• Apparent 14C Ages of Marine Mollusk Shells from a Greek Island: Calculation of the Marine Reservoir Effect in the Aegean Sea

      Facorellis, Yorgos; Maniatis, Yannis; Kromer, Bernd (Department of Geosciences, The University of Arizona, 1998-01-01)
      The excavation of the Cyclope cave, situated on the deserted island of Youra in the Northern Sporades (39 degrees 22'N, 24 degrees 10'E), revealed material of marine and terrestrial origin in undisturbed layers, suitable for radiocarbon dating. In some cases, material from different reservoirs was found together in the same archaeological layer. This research had two aims. The first was the dating of charcoal-seashell pairs in order to determine the marine reservoir effect in this region, based on samples with ages spanning from the end of the 8th millennium to the beginning of the 7th millennium BC. The second aim was dating the stratigraphy of this site, by using the calculated Delta-R value in conjunction with the marine calibration curve. This enabled the accurate calibration of the 14C ages of marine samples found in layers without charcoal pieces. The results show that this is the oldest human settlement ever found on an island in the Aegean Sea.
    • Interpreting Radiocarbon Dates from Neolithic Halai, Greece

      Facorellis, Yorgos; Coleman, John E. (Department of Geosciences, The University of Arizona, 2012-10-15)
      Archaeological investigations at Halai, a small city-state on the sea coast of East Lokris in Greece, have been carried out since 1986 by the Cornell Halai and East Lokris Project (CHELP). The town’s acropolis, first inhabited in the Neolithic period, was in Greco-Roman times a political and cultural center controlling and serving a considerable territory. Radiocarbon dating of charred material unearthed from Neolithic deposits indicate that the Neolithic occupation probably lasted from about 6000 to 5300 BC. Details of dating are somewhat problematic, however, because of outlying determinations and lack of close agreement between determinations from the same or stratigraphically comparable material.
    • Locating Archaeological Horizons with 14C Sediment Dating: The Case of the Lost City of Helike

      Maniatis, Yannis; Facorellis, Yorgos; Soter, Steven; Katsonopoulou, Dora; Kromer, Bernd (Department of Geosciences, The University of Arizona, 1995-01-01)
      In 373 BC a catastrophic earthquake and seismic sea wave destroyed Helike, a Greek city near Aigion on the southern shore of the Gulf of Corinth. The ruins were buried by sediments of unknown depth, leaving no trace of the city. We here discuss the radiocarbon dating of organic sediment samples recovered from seven boreholes drilled on the coastal plain in the area where ancient sources located Helike. Most of the samples apparently acquired a substantial addition of older carbon from natural sources, and hence their apparent ages are older than the true ages of sedimentation. However, if we assume that the addition is systematic, we can use the apparent ages to show that the sedimentation rate was initially rapid (about 1 cm yr-1) for the strata between 40 and 10 m below the surface, and then decreased by an order of magnitude about 6500 yr ago. A related change in the sediment deposition at about the same time has been found in many other marine deltas throughout the world, probably due to the deceleration of the global sea-level rise. We conclude that in the boreholes sampled by the present data, the horizon corresponding to ancient Helike is less than 8 m deep.
    • Study of the Parameters Affecting the Correlation of Background Versus Cosmic Radiation in CO2 Counters: Reliability of Dating Results

      Facorellis, Yorgos; Maniatis, Yannis; Kromer, Bernd (Department of Geosciences, The University of Arizona, 1997-01-01)
      Systematic treatment of the data recorded by our guard counters and corrections introduced for meteorological factors has allowed observations on solar events clearly manifested in the readings. Examples are the solar flares of March 1989 and especially of June 1991, which caused a ca. 10% decrease in the cosmic radiation flux reaching the counters. A sinusoidal variation in the cosmic-ray flux with a period of one year is also clearly manifested in the data. The observation that the background in the 14C measurements depends on the intensity of the cosmic radiation has led to the use of monthly correlations for the determination of the best background value to be used in the age calculations. This reduces the error significantly. However, various factors such as random statistical fluctuations of the background measurements may affect the slope of the correlations and consequently the calculated age of the samples. Long-term observations of the relation between background values and coincidence counts have led to constraints in the slope of the correlation. A simple extension of the fitting procedure is explored, which maintains the physically meaningful range of the slopes, but is flexible to adjust for the seasonally varying contributions to the variations of the cosmic-ray flux.
    • The Cave of Theopetra, Kalambaka: Radiocarbon Evidence for 50,000 Years of Human Presence

      Facorellis, Yorgos; Kyparissi, Apostolika Nina; Maniatis, Yannis (Department of Geosciences, The University of Arizona, 2001-01-01)
      The cave of Theopetra is located on the northeast side of a limestone rock formation, 3 km south of Kalambaka (21 degrees 40'46"E, 39 degrees 40'51"N), in Thessaly, central Greece. It is a unique prehistoric site for Greece, as the Middle and Upper Paleolithic, Mesolithic, and Neolithic periods are present here, bridging the Pleistocene with the Holocene. Several alternations of the climate during the Pleistocene are recognized in its stratigraphy. Among the most striking finds, two human skeletons, one from the Upper Paleolithic period after the Last Glacial Maximum and one from the Mesolithic period, should be emphasized, while in a deep Middle Paleolithic layer, the oldest human footprints, with remains of fire, were uncovered. During the 13 years of excavation, evidence of human activity suitable for radiocarbon dating was collected, such as charcoal samples from hearths and bones from the two human skeletons. The use of proportional counters for the measurement of 14C in combination with the recent improvement of the calibration curve has enabled the production of high-precision reliable ages Sixty 14C-dated samples, originating from 19 pits and from depths ranging from 0.10 m to 4.20 m, have already provided an absolute time framework for the use of the cave. The earliest limit of human presence probably exceeds 48,000 BP and the latest reaches World War II. Within these limits the 14C dating of samples from consecutive layers, in combination with the archaeological data, permits the resolution of successive anthropogenic and environmental events.