to 500 cal yr BP with eolian activity occurring before and after each of these periods. Episodes of eolian activity may correspond to periods of regional drought, whereas paleosols mark periods of increased moisture availability and stabilization by vegetation. The geochemistry of the eolian sands, paleosols and source sediments indicates that partial leaching of carbonates occurs from pedogenesis during humid climatic phases, and that this is probably the primary mechanism of carbonate depletion of eolian sands in this area. Recent trends in sand dune activity from historic aerial photography and early explorers’ accounts indicate that the few active dunes that presently exist have stabilized at a rate of 10–20% per decade, despite several severe droughts in the 20th century. This may be attributed to pre-settlement droughts that were more severe than those in historic times although regional dune stabilization may also be related, in part, to the spread of forest cover in the past few hundred years.

Radiocarbon age determinations of peat and wood samples from mount fulufjället, dalarna, sweden

During the investigation of the erosional effects of the rainstorm on 30‐31 August 1997 on Mount Fulufjället, two samples have been radiocarbon age determined. The results give a maximum age of events occurring earlier. One sample of an exposed Picea trunk in the sandur of the stream St Göljån was radiocarbon dated to 1320±120 14C years BP. The lowermost part of a peat sequence in a soligenous mire in the valley of the stream Tangån was radiocarbon dated to 1455±70 14C years.

Radiocarbon Age Determinations of Peat and Wood Samples from Mount Fulufjallet, Dalarna, Sweden

Radiocarbon Age Determinations of Peat and Wood Samples from Mount Fulufjallet, Dalarna, Sweden

Atolls as settlement landscapes: Ujae, Marshall Islands

Williamson and Sabath (1982) have demonstrated a significant relationship between modern population size and environment by examining atoll area and rainfall in the Marshall Islands. The present work seeks to extend that argument into prehistory by examining the relationship of ancient habitation sites and size of aroid pit argricultural systems to atoll land area and rainfall regime along the 1,500-3,500 mm precipitation gradient in the Marshall Islands. Four atolls were selected for study: Ebon at the wettest extent in the extreme south; Ujae and Maloelap near the center of the archipelago; and Utrok at the dry north. The first phase of this long-term archaeological program is reported. During the survey of Ujae Atoll (98°05'N, 165°40'E), three habitation sites, an aroid pit agricultural zone, one early historic burial, and seven fish traps, weirs, and enclosures were recorded. Along with excavations at two habitation sites (8m total area), 35 traditional artifacts were recovered (shell adzes, ornaments, and manufacturing tools). Seven radiocarbon age determinations document land use beginning as early as the third century A.D.A beachrock sample dated to 2450±70 BP relates to atoll development. Some 4,748 bones of fish, birds, turtles, Pacific rats, lizards, humands, and possible cetaceans, along with nearly 13 kg of shellfish, provide the basis for understanding prehistoric subsistence, human adaptations to the atoll setting, and land use patterns.

The Context of Early Southeastern Prehistoric Cave Art: A Report on the Archaeology of 3rd Unnamed Cave

In the deep recesses of “3rd Unnamed Cave,” a karst cavern in Tennessee, evidence for an ancient association between dark zone cave art and chert mining has recently been documented. The art comprises petroglyphs on the ceiling of a chamber more than 1 km from the cave entrance. On the floor below the art, natural sediments were excavated prehistorically to obtain high-quality chert nodules. Radiocarbon age determinations place the mining during the Terminal Archaic period. Studies in lithic technology, geoarchaeology, and petroglyph description are presented.

Age and origin of tephras recorded in postglacial lake sediments to the west of the southern Andes, 44°S to 47°S

Tephra deposits preserved in lake sediments to the west of the Andes, between 44° and 47°S in southern Chile, provide a record of local postglacial eruption history. A series of 32 tephra layers in the sediments of eight small lakes in the study area have been investigated by mineral magnetic analysis, electron microprobe analysis and radiocarbon age determinations. Comparisons with geochemical data from other volcanic sources in southern Chile indicate that Hudson volcano is the most likely source vent for at least seven of the tephra layers found in Chonos–Taitao lake sediments. The seven tephra eruptions that have been identified from widespread and identical tephra deposits, date to 14 560, 13 890, 11 060, 7540, 3840, 2740, and 1560 calendar years ago. The frequency of Hudson volcano eruptions in which tephra is dispersed in both a westerly and easterly direction, similar to that recorded in 1991 from Hudson volcano, may be around 1 per 3800 calendar years during the postglacial period.

Palaeoecological investigations of middle and late Flandrian buried peats on the Caldicot Levels, Severn Estuary, Wales

Pollen, plant macrofossil, coleopteran, diatom and molluscan data, along with a suite of radiocarbon dates, are described from two middle to late Flandrian peat sequences (Vurlong Reen and Barland's Farm) that are buried beneath estuarine and/or marine sediments on the Caldicot Levels, southeast Wales. Radiocarbon age determinations on the basal pears indicate that these began to form following marine regression late in the seventh or early in the sixth millennium BP (measured in conventional 14 C years). The alder fen or carr that subsequently developed in this near-coastal environment was succeeded at Barland's Farm around 5000 14 C years BP by raised bog, and at Vurlong Reen at c. 4000 14 C years BP by sedge fen. There are indications of possible human activity at Vurlong Reen during the Neolithic, and at both sites throughout the Bronze Age. The present 'cultural landscape' of this part of South Wales appears to have been established by the middle to later Bronze Age. Marine transgression, beginning early in the third millennium BP and culminating, perhaps, some time after 2500 I4 C years BP, resulted in the inundation of the coastal mires and burial of the peats beneath several metres of estuarine silt and clay.

Norse settlement of Iceland — close to ad 700?

Radiocarbon age determination in the 1970s of some 40 archaeological samples strongly indicates a Norse settlement (landnam) in both Reykjavik and the Westman Islands, Iceland, at about AD 700. This early date has generally been rejected by Icelandic scientists because it contradicts the firmly established dating of the settlement (landnam) at about AD 870. In the present article a critical search for an error in the radiocarbon dating work resulted in no weakness being found in the dating material. The history of the landnam of Iceland is thus caught in a dilemma, one which also affects the history of neighbouring countries. A necessary programme for extensive and more precise radiocarbon dating and a critical re‐evaluation of arguments for the conventional date of settlement are outlined.

Marine reservoir corrections for bowhead whale radiocarbon age determinations

Twenty-two pairs of radiocarbon dates on driftwood and bowhead whale (Balaena mysticetus) bones from raised beaches, dates on whale bone and terrestrial plant detritus from a stratigraphie section, and 25 additional dates on whale bones from the lowest (≤1 ka BP) raised beaches in the eastern Canadian Arctic suggest that a marine reservoir correction of about −200 years is appropriate for normalized age determinations on bone collagen from the bowhead whale in this region. This is less than the correction (−400 years) normally applied to carbonate shells of marine molluscs from this region. The carbon in bowhead collagen appears to be derived from the whales' zooplankton food rather than from marine bicarbonate.