Pollen and preservation at Star Carr: A 60-year perspective
Introduction
Star Carr, in the Vale of Pickering, North Yorkshire, is one of the best known early Mesolithic sites in Europe, famous for the exceptional preservation of a wide range of organic artefacts – including barbed antler points and antler ‘head-dresses’ – in the waterlogged deposits at the edge of a former lake (Clark, 1954, Mellars and Dark, 1998). Recent concerns over the effects of ongoing drying and acidification of these deposits on organic artefacts remaining in situ have prompted a new phase of excavation and sedimentological analyses of the site and its environs (Milner, 2007, Milner et al., 2011, Conneller et al., 2012, Milner et al., 2015). An important aspect of determining the significance and rate of the deterioration now apparent is comparison with the state of preservation of biological remains retrieved in previous work at the site. This has so far been achieved by comparative analysis of antler from Clark's site and from recent excavations (Milner et al., 2011), assessment of geochemical indices in archived and recent sediment/peat samples (Boreham et al., 2011b), and comparison between the writer's pollen sequences from samples taken 1989–92 (Dark, 1998a) with a more recent sequence (Albert et al., 2016). While these studies demonstrate marked desiccation, oxidation and acidification of some of the deposits, and degradation of the pollen archive, over the intervening two decades, it is unclear whether these changes are part of a longer-term trend or result specifically from recent events. This contribution provides a longer-term perspective on the question of organic preservation at Star Carr, particularly with reference to the original pollen data from the site (Walker, 1950, Walker and Godwin, 1954) – which have never been fully published – demonstrating the potential of pollen analysis to provide an objective quantified index of long-term change in preservation conditions at wetland sites.
Section snippets
Star Carr in context
The site of Star Carr lies at the edge of a large former lake (‘Lake Flixton’) which occupied the eastern end of the Vale of Pickering, in what it is today agricultural land, flanked to the north by the North York Moors and to the south by the Yorkshire Wolds. The lake accumulated a succession of minerogenic, marl and organic deposits throughout the lateglacial and early-mid Holocene, with colonization by reedswamp and fen carr as the waters shallowed (Walker and Godwin, 1954, Day, 1996, Dark,
Grahame Clark's excavations (1949–51)
Clark found considerable variation in the state of preservation of organic artefacts in his trenches, which ran from the former edge of dry land out towards the open waters of the lake, depending both on horizontal distance from the former shore and vertical height in the sequence. In deposits closest to what would have been dry land, the few ‘scraps of antler and bone’ were ‘dark in colour and soft as leather’ (Clark, 1954, p. 1) and ‘wood survived only where carbonised’ (Clark et al., 1949,
Excavations in the 1980s–90s
The period 1985–1992 saw limited new excavation 20 m east of Clark's trenches (Mellars and Dark, 1998), primarily to provide samples for high-resolution pollen analysis (Cloutman and Smith, 1988, Dark, 1998a, Dark, 1998b, Dark, 1998c). A trench (originally termed VP85A, but renamed Trench A by Mellars and Dark, 1998) was excavated across the transition from dry land out towards the area of former open water (Fig. 1), accompanied by a second smaller trench further into the area of former open
Comparing the pollen sequences sampled 1949 and 1992
As noted above, the two pollen sequences were just 4.5 m apart, Walker's being closer to former dry land, near the 23.25 m subsurface contour, and the 1992 core further towards open water, near the 23.00 m contour. Comparison of the depth of deposits at each sampling point provides an indication of the degree of peat shrinkage in the intervening period: in 1949 the depth of organic deposits at Walker's sampling point was 195 cm, while in 1992 it was 151 cm at the core location, suggesting loss of at
The twenty-first century
The latest phase of excavations, 2004–15, began in response to concerns over the effects of ongoing drainage and consequential peat shrinkage and acidification (Milner, 2007, Conneller et al., 2012, Milner et al., 2015). Initial fieldwork revealed a number of poorly preserved bone and antler artefacts, including what was described as a ‘jelly-bone’ from a trench (SC24, first excavated in 2007) at the eastern edge of Clark's 1951 excavation (Milner et al., 2011). The significance of such
Discussion and conclusions
For Star Carr the availability of closely adjacent pollen sequences sampled over a 60-year period offers an important – perhaps unique – opportunity to provide quantified objective data on changing conditions for organic preservation at a wetland archaeological site since the mid-twentieth century. Inevitably such a study, involving sequences analysed by different researchers, with differing research objectives, over such a relatively long period, faces problems of data comparability,
Conflicts of interest
The author declares that she has no conflict of interest.
Funding
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Acknowledgements
I thank Donald Walker for most generously providing copies of his notebooks and pollen counts, and Keith Bennett (formerly of the Sub-Department of Quaternary Research, University of Cambridge) for drawing my attention to Harry Godwin's field notebook covering 1949. Thanks also to the referees for helpful comments on an earlier version of this paper.
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