Variable 14C ages of paleosol organic matter (OM) cause difficulties in interpreting 14C data. We attempt to determine the reliability of OM 14C dates by examining different carbon-containing materials from soil horizons and paleosol fractions.

Accurate high-precision 14C dating (i.e., +/- 20 yr precision or less on the 14C date) provides the narrowest calendrical band width and, hence, the best age range determination possible. However, because of the structure in the 14C calibration curve, the calendar age range for a given 14C precision is not constant throughout the calibration range. In this study, we quantify the calendar band widths for a range of 14C previsions throughout the calibration range. We show that an estimate of the likely calendar band width in years can be obtained from the expression: Band width (yr) = 2.12 x 14C precision (1 sigma) + 54.6. We also show that calendar band widths are widest around 4000 BP at the start of the Bronze Age, and become narrow through the later Bronze Age and Iron Age and back into the Neolithic.

On 23 November 1980, a major earthquake (M3 = 6.9) struck a large area of the southern Apennines (Campania and Lucania regions, southern Italy). This seismic event, the largest in Italy over the last 80 years, almost completely destroyed 15 villages and caused extensive damage to other towns, including Naples. The quake produced the first well-documented example in Italy of surface dislocation, represented by a fault scarp 38 km long. We undertook a study that included 14C dating of organic materials from layers displaced by paleoseismic events to assess the seismologic hazard for the area. We collected peat and charred wood samples from the walls of two trenches excavated across the 1980 fault at Piano di Pecore di Colliano, Salerno, where the sedimentary suite is faulted and warped by five quakes (including that of 1980). This produced comparable vertical throw and deformation patterns. Chronological data for pre-1980 events, coupled with detailed stratigraphic analysis, yielded a dip-slip rate and a recurrence interval of 0.4 mm/yr and 1700 yr, respectively.

Between 1988 and 1991, I directed five archaeological research projects in American Samoa. The goal of that research was to reveal changes in the prehistoric settlement system of Samoa, from initial colonization of the archipelago to the time of significant European contact. The chronological placement of key sites was an essential facet of the research. A secondary goal was to locate sites with ceramic components, particularly sites with Lapita ceramics, and relate the ceramic assemblages typologically and chronologically to those known for Western Samoa. These investigations generated 16 14C dates from archaeological contexts. I present here the previously unpublished 14C data from those samples, and briefly summarize their importance for understanding Samoan prehistory.

Extensive eruptions of alkalic basalt from low-elevation fissures and vents on the southern flank of the dormant volcano, Cerro Evermann, accompanied the most recent phase of volcanic activity on Socorro Island, and created the Lomas Coloradas, a broad, gently sloping terrain comprising the southern part of the island. We obtained 14C ages of 4690 +/- 270 BP (5000-5700 cal BP) and 5040 +/- 460 BP (5300-6300 cal BP) from lacustrine deposits that occur within volcanic sequences of the lower Lomas Coloradas. Apparently, the sediments accumulated within a topographic depression between two scoria cones shortly after they formed. The lacustrine environment was destroyed when the cones were breached by headward erosion of adjacent stream drainages. This was followed by the eruption of a thin basaltic flow from fissures near the base of the northernmost cone. The flow moved downslope for a short distance and into the drainages that presently bound the study area on the east and west. The flow postdates development of the present drainage system and may be very recent. Our 14C data, along with historical accounts of volcanic activity over the last century, including submarine eruptions that occurred a few km west of Socorro in early 1993, underscore the high risk for explosive volcanism in this region and the need for a detailed volcanic hazards plan and seismic monitoring.