From riches to rags: organic deterioration at Star Carr

Geochemical indicators of preservation status and site deterioration at Star Carr

“…This detailed study of soil conditions and site deterioration in the largely unexcavated 'archaeologically sensitive area' of the Star Carr site has revealed the causes of and processes behind the deterioration of organic material described in Milner et al, (2011). The project has detected a limited 'halo' effect from the adjacent backfilled archaeological excavations.…”

“…These redox-vulnerable sediments seem to be associated with backfilled trenches and may represent a 'halo' effect. These sediments have poor preservation potential for bone/antler (see Milner et al, 2011), but a better chance of preserving pollen/plant remains.…”

“…It was noted however during small-scale excavations in the 1980s (Mellars and Dark, 1998) that preservation of organic remains was not of the quality encountered by Grahame Clark in the initial excavations carried out from 1949e51 (Clark, 1954). More serious problems were discovered in excavations undertaken at the site from 2004e2008, which produced severely demineralised antler and bone, and degraded wood (Milner, 2007;Milner et al, 2011). pH tests on the sediments undertaken in 2007 demonstrated that the peat which historically had been circum-neutral and had thus previously protected the organic material had turned highly acidic, constituting, along with dewatering and deep ploughing, a considerable threat to the site (Needham, 2007).…”

Lessons from Star Carr on the vulnerability of organic archaeological remains to environmental change

“…At Star Carr, in addition to this loss of waterlogging, high concentrations of sulfur have been identified that are thought to originate from pre-Holocene pyrite-rich Kimmeridge and Speetum marine clay deposits underlying the peats, which contain the archaeological materials (14).The combination of the introduction of oxygen to the sediments and these sulfur-rich deposits has led to oxidation of sulfides to sulfuric acid, causing sediment pH as low as 2 (14). However, robust data linking these environmental changes with the striking organic deterioration witnessed within 30 y at Star Carr were severely lacking (11), making an informed decision on the appropriate management of the site impossible. Focusing on the effects of site acidity on the macroscopic and archaeological remains, we undertook laboratory-based experiments to investigate the behavior of bone (18) and wood (19) in high concentrations of sulfuric acid.…”

In situ Measurements of Oxygen Dynamics in Unsaturated Archaeological Deposits

“…The oxygen content is higher and the oxygen supply is much faster in air‐filled soil pores than in water‐filled pores (Elberling ), which is one of the main reasons why drainage of waterlogged archaeological layers can lead to dramatic changes and rapid deterioration of material that has been preserved for millennia (Milner et al . ).…”