Revised `Absolute' Dating of the Early Mesolithic Site of Star Carr, North Yorkshire, in the Light of Changes in the Early Holocene Tree-Ring Chronology

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The early Mesolithic lake-side site of Star Carr, North Yorkshire, was originally excavated by J.G.D. Clark between 1949 and 1951, and is well known for its rich finds of bone, antler and other organic artefacts (Clark 1954). The site has become central to debates surrounding the nature of early Mesolithic settlement in northwest Europe, and has provided a focus for palaeo-environmental reconstructions based on the lake sediments, which span the lateglacial to mid-Holocene periods (see Mellars & Dark 1998 for an overview of research on the site).

In 1985 a new trench was excavated by R.T. Schadla-Hall, 20 m to the east of Clark's original excavations. This located a layer of worked timbers, associated with flint and antler artefacts, apparently forming part of a deliberately laid wooden platform at the edge of the former lake. In the 1990s high-resolution pollen and charcoal analyses were undertaken on deposits from this trench, designed to shed light on the date and length of the occupation and the nature of any impacts on the local environment (Dark 1998a; 1998b).

The distribution of macroscopic charcoal particles through the lake-edge deposits was used as an indicator of periods of local human activity, independent of the presence of artefacts. An `absolute' chronology was provided by `wiggle-matching' a series of 12 radiocarbon accelerator dates on charcoal and macroscopic plant remains from the deposits to the radiocarbon calibration curve for the early Holocene, as published by Kromer & Becker in 1993 (Day & Mellars 1994; Dark 1998a). Two phases of activity were identified, the earliest corresponding with the deposition of the wooden platform. This first phase began at a date then calibrated to c. 8770 cal BC (10,720 cal BP) and lasted c. 80 years, followed by a second phase beginning at c. 8590 cal BC (10,540 cal BP) and lasting c. 130 years.

Calibration curve changes and their implications for Star Carr

The calibration curve for the early Mesolithic period as available in 1993 had been produced at the tree-ring laboratory at Hohenheim as a result of a tentative tree-ring linkage between a sequence of German oaks (Quercus) believed to extend back to 8021 cal BC (Becker 1993) and a German pine (Pinus) series spanning the boundary between the end of the lateglacial (Younger Dryas/Loch Lomond Stadial) and the start of the Holocene (Kromer & Becker 1993).

Since 1993 the Hohenheim oak and pine chronologies have been revised. For the oak chronology the discovery of missing years and addition of new trees has produced an extension of the chronology by over 450 years, back to 8480 cal BC (Spurk et al. 1998). This provided the opportunity to improve the link to the pine chronology, which was itself augmented by the addition of new trees. The pine series has been matched to the oak series by wiggle-matching the radiocarbon dates, producing a span of 9922-7951 cal BC (11,871-9900 cal BP) with a potential error of only [+ or -] 20 years (Kromer & Spurk 1998). The pine chronology has thus been shifted back in time by approximately two centuries.

The exact size of the shift produced by the revised pine chronology varies, but for most of the portion of the curve covered by the radiocarbon dates from Star Carr it is 200 years. This means that the chronology for occupation at Star Carr must be revised by shifting the dates back 200 years. So, the beginning of occupation, based on the first appearance of charcoal, now dates to c. 8970 cal BC (10,920 cal BP), and the second phase of activity began at c. 8790 cal BC (10,740 cal BP). The estimated length of both phases remains unchanged at c. 80 years and c. 130 years respectively (TABLE 1).

TABLE 1. Chronology of human activity at Star Carr based on the presence of macroscopic charcoal.

                      date of onset                    duration
          original calibration   new calibration
          (1993 data)            (INTCAL98)

          cal BC    cal BP       cal BC    cal BP      cal years

Phase 1   c. …