THERMOLUMINESCENT DATING: ASSESSMENT OF ALPHA PARTICLE CONTRIBUTION

A new system for specifying alpha source strength, in terms of track length per unit volume of sample, is proposed. It is based on the experimental observation that the TL induced per unit length of track is essentially independent of alpha particle energy. The new system avoids the need to make assumptions about sampple stopping power and it is shown to be consonant with the old system as long as up-to-date evaluation of alpha ranges is used. A revised table of dose-rate data is given.     

THE SUBTRACTION TECHNIQUE OF THERMOLUMINESCENT DATING

Combination of the routine approaches of thermoluminescence dating, the fine-grain and inclusion methods, allows an age to be determined that is independent of knowledge of the environmental dose-rate. This socalled subtraction technique is exampled by several terracottas of museum origin and some pottery collected from archaeological contexts without associated burial media. Age determination is estimated to have an accuracy of around ± 12%, in favourable conditions.     

THERMOLUMINESCENT DATING OF COLOMBIAN POTTERY IN THE YOTOCO STYLE

Two contexts from the Colombian sites, Yotoco Ferry and Moralba, had been linked by archaeological similarities in pottery style, and dated by association with ware from other sites at circaa.d. 1000. However, radiocarbon dating of those contexts set Moralba at circa 800 b.c. , some 2000 yr older than Yotoco Ferry. Thermoluminescent dating of pottery from Yotoco Ferry dated it at circaa.d. 900, and pottery from Moralba was dated at circaa.d. 870. In addition a metal-smelting pottery crucible, thought to be prehispanic, was studied by thermoluminescence and dated, on the contrary, at less than 120 yr old.     

THERMOLUMINESCENT DATING OF BAKED CLAY BALLS OF THE POVERTY POINT CULTURE

Seven sites in Mississippi, Louisiana and Arkansas have been dated. For six sites (Terral Lewis, Poverty Point, Jaketown, Teoc Creek, Shoe Bayou, and Claiborne) the results are not inconsistent with contemporaneity; excluding Claiborne the average date is 1000 b.c. , with an error limit in absolute terms of ± 200 years. The seventh site (Loggy Bayou), in which sherds and balls were found in association, gave a date some fifteen hundred years more recent.     

THERMOLUMINESCENT AUTHENTICITY STUDY AND DATING OF RENAISSANCE TERRACOTTAS

A comparative study is made of the thermoluminescence (TL) of terracottas of the Renaissance era and some known limitations of such ware dating to the middle of the last century. The data shows that conclusions on authenticity of an unknown work can be reliably obtained using this scientific method. Also examples are presented of accurate dating of genuine terracottas despite a lack of knowledge about the environmental circumstances of each piece's archaeological past.     

THERMOLUMINESCENT DATING OF NEOLITHIC AND CHALCOLITHIC POTTERY FROM SITES IN CENTRAL PORTUGAL

Samples of Neolithic and Chalcolithic pottery from nine sites in the Upper Alentejo and Estremadura regions of Portugal have been dated by the thermoluminescence method (quartz inclusion technique). The project was designed to help establish an absolute chronology for the Neolithic and Chalcolithic periods in this area, and to try to elucidate the chronological relationships between settlement sites and burial sites (‘dolmens’) in the same area. Portugal was confirmed, together with Brittany, as being one of the earliest foci of megalith builders.     

RADIOCARBON DATING BY THERMOLUMINESCENT DOSIMETRY

Work is presented that tests the possibility of performing radiocarbon dating measurements by using the thermoluminescence induced in sensitive phosphors, using existing thermoluminescence equipment. It is concluded that, for such a technique to be viable, a more specifically designed, and more elaborate, system will be necessary. Some comparative results on certain TLD phosphors are also given.     

THE ASSESSMENT OF RADIONUCLIDE DISTRIBUTION IN SILEX BY AUTORADIOGRAPHY IN THE CONTEXT OF DOSE RATE DETERMINATION FOR THERMOLUMINESCENCE DATING

A combination of two autoradiography methods was applied to investigate the radionuclide distribution patterns in a range of different silices. We obtained greyscale images (β‐radiation) and α‐track patterns for qualitative assessment, and used a statistical approach to quantify the degree of uniformity of the radiation fields. It was found that almost all samples are poor in potassium, thorium and uranium, and that locally high concentrations are present only in dark‐coloured veins and inclusions. Statistical analyses reveal evidence of radionuclide clustering in more than half of the 21 specimens. Concerning thermoluminescence dating of burnt lithics, such gradients should be taken into account to improve precision and accuracy in cases where the external radiation is not strongly dominating for the sample under consideration.     

THERMOLUMINESCENT DATING OF EGYPTIAN PREDYNASTIC POTTERY FROM HEMAMIEH AND QURNA-TARIF

Eight sherds from Hemamieh and two from Qurna-Tarif, both Predynastic settlement sites in the Nile valley, have been dated by the thermoluminescence method (quartz inclusion technique). The results put the Badarian phase at Hemamieh in the sixth and fifth millenium b.c. , and the Gerzean phase in the first half of the fourth millenium b.c. The dates for the village of Qurna-Tarif fall around 4000 b.c.     

THERMOLUMINESCENT DATING OF FIRED ROCK-CRYSTAL FROM BELLAN BANDI PALASSA,CEYLON

Fired rock-crystal was found within the matrix of a Balangodese (pre-Vedda) burial in a Mesolithic midden in Ceylon; thermoluminescent measurements indicated a date of about 7000 years before present.