An archeomagnetic study was carried out on potsherds samples from sites in Ontario with ages ranging from A.D. 90 to A.D. 1640 as determined by 14 C dating. Thellier double‐heating paleointensity experiments were performed in air on 65 specimens of 52 samples from seven sample sets. Reliable paleointensity estimates were obtained for 49 specimens. Alternating field and thermal demagnetization, temperature dependence of weak‐field susceptibility, and hysteresis measurements indicate that magnetite of pseudo‐single‐domain grain size is the carrier of natural remanent magnetization. The paleointensity results follow a half‐cycle sine curve, with a steady decrease from 54.0±5.9 μT to 37.6±5.7 μT between A.D. 90 and A.D. 885 and a monotonic increase from 52.0±6.1 μT to 59.4±1.7 μT between A.D. 1200 and A.D. 1900. The paleointensities determined yield virtual axial dipole moments (VADMs) of the Earth's magnetic field that agree well with those from other parts of North America, except between A.D. 900 and A.D. 1400, when they are systematically lower. This discrepancy is probably caused by a substantial non‐dipole field in southwestern North America from the tenth to the fifteenth century, since secular variation studies using potsherds from Arizona and lake sediments from Minnesota show different inclination variations during that period.
Instrumental neutron activation of sixty-one copper-based metal samples from Mi'kmaq First Nations archaeological sites at Northport, Pictou, and Avonport in Nova Scotia shows that all samples are of European origin. There are two brass and one gun metal samples; all are of different trace element chemistries. The remaining fifty-eight pieces of European copper displayed from six to thirteen different trace element chemistries, implying that a minimum of this number of cooking pots was associated with the assemblage. Six of the seven Northport copper samples match with different Pictou copper chemistries, linking the sites. Since two Northport samples were from essentially whole pots, and since they match trace element groupings 1 and 2i, at least two pots of each of these chemistries must have arrived at Northport and Pictou. On the other hand, the two copper samples from Avonport are chemically unique in this small collection, matching nothing from Northport or Pictou.
Fifty‐three copper‐based metal fragments, recovered from the Robitaille site in southcentral Ontario, were analysed by neutron activation to establish their chemical make‐up and to sort them by their trace elemental chemistries. Three different European copper samples, one brassy copper and 48 brass samples with five different chemistries were found. As few as eight trading actions may account for all of the recovered European metal fragments.
Lithic artifacts from Portugal were analyzed by rapid instrumental neutron activation analysis (INAA). Concentrations of 15 short-lived isotope-producing elements were determined in both archaeological and geological samples. The archaeochemical objectives were the identification and source determination of materials used in prehistoric stone tool production. Elements measured in the materials were present in low concentrations, and many were attributable to contamination and diagenesis. INAA results demonstrate the heretofore unknown use of rhyolitelike rock in the Portuguese coastal Mesolithic period and suggest as its source a volcanic zone 20 km inland.
Abstract Weathering of chert artifacts from three Lapita sites (ca. 3000–2000 B.P.) in the Southeast Solomons is examined. It is shown that the rate of weathering is strongly influenced by soil pH, mineralogy, and prehistoric burning of the material. The concentrations of some major elements (Na, Cl, K, Al) are shown to have been altered during the weathering process. Implications of this work for the sourcing and dating of cherts are discussed.
The small but vital role of 14 C dating in archaeometric research is clearly shown in the copper project reported herein. The 14 C ages place a time perspective on the “Old Copper Culture Complex,” substantiating early Libby dates that had been questioned. The respective roles of INAA, PGE and Pb isotope work are briefly summarized. A long tradition of heat treatment from Paleoindian stone to Archaic copper is suggested.
