University of Washington Dates IV

Abstract

The dates reported in this list are for geologic and archaeologic samples only. During the interval since our last date list (R, 1966, v 8, p 498-506) most of our measurements have been on samples of sea water. These will be reported separately at a later time. The methods used are essentially those reported previously (R, 1963, v 5, p 80-81) but with the following notable changes and additions: We now prepare our methane counting gas as described in Buddemeier et al (1970). Our IL membrane counter has since been augmented by 3 additional counters. Two of these are IL quartz proportional counters inside geiger anticoincidence shields. Operating pressures are ca 1.5 to 4atm. Backgrounds of these 2 counters are in the neighborhood of 1.8 and 3cpm and the net counting rate of NBS oxalic acid ranges from 7 to 18.7cpm, depending on the pressure. The third counter (“minicounter”) is rather special: .IL quartz proportional counter inside a methane proportional anticoincidence counter. Sample and anticoincidence counting gases are introduced simultaneously with a differential pressure that never exceeds a few cm Hg. The sample filling side is constructed so as to minimize dead volume; over 80% of the sample gas is inside the active volume of the 14C counter. The range of filling pressures which are possible is ca 1 to 4atm.

Pleistocene Palaeoart of Africa

“…Similar beads were excavated from three different levels in Bushman Rock Shelter (Plug 1982) [168], the middle one of which is 14 C dated to >57 ka BP (Vogel 1969;Plug 1981) [193,167]. One single ostrich eggshell bead comes from a MSA horizon in Boomplaas Cave, southern South Africa (Deacon 1984; [87,88], that has been dated to 42-44 ka ago by 14 C, AAR and U-series analyses (Fairhall et al 1976;Miller et al 1999;Vogel 2001) [97,153,194]. Two more ostrich eggshell beads as well as several fragments of them were found in an undated MSA deposit in Loiyangalani River valley, in the Serengeti National Park, Tanzania.…”

Humanity from African Naissance to Coming Millennia

“…A set of radiocarbon dates for the site was initially produced by Fairhall et al (1976) and later supplemented by us with six charcoal dates given in Table 1. The age-depth relationship, using the approximate depths given by Deacon (1979) and , is shown in Fig.…”

“…Deacon revealed some 5m of deposit containing a long sequence of Stone Age occupation levels (Deacon, 1979). The culture-stratigraphic sequence as briefly mentioned by Deacon (1979 ranges from a historic and herder level at the top through Later Stone Age (LSA) levels down to c. 2.2m depth, followed by two late Middle Stone Age (MSA) occupation levels and at the base layers containing an artefact assemblage assigned to the distinctive Howieson's Poort (HP) Industry of the MSA.A set of radiocarbon dates for the site was initially produced by Fairhall et al (1976) and later supplemented by us with six charcoal dates given in Table 1. The age-depth relationship, using the approximate depths given by Deacon (1979) and , is shown in Fig.…”

“…The uranium contents are very low and all three samples contained significant amounts of natural thorium, 232 Th. This detrital thorium is derived from the impurities in the Open squares: 14 C dates on charcoal by Fairhall et al (1976) Filled squares: 14 C dates on charcoal from Table 1 Pluses: 14 C dates on dripstone from Table 1 Crosses: Uranium-series dates on dripstone from Table 2 dripstone and indicates that the sample also would initially have incorporated some radiogenic 230 Th. Calculation of the age since formation from the 230 Th/ 234 U ratio thus gives a maximum age.…”

Current research and recent radiocarbon dates from Northern Africa

“…739) have now appeared. 87 The range for the entire site is late eighth to late fourth millennium B.C. Other previously unreported dates for stratified Neolithic sites in the Hoggar include a late fourth millennium date (MC.…”