Weathering and durability of the Goldsworthy Chalk Stones, South Downs, West Sussex, England

The Goldsworthy Chalk Stones, 14 roughly shaped balls of chalk, each approximately 2 m in diameter, were installed in June 2002. Initial assessments by the artist, Andy Goldsworthy, and the Strange Partners commissioning team concluded that they would last for about 2 years. The balls' disintegration has been measured as part of an ongoing scientific monitoring programme designed to assess their durability and to study controls on rates of chalk weathering. Preliminary assessment of the first 3 years of data shows that 76% of the total mass loss occurred during year 1, 19% during year 2 and 5% during year 3. This might reflect the fact that winter rainfall amounts decreased substantially over the period of study. The west facing sides of the balls have tended to show greater mass loss than those facing east, which might also be a function of exposure to rain. Judging from their present slow rates of weathering, the balls will last for over 200 years but an exceptionally cold wet winter might cause sudden and massive breakdown. Three models of chalk mass weathering are presented. The ongoing scientific monitoring programme will focus experimental work on four key research themes: process, lithology, environment and stress history.