Pumice from thera (santorini) identified from a greek mainland archeological excavation

Pumice fragments recovered from an archeological excavation on the Greek mainland have been correlated by means of index of refraction measurements with the Late Bronze Age volcanic eruption on the island of Thera (Santorini) in the Aegean Sea. Pottery from the strata containing the pumice dates from the 15th century B.C.     

Santorini eruption radiocarbon dated to 1627-1600 B.C

Precise and direct dating of the Minoan eruption of Santorini (Thera) in Greece, a global Bronze Age time marker, has been made possible by the unique find of an olive tree, buried alive in life position by the tephra (pumice and ashes) on Santorini. We applied so-called radiocarbon wiggle-matching to a carbon-14 sequence of tree-ring segments to constrain the eruption date to the range 1627-1600 B.C. with 95.4% probability. Our result is in the range of previous, less precise, and less direct results of several scientific dating methods, but it is a century earlier than the date derived from traditional Egyptian chronologies.     

Paleoindians in beringia: evidence from arctic alaska

Excavations at the Mesa site in arctic Alaska provide evidence for a Paleoindian occupation of Beringia, the region adjacent to the Bering Strait. Eleven carbon-14 dates on hearths associated with Paleoindian projectile points place humans at the site between 9,730 and 11,660 radiocarbon years before present (years B.P.). The presence of Paleoindians in Beringia at these times challenges the notion that Paleoindian cultures arose exclusively in mid-continental North America. The age span of Paleoindians at the Mesa site overlaps with dates from two other cultural complexes in interior Alaska. A hiatus in the record of human occupation occurs between 10,300 and 11,000 years B.P. Late Glacial climatic fluctuations may have made northern Alaska temporarily unfavorable for humans and spurred their southward dispersal.     

Atmospheric radiocarbon calibration to 45,000 yr B.P.: late glacial fluctuations and cosmogenic isotope production

More than 250 carbon-14 accelerator mass spectrometry dates of terrestrial macrofossils from annually laminated sediments from Lake Suigetsu (Japan) provide a first atmospheric calibration for almost the total range of the radiocarbon method (45,000 years before the present). The results confirm the (recently revised) floating German pine chronology and are consistent with data from European and marine varved sediments, and combined uranium-thorium and carbon-14 dating of corals up to the Last Glacial Maximum. The data during the Glacial show large fluctuations in the atmospheric carbon-14 content, related to changes in global environment and in cosmogenic isotope production.     

Early archeological evidence for shellfish collecting

Geologic evidence, supported by infinite carbon-14 dates and Middle Stone Age cultural associations, indicates that two open-air shell middens recently found at Sea Harvest and Hoedjies Punt, Saldanha Bay, South Africa, date from the terminal part of the Last Interglacial, about 70,000 to 60,000 years ago. These middens are among the oldest known records for systematic human exploitation of marine resources anywhere in the world. The faunal contents of the middens suggest that the Middle Stone Age people who accumulated them utilized marine resources less intensively than their Later Stone Age successors in similar coastal settings.     

Age determination of burned flint by a thermoluminescent method

Interference by tribothermoluminescence and by regeneration thermoluminescence can be eliminated for burned flint if thin polished slices are used instead of the powders conventionally used in thermoluminescent measurements. Measurement of the internal and external radiation dose rates then makes possible the absolute determination of the date of pyrolization of small fragments of chert or chalcedony to an accuracy of about 10 to 15 percent. The method may be usable to ages in the range from 200,000 to 300,000 years before the present (B.P.). For samples from the archeological site at Carigüela in southern Spain dates from 12,000 to 50,000 years B.P. have been determined, covering deposits ranging from Late Paleolithic-Epipaleolithic to Mousterian. One Bronze Age specimen gave an age of 4,300 years B.P., in excellent agreement with the age determined by other methods.     

Carbon-14 time scale extended: comparison of chronologies

Thermal diffusion isotopic enrichment of carbon-14 has extended the radiocarbon dating range to about 75,000 years ago. Twenty-eight samples obtained up to June 1976, mainly from northwest Europe, were dated. Consideration of the basic assumptions of carbon-14 dating and of the sources of contamination indicates that the ages are generally reliable. Together with the pollen analytic and stratigraphic the dates yield a more detailed radiocarbon time scale for climatic variations in northwest Europe, showing three early glacial interstades. The radiocarbon time scale agrees with the Camp Century chronology and with the thorium-230 ages of corals representing high sea level stands on New Guinea. Ther is a discrepancy between the radiocarbon time scale and the deep-sea chronology, which may be due to correlation errors. With a modified interpretation of the correlation, all four time scales agree within the estimated experimental uncertainties of the dating techniques used.     

Hoabinhian: a pebble-tool complex with early plant associations in southeast Asia

The term "Hoabinhian" has been applied to "mesolithic" assemblages from all parts of mainland Southeast Asia. Recent excavation in north Thailand has yielded the first associated carbon-14 dates and provided evidence for the early (about 7000 B. C.) domestication of plants in Southeast Asia.     

Interhemispheric correlation of late pleistocene glacial events

A radiocarbon chronology shows that piedmont glacier lobes in the Chilean Andes achieved maxima during the last glaciation at 13,900 to 14,890, 21,000, 23,060, 26,940, 29,600, and >/=33,500 carbon-14 years before present ((14)C yr B.P.) in a cold and wet Subantarctic Parkland environment. The last glaciation ended with massive collapse of ice lobes close to 14,000(14)C yr B.P., accompanied by an influx of North Patagonian Rain Forest species. In the Southern Alps of New Zealand, additional glacial maxima are registered at 17,720(14)C yr B.P., and at the beginning of the Younger Dryas at 11,050 (14)C yr B. P. These glacial maxima in mid-latitude mountains rimming the South Pacific were coeval with ice-rafting pulses in the North Atlantic Ocean. Furthermore, the last termination began suddenly and simultaneously in both polar hemispheres before the resumption of the modern mode of deep-water production in the Nordic Seas. Such interhemispheric coupling implies a global atmospheric signal rather than regional climatic changes caused by North Atlantic thermohaline switches or Laurentide ice surges.     

Late Bronze Age glass production at Qantir-Piramesses, Egypt

It has been uncertain whether the glass produced during the Late Bronze Age (LBA) originated in Egypt or Mesopotamia. Here we present evidence for the production of glass from its raw materials in the eastern Nile Delta during the LBA. Glass was made in workshops that were separate from where the production of objects took place. The initial melting of the raw materials to semi-finished glass was done at temperatures of 900 degrees to 950 degrees C, followed by coloration and ingot production at 1000 degrees to 1100 degrees C.     

Banded corals: changes in oceanic carbon-14 during the little ice age

Radiocarbon analyses and stable isotope measurements are presented foro recent cores of banded corals from the Florida Straits. These values provide a record of variations in the ratio of carbon-14 to carbon-12 in the dissolved inorganic carbon in the surface waters of the Gulf Stream from A.D. 1642 to 1800. An increase in the carbon-14/carbon-12 ratio of 7 per mil for coral growth during the early 1700's was most likely induced by an increase in the carbon-14/carbon-12 ratio of 20 per mil in the atmospheric carbon dioxide that occurred at about 1700. The ratios of oxygen 18 to oxygen-16 in these coral bands show a small decrease of a water temperature ( approximately 1 degrees C) during the latter part of the Little Ice Age (1700 to 1725). These results support the hypothesis that the increase in atmospheric carbon-14 at about 1700, and possibly the temperature change as well, was caused by a decrease in solar activity (Maunder sunspot minimum).     

Application of carbon isotope stratigraphy to late miocene shallow marine sediments, new zealand

A distinct (0.5 per mil) carbon-13/carbon-12 isotopic shift in the light direction has been identified in a shallow marine sedimentary sequence of Late Miocene age at Blind River, New Zealand, and correlated with a similar shift in Late Miocene Deep Sea Drilling Project sequences throughout the Indo-Pacific. A dated piston core provides an age for the shift of 6.2 +/- 0.1 million years. Correlations based on the carbon isotopic change require a revision of the previously established magnetostratigraphy at Blind River. The carbon shift at Blind River occurs between 6.2 and 6.3 +/- 0.1 million years before present. A new chronology provides an age for the evolutionary first appearance datum of Globorotalia conomiozea at 6.1 +/- 0.1 million years, the beginning of a distinct latest Miocene cooling event associated with the Kapitean stage at 6.2 +/- 0.1 million years, and the beginning of a distinct shallowing of water depths at 6.1 +/- 0.1 million years. The Miocene-Pliocene boundary as recognized in New Zealand is now dated at 5.3 +/- 0.1 million years. Extension of carbon isotope stratigraphy to other shallow Late Miocene sequences should provide an important datum for international correlation of Late Miocene shallow and deep marine sequences.     

Variation in atmospheric carbon-14 activity relative to a sunspot-auroral solar index

Radiocarbon activity was negatively correlated (P相似文献   

Bronze age copper sources in the mediterranean: a new approach

Efforts by scientists to locate the sources of copper used in ancient Mediterranean and Near Eastern cultures through comparative chemical analyses of copper ores and archeological artifacts have largely failed for various mineralogical and metallurgical reasons. The isotopic composition of lead, an element present in a minor amount in many copper ores and bronze objects, is unchanged through metallurgical processes and may in principle be used to determine the sources of the copper used in Bronze Age artifacts. Results suggest that for Late Bronze Age Crete the Laurion region in Attica, Greece, may have been a more important copper source than Cyprus.     

Stem rust of wheat 3300 years old found in Israel

A fungus parasite observed on two ancient lemma fragments of wheat was identified as Puccinia graminis. The fragments were found in a storage jar from the Late Bronze Age excavated at Tel Batash, Israel, Uredia, hyphae, and germinating uredospores, though charred, were well preserved.     

Late colonization of Easter Island

Easter Island (Rapa Nui) provides a model of human-induced environmental degradation. A reliable chronology is central to understanding the cultural, ecological, and demographic processes involved. Radiocarbon dates for the earliest stratigraphic layers at Anakena, Easter Island, and analysis of previous radiocarbon dates imply that the island was colonized late, about 1200 A.D. Substantial ecological impacts and major cultural investments in monumental architecture and statuary thus began soon after initial settlement.     

Radiocarbon Dating: Fictitious Results with Mollusk Shells

Evidence is presented to show that modern mollusk shells from rivers can have anomalous radiocarbon ages, owing mainly to incorporation of inactive (carbon-14-deficient) carbon from humus, probably through the food web, as well as by the pathway of carbon dioxide from humus decay. The resultant effect, in addition to the variable contributions of atmospheric carbon dioxide, fermentative carbon dioxide from bottom muds, and, locally, of carbonate carbon from dissolving limestones, makes the initial carbon-14-activity of ancient fresh-water shell indeterminate, but within limits. Consequent errors of shell radiocarbon dates may be as large as several thousand years for river shells.     

Single-Crystal 40Ar/39Ar Dating of the Eocene-Oligocene Transition in North America

Explanations for the causes of climatic changes and associated faunal and floral extinctions at the close of the Eocene Epoch have long been controversial because of, in part, uncertainties in correlation and dating of global events. New single-crystal laser fusion (SCLF) (40)Ar/(39)Ar dates on tephra from key magnetostratigraphic and fossilbearing sections necessitate significant revision in North American late Paleogene chronology. The Chadronian-Orellan North American Land Mammal "Age" boundary, as a result, is shifted from 32.4 to 34.0 Ma (million years ago), the Orellan-Whitneyan boundary is shifted from 30.8 to 32.0 Ma, and the Whitneyan-Arikareean boundary is now approximately 29.0 Ma. The new dates shift the correlation of Chron C12R from the Chadronian to within the Orellan-Whitneyan interval, the Chadronian becomes late Eocene in age, and the North American Oligocene is restricted to the Orellan, Whitneyan, and early Arikareean. The Eocene-Oligocene boundary, and its associated climate change and extinction events, as a result, correlates with the Chadronian-Orellan boundary, not the Duchesnean-Chadronian boundary.