With this placement 4A1B – „TURNER“ we created a bridge between the Celtic mound of Silbury Hill (At 39.3 metres (129 ft) high, the hill is the tallest prehistoric man-made mound in Europe and one of the largest in the world; it is similar in volume to contemporary Egyptian pyramids) and our contemporary Land Art project WEARTH, in this case particularly remembering the great English painter Joseph Mallard William Turner.
Silbury Hill is part of the complex of Neolithic monuments around Avebury, which includes the Avebury Ring and West Kennet Long Barrow. Its original purpose is still debated. Several other important Neolithic monuments in Wiltshire, including the large henges at Marden and Stonehenge, may be culturally or functionally related to Avebury and Silbury.
Structure
Composed mainly of chalk and clay excavated from the surrounding area, the mound stands 39.3 metres (129 ft) high and covers about 2 hectares (5 acres). The hill was constructed in several stages between c. 2400~2300 BCE and displays immense technical skill and prolonged control over labour and resources. Archaeologists calculate that it took 18 million man-hours, equivalent to 500 men working for 15 years to deposit and shape 248,000 cubic metres (324,000 cu yd) of earth and fill. Euan MacKie asserts that no simple late Neolithic tribal structure as usually imagined could have sustained this and similar projects, and envisages an authoritarian theocratic power elite with broad-ranging control across southern Britain.
The base of the hill is circular and 167 metres (548 ft) in diameter. The summit is flat-topped and 30 metres (98 ft) in diameter. A smaller mound was constructed first, and in a later phase much enlarged. The initial structures at the base of the hill were perfectly circular: surveying reveals that the centre of the flat top and the centre of the cone that describes the hill lie within a metre of one another. There are indications that the top originally had a rounded profile, but this was flattened in the medieval period to provide a base for a building, perhaps with a defensive purpose.
The first clear evidence of construction, dated to around 2400 BCE, consisted of a gravel core with a revetting kerb of stakes and sarsen boulders. Alternate layers of chalk rubble and earth were placed on top of this: the second phase involved heaping further chalk on top of the core, using material excavated from a series of surrounding ditches which were progressively refilled then recut several metres further out. The step surrounding the summit dates from this phase of construction, either as a precaution against slippage, or as the remnants of a spiral path ascending from the base, used to raise materials during construction, and later as a processional route.
Silbury Hill was originally entirely white since it had a chalk (limestone) exterior, and the surrounding ditch may have been regularly filled with water from underground springs.