Case Studies:Case study 35

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[edit] Research into Natural and Anthropogenic Deposits from the Excavations at Flixborough, Humberside

Matthew Canti

This case study is based on Canti, M. Research into Natural and Anthropogenic Deposits from the Excavations at Flixborough, Humberside Ancient Monuments laboratory Report 53/92, English Heritage

[edit] Abstract

Excavations at Flixborough, Humberside discovered middle-Saxon deposits containing extensive ash and bone dumps with an unusually high degree of preservation. Particle-size analyses was needed to: determine the nature of the blown sand and its relation to the extreme preservation of the bone; and identify the anthropogenic deposits located during the excavation. The anthropogenic deposits show the clear effect of woodash in maintaining a high pH and thus promoting the preservation of calcareous components including bone. The blown sand is weakly calcareous material, consistently undergoing leaching, but not yet having developed any significant acidity. The sand’s accretion since Saxon times means that a constant supply of calcium carbonate has been added to the top of the profile at regular intervals. The bone preservation can be seen as a coincidental relationship between two factors – the woodash itself, and the calcareous component of the blown sand. Constant accretion of the sand has meant that the residual calcium carbonate in the ash has never had to undergo the acid leaching that would be expected on such a substrate if it were pure quartz. This has slowed down its removal. The volume of ash and the speed of deposition may also have aided bone reservation.

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Research into Natural and Anthropogenic Deposits from the Excavations at Flixborough, Humberside