Calcareous tufa from five sites in southern Poland, representing several most typical conditions of tufa sedimentation, were chosen for 14C, 13C, and 18O measurements. These tufas were deposited in a high-energy turbulent stream (the Racławka site), in streams with moderate but variable flow (Rzerzuśnia and Trzebienice), and in semilimnic conditions (Sieradowice site). Sediments of the Gliczarów site represent spring travertines. In all but the latter site, direct comparison of 14C dates of carbonate and organic fractions was possible, leading to an estimate of initial apparent age of carbonate sediments. Clear correlation was found between the value of initial apparent age of tufas and the hydrodynamic conditions of sedimentation. Corresponding values range from ca 3900 yr (Racławka) to 910 yr for semilimnic sediments (Sieradowice). Intermediate, almost identical values, equal to 2460 ± 200 yr and 2100 ± 160 yr, were obtained for tufas from Rzerzuśnia and Trzebienice, respectively. Detailed sedimentologic classification of tufaceous deposits is presented and some primary and secondary factors affecting the accuracy of radiocarbon dates of various types of tufas are also discussed.

Small sample 14C dating is tested using conventional as well as high-resolution low-level liquid scintillation (LS) spectrometers. Contrasted are the results obtained dating ∼25, 125 and 250mg of elemental carbon in standard size counting vials (3mL) and 0.3mL teflon and quartz vials. It is demonstrated that the improved performance of the 0.3mL counting vials enables just adequate resolution of 25mg and very good resolution of 100mg carbon samples both at Modern and Old age limits when the determination is made in a high-resolution low-level LS spectrometer.

A method is given for modifying the estimated radiocarbon dates of two samples when they are known to be in the wrong order.

Three decades of archaeological excavations in Melanesia and Western Polynesia have led to a consensus among Oceanic prehistorians that the initial human colonization of the southwestern Pacific (east of the Solomons) was effected by populations of the Lapita Cultural Complex (Green, 1979; Kirch, 1982, 1984; Allen, 1984; Spriggs, 1984). Although the western Melanesian islands of New Guinea, the Bismarck Archipelago, and possibly the Solomon Islands were settled in the late Pleistocene by small hunter-gatherer populations (Downie & White, 1979; Specht, Lilley & Normu, 1981; Groube et al, 1986), discovery and occupation by humans of the more remote island chains to the east required sophisticated voyaging and colonization strategies. That the Austronesian-speaking Lapita people possessed long-distance voyaging craft is suggested both by lexical reconstructions, and by the archaeological evidence of long-distance transport of obsidian and other exotic materials over distances of up to 3700km (Ambrose & Green, 1972; Best, 1987). Lapita sites are marked by a distinctive complex of dentate-stamped earthenware ceramics, and associated shell, bone, and stone artifacts. Sites yielding such assemblages have been recorded between the Bismarck Archipelago in the west, through Melanesia, and as far east as Samoa and Tonga, a straight-line distance of ca 4500km.

A re-evaluation of the Longin collagen-extraction method shows that a lower reflux temperature reduces degradation of protein (“collagen”) remnants. This allows additional purification through ultrafiltration to isolate the >30kDalton fraction of the reflux product.

Most of the 14C measurements reported here were made between October 1986 and June 1987. Equipment, measurement, and treatment of samples are as reported previously (R, 1968, v 10, p 36–37; 1976, v 18, p 290; 1986, v 28, no. 3, p 1111).

This list continues our program to put into print our large backlog of unpublished dates. Those listed here are not a specific block of dates but simply those ready for publication.