• Extension of the Holocene Dendrochronology by the Preboreal Pine Series, 8800 to 10,100 BP

      Becker, Bernd; Kromer, Bernd (American Journal of Science, 1986-01-01)
      Holocene tree-ring chronologies have been established for south-central Europe covering the past 11,000 years. The Hohenheim absolute oak chronology extends to 4089 BC. The 14C-calibrated mid-Holocene floating oak master covers a 3181-year period from ca 4045 to 7225 BC. The earliest well-replicated floating oak master (estimated calendar age 7215 to 7825 BC) extends the European oak dendrochronology back to Boreal times. Further extension of the Holocene dendrochronology has been achieved by subfossil oak and pine trees from the Rhine, Main, and Danube Rivers. A 774-year floating series of Preboreal pine has been established. 14C ages range (from younger to older end) from 9200 to 9800 BP. Within this series a major atmospheric 14C variation is indicated, resulting in nearly constant 14C ages (9600 BP) over a period of 370 tree-rings. The European oak and pine tree-ring chronologies cover without major gaps the entire Holocene epoch. Based on the length of the dendro-records, an approximate solar year age of 11,280 years is calculate for the Holocene/Pleistocene boundary. The Preboreal pine forests along the rivers were replaced by mixed oak forests between 9200 and 8800 BP. By linking the earliest oak masters and the Preboreal pine series, the European dendrochronology can be extended up to the end of Late Glacial times.
    • High-Precision 14C Measurement of Irish Oaks to Show the Natural 14C Variations from AD 1840-5210 BC

      Pearson, Gordon W.; Pilcher, J. R.; Baillie, M. G. L.; Corbett, D. M.; Qua, F. (American Journal of Science, 1986-01-01)
      High-precision measurement of dendrochronologically dated Irish oak at bidecade/decade intervals has continued in the Belfast laboratory, extending the 14C data base from ca AD 1840 to 5210 Bc. The dendrochronology is now considered absolute (see Belfast dendrochronology this conference) (Brown et al, 1986) and a continuous detailed curve is presented, showing the natural variations in the atmospheric concentration of 14C over >7000 years. Each data point has a precision of <2.50 per mil, and some 4500 years have now been compared with Seattle, giving excellent agreement. Discussion of this data base and the justification of the claimed accuracy is given together with a comparison of other chronologies. Some of the advantages and limitations of the above are discussed.
    • High-Precision Calibration of the Radiocarbon Time Scale, 3930-3230 Cal BC

      De Jong, A. F. M.; Becker, Bernd; Mook, W. G. (American Journal of Science, 1986-01-01)
    • High-Precision Calibration of the Radiocarbon Time Scale, 500-2500 BC

      Pearson, G. W.; Stuiver, Minze (American Journal of Science, 1986-01-01)
    • High-Precision Calibration of the Radiocarbon Time Scale, AD 1950-500 BC

      Stuiver, Minze; Pearson, Gordon W. (American Journal of Science, 1986-01-01)
    • High-Precision Decadal Calibration of the Radiocarbon Time Scale, AD 1950-2500 BC

      Stuiver, Minze; Becker, Bernd (American Journal of Science, 1986-01-01)
    • High-Precision Radiocarbon Dating of Bristlecone Pine from 6554 to 5350 BC

      Linick, Timothy W.; Long, Austin; Damon, Paul E.; Ferguson, C. Wesley (American Journal of Science, 1986-01-01)
      New results of radiocarbon dating of ca 100 decadal bristlecone pine samples from 6554 to 6084 BC and from 5820 to 5350 BC are presented. Using 3 new 2.5L counters filled to ca 3atm with carbon dioxide, high-precision dating has been performed by this laboratory for more than two years. Demonstration of the precision and accuracy of these counters is presented using +/2 per mil measurements from the Spörer minimum period. For the older samples, +/3 per mil measurements were made using ca 12-day counting times. Results are presented both as 14C age BP vs dendro-year BC, particularly for calibration purposes, and as Delta-14C vs time.
    • Illinois State Geological Survey Radiocarbon Dates IX

      Liu, Chao-Li; Riley, Kerry M.; Coleman, Dennis D. (American Journal of Science, 1986-01-01)
    • Illinois State Geological Survey Radiocarbon Dates VIII

      Liu, Chao-Li; Riley, Kerry M.; Coleman, Dennis D. (American Journal of Science, 1986-01-01)
    • Institut Royal du Patrimoine Artistique Radiocarbon Dates XI

      Dauchot-Dehon, Michele; Van Strydonck, Mark; Heylen, Jon (American Journal of Science, 1986-01-01)
    • Radiocarbon Age Calibration Back to 13,300 Years BP and the 14C Age Matching of the German Oak and US Bristlecone Pine Chronologies

      Stuiver, Minze; Kromer, Bernd; Becker, Bernd; Ferguson, C. W. (American Journal of Science, 1986-01-01)
    • Radiocarbon Age Calibration of Marine Samples Back to 9000 Cal Yr BP

      Stuiver, Minze; Pearson, Gordon W.; Braziunas, Thomas F. (American Journal of Science, 1986-01-01)
    • Radiocarbon Fluctuations During the Third Millennium BC

      Vogel, J. C.; Fuls, Annemarie; Visser, Ebbie; Becker, Bernd (American Journal of Science, 1986-01-01)
      Precision 14C analyses have been performed on samples comprising 1 to 4 annual rings from the south-central European dendrochronologic sequence of sub-fossil oak wood covering the period 1930 to 3100 BC. Apart from a ajor deviation in the 29th century BC, the 14C fluctuations have amplitudes of ca 10 per mil and a possible periodicity of 90 years. A 14C peak at 2190 BC has a riseand decay-time of <20 years indicating rather abrupt changes in the production rate of 14C. The 14C calibration curve derived from these data can be used for precise dating of the Early Bronze Age in the Near East.
    • Secular Variations of Cosmogenic 14C on Earth: Their Discovery and Interpretation

      Suess, Hans E. (American Journal of Science, 1986-01-01)
      Measurement of 14C in samples of wood of precisely known age have shown that the cosmogenic 14C content of the CO2 in the atmosphere has not remained constant during the period of time covered by radiocarbon dating. As the terrestrial atmosphere mixes with a time constant of less than 3 years, these variations must be essentially independent of geographic location. The 14C in atmospheric CO2 must be a quantity that, at a given time, pertains to the terrestrial atmosphere as a whole. Not only is its knowledge necessary for deriving accurate radiocarbon dates, but it is also valuable in connection with many geophysical and astrophysical problems. Unfortunately, progress in our knowledge of 14C variations in the terrestrial atmosphere has been delayed by hidden experimental errors in results obtained by many laboratories. By rigorous statistical analysis of the La Jolla results, it is now possible to show that the 14C variations are not simple random fluctuations but show distinct regularities. Similar patterns of variations have been found in the growth rate of trees during the last 5000 years. Measurements of radiogenic 10Be currently being done by European workers promise to conclusively elucidate the 14C findings.
    • Trends of 13C/12C Ratios in Pinyon Tree Rings of the American Southwest and the Global Carbon Cycle

      Leavitt, S. W.; Long, Austin (American Journal of Science, 1986-01-01)
      An accurate atmospheric 13C/12C chronology can provide important constraints to models of the global carbon cycle. Trees accumulate carbon from atmospheric CO2 into growth rings and offer potential for 13C/12C reconstructions, but results have not been reproducible. This paper presents 5 degree C curves from 5 sites, representing 20 pinyon (Pinus edulis) trees, where cores of 4 trees from each site have been pooled into a composite sample. Isotopic analysis of cellulose in 5-yr ring groups produces curves with a general trend of decreasing 5 degree C after 1800, but with pronounced short-term fluctuations superimposed upon the trend. Evidence indicates the fluctuations are strongly related to moisture availability (drought). A mean curve of the 5 delta-13C chronologies from which the fossil-fuel component is subtracted suggests a substantial biospheric CO2 contribution to the atmosphere since 1800.
    • University of Granada Radiocarbon Dates III

      Gonzalez-Gomez, Celilio; Sanchez-Sanchez, Purificacion; Villafranca-Sanchez, Elena (American Journal of Science, 1986-01-01)
    • University of Lund Radiocarbon Dates XIX

      Håkansson, Sören (American Journal of Science, 1986-01-01)
    • University of Lund Radiocarbon Dates XVIII

      Håkansson, Sören (American Journal of Science, 1986-01-01)