THE ASSESSMENT OF ERROR LIMITS IN THERMOLUMINESCENT DATING

This paper discusses known sources of error, both random and systematic; suggests quantitative limits; and proposes a consistent method for compounding them to yield an overall error in age, both for individual sherds and for the weighted average of a number of sherds from the same context. It is proposed that two error limits should be quoted for the date of a context: first, the standard error of the mean value as calculated from the experimentally observed root-mean-square deviation of the individual samples, and secondly, the expected overall error from the sources discussed in the paper. The former can be considered as a lower limit and relevant when comparing contexts on the same or similar sites whereas the latter is more realistic when comparing TL dates with radiocarbon or archaeologic chronology.     

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: 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.     

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.     

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.     

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.     

USE OF A WIRE SAW FOR SLICING CERTAIN SAMPLE MATERIALS FOR THERMOLUMINESCENT DATING

A method is described for obtaining accurate thin slices for thermoluminescence measurement of uniform materials, in particular burnt flint, which does not subject these materials to heat during the cutting process. Cutting is by means of a fine wire impregnated with diamond grit and gives a high standard of surface finish such that very little further preparation is needed. Thus, by the use of this method, there is a considerable saving in time as well as minimal risk of damage to the TL record of the materials during sampling.     

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.     

THE PRE-DOSE TECHNIQUE: A NEW THERMO-LUMINESCENT DATING METHOD

A thermoluminescent (TL) glow-curve peak occurs around 110°C for the mineral quartz. Its sensitivity may be changed by application of a radiation dose (termed the pre-dose) followed by a heating of the quartz to 500°C: heating alone causes no sensitivity change. The enhancement observed (measured relative to the sensitivity of the peak prior to heating) is a measure of the magnitude of the pre-dose. For quartz extracted from pottery the sensitivity enhancement induced by laboratory heating records a natural pre-dose, i.e. the accumulated dose experienced during archaeological burial. The latter quantity is used in TL age-determination and a test programme is reported on the application of the pre-dose dating method to sites covering the Roman era in Britain forward to modern times.